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    • 专利摘要:
    According to one aspect, the invention relates to a remote polarimetric characterization device (100) of a sample (S). It comprises an emission source (10) of at least one light wave incident at at least a first wavelength (λE); a monomode optical fiber (30) in which the incident light wave is intended to propagate; a polarization state generator (PSG) arranged on the proximal side of the optical fiber; a reflector (40) for arranging the distal side of the optical fiber; a polarization state analyzer (PSA) arranged on the proximal side of the optical fiber and allowing, for each probe state of the incident wave generated by the polarization state generator, the analysis of the polarization of the wave light obtained after propagation of the incident wave in the optical fiber (30), reflection of the distal side of the optical fiber and reverse propagation in the optical fiber (30). Processing means (70) allow, from a first polarimetric characterization of the optical fiber, to determine a Mueller matrix (MF) associated with the optical fiber and, from a second polarimetric characterization of the whole comprising the optical fiber and the sample, a Mueller matrix (MT) associated with said set. The Mueller matrix (MO) associated with the sample is determined from the Mueller matrices associated respectively with the optical fiber and with the assembly comprising the optical fiber and the sample.
    公开号:FR3018914A1
    申请号:FR1452244
    申请日:2014-03-18
    公开日:2015-09-25
    发明作者:Martino Antonello De；Dominique Pagnoux；Jeremy Vizet；Sandeep Manhas；Jean-Charles Vanel；Stanislas Deby
    申请人:Centre National de la Recherche Scientifique CNRS；Ecole Polytechnique；
    IPC主号:
    专利说明:

    [0001] STATE OF THE ART Technical Field of the Invention The present invention relates to a polarimetric method and device for remote optical fiber polarimetric characterization and is particularly applicable to endoscopy for the in vivo polarimetric characterization of biological tissues. State of the art It is known to describe the polarization state of an electromagnetic wave (including visible light) by a set of four values called Stokes parameters, often noted in the form of a vector, the vector of Stokes (+ /), (/ (So - SX y (1) I45 - I45 S2 IG - ID) V) S3) The Stokes vector comprises four components generally denoted by /, Q, U, V and which respectively describe the total intensity / beam (/ = /), + I the differences between the horizontal and vertical components of the electric field (/), - It), to ± 450 (145. - I_45) and circular left and right (IG -ID). They make it possible to fully describe unpolarized, partially polarized and fully polarized light. The Poincaré sphere is a graphical representation of the polarization of light, an example of which is illustrated in FIG. 1A. A generic Stokes vector is represented by its reduced coordinates q = Q / I, u = U / I and v-T7 // which define the polarization state independently of the overall intensity. The totally polarized states are on the surface of the sphere, of unit radius (for example the point referenced A in FIG. 1A). The partially polarized states, whose degree of polarization p is defined by: p = q2 + Li2 + V2 (2) lie within the sphere, at a distance p <I from the center (for example the point referenced B in Figure 1A). The polar coordinates s and 8 respectively define the ellipticity and azimuth of the major axis of a generally elliptical polarization as shown in FIG. 1B. FIG. 1C thus shows examples of polarized wave Stokes vectors, given polarizations, respectively of Stokes vectors corresponding to a horizontal linear polarization (H), a vertical linear polarization (V), linear polarizations oriented to ± 45 ° (P and M), right (R) and left (L) circular polarizations and an elliptical polarization (A), each of the corresponding polarization states being further represented by a dot on the Poincaré sphere shown in FIG. 1A . The Mueller matrix of a sample is a set of 16 data that completely determines the polarimetric response of this sample and provides a means of structural characterization of this sample. The technique for measuring this matrix, called "Mueller polarimetry", consists of illuminating the sample with at least four different polarization states and analyzing the polarization states returned, as shown in FIG. a source of light emission, for example a laser or a laser diode, makes it possible to send a light beam into a device called a "polarization state generator" or PSG (according to the abbreviation for the English expression). Saxon "Polarization State Generator") for generating four known and known light polarization states ("probe polarization states"), each defined by a Stokes vector as previously described. The PSG consists for example of a succession of polarizers and delay blades whose characteristics can be changed for example by an electrical control. These blades may for example consist of liquid crystal plates oriented by the application of a control voltage. For each of the four outgoing polarization states of the PSG, the polarization state of the light reflected by the sample is analyzed by means of a "polarization state analyzer" or PSA (according to the abbreviation for 'Anglo-Saxon expression' Polarization State Analyzer '). The PSA makes it possible to measure the intensity of the light wave returned through four polarization filters which may be identical to those which made it possible to generate the probe polarization states. For example, the PSA may be the "mirror image" of PSG, with the same components, but traversed in the reverse order. The PSA may also be different from PSG, but in all cases it must make at least four different polarization filters to completely determine the Stokes vector of light emerging from the sample. Finally, at least 16 intensity measurements are made to construct the Mueller matrix of the sample. Various studies have shown how the analysis of the Mueller matrix coefficients makes it possible to trace back to the polarimetric information concerning the characterized sample (linear and circular birefringences, linear and circular diathesis (or dichroism), depolarization rate). For example, Lu and Chipman (S. Lu et al., "Interpretation of Mueller matrices based on polar decomposition", J. Opt.Soc.Am.A 13, 1106-1113 (1996)) have demonstrated that it is possible to to decompose a non-degenerate Mueller matrix into a matrix product, each of which is characteristic of a specific optical effect, namely depolarization (reduction of the degree of polarization as defined in equation (2) above at the time of interaction with the sample), the linear or circular delay (or phase delay introduced between two opposite orthogonal or circular linear polarization states) and the linear or circular diattenuation (or transmission difference introduced between two orthogonal or circular linear polarization states) opposite). The polarimetric information then makes it possible to determine on biological samples information on the physicochemical structure of the analyzed materials. For example, depolarization, which is the most important effect in thick tissues (other than those of the eye), is mainly due to the multiple scattering of light on objects such as collagen fibers or nodules, intracellular organelles, nuclei, etc. The linear delay is observed on thin tissue (histological slides) or thick in the presence of fibrillar proteins, such as collagen I, if these fibers have a preferred orientation. The attenuation is generally negligible, except in the case of tissues observed at grazing incidence, where the crossing of the interface can create a significant diattenuation, the polarization in the plane of incidence being better transmitted than that perpendicular to this plane. Thus, ex-vivo studies of colonist samples (see A. Pierangelo et al., Opt.Express 19, 1582-1593 (2011)) have shown that these samples behave as pure depolarizers, and that depolarization provides useful contrasts for the detection of tumors at an early stage (they depolarize less than the surrounding healthy tissue), for the evaluation of the degree of penetration of more advanced tumors or for the detection of residual tumors after radiochemotherapy (A. Pierangelo et al. J. Biomed, Opt.18, 046014 (2013)). In the case of cervical tissue analysis (A. Pierangelo et al, Opt.Express 21, 14120-30 (2013)), both depolarization and delay are observed, the latter being present only in healthy areas, which makes it a powerful marker. Depolarization, in turn, distinguishes healthy areas from those with precancerous lesions (dysplasias). Published patent application WO 2007003840 shows how Mueller polarimetry can be added in addition to a colposcope, that is to say a binocular microscope with a long working distance intended for detailed examination of the cervix in vivo. For the analysis of biological objects in vivo, or more generally any object difficult to access, there is an obvious interest in the realization of a remote polarimetric characterization, allowing to deport the object to analyze the sets source / PSG on the one hand and PSA / detection / analysis on the other hand. Such remote characterization can be done by means of a light guide such as an optical fiber for example. In this case, we know the polarization states sent by the PSG in the optical fiber in the direction of the object, and we can analyze with the PSA polarization states of light from the object, after they have crossed the optical fiber back. But this optical fiber induces disturbances of the polarization states of the light passing through it, as much on the go (source-object path of interest) as on the return (object-system detection and analysis path). These disturbances, unpredictable, uncontrollable, are highly dependent on the conditioning of the optical fiber (curvatures, twists ...) and the environment (temperature, ...). They prevent to know the states of polarization really incidents on the object, and to have access to the states of polarization that this object returns in the optical fiber to analyze them.
    [0002] Under these conditions, the characterization of the object by Mueller polarimetry is no longer possible. Solutions have been proposed recently to try to overcome the disturbances induced by the optical fiber, or more generally by the waveguide used to deport the object to be analyzed, in order to access polarimetric information of a sample .
    [0003] In the published patent application FR 2941047, a linearly polarized wave is sent through a device capable of generating a large number of well-distributed polarization states on the Poincaré sphere, these polarization states being sent through a polarization guide. wave, then reflected on the object, and the polarization of the reflected wave being analyzed after passing through the waveguide back. A Faraday rotator is positioned on the distal side, i.e., on the end of the waveguide at which the object to be analyzed is located, the Faraday rotator allowing a 450 rotation of the polarization . This Faraday rotator has the effect of compensating, for each state of polarization sent on the object, the delay introduced by the fiber. For each of these probe polarization states, the fraction F of the intensity detected in return is measured, carried by the polarization parallel to the linear polarization sent. From the set of measured fractions F, which depend on the probe polarization states, the minimum value F. and the maximum value Fmax from which the depolarization rate and the phase delay introduced by the object are deduced are determined. However, this technique does not allow access to the diathesis or circular dichroism of the sample.
    [0004] More recently, a device for polarimetric measurement through a single-mode fiber has been described (see for example the patent application FR 2977033 of Alouni et al.) Which makes it possible to detect whether the orthogonality of two polarizations incident on the object analysis has been broken, which may be due to the depolarization or the attenuation due to the object, but without being able to distinguish between these two effects. In addition, the delay possibly introduced by the object is not measurable by this method.
    [0005] The article by Wood et al. (TC Wood et al., "Biomedical Optics Express 463, Vol 1, No. 2 (2010)), highlights and characterizes commercial rigid endoscopes (otherwise called laparoscopes) of birefringence in particular, which are attributed to a sapphire entrance window. The article suggests replacing sapphire with a non-birefringent material compatible with sterilization constraints to limit these birefringence effects and allow complete polarimetric characterizations on in vivo samples. However, residual birefringence effects may remain, which can be troublesome, especially if they vary over time or with the position of the instrument.
    [0006] Qi et al. also disclose a laparoscope equipped with a linear polarizer at the distal end and a wheel with linear polarizers at different proximal orientations (Qi et al., "Narrow band 3X3 polarimetric endoscopy", Biomedical Optics Express, Vol 4 No. 11, (2013)). This apparatus allows the acquisition of partial Mueller matrices, limited to the first three lines and first three columns, by rotating the instrument around its axis to vary the orientation of the polarizer at detection. This approach has two limitations: on the one hand we do not have access to circular delays and diattension, and on the other hand the rotation of the instrument around its axis is really impractical under real conditions of examination, because in particular, the need to perform this rotation around the axis of the endoscope with excellent accuracy, to prevent the image from moving in the field between two acquisitions. Even if this condition is fulfilled, it is feared that "non-rigid" deformations of the organs examined in vivo will occur during the rotation, which may disqualify the method in many situations. The present invention proposes a method and a remote characterization system that allows access by means of a flexible optical fiber to a characterization of the complete Mueller matrix of a sample. It is thus possible to have simultaneous access to all the polarimetric information of the sample, including linear and circular diattenuations and delays. This complete characterization of the Mueller matrix has many advantages for the analysis of biological samples in particular. Indeed, even if in most cases the tissues have essentially linear intrinsic effects, it is possible to observe simultaneously, under grazing incidence (which may be frequent in endoscopy), a significant diattenuation at the crossing of the tissue surface, which may give rise to circular diattenuation if the tissue otherwise has linear birefringence.
    [0007] SUMMARY OF THE INVENTION According to a first aspect, the invention relates to a device for remote polarimetric characterization of a sample comprising: a source of emission of at least one light wave incident at at least a first wavelength; a monomode optical fiber in which the incident light wave is intended to propagate; a polarization state generator arranged on the proximal side of the optical fiber and enabling the generation of a given number of polarization states of the incident light wave, called probe states; a reflector intended to be arranged on the distal side of the optical fiber; a polarization state analyzer arranged on the proximal side of the optical fiber and making it possible, for each probe state of the incident wave, to analyze the polarization of the light wave obtained after propagation of the incident wave in the optical fiber, reflection of the distal side of the optical fiber and reverse propagation in the optical fiber; processing means for determining: from a first polarimetric characterization of the optical fiber, obtained by analyzing for each probe state, the polarization of at least one reflected wave on the distal side of the optical fiber; by means of the reflector, a Mueller matrix associated with the optical fiber at the first wavelength; from a second polarimetric characterization of the assembly comprising the optical fiber and the sample, obtained by analyzing for each polarization probe state, a wave returned to the distal side of the fiber by the sample and propagated in reverse direction in the optical fiber, a Mueller matrix associated with said set at the first wavelength; from the Mueller matrices associated respectively with the optical fiber and the assembly comprising the optical fiber and the sample, the Mueller matrix associated with the sample at the first wavelength. The original arrangement of the polarimetric characterization device makes it possible to access all the polarimetric information of a sample by means of a complete determination of the Mueller matrix of this sample.
    [0008] According to a first variant, the emission source allows the emission of a wave at the first wavelength and the emission of a wave at a second wavelength distinct from the first wavelength. According to this variant, the reflector is advantageously a spectral reflector allowing reflection of a wave propagating in the optical fiber at the second wavelength for the polarimetric characterization of the optical fiber at the second wavelength and the passage of the wave at the first wavelength for the polarimetric characterization of the assembly comprising the optical fiber and the sample at the first wavelength. The processing means make it possible to determine: from the polarimetric characterization of the optical fiber at the second wavelength, a Mueller matrix associated with the optical fiber at the second wavelength; from the Mueller matrix associated with the optical fiber at the second wavelength, a Mueller matrix associated with the optical fiber at the first wavelength. This first variant based on a chromatic separation of the light waves allows a simultaneous determination of the Mueller matrices of the optical fiber on the one hand and the assembly comprising the optical fiber and the sample. Moreover, it does not require active optical elements on the distal side of the optical fiber.
    [0009] Advantageously, the two wavelengths are distinct but close; typically, the difference between the two wavelengths does not exceed 100 nm. Advantageously, when the phase delay generated by the optical fiber is greater than 27c, the characterization of the optical fiber can be done by means of two distinct wavelengths.
    [0010] Thus, according to this example, the emission source also allows the emission of a wave at a third wavelength distinct from the first and second wavelengths. The spectral reflector allows the reflection of waves propagating in the optical fiber at the second and third wavelengths for the polarimetric characterization of the optical fiber at the second and third wavelengths. Moreover, the processing means make it possible to determine: from a polarimetric characterization of the optical fiber at the second wavelength and from a polarimetric characterization of the optical fiber at the third wavelength, respectively a Mueller matrix associated with the optical fiber at the second wavelength and a Mueller matrix associated with the optical fiber at the third wavelength; from the Mueller matrices associated with the optical fiber at the second and third wavelengths, the Mueller matrix associated with the optical fiber at the first wavelength. Here again, the wavelengths are distinct but remain close, the difference between the wavelengths remaining advantageously less than 100 nm. According to a second variant, the reflector is a reflector switchable between a reflecting position and a passing position. Such a reflector allows, in the reflective position, the reflection of a wave propagating in the optical fiber at the first wavelength for the polarimetric characterization of the optical fiber and, in the passing position, the reflection of the wave by the sample for the polarimetric characterization of the assembly comprising the optical fiber and the sample. This second variant has the advantage of being able to carry out the characterization of the optical fiber directly at the first wavelength, that is to say at the wavelength used to characterize the assembly comprising the optical fiber and the sample. This allows in particular a greater flexibility in the choice of the monomode optical fiber used. Advantageously, and whatever the variant implemented, the monomode optical fiber is a polarization-maintaining optical fiber, which eliminates any chiral effect. According to an exemplary embodiment, the monomode optical fiber comprises a first section of a polarization maintaining monomode optical fiber and a second section of the same polarization maintaining monomode optical fiber, the sections being of the same length and interconnected. so that the fast axis of the first section is aligned with the slow axis of the second section and vice versa. This fiber example makes it possible in particular to reduce the phase delay introduced by the fiber while eliminating any chiral effect thus facilitating its characterization. According to a variant, the device according to the first aspect further comprises, on the distal side of the optical fiber, means for focusing a wave at the first wavelength for the characterization of a point zone of the sample. Advantageously, the device according to the first aspect further comprises, on the distal side of the optical fiber, scanning means for the polarimetric characterization of a set of point areas of the sample. According to a second aspect, the invention relates to one or more methods for remote polarimetric characterization of a sample implemented by the device (s) according to the first aspect. Thus, the invention relates to a method of remote polarimetric characterization of a sample comprising: the emission of a light wave incident at at least a first wavelength intended to propagate in a monomode optical fiber; the polarimetric characterization of the optical fiber at the first wavelength, comprising: generating a given number of polarization states of the incident light wave, called probe states, by means of a generator of polarization states arranged on the proximal side of the optical fiber; o the analysis, for each probe state of the incident wave, of the polarization of the light wave obtained after propagation of the incident wave in the optical fiber, reflection by means of a reflector arranged on the distal side of the fiber optical and reverse propagation in the optical fiber; the determination of a Mueller matrix associated with the optical fiber at the first wavelength; the polarimetric characterization of the assembly comprising the optical fiber and the sample at the first wavelength, comprising: by means of said polarization state generator and polarization state analyzer, the analysis for each state; polarization probe, of a wave returned to the distal side of the fiber by the sample and propagated in the opposite direction in the optical fiber; o determining a Mueller matrix associated with said set at the first wavelength; the determination of the Mueller matrix associated with the sample from the Mueller matrices respectively associated with the optical fiber and with the assembly comprising the optical fiber and the sample.
    [0011] According to a first variant of the method, the method further comprises transmitting a light wave at a second wavelength distinct from the first wavelength. According to this variant, the reflector is a spectral reflector allowing the reflection of a wave propagating in the optical fiber at the second wavelength for the polarimetric characterization of the optical fiber at the second wavelength and the passage of the wave at the first wavelength for the polarimetric characterization of the assembly comprising the optical fiber and the sample at the first wavelength. Moreover, the determination of the Mueller matrix associated with the optical fiber at the first wavelength comprises: o from the polarimetric characterization of the optical fiber at the second wavelength, a Mueller matrix associated with the optical fiber at the second wavelength; from the Mueller matrix associated with the optical fiber at the second wavelength, a Mueller matrix associated with the optical fiber at the first wavelength. According to a variant, the method comprises transmitting a wave at a third wavelength distinct from the first and second wavelengths, and the spectral reflector allows the reflection of waves propagating in the optical fiber at the second and second wavelengths. third wavelengths for polarimetric characterization of the optical fiber at the second and third wavelengths; the determination of the Mueller matrix associated with the optical fiber at the first wavelength comprises: o from a polarimetric characterization of the optical fiber at the second wavelength and from a polarimetric characterization of the optical fiber at the third wavelength, respectively a Mueller matrix associated with the optical fiber at the second wavelength and a Mueller matrix associated with the optical fiber at the third wavelength; from the Mueller matrices associated with the optical fiber at the second wavelength and the third wavelength, the Mueller matrix associated with the optical fiber at the first wavelength. According to a second variant of the method, wherein the reflector is a switchable reflector between a reflective position and a passing position, allowing, in the reflecting position, the reflection of a wave propagating in the optical fiber at the first wavelength for the polarimetric characterization of the optical fiber and, in the passing position, the reflection of the wave by the sample for the polarimetric characterization of the assembly comprising the optical fiber and the sample. Advantageously, the method according to one of the variants described above further comprises, on the distal side of the optical fiber, the focusing of a light wave at the first wavelength to the focusing means for the characterization of a point zone. of the sample. The method may also include, on the distal side of the optical fiber, scanning by scanning means of the focused light wave for the polarimetric characterization of a set of point areas of the sample.
    [0012] BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and characteristics of the invention will appear on reading the description, illustrated by the following figures: FIGS. 1A and 1B, a representation of the Poincaré sphere and of an elliptical polarization state (already described) FIG. 1C, a table showing the Stokes vector components of different polarization states (already described); FIG. 2, a diagram illustrating an experimental setup for Mueller polarimetry characterization according to the prior art (already described); 3, a diagram illustrating a polarimetric characterization device according to the present description, according to a first example; - Figure 4, a diagram illustrating a polarimetric characterization device according to the present description, according to a second example; 5, a diagram showing in a partial view, a variant of a polarimetric characterization device according to the present description; FIG. 6, a diagram illustrating an experimental setup used for the experimental validation of an example of a characterization method according to the present description; Figures 7 and 8, experimental curves obtained with the scheme shown in Figure 6 and compared with expected theoretical values; FIG. 9A, a partial diagram of the diagram of FIG. 6, showing a sample used for the validation of an example of a characterization method according to the present description; Figure 9B, experimental curves obtained with the sample shown in Figure 9A and compared with expected theoretical values; FIG. 10A, a partial diagram of the diagram of FIG. 6, showing a sample used for the validation of an exemplary characterization method according to the present description; Figure 10B, experimental curves obtained with a sample of the type of that shown in Figure 10A and compared with expected theoretical values; FIG. 11A, a partial diagram of the diagram of FIG. 6, showing another sample used for the validation of an example of a characterization method according to the present description; shown in Fig. 11A and compared with expected theoretical values. DETAILED DESCRIPTION FIG. 3 represents a polarimetric characterization device 100 according to a first example, for the implementation of a polarimetric characterization method according to a first aspect of the present description. The polarimetric characterization device 100 generally comprises a source of emission of at least one light wave at at least a first wavelength XE and a monomode optical fiber in which the light wave is intended to propagate. for a remote characterization of a sample S. A monomode optical fiber has the advantage over a multimode fiber not to depolarize the incident light even if it can be brought according to its nature and the experimental conditions to change the polarization. The sample to be analyzed or "analysis object" S is located, with respect to the emission source 10, at the other end of the optical fiber 30.
    [0013] In the remainder of the description, the part of the device located on the side of the optical fiber where the source of emission and the distal part of the device will be called the proximal part of the polarimetric characterization device, all the part of the device located at the end of the description. other end of the optical fiber, that is to say where is the sample. The device 100 further comprises a PSG polarization state generator arranged on the proximal side of the optical fiber and allowing the generation of a given number of polarization states of the light wave (probe polarization states) and an analyzer. of PSA polarization states arranged on the proximal side of the optical fiber and for analyzing the polarization states of the light wave after reflection on the distal side of the optical fiber and reverse propagation in the optical fiber.
    [0014] In the example of FIG. 3, the source 10 allows the emission of a wave at a first wavelength 11E and the emission of at least one wave at a second wavelength 2F1 distinct from the first wavelength 11E. According to a variant which will be described in detail later, the source 10 allows the emission of two waves respectively at wavelengths 2F1 and 2F2, distinct from each other and distinct from 11E. The source 10 comprises, for example, a set of monochromatic sources, for example laser diodes, respectively denoted 12, 14, 16 in FIG. 3, each emitting at one of the distinct wavelengths. Alternatively, the source 10 may consist of a single source emitting at all wavelengths, for example a source of "supercontinuum source" type generated by spectral broadening of a laser beam within a fiber optical. Advantageously, the emission sources are continuous sources. Alternatively, it may be pulsed sources of peak powers sufficiently low not to generate in the optical fiber nonlinear optical effects. Another option is to use a continuous source modulated by a chopper and implement a synchronous detection on all detectors, to possibly improve the signal-to-noise ratio with respect to a continuous source. In this case, the modulation is advantageously performed at a frequency much greater than the switching frequency of the liquid crystals of PSG and PSA, which is at most of the order of kHz, which does not pose a problem a priori, the detection synchronous being typically implemented up to 100 kHz frequencies with commercial systems. The polarimetric characterization device furthermore comprises, in the example described in FIG. 3, a wavelength-selective reflector 40, arranged on the distal side of the optical fiber, as well as focusing means 42. The reflector 40 makes it possible to reflect the waves at the wavelength 2F1, or at the wavelengths 2F1 and 2F2, while allowing the waves to pass at the wavelength 2E. The reflector 40 is for example a spectral filter placed at the output of the optical fiber 30; this filter can be for example a high pass filter cutting between 2F2 and 2E, if one chooses 2F1 <2F2 <2E. This filter may also, for example, be a bandpass filter around XE if 2F1 <2E <2F2 is chosen or low pass if 2E <2F1 <2F2 is chosen. The polarimetric characterization device 100 furthermore comprises a separator plate 22 and wavelength separating elements 65, 63, for example spectral filters, arranged after the PSA polarization state analyzer, and making it possible to separate according to of the wavelength, the retroreflected or backscattered waves on the distal side of the fiber and propagated back into the fiber. The light waves thus separated are sent to photodetectors respectively denoted DE, DR, DF2 in FIG. 3, for example photodiodes, respectively sensitive to the wavelengths 2E, 2F1 and 2F2. The polarimetric characterization device 100 also comprises means for processing 70 allowing from the electronic signals emitted by the photodetectors to determine the Mueller matrix of the sample S, as described below. The processing means 70 ensure in particular the control and synchronization of the PSG and PSA, the collection and processing of the signals emitted by the photodetectors, the construction of the Mueller matrices. The general principle of the polarimetric characterization method according to the first variant implemented for example by means of a device as described in FIG. 3 is based on simultaneous measurements made at different wavelengths but close, typically separated less than 100 nm, to characterize the optical fiber on the one hand and the fiber-object assembly on the other hand. More precisely, one or two wavelengths can be used to characterize the fiber (2F1 and 2F2), and one is sufficient for the fiber-object-of-interest (2E) assembly. Thus, light waves, for example monochromatic waves. or almost monochromatic (typically spectral widths less than 40 nm) are sent in the monomode optical fiber 30 by means of an injection lens 24. After crossing the selective reflector wavelengths 40, the beam length 11E is focused on the object by the focusing means 42, for example a lens or any other optical element capable of performing the focusing function. Part of the light reflected by this object, still at 2E, crosses the optical focusing element 42 and the spectral filter 40 to be reinjected into the optical fiber 30. The beam or beams (x) at wavelengths different from 2E, in this example the wavelengths 2F1 and 2F2 are reflected by the spectral filter 40 and reinjected into the optical fiber 30 without being impacted by the sample S. In return, the set of beams at 2F1 , 2F2 and 2E are deflected towards the PSA, then separated at the output of the PSA by means of the separating elements 65, 63 to the detectors 62, 64, 66. In the case of the use of a single source with a broad spectrum emitting the wavelengths 2E, 2F1 and 2F2, a narrow-band spectral filter (typically <40 nm) may advantageously be placed in front of each of the detectors 62, 64 and 66 so as to pass only a narrow spectral band around 2E , 2F1 and 2F2 respectively. Firstly, an embodiment of the method according to the present description is described, in which a second wavelength 2F1 is used to characterize the monomode optical fiber 30.
    [0015] According to this example, the polarimetric characterization of the optical fiber at the second wavelength 2F1 is carried out, then the determination of a Mueller matrix associated with the optical fiber at the second wavelength 2F1. A Mueller matrix (MF) associated with the optical fiber at the first wavelength 11E is deduced from the Mueller matrix associated with the optical fiber at the second wavelength 2F1. Simultaneously with the characterization of the optical fiber at the second wavelength 2F1, a polarimetric characterization of the assembly comprising the optical fiber and the sample is obtained at the first wavelength 11E by the analysis of the polarization states a wave retroreflected and / or backscattered by the sample. A Mueller matrix (MT) associated with said set at the first wavelength 11E is obtained from this characterization. It is then possible from the Mueller matrices associated respectively with the optical fiber (MF) and the assembly comprising the optical fiber and the sample (MT), to determine the Mueller matrix (Mo) associated with the sample. at the wavelength 2E. It should be noted that the polarimetric characterization of the optical fiber generally comprises the characterization of the optical fiber and of all the elements between the output end of the optical fiber (distal end) and the reflector 40. in some cases, this characterization can be likened to a characterization of the optical fiber alone, either because there are no other elements, or because these elements do not change the polarization. Moreover, the optical elements that may be between the selective reflector 40 and the sample S are chosen such as to not modify the polarization of the propagated waves. This is the case for example with lenses, or other optical elements such as frequency selective mirrors, or more generally blades made of optically isotropic materials and possibly carrying dielectric or metal layers, these blades being used at very similar angles. normal (typical tolerance of about 5 °). The polarimetric characterization at a given wavelength of an object to be analyzed, in this case the optical fiber or the optical fiber / sample assembly, is made in a known manner and described, for example, in the European patent EP 1411333. light wave is sent on the PSG polarization state generator, which can be for example electrically controlled, in order to define the 4 polarization states probe. Advantageously, these polarization states are the most independent possible. They are then distributed on the Poincaré sphere according to a regular tetrahedron. In practice, it is possible to work with a greater number of probe polarization states but it is shown that 4 probe states are the minimum number of probe states for the polarimetric analysis. To generate the probe polarization states, the PSG comprises, for example and in a known manner, a set of elements including a linear polarizer, a first electrically controllable liquid crystal cell, a quarter wave plate and a second controllable liquid crystal cell. electrically. The 4 Stokes vectors corresponding to the 4 polarization states thus generated are arranged in 4 columns to form a 4x4 modulation matrix denoted W. After interaction with the sample, the polarization states returned are analyzed by means of the analyzer. PSA polarization states, which comprises elements identical to those of the PSG but arranged in the opposite direction with respect to the direction of the light, such that, for example, the light passes first through the second liquid crystal cell, then the quarter wave plate, then the first liquid crystal cell and the linear polarizer. The Stokes vectors corresponding to the 4 polarization states analyzed by the PSA are arranged in 4 lines to form a 4x4 analysis matrix denoted A. Thus, for each of the 4 polarization states resulting from the PSG, measurement is made by means of a detects the luminous intensity at the output of the PSA, according to each of the polarization states analyzed. A matrix B of the 16 levels of measured light intensities is obtained such that: B = A.M.W (4) Where M is the Mueller matrix of the sample. The inversion of the known matrices A and W then makes it possible to determine the Mueller matrix according to the formula: A4.B.w4 (5) Advantageously, a calibration can be made to correct imperfections and misalignment of the elements constituting the PSG and PSA. In fact, the modulation and analysis matrices W and A may be different from the values calculated theoretically as a function of the elements constituting the generator and analyzer of the polarization states. To perform this calibration, it is possible, for example, to successively place 4 calibration samples in the place of the sample, which will make it possible to obtain 4 intensity matrices respectively. From calibration algorithms described in the literature (see for example the patent EP 1411333 cited above), it is then possible to obtain the actual modulation and analysis matrices W and A. In the example of polarimetric characterization of a sample cited above, the PSG and PSA comprise liquid crystals (nematic or ferroelectric). Many other systems can be used for the implementation of the method according to the present description. For example, PSG can control polarization by means of Pockels cells (see, for example, E. Compain et al., "Complete Mueller Matrix Measurement with a Single High Frequency Modulation," Thin Solid Films 313-314, 47-52, 1998. ) or by means of a photoelastic modulator (see, for example, E. Compain et al., "Complete high-frequency measurement of Mueller matrices based on a new coupled-phase modulator," Rev. Sci., Instrum., 68, 2671-2680. -1997). These systems make it possible to code the four states of PSG simultaneously on four different frequencies. On the PSA side, the use of amplitude divider systems, such as the "DOAP" described by E. Compain et al. (See for example US 6177995 B1) and which uses a separating prism and four detectors in parallel. This type of PSA can advantageously be coupled to a PSG with frequency coding; the signal of each of the detectors can thus be demodulated on the four frequencies of the PSG, the set of demodulated signals thus providing the 16 measurements from which the Mueller matrix can be obtained. An example of this type of instrument is described in US Patent 6175412 Bi. Other PSGs and PSAs use fixed linear polarizers and rotating retarders (see for example US Patent 7298480 B2). The implementation of the characterization method by means of the device shown in FIG. 3 first makes it possible to measure a Mueller Mriu matrix (2F1) of the optical fiber at the second wavelength XF1, such that: 1Vin ( 2F1) = R (-81). MFR (2F1) .1V1F (41). R (81) (3) where 1V1F (2F1) and MFR (2Fi) are respectively the Mueller matrices of the optical fiber, in the forward and backward direction, and where R (60 and R (-81) are respectively angular rotation matrices 81 and 81, 81 being the unknown angle a priori between the neutral axes of the fiber at the entrance thereof and the reference of the laboratory in which the Stokes vectors are defined. Assuming that the fiber behaves like a pure phase shifter, the product 1V1FR (41) IVIF (2F1) corresponds to the matrix of a pure linear phase shifter representing this fiber on a round trip, the angles 81 and -81 are thus determined so that the product R (-81), IVInu (2F1), R (01) -1 = MFR (41), IVIF (2F1) corresponds to the matrix of such a pure linear phase shifter. be known from the position in rotation of the fiber, whose neutral axes have been previously identified.If the fiber has no chiral effects (diattension and retar d), which is the case for a standard single-mode fiber if one takes care not to "twist" it, the matrix 1V1FR (2F1) and MF (2F1) are those of two identical linear retarders. It is easy to deduce from the product MFR (41). MF (2F1) directly measured each of the MF (2F1) and MFR (2F1) matrices of the fiber, respectively back and forth, at the first wavelength 2E. However, the Mueller MT matrix at the first wavelength 11E of the optical fiber and sample assembly, which is also directly measured, is given by the equation: MT (2E) - MFR (2E) -Mo. MF (2E) (4) Where Mc, is the desired Mueller matrix of the sample at wavelength 2E. In some cases, it may also be useful to determine the angle 82 defining the azimuth of one of the axes of the fiber at its output, ie at its distal end, relative to the benchmark of the laboratory, in order to correct the matrix Mc, previously obtained of possible chiral effects. In the case of polarization maintaining fibers for example, this azimuth is bonded to the fiber and can be determined "mechanically". It is thus possible to deduce by matrix inversion the Mueller matrix of the sample: Mo = (MFR (2E)) - 1. MT (2E). (MF (2E)) - 1 (5) The method described above may work well if the wavelengths 2F1 and 2E are distinct but sufficiently close, that is to say having a difference of less than 100 nm, advantageously less than 50 nm, and if the fiber behaves well as a linear retarder with neutral axes of well identified directions, such that the optical fiber induces a phase delay SçoFi neutral axes sufficiently low (between 0 and 27c ). In this case, it is possible to deduce from the matrix of the optical fiber at the second wavelength 2F1, the matrix of the optical fiber at the first wavelength 2E, by deducing the phase delay SçoE at 2E from phase delay gcoFi at 2F1 (gcoE = SÇOF 1 * 2F1 / 2E).
    [0016] According to a second variant of the polarimetric characterization method that can also be implemented with a device such as that represented in FIG. 3, two wavelengths 2F1, 2F2 that are distinct from each other and distinct from the first wavelength 2E are used for the polarimetric characterization of the optical fiber. Thus according to this variant, the emission source further allows the emission of a wave at a third wavelength 2F2 distinct from the first and second wavelengths 2E and 2F 1. The selective reflector 40, for example a spectral filter passes high, is adapted to allow the reflection of waves propagating in the optical fiber at the second and third wavelengths 2F 1, 2F2 and allows the waves propagating to the first wave to pass through. wavelength 2E if one chooses 2F1 <2E <2F 2.
    [0017] According to this variant, a polarimetric characterization of the optical fiber at the second and third wavelengths 2F1 and 2F2 is carried out, for example according to the means described above, in order to determine a Mueller matrix associated with the optical fiber at the second length of FIG. wave (2F 1) and a Mueller matrix associated with the optical fiber at the third wavelength (2F2). The measurement of the Mueller matrix at the wavelength 2F1 makes it possible to determine a phase delay Sm.sub.-1 equal to the real phase delay Mi, modulo 27c. In other words, the desired phase delay at 2F1 is βF1 = SÇOF 1 mes ± 2nue, with m integer. Similarly, the measurement of the Mueller matrix at the wavelength 2F2 makes it possible to determine a phase delay λak-2 equal to the real phase delay M2 modulo 27z-. The desired phase retardation at 2F2 is &nbsp; 2 - SQOF 2 mes ± 2m 'r, with m' integer. As the two wavelengths 2F1 and 2F2 are close together, the SçoFi / Sço ratio F2 is, in the first order, equal to the inverse ratio of the wavelengths 2F2 / 2F1. By ensuring that the residual phase shifts SçoFi and M2 remain small, which means that the integers m and m 'remain small, typically less than 5, the pair (m, m') allowing the respect of the condition gcoFi / gcoF2 = 2F2 / 2F1 can be easily identified, which allows to deduce the values of gcoF1 and M2. In a second step, the phase lag & PE at XE is calculated by the rule of three: SçoE = SÇOFI * / 11E (1 = 1 or 2). It is thus possible to deduce the matrices of the forward and back optical fiber at the wavelength 2E and to determine the desired matrix of the sample, as explained previously (equation 5). In practice, the current technology of standard single-mode fibers has the disadvantage of having a neutral axes orientation not sufficiently well defined and may vary depending on the constraints, the temperature, etc. It is possible, in a variant, to prefer the use of polarization-maintaining fibers whose orientation of the neutral axes at the input and at the output is known and fixed. However, it turns out that the phase delay introduced by a standard polarization maintaining optical fiber is large (typically 7z-per mm), which can be troublesome for the implementation of the method according to the variants described. by means of FIG. 3. The applicants have developed a monomode optical fiber that is particularly advantageous for implementing the polarimetric characterization method according to the present description. This optical fiber, hereinafter referred to as "monomode fiber with polarization-maintaining and compensated delay", comprises two sections of the same single-mode polarization-maintaining fiber, of equal length, connected together (by a solder for example), the fast axis of the first section being aligned with the slow axis of the second section. With this arrangement, the direction of the neutral axes of this fiber, at the input as at the output, can be easily determined by placing it between crossed polarizers and seeking the extinction of the transmitted field. In this situation, the direction of the input (respectively output) polarizer is that of one of the neutral axes of the fiber at the input (respectively at the output). Thus, if the lengths of the sections are strictly equal and if the two sections are conditioned in the same way (same curvatures, same temperature, etc.), it is expected that the phase delay provided by the monomode fiber maintaining polarization and compensated delay between the two components of the injected field is zero or negligible, the second section compensating exactly the first. In reality, a slight difference in length between the two fibers and / or the packaging and / or a different environment for the two sections may induce the existence of a residual phase shift, provided by the monomode fiber maintaining the polarization and compensated delay between the two components of the field at the output of the fiber. Applicants have shown that this residual phase difference may be less than 87z- regardless of the length of the fiber, or even below 47c. The method as described above will then make it possible, by measurement of the Mueller matrix of the optical fiber at a second wavelength 2F1, or even at two wavelengths 2F1, 2F2, as has been described, to determine perfectly the matrix of the optical fiber at the first wavelength 2E and deduce the Mueller matrix from the sample. Moreover, such a fiber has few chiral effects.
    [0018] FIG. 4 represents a polarimetric characterization device 200 according to a second example, for the implementation of a polarimetric characterization method according to the present description. The device 200 comprises a number of elements identical to the elements of the device 100 and which are not described again, including in particular the PSGs 20 and PSA 50, the monomode optical fiber 30, the processing means 70. According to this variant, the emission source comprises only a transmission source 12 emitting at the first wavelength 2E, for example a laser diode, and a detector at the output of the PSA sensitive to this same wavelength, for example a photodiode. The selective reflector described in FIG. 3 is replaced by a removable reflector, for example a switchable reflector, for example of the MEMS type, that can operate in an ON mode when it is positioned at the fiber output and OFF when it is discarded. of the end of the fiber, as illustrated in FIG. 4. According to this variant, it is possible alternatively to carry out a characterization of the optical fiber directly at the wavelength of interest XE, then a characterization of the The assembly comprising the optical fiber and the sample also at this same wavelength. If the characterizations of the fiber and of the fiber / sample assembly are made in a sufficiently short time (typically less than 10 ms), it is possible to implement the method with a simple single-mode optical fiber or a single-mode optical fiber. maintaining standard polarization. Of course, this method can also be implemented with the monomode optical fiber maintaining polarization and delay compensated as described above. The Mueller matrix of the sample can then be determined from the Mueller matrices of the fiber and the assembly comprising the fiber and the sample, as previously explained (equation 5). FIG. 5 shows a variant applicable to one or the other of the examples of devices described by means of FIGS. 3 and 4. According to this variant, a scanning system 46 is arranged on the proximal side, following the means of FIG. In another arrangement, the scanning system 46 may be placed between the fiber 30 and the focusing means 42. In this case, it may advantageously be preceded by collimation means of the beam emerging from the fiber 30. The system Scanning allows the sample to be scanned to reconstruct an image of a region of interest. Applicants have also shown that it is possible thanks to a microbrewing on a set of points adjacent to the sample to overcome artefacts that could result from a one-off measurement. In particular, the Mueller matrix measured at the point of focus of the beam on an object can reveal a depolarization rate lower than the rate of depolarization that would be obtained by analyzing a wider region. The rate of depolarization produced by such a larger region can be obtained from the average of a series of Mueller matrices measured punctually at various locations in this region. Figures 7 to 11 show first experimental results obtained with the method according to the present description. These first results are obtained with a device of the type of that of Figure 4 and on samples "tests" well calibrated. Figure 6 shows the experimental setup used for these validations. All the elements used are identical to those shown in FIG. 4, but the sample S is formed here of a calibrated analysis object 48 and a plane mirror 49. In the case of the results shown in FIG. the sample is formed of an X / 8 blade waveguide followed by a mirror. The 2/8 blade introduces a phase retardation of 450 between its neutral axes when crossed in single pass by the light. This blade is rotated in the plane perpendicular to the direction of propagation of the light so as to vary the orientation of its neutral axes relative to the benchmark of the laboratory. The curve C1 shows the orientation given to the blade relative to an arbitrary reference orientation, between 00 and 90 ° (solid lines), and the orientation measured by the device (points). Curve C2 shows, for each of these orientations, the measured phase delay for this blade. This delay, equal to 90 °, corresponds to the accumulated phase delay during the double crossing of the 2/8 (return) blade analyzed. In the case of the results shown in FIG. 8, the sample consists of a Babinet-Soleil compensator followed by a mirror. The Babinet-Soleil compensator introduces a known and adjustable phase delay between its neutral axes when traversed by light. Curve C3 shows the linear phase delay introduced on a round-trip of the light adjusted by adjusting the Babinet Soleil compensator (solid lines) and the corresponding measured phase delay (points). FIG. 9A illustrates a sample consisting of a parallel-faced plate 48 followed by a mirror 49. The faces of the plate are perpendicular to the plane of incidence of the light beam coming from the collimation system 24 and their normal is inclined. an angle adjustable with respect to the direction of the beam. This blade therefore behaves as a pure linear diatténuateur component whose diatténuation is adjustable via the angle a. FIG. 9B shows the linear diattension of the parallel-sided blade on a round trip of the light (solid lines) calculated as a function of the angle a and the corresponding measured linear attenuation (dots). It is furthermore shown that for each of these points, the circular diattenuation and the measured linear phase retardation are zero. FIG. 10A shows a sample consisting of a Babinet-Soleil compensator 47, followed by a parallel-sided blade 48 and a mirror 49. The parallel-sided blade is positioned relative to the incident beam as in the case of Figure 9A. In this arrangement, the normal to the blade is inclined relative to the incident beam by an angle a such that it introduces a 35% linear attenuation on a round trip of the light. As regards the Babinet-Soleil compensator, its fast axis is oriented, in the plane perpendicular to the beam, so that it makes an angle of 45 ° with respect to the axis of rotation of the blade. With this arrangement, the blade remaining fixed, the phase delay introduced by the compensator Babinet is adjusted between 0 ° and 90 ° for a single crossing, that is to say between 0 ° and 180 ° on a round trip light. Numerical simulations show that, when the Babinet-Soleil compensator is set to introduce a phase delay of between 0 ° and 90 ° during a single traversal, the parallel-face compensator + blade assembly behaves as a component introducing a phase delay 27 over a round trip and a combination of linear DL and circular Dc denaturation such as the resulting D = NID diattenuation; + D, 2 = 35%. When 7 = 0 °, the diattenuation is a pure linear diattenuation D = DL = 35% and when y = 90 °, the diattenuation is a pure circular diattenuation D = D, = 35%. The curves C5, C6 and C7 of FIG. 10B show in solid lines the results of the simulations respectively calculating the phase delay, the circular diattenuation and the linear attenuation in the arrangement of FIG. 10A. The points associated with curves C5, C6 and C7 show the results of the corresponding experimental measurements. Figure 11A shows a sample identical to that of Figure 10A but in which the order of the components is reversed. In other words, the sample consists of a parallel-faced plate 48 followed by a Babinet-Soleil compensator 47 and a mirror 49, all other settings being kept identical to those of FIG. 10A. Numerical simulations show that, when the Babinet-Soleil compensator is set to introduce a phase delay of between 0 ° and 90 ° during a single traversal, the parallel-face compensator + blade assembly behaves as a component introducing a phase delay 27 over a round trip and a combination of linear and circular DL diacetations Dc such that the linear attenuation decreases from 35% to 0% when the phase delay changes from 00 to 90 °, and circular diattenuation It increases from 0% to 17.5% and then decreases to 0% when the phase delay changes from 0 ° to 90 °. The curves C8, C9 and C10 of FIG. 11B show in full lines the results of the simulations respectively calculating the phase delay, the circular diattenuation and the linear attenuation in the arrangement of FIG. 11A. The points associated with curves C8, C9 and C10 show the results of the corresponding experimental measurements.
    [0019] The experimental results thus presented show the feasibility of the polarimetric characterization method according to the present description and the possibilities of accessing accurate and complete polarimetric information relating to the sample, in particular linear phase delays and linear and circular di attenuation. . The method thus described can be implemented not only for the polarimetric characterization of biological samples in endoscopy but also for the characterization of difficult-to-access samples, such as for example the characterization of insulating or conducting materials in a hostile environment (presence of nuclear radiation, strong electromagnetic fields, very high or very low temperatures, etc.). Although described through a number of detailed exemplary embodiments, the method and the polarimetric characterization device according to the invention comprise various variants, modifications and improvements which will be obvious to those skilled in the art, being understood that these different variants, modifications and improvements are within the scope of the invention, as defined by the following claims.
    权利要求:
    Claims (14)
    [0001]
    REVENDICATIONS1. Device for the remote polarimetric characterization (100, 200) of a sample (S) comprising: - a source of emission (10) of at least one light wave incident at at least a first wavelength (2E); a monomode optical fiber (30) in which the incident light wave is intended to propagate; a polarization state generator (PSG) arranged on the proximal side of the optical fiber and enabling the generation of a given number of polarization states of the incident light wave, called probe states; a reflector (40, 44) intended to be arranged on the distal side of the optical fiber; a polarization state analyzer (PSA) arranged on the proximal side of the optical fiber and making it possible, for each probe state of the incident wave, to analyze the polarization of the light wave obtained after propagation of the wave incident in the optical fiber (30), reflection of the distal side of the optical fiber and reverse propagation in the optical fiber (30); processing means (70) making it possible to determine: from a first polarimetric characterization of the optical fiber, obtained by analyzing for each probe state, the polarization of at least one reflected wave on the distal side of the optical fiber; the optical fiber by means of the reflector, a Mueller matrix (1VIF (2E)) associated with the optical fiber at the first wavelength; from a second polarimetric characterization of the assembly comprising the optical fiber and the sample, obtained by analyzing for each polarization probe state, a wave returned to the distal side of the fiber by the sample and propagated in opposite direction in the optical fiber (30), a Mueller matrix (MT) associated with said set at the first wavelength; from the Mueller matrices associated respectively with the optical fiber and the assembly comprising the optical fiber and the sample, the Mueller matrix (Mo) associated with the sample at the first wavelength.
    [0002]
    2. polarimetric characterization device according to claim 1, wherein: the emission source allows the emission of a wave at the first wavelength (20) and the emission of a wave at a second length; wave (2F1) distinct from the first wavelength, the reflector is a spectral reflector allowing the reflection of a wave propagating in the optical fiber at the second wavelength (2F1) for the polarimetric characterization of the optical fiber at the second wavelength (2F1) and the passage of the wave at the first wavelength (20 for the polarimetric characterization of the assembly comprising the optical fiber and the sample at the first length of wave (2E) - the processing means make it possible to determine: o from the polarimetric characterization of the optical fiber at the second wavelength (2F1), a Mueller matrix (MF (2F1)) associated with the fiber optical at the second wavelength e (2F1); O from the Mueller matrix associated with the optical fiber at the second wavelength (2F1), a Mueller matrix (1VIF (2E)) associated with the optical fiber at the first length of wave (20.
    [0003]
    3. polarimetric characterization device according to claim 2, wherein: the emission source further allows the emission of a wave at a third wavelength (2F2) distinct from the first and second wavelengths, the spectral reflector allows the reflection of waves propagating in the optical fiber at the second and third wavelengths (2F1, 2F2) for the polarimetric characterization of the optical fiber at the second and third wavelengths (2F1, 2F2) ; the processing means make it possible to determine: from a polarimetric characterization of the optical fiber at the second wavelength (2F1) and from a polarimetric characterization of the optical fiber at the third wavelength (2F2), respectively a Mueller matrix (1V1F (41)) associated with the optical fiber at the second wavelength (2F1) and a Mueller matrix (1VIF (2F2)) associated with the optical fiber at the third length of wave (2F2); o from the Mueller matrices associated with the optical fiber at the second wavelength (2F1) and the third wavelength (2F2), the Mueller matrix (1VIF (2E)) associated with the optical fiber at the first length wave (2E).
    [0004]
    Polarimetric characterization device according to claim 1, in which the reflector is a switchable reflector between a reflecting position and a passing position, allowing, in the reflecting position, the reflection of a wave propagating in the optical fiber at the first wavelength for the polarimetric characterization of the optical fiber and, in the passing position, the reflection of the wave by the sample for the polarimetric characterization of the assembly comprising the optical fiber and the sample.
    [0005]
    The device of any preceding claim, wherein the monomode optical fiber (30) is a polarization-maintaining optical fiber.
    [0006]
    6. Device according to claim 5, wherein the monomode optical fiber comprises a first section of a polarization maintaining monomode optical fiber and a second section of the same polarization maintaining monomode optical fiber, the sections being of equal length and length. interconnected so that the fast axis of the first section is aligned with the slow axis of the second section and vice versa.
    [0007]
    7. Device according to any one of the preceding claims, further comprising, on the distal side of the optical fiber, means for focusing (42) a wave at the first wavelength for the characterization of a point zone of the sample.
    [0008]
    8. Device according to claim 7, further comprising the distal side of the optical fiber, scanning means (46) for the polarimetric characterization of a set of point areas of the sample.
    [0009]
    9. A method of remote polarimetric characterization of a sample comprising: - the emission of a light wave incident at at least a first wavelength (2E) intended to propagate in a monomode optical fiber (30); polarimetric characterization of the optical fiber at the first wavelength, comprising: generating a given number of states of polarization of the incident light wave, called probe states, by means of a state generator of polarization (PSG) arranged on the proximal side of the optical fiber; o analyzing, for each probe state of the incident wave, the polarization of the light wave obtained after propagation of the incident wave in the optical fiber (30), reflection by means of a reflector (40, 44). ) arranged on the distal side of the optical fiber and reverse propagation in the optical fiber (30); o determination of a Mueller matrix (1VIF (2E)) associated with the optical fiber at the first wavelength; the polarimetric characterization of the assembly comprising the optical fiber and the sample at the first wavelength, comprising: by means of said polarization state generator (PSG) and polarization state analyzer (PSA), analyzing for each probe state of the polarization, a wave returned to the distal side of the fiber by the sample and propagated in the opposite direction in the optical fiber (30); o determining a Mueller matrix (MT) associated with said set at the first wavelength; determination of the Mueller matrix (Mo) associated with the sample from the Mueller matrices respectively associated with the optical fiber and with the assembly comprising the optical fiber and the sample.
    [0010]
    10. polarimetric characterization method according to claim 9, comprising: the emission of a light wave at a second wavelength (2F1) distinct from the first wavelength (2E), and in which: reflector is a spectral reflector allowing the reflection of a wave propagating in the optical fiber at the second wavelength (2F1) for the polarimetric characterization of the optical fiber at the second wavelength (2F1) and the passage of the wave at the first wavelength (2E) for the polarimetric characterization of the assembly comprising the optical fiber and the sample at the first wavelength (2E) - the determination of the Mueller matrix (MF ()) associated with the optical fiber at the first wavelength comprises: o from the polarimetric characterization of the optical fiber at the second wavelength (2F1), an associated Mueller matrix (MF (2F1)) to the optical fiber to the second lon wavelength (2F1); O from the Mueller matrix associated with the optical fiber at the second wavelength (2F1), a Mueller matrix (1VIF (2E)) associated with the optical fiber at the first wavelength (20.
    [0011]
    11. polarimetric characterization method according to claim 10, comprising: the emission of a wave at a third wavelength (2F2) distinct from the first and second wavelengths, and in which: the spectral reflector allows the reflection of waves propagating in the optical fiber at the second and third wavelengths (2F1, 2F2) for the polarimetric characterization of the optical fiber at the second and third wavelengths (2F1, 2F2); the determination of the Mueller matrix (MF ()) associated with the optical fiber at the first wavelength comprises: o from a polarimetric characterization of the optical fiber at the second wavelength (2F1) and from a polarimetric characterization of the optical fiber at the third wavelength (2F2), respectively a Mueller matrix (1V1F (41)) associated with the optical fiber at the second wavelength (2F1) and a Mueller matrix (1VIF (2F2)) associated with the optical fiber at the third wavelength (2F2) O from the Mueller matrices associated with the optical fiber at the second wavelength (2F1) and the third length of wave (2F2), the Mueller matrix (1VIF (2E)) associated with the optical fiber at the first wavelength (20.
    [0012]
    The method of polarimetric characterization according to claim 9, wherein the reflector is a switchable reflector between a reflective position and a passing position, allowing, in the reflective position, the reflection of a wave propagating in the optical fiber at first. wavelength for the polarimetric characterization of the optical fiber and, in the passing position, the reflection of the wave by the sample for the polarimetric characterization of the assembly comprising the optical fiber and the sample.
    [0013]
    The method according to any one of claims 9 to 12, further comprising the distal side of the optical fiber, focusing a light wave at the first wavelength to the focusing means (42) for characterizing the light. a point zone of the sample.
    [0014]
    The method of claim 13, further comprising the distal side of the optical fiber, scanning by scanning means (46) of the focused light wave for polarimetric characterization of a set of point areas of the sample. .
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    FR2755254B1|1996-10-25|1999-01-15|Centre Nat Rech Scient|OPTICAL MODULATION COMPONENT, POLARIMETER AND ELLIPSOMETER FROM MUELLER INCLUDING SUCH AN OPTICAL COMPONENT, METHOD FOR CALIBRATION OF THIS ELLIPSOMETER AND METHOD FOR ELLIPSOMETRIC MEASUREMENT|
    FR2774766B1|1998-02-09|2000-04-28|Centre Nat Rech Scient|POLARIMETER AND CORRESPONDING MEASUREMENT METHOD|
    DE60209672T2|2002-10-15|2006-11-16|Centre National De La Recherche Scientifique |Liquid crystal based polarimetric system, method for its calibration, and polarimetric measurement method|
    JP5175101B2|2004-10-29|2013-04-03|ザジェネラルホスピタルコーポレイション|System and method for performing Jones matrix based analysis to measure unpolarized polarization parameters using polarization sensitive optical coherence tomography|
    US7823215B2|2005-05-12|2010-10-26|The University Of Akron|Molecular imaging and nanophotonics imaging and detection principles and systems, and contrast agents, media makers and biomarkers, and mechanisms for such contrast agents|
    AT385736T|2005-07-01|2008-03-15|Ecole Polytech|POLARIMETRIC ELECTRONIC IMAGING SYSTEM FOR A COLPOSCOPIC DEVICE|
    JP4822454B2|2005-11-22|2011-11-24|株式会社松風|Dental optical coherence tomography system|
    US7298480B2|2005-12-23|2007-11-20|Ecole Polytechnique|Broadband ellipsometer / polarimeter system|
    FR2941047A1|2009-01-15|2010-07-16|Centre Nat Rech Scient|DEVICE AND METHOD FOR DETERMINING POLARIZATION INFORMATION AND POLARIMETRIC IMAGER|
    JP5412387B2|2010-08-24|2014-02-12|富士フイルム株式会社|Endoscope device and endoscope diagnosis device|
    FR2977033B1|2011-06-23|2013-07-05|Univ Rennes|SYSTEM AND METHOD FOR ANALYSIS BY DETERMINING A DEPOLARIZING OR DICHROIC CHARACTER OF AN OBJECT|US10215642B2|2012-05-17|2019-02-26|The University Of Akron|System and method for polarimetric wavelet fractal detection and imaging|
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1452244A|FR3018914B1|2014-03-18|2014-03-18|DEVICE AND METHOD FOR POLARIMETRIC CHARACTERIZATION DEPORTEE|FR1452244A| FR3018914B1|2014-03-18|2014-03-18|DEVICE AND METHOD FOR POLARIMETRIC CHARACTERIZATION DEPORTEE|
    JP2016558108A| JP6599352B2|2014-03-18|2015-02-18|Remote polarimetry apparatus and method|
    US15/126,798| US10094766B2|2014-03-18|2015-02-18|Device and method for remote polarimetric characterization|
    EP15709113.3A| EP3120134B1|2014-03-18|2015-02-18|Device and method for remote polarimetric characterization|
    PCT/EP2015/053437| WO2015139907A1|2014-03-18|2015-02-18|Device and method for remote polarimetric characterisation|
    ES15709113.3T| ES2668022T3|2014-03-18|2015-02-18|Device and displaced polarimetric characterization method|
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