• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The general field of the invention is that of optical lidars comprising an optical port (17) and operating at a first wavelength. The lidar optical port according to the invention comprises a layer or a strip made of an optical material. The lidar comprises illumination means (20, 21, 22) of said layer or said plate at a second wavelength different from the first wavelength, said material being transparent at the first wavelength and absorbing at the second wavelength.
    公开号:FR3021753A1
    申请号:FR1401220
    申请日:2014-05-28
    公开日:2015-12-04
    发明作者:Philippe Rondeau；Nicolas Bastien；Patrick Feneyrou
    申请人:Thales SA；
    IPC主号:
    专利说明:

    [0001] The field of the invention is that of aircraft-mounted Lidar Doppler systems. These systems make it possible to measure the relative velocity of the air at a certain distance from said aircraft.
    [0002] This technique is based on the measurement of the Doppler shift induced by the particles present in the atmosphere on the backscattered laser wave. The use of a plurality of laser beams or a beam scanning system provides access to the three components of the air velocity vector throughout the wearer's flight range.
    [0003] These systems require the use of a quasi-optical optical window on the wearer's skin. This window allows the laser beam to pass into the atmosphere without altering its optical and geometrical properties and without attenuating the power emitted. Given the conditions of use on aircraft, a suitable heating system is essential to prevent icing of the window when atmospheric conditions of temperature and water presence are met. The icing has the effect of degrading the optical performance of the window and thus reduce the accuracy of the speed measurement. Under certain conditions of strong icing, the measurement is even totally lost. To prevent icing of the porthole, several technical solutions exist. A first solution is to implement conductive heating. Electrical resistors are in contact with the holding structure of the window and can generate the necessary thermal power. A second solution is to have a resistive film on the surface or in the thickness of the window. This second solution is, for example, used for deicing aircraft windshields. A thin resistive layer is then disposed between two blades constituting the windshield.
    [0004] The main defects of these two solutions are as follows. The first solution leads to high thermal stresses due to the localized injection of the thermal power. These constraints deform the wavefront of the optical wave transmitted on transmission and reception. This deformation can cause a significant drop in the received signal level and produce a degradation of the measurement accuracy, or even prevent the measurement if the signal to noise ratio is too degraded. On the other hand, this technique is unthinkable for deicing large optical surfaces. Finally, the heating of the frame of the window represents a significant power consumption due to the dissipation over a larger area of the thermal energy provided. A solution that partially overcomes these disadvantages is the use of a sapphire porthole. This material has a very high thermal conductivity. If the door is provided with sufficient surface area, the heating resistors can be glued directly to the non-optically useful surface of the sapphire window. However, the use of sapphire has a disadvantage: it is birefringent.
    [0005] When working in polarized light, the birefringence can decrease the useful signal level if it is not properly taken into account. The main disadvantage of the second solution is a loss of transmission due to the reflectivity of the heating films.
    [0006] The lidar according to the invention does not have these disadvantages. It comprises an optical port which is both transparent to the emission wavelengths of the lidar and absorbs in a second wavelength range. It can thus be heated by illuminating it in this second spectral range. More specifically, the subject of the invention is an optical lidar 25 comprising an optical port and operating at a first wavelength, characterized in that the window comprises a layer or a strip made of an optical material and lighting means said layer or said plate at a second wavelength different from the first wavelength, said material being transparent at the first wavelength and absorbing at the second wavelength. Advantageously, the window comprises only a blade made in said optical material. Advantageously, the lighting means having a known emission diagram, they are distributed so as to optimize the illumination homogeneity of the window according to said emission diagram.
    [0007] Advantageously, the lighting means are light-emitting diodes. Advantageously, the first wavelength is located in the near infrared and the second wavelength in the visible spectrum.
    [0008] Advantageously, the first wavelength is located in the ultraviolet and the second wavelength in the visible or near infrared. Advantageously, the material is a FLG850 reference glass of the Schott® brand.
    [0009] The invention will be better understood and other advantages will become apparent on reading the following description, which is given in a nonlimiting manner and by virtue of the appended figures, in which FIG. 1 represents the general architecture of a lidar according to FIG. FIG. 2 represents the spectral transmission of the material of an optical porthole according to the invention. FIG. 3 represents the spectral emission of the illumination means of said optical port according to the invention; FIG. 4 represents the block diagram of an optical helical head according to the invention. FIG. 1 represents the general architecture of a lidar according to the invention, mounted on an aircraft. It comprises a first assembly 10 which provides the actual speed measurement. This set comprises a transmission laser source 11, an optical separator 12, a transceiver optics 13, an interferometer 14, detection means 15 and signal processing 16. In the case of FIG. The transmission-reception optics 13 is represented by a single lens and placed upstream of a port 17 for separating the lidar from the outside. The window 17 is mounted on the skin 30 of the aircraft. The icing conditions are represented by flakes in this FIG. 1. This transmission-reception optic 13 focuses the emission radiation at a determined distance from the skin of the aircraft. It is known that, by Doppler effect, the optical radiation backscattered by the atmospheric particles present at the focusing point is slightly shifted in frequency by a value proportional to the relative velocity of the particles relative to the aircraft. The received radiation passes through the optical separator 12 and 5 interferes with a fraction of the radiation emitted by the emitting laser source 11 in the interferometer 14. A beat signal at the Doppler frequency is obtained. This is received by a photodetection assembly 15. The electronic assembly 16 makes it possible to perform the processing of the signal thus obtained and to calculate the relative speed of the aircraft from the knowledge of the beat frequency. The lidar according to the invention comprises a second assembly 20 said defrosting the window 17. It essentially comprises means of supply, management and control 21 and lighting means 22 of the porthole. The radiation emitted by the illumination means 22 is represented by chevrons in FIG. 1. The operating principle is as follows. The window has a layer of material or is made of a material whose absorption coefficient varies greatly depending on the wavelength. Thus, it is possible to choose the wavelength of the source 22 sufficiently different from that of the lidar emission wave so that the window absorbs the wavelength of the illumination source 22 and transmits the emission wavelength. By absorbing the light from the source 22, the window heats up and the defrosting function is performed. If the layer of absorbent material is thin, the heating is essentially surface, if the entire porthole is made of absorbent material, the heating is substantially volume. This second solution is preferable to the first and allows a more homogeneous absorption and therefore a better quality of the transmitted wavefront. Optical materials having this absorption property are essentially colored glasses. By way of example, FIG. 2 represents the absorption variation of a colored glass known under the reference FLG850 and marketed by Schotte. The transmission of the colored glass is given for wavelengths between 400 nanometers and 2000 nanometers. The scale of transmissions is logarithmic. This material has a cut-off wavelength centered at 5 nanometers. Below this wavelength, the material absorbs light, beyond this wavelength it is transparent. For example, if the emission wavelength of the lidar is in the near infrared around 1550 nanometers, it is entirely transmitted by the FLG850. Conversely, if the lighting and reheating means emit in the visible, the emitted light is fully absorbed. In the case of lidar using an ultraviolet rather than an infrared wavelength, colored glass materials can be selected which absorb visible and infrared radiation while transmitting ultraviolet radiation. The illumination sources 22 may be light-emitting diodes. By way of example, FIG. 3 represents the emission spectrum of a light emitting diode emitting in blue. The emission is given for wavelengths between 400 nanometers and 560 nanometers. The scale of the power emitted is normalized in this FIG. 3. The spectrum comprises an emission peak at 450 nanometers and has a spectral width at mid-height of 25 nanometers. LEDs of this type can emit a luminous flux of several watts with excellent energy efficiency.
    [0010] FIG. 4 represents an exemplary embodiment of an optical transceiver head of a lidar according to the invention. The light is derived from an optical fiber 121 connected to the LIDAR transmission and reception means. For example, the emission wavelength of the lidar is close to 1.55 μm. The optical head essentially comprises optics 131 and an outlet port 132. The reheating of the window 132 is ensured by a ring of light-emitting diodes 221 emitting in the visible range, that is to say in a wavelength range. between 400 nanometers and 800 nanometers. These diodes can emit at the wavelength of 450 nanometers as described above. These diodes are integrated in the mechanical structure of the optical head. They are arranged so as to optimize the homogeneity of the illumination of the optical window 132 as a function of their emission diagram. A single optic may optionally be associated with each transmitter to improve the homogeneity or efficiency of the illumination. The optical port can be made of FLG 850. In this case, the transmission of the emission radiation is greater than 99% and the absorption of the radiation emitted by the heating diodes is greater than 99%. The advantages of the de-icing system according to the invention are as follows: Homogeneous absorption of the heating energy over the entire surface of the window, thus avoiding the problems of thermal stresses and transmitted wavefront deformation; - Defrosting perfectly limited to the useful area of the window and thus limitation of conductive losses compared to a deicing solution 15 by conduction; - Possibility of performing antireflection treatment adapted to the emission wavelength of the lidar to further limit the losses by glassy reflection; Natural filtering of solar radiation emitted essentially in the visible; - Low cost of system realization; - High reliability of the system.
    权利要求:
    Claims (6)
    [0001]
    REVENDICATIONS1. Optical lidar comprising an optical port (17, 132) and operating at a first wavelength, characterized in that the porthole comprises a layer or a blade made of an optical material and lighting means (20, 21, 22, 221) of said layer or said plate at a second wavelength different from the first wavelength, said material being transparent at the first wavelength and absorbing at the second wavelength.
    [0002]
    2. optical lidar according to claim 1, characterized in that the window comprises only a blade made in said optical material. 15
    [0003]
    3. optical lidar according to one of the preceding claims, characterized in that the illumination means are light emitting diodes (221).
    [0004]
    4. Optical lidar according to claim 3, characterized in that the light-emitting diodes are distributed in a ring.
    [0005]
    5. Optical lidar according to one of the preceding claims, characterized in that the first wavelength is located in the near infrared and the second wavelength in the visible spectrum.
    [0006]
    6. The optical lidar according to one of claims 1 to 4, characterized in that the first wavelength is located in the ultraviolet and the wavelength wavelength in the visible or near infrared.
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    同族专利:
    公开号 | 公开日
    US20150346328A1|2015-12-03|
    US9588220B2|2017-03-07|
    FR3021753B1|2017-12-01|
    EP2950117A1|2015-12-02|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JP2013001611A|2011-06-17|2013-01-07|Kureha Corp|Method for heating laminated glass, and defroster apparatus|
    WO2013139347A1|2012-03-23|2013-09-26|Windar Photonics A/S|Multiple directional lidar system|
    FR2768122B1|1997-09-09|1999-11-19|Sextant Avionique|OPTICAL DEVICE FOR DETECTION OF ICING CONDITIONS ON AIRCRAFT|
    US6206325B1|1998-09-18|2001-03-27|Sunlase, Inc.|Onboard aircraft de-icing using lasers|
    US6377207B1|2000-09-27|2002-04-23|Fredrick S. Solheim|Passive polarimetric microwave radiometer for detecting aircraft icing conditions|
    US7306337B2|2003-03-06|2007-12-11|Rensselaer Polytechnic Institute|Calibration-free gaze tracking under natural head movement|
    US7986408B2|2008-11-05|2011-07-26|Rosemount Aerospace Inc.|Apparatus and method for in-flight detection of airborne water droplets and ice crystals|
    US8575527B2|2010-11-10|2013-11-05|Lockheed Martin Corporation|Vehicle having side portholes and an array of fixed EO imaging sub-systems utilizing the portholes|
    FR2967506A1|2010-11-16|2012-05-18|Thales Sa|OPTRONIC TRANSPARENT IR TRANSPARENT AND RF REFLECTIVE|
    WO2012078192A1|2010-12-07|2012-06-14|Rockwell Thomas L|Apparatus and method for detecting the presence of water on a remote surface|
    FR2994273B1|2012-07-31|2015-04-17|Thales Sa|PROBE SYSTEM, PRIMARY REFERENCE MIXED PROBE FOR AIRCRAFT, AIRCRAFT AND METHOD OF MEASUREMENT THEREOF|US10816661B2|2016-06-08|2020-10-27|Rosemount Aerospace Inc.|Airborne ice detector using quasi-optical radar|
    US10560983B2|2017-01-26|2020-02-11|Ford Global Technologies, Llc|Self-defrosting sensor|
    US10351103B2|2017-09-29|2019-07-16|Aptiv Technologies Limited|LIDAR device with heated cover useful for automated vehicles|
    DE102019103044A1|2019-02-07|2020-08-13|Automotive Lighting Reutlingen Gmbh|Headlights of a motor vehicle|
    CN109917349B|2019-04-04|2021-11-19|山东富锐光学科技有限公司|Scanning laser radar|
    DE102019117968A1|2019-07-03|2021-01-07|HELLA GmbH & Co. KGaA|Device for heating a cover of a vehicle|
    CZ308648B6|2019-09-27|2021-01-27|ŠKODA AUTO a.s.|Vehicle detection system assembly|
    法律状态:
    2015-05-08| PLFP| Fee payment|Year of fee payment: 2 |
    2015-12-04| PLSC| Publication of the preliminary search report|Effective date: 20151204 |
    2016-04-26| PLFP| Fee payment|Year of fee payment: 3 |
    2017-04-27| PLFP| Fee payment|Year of fee payment: 4 |
    2018-05-01| PLFP| Fee payment|Year of fee payment: 5 |
    2019-04-29| PLFP| Fee payment|Year of fee payment: 6 |
    2020-05-05| PLFP| Fee payment|Year of fee payment: 7 |
    2021-04-26| PLFP| Fee payment|Year of fee payment: 8 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1401220A|FR3021753B1|2014-05-28|2014-05-28|LIDAR COMPRISING OPTICAL MEANS FOR DEFROSTING OR PREVENTING GIFRAGE|FR1401220A| FR3021753B1|2014-05-28|2014-05-28|LIDAR COMPRISING OPTICAL MEANS FOR DEFROSTING OR PREVENTING GIFRAGE|
    US14/721,950| US9588220B2|2014-05-28|2015-05-26|Lidar comprising optical means for deicing or preventing icing|
    EP15169101.1A| EP2950117A1|2014-05-28|2015-05-26|Lidar comprising optical de-icing or ice-prevention means|
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