• 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:
    @ Apparatus for measuring displacement comprises a member, such as a reading head, which carries a stepped index diffraction grating (14) and is movable with respect to a reflective scale grating (16). The head also carries a source (10) and lens for directing light on to the index grating and thence on to the scale grating for reflection to the index grating, with the resultant Moire bands detected by a photodetector (18) on the reading head. In order to determine the phase separation or offset, and to avoid high sensitivity thereof to the spacing between the gratings, the index grating (14) has a square-stepped profile resulting in graded, increasing thickness. Alternatively, a conventional index grating may be employed in conjunction with a stepped profile optical element interposed between the two gratings.
    公开号:SU1450761A3
    申请号:SU843767323
    申请日:1984-07-27
    公开日:1989-01-07
    发明作者:Мартин Петтигрю Роберт
    申请人:Др.Йоханнес Хайденхайн Гмбх (Фирма)；
    IPC主号:
    专利说明:

     ABOUT
    The invention relates to a measurement technique, to devices for measuring relative displacements based on the use of interference moire strips, from which.-Linear and angular displacements can be measured.
    The purpose of the invention is to increase the resolution due to is. use of diffraction gratings with a pitch of 40 mm.
    FIG. Figure 1 shows the optical layout of the device; in fig. 2 is a diagram of transparent and reflective gratings; FIG. 3 shows the optical design of the device.
    The device contains an optical radiation source 1 and a collimating lens 2 successively installed along the radiation path, a penetrating lattice 3 attached to one of the objects, made of a material with a refractive index different from that of the medium, having a monotonically varying Optical thickness, and three large scale detectors 4-7 located on the source side 1 of the focal plane of the lens 2 in the zone of the formation of zero order and positive and negative corresponding first-order diffraction images, respectively. The transparent grating 3 is oriented so that the optical lengths of the light paths in the direction from the transparent grating 3 to the reflective grating 4 and from the reflective grating 4 to the transparent grating are different.
    In addition, the grating 3 can have a monotonously increasing optical thickness, is made with a stepped profile and is set so that its profile faces the reflection grating 4 strokes of which are made in the form of rectangular grooves, and the device is equipped with an optical element - and reflective 4 gratings. and having a monotonously increasing optical thickness and a step profile, the steps of which have the same height and width.
    The device works as follows.
    When the transparent 3 and reflective 4 gratings are illuminated with a light beam from a source of optical radiation, the image of the transparent grating 3 attached to the object interacts with the reflective grating 4, which leads to the formation of an interference pattern. Due to the fact that the optical path length during the passage of light from the transparent grating 3 to the reflective grating is different from the path length when the light passes back from the reflective grating 4 to the transparent one, because the light passes through different material thicknesses,
    the refractive index of which is different from the refractive index of the environment,. phase shift occurs
    Shifts or shifts of the output signals detected by photodetectors 5-7 installed in the focal plane of lens 2 in the zone of the formation of zero order and positive and negative first orders of the diffraction image, respectively. These signals carry information about the relative movements of two objects.
    Different optical paths are achieved with the help of a stepped profile of the transparent grid 3. In another embodiment, the transparent grid is usual, and the element with the step profile is placed between the transparent 3 and the wall. 4 lattices and serves to obtain the required optical path length difference.
    The step height of the profile transparent grid 3 determines the phase shift of the output signals. Preferably, it should be such as to provide a phase shift of 120. In the preferred embodiment, the pro-
    The grid grating 3 has a rectangular profile. It should generally provide maximum light transmission and maximum-contrast bands in the first diffraction order.
    The reflector grid must have a 100% reflection and is preferably made from a durable and durable material. Profile rectangular grooves. In the practical version, components 1-3 and 5-7 should be located on the reading head, movable relative to the reflective dashed grating 4, Output signals from photodetectors 5-7 are characterized in this: In the case, the magnitude and direction of movement of the read head is relative; fixed grid 4. Thus, linear and angular relative displacements of objects can be measured.
    权利要求:
    Claims (5)
    [1]
    1. A device for measuring the relative displacements of two objects containing a source of optical radiation and a collimating lens sequentially installed along the radiation path, a transparent grid attached to one of the objects, and a reflective scale grid attached to another object, and three detectors, located on the side of the source in the focal plane of the lens in the zone of formation of the zero order and the positive and negative first orders of the diffraction image, respectively. This, in order to increase the resolution, the transparent lattice, made of a material with a refractive index different from that of the medium, has a monotonically varying optical effect.
    the thickness is oriented so that the optical lengths of the put; the light from it in the direction from the transparent lattice to g to the reflective lattice and from the reflective lattice to transparent is different.
    [2]
    2. A device pop 1, characterized by the fact that a transparent 10 on the lattice has a monotonically increasing optical thickness.
    [3]
    3. The device according to paragraphs. 1-2, which is comparable with the fact that the transparent lattice is made with a step-like profile and is installed so that
    that its profile is facing the reflective lattice.
    [4]
    4. The device according to claim 1, about tl and - so that it provides
    20 is an optical element installed between the transparent and reflector gratings and having a monotonically increasing optical thickness and a stepped profile.
    25
    [5]
    5. Device on PP. 3-4, characterized in that all steps. Profiles have the same height and width of 1-5.
    6, the Device in PP. 1-5, characterized in that the strokes of the reflective lattice are made in the form of grooves of a rectangular shape.
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    同族专利:
    公开号 | 公开日
    KR850001422A|1985-03-18|
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    EP0132978A3|1986-09-17|
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    BR8403768A|1985-07-02|
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US3344700A|1961-05-23|1967-10-03|British Aircraft Corp Ltd|Displacement measuring system|
    US3883232A|1973-12-03|1975-05-13|Hitachi Ltd|Random phase plate and optical system incorporating said plate|
    GB1474049A|1974-01-12|1977-05-18|Leitz Ernst Gmbh|Arrangement for the modulation of light|
    GB1523165A|1974-08-03|1978-08-31|Matsushita Electric Ind Co Ltd|Fourier-transform holography by pseudo-random phase shifting|
    GB1516536A|1975-08-22|1978-07-05|Ferranti Ltd|Measuring apparatus|
    DE3213839A1|1982-04-15|1983-10-27|Philips Patentverwaltung Gmbh, 2000 Hamburg|OPTICAL WAVELENGTH MULTIPLEX OR -DEMULTIPLEX ARRANGEMENT|JPH0349370B2|1984-07-02|1991-07-29|Ookuma Kk|
    DE3543179A1|1985-12-06|1987-06-11|Philips Patentverwaltung|OPTICAL TRAVEL SENSOR WITH A FILTER|
    GB2194042A|1986-08-14|1988-02-24|Bicc Plc|Displacement measurement|
    US5064290A|1987-12-12|1991-11-12|Renishaw Plc|Opto-electronic scale-reading apparatus wherein phase-separated secondary orders of diffraction are generated|
    GB8729246D0|1987-12-15|1988-01-27|Renishaw Plc|Opto-electronic scale-reading apparatus|
    US4943716A|1988-01-22|1990-07-24|Mitutoyo Corporation|Diffraction-type optical encoder with improved detection signal insensitivity to optical grating gap variations|
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    GB8903725D0|1989-02-18|1989-04-05|Cambridge Consultants|Coherent tracking sensor|
    DE4006365C2|1990-03-01|1992-06-04|Dr. Johannes Heidenhain Gmbh, 8225 Traunreut, De|
    DE9007559U1|1990-03-13|1992-09-24|Dr. Johannes Heidenhain Gmbh, 8225 Traunreut, De|
    EP0482224B1|1990-10-20|1994-01-12|Dr. Johannes Heidenhain GmbH|Interferometric measuring device for at least one measuring direction|
    GB9022969D0|1990-10-23|1990-12-05|Rosemount Ltd|Displacement measurement apparatus|
    DE59203396D1|1992-07-18|1995-09-28|Heidenhain Gmbh Dr Johannes|Optical device.|
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    NO20130884A1|2013-06-21|2014-12-22|Sinvent As|Optical offset sensor element|
    JP6386337B2|2014-10-23|2018-09-05|株式会社ミツトヨ|Optical encoder|
    FR3031400B1|2015-01-06|2017-02-10|Commissariat Energie Atomique|OPTICAL FOCUSING DEVICE|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    GB838320629A|GB8320629D0|1983-07-30|1983-07-30|Displacement measuring apparatus|
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