CN212747682U - Detection system and grating ruler - Google Patents
Detection system and grating ruler Download PDFInfo
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- CN212747682U CN212747682U CN202021708709.4U CN202021708709U CN212747682U CN 212747682 U CN212747682 U CN 212747682U CN 202021708709 U CN202021708709 U CN 202021708709U CN 212747682 U CN212747682 U CN 212747682U
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Abstract
The utility model discloses a detecting system and grating chi, wherein, detecting system includes: the light source module is used for providing a detection light beam; the light splitting module is used for receiving the detection light beam and performing light splitting processing to generate a plurality of first light beams and a plurality of second light beams; the reference grating module is used for modulating the first light beam and generating reference light; the detection grating module is used for modulating the second light beam and generating detection light; the measuring module is used for detecting and processing coherent light generated by interference of the reference light and the detection light to obtain coherent information; and obtaining the displacement variable quantity of the detection grating module according to the coherent information. The detection system is simple in structure, is less influenced by the environment, and can realize high-precision measurement.
Description
Technical Field
The utility model belongs to the technical field of the precision measurement and specifically relates to a detecting system and grating chi are related to.
Background
The grating ruler distance measurement method is widely applied to micro-displacement detection of devices and has the advantages of high precision, small influence of environment and the like. The length of the grating ruler determines the measuring range of the corresponding measuring device, but a single long-scale grating ruler is difficult to obtain due to the influence of the processing technology and the material factors.
The long-scale grating is usually prepared by splicing a plurality of small-scale gratings, but the difficulty of the method is how to ensure the attitude consistency of the gratings, and the existing grating method has a complex structure and low feasibility.
SUMMERY OF THE UTILITY MODEL
The utility model discloses aim at solving one of the technical problem that exists among the prior art at least. Therefore, the utility model provides a detection system, this detection system simple structure receives environmental impact less, can realize the high accuracy measurement.
The utility model also provides a detection method who has above-mentioned detecting system.
The utility model discloses still provide a grating chi with above-mentioned detecting system.
According to the utility model discloses detection system that first aspect provided, include:
the light source module is used for providing a detection light beam;
the light splitting module is used for receiving the detection light beam and performing light splitting processing to generate a plurality of first light beams and a plurality of second light beams;
the reference grating module is used for modulating the first light beam and generating reference light;
the detection grating module is used for modulating the second light beam and generating detection light;
the measuring module is used for detecting and processing coherent light generated by interference of the reference light and the detection light to obtain coherent information;
and obtaining the displacement variable quantity of the detection grating module according to the coherent information.
According to the utility model discloses detection system of first aspect has following beneficial effect at least: by using the optical principle of the grating and taking the reference light generated by the reference grating module as the reference, the detection light generated by the detection grating module is subjected to grating displacement detection, so that the attitude consistency of each detection grating can be ensured, accurate displacement variation can be obtained, and high-precision and small-error device microspur displacement measurement can be realized.
According to some embodiments of the invention, the light source module comprises: a plurality of light sources for generating an initial light beam; the beam expanding lenses are used for performing beam expanding processing on the initial light beams and generating initial collimated light beams; a plurality of diaphragms for adjusting the effective area of the initial collimated light beam; and the linear polaroids are used for carrying out polarization processing on the initial collimated light beam and forming a detection light beam.
According to some embodiments of the present invention, the light splitting module comprises: the polarization beam splitting prism is used for carrying out beam splitting processing on the detection light beam to generate a plurality of first light beams and a plurality of second light beams; the light splitting flat plate is arranged between the polarization light splitting prism and the detection grating and is used for splitting the second light beam; and the second quarter wave plate is arranged between the light splitting flat plate and the polarization light splitting prism.
According to some embodiments of the invention, the reference grating module comprises: a reference grating that modulates the first beam; the plurality of right-angle reference reflecting prisms comprise a first right-angle reference reflecting prism and a second right-angle reference reflecting prism, the first right-angle reference reflecting prism and the second right-angle reference reflecting prism are arranged between the reference grating and the light splitting module, and the first right-angle reference reflecting prism and the second right-angle reference reflecting prism are symmetrical about the central axis of the reference grating.
According to some embodiments of the present invention, the detection grating module comprises: the detection gratings modulate the second light beam; the right angle detection reflecting prisms comprise a first right angle detection reflecting prism and a second right angle detection reflecting prism, the first right angle detection reflecting prism and the second right angle detection reflecting prism are arranged between the detection grating and the light splitting module, and the first right angle detection reflecting prism and the second right angle detection reflecting prism are symmetrical about the central axis of the detection grating.
According to some embodiments of the invention, the measurement module comprises: the displacement measurement module is used for detecting the coherent light and obtaining displacement variation; and the angle measurement module is used for detecting the coherent light and obtaining the angular displacement variable quantity.
According to some embodiments of the invention, the displacement measurement module comprises: the non-polarization beam splitter prism is used for carrying out beam splitting processing on the reference light and the detection light; a third quarter-wave plate for phase modulating the detection light; the first polaroid is used for modulating the reference light and the detection light and generating a first coherent light beam; a first photodetector for detecting the first coherent light beam; the second polaroid is used for modulating the reference light and the detection light and generating a second coherent light beam; a second photodetector for detecting the second coherent light beam; the non-polarizing beam splitter prism is at least provided with two adjacent surfaces, wherein the two adjacent surfaces comprise a first sub surface and a second sub surface, the first polarizing plate is arranged opposite to the first sub surface, and the second polarizing plate is arranged opposite to the second sub surface.
According to some embodiments of the invention, the angle measurement module comprises: a plurality of reflecting prisms for adjusting a propagation path of the coherent light beam; the focusing convex lenses are used for focusing the coherent light beams; and the photoelectric detectors are used for detecting the coherent light beams and generating angle variation.
According to the utility model discloses grating chi that the second aspect provided, include according to the utility model discloses the detecting system that the first aspect provided.
According to the utility model discloses detection method that the second aspect provided has following beneficial effect at least: by using the optical principle of the grating and taking the reference light generated by the reference grating module as the reference, the detection light generated by the detection grating module is subjected to grating displacement detection, so that the attitude consistency of each detection grating can be ensured, accurate displacement variation can be obtained, and high-precision and small-error device microspur displacement measurement can be realized.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic structural diagram of a detection system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a light source module according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a light splitting module according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a reference grating module according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a detection grating module according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a measurement module according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a displacement measurement module according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of an angle measuring module according to an embodiment of the present invention;
reference numerals: the light source module 100, the light source 110, the first light source 111, the second light source 112, the beam expander 120, the first beam expander 121, the second beam expander 122, the stop 130, the first stop 131, the second stop 132, the linear polarizer 140, the reflecting prism 150, the beam splitting module 200, the polarization beam splitter prism 210, the beam splitting plate 220, the first quarter wave plate 230, the second quarter wave plate 240, the reference grating module 300, the reference grating 310, the right-angle reference reflecting prism 320, the detection grating module 400, the detection grating 410, the right-angle detection reflecting prism 420, the measuring module 500, the displacement measuring module 510, the non-polarization beam splitter prism 511, the third quarter wave plate 512, the first polarizer 513, the first photodetector 514, the second polarizer 515, the second photodetector 516, the angle measuring module 520, the reflecting prism 521, the focusing convex lens 522, and the photodetector 523.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present invention, and should not be construed as limiting the present invention.
In the description of the present invention, it should be understood that the orientation or positional relationship indicated with respect to the orientation description, such as up, down, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, a plurality of means are one or more, a plurality of means are two or more, and the terms greater than, less than, exceeding, etc. are understood as not including the number, and the terms greater than, less than, within, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless there is an explicit limitation, the words such as setting, installation, connection, etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in combination with the specific contents of the technical solution.
Referring to fig. 1, there is shown a detection system according to a first aspect of the present invention, including: the light source module 100 is configured to provide a detection light beam. Wherein the detection light beam may be an initial light beam of the detection system. The light source module 100 may include a plurality of light sources, and each of the plurality of light sources may provide a plurality of detection light beams with equal power.
And the light splitting module 200 is configured to receive the detection light beam and perform light splitting processing to generate a plurality of first light beams and a plurality of second light beams. The first light beams and the second light beams can be different light beams with the same specification. The PBS marked in fig. 1 may be represented as a polarization beam splitter prism, and the polarization beam splitter prism may be used for splitting the detection beam. The detection light beams generated by the light source module can be split by the splitting module 200 and respectively emitted to different grating modules to obtain corresponding reference light and detection light, and the displacement variation can be obtained by analyzing coherent light formed by the reference light and the detection light.
And a reference grating module 300 for modulating the first light beam and generating reference light. Wherein the reference light may be several beams. The reference grating module 300 may diffract the first beam, and thus may generate several reference lights. The reference lights can be used as detection reference lights of the detection system for comparison and measurement with the detection lights generated by the detection grating module 400.
And a detection grating module 400 for modulating the second light beam and generating detection light. Wherein the detection light may be several beams. The detection grating module 400 may diffract the second light beam, thereby generating a number of detection lights. The detection lights can be used for comparing with the reference lights to obtain a measurement result.
The measuring module 500 is used for detecting coherent light generated by interference of reference light and detection light to obtain coherent information; and obtaining the displacement variable quantity of the detection grating module according to the coherent information. The displacement variation may be the displacement of the detection grating in the detection grating module 400, and the coherent light may be obtained by interference between the reference light and the detection light. The NPBS marked in fig. 1 may be represented as an unpolarized beam splitter prism, and the unpolarized beam splitter prism may be used to split reference light and detection light respectively. The measurement module 500 may perform detection processing on the coherent light to obtain coherent information, and finally obtain a displacement variation corresponding to the detection system through calculation.
According to the detection system, the optical principle of the grating is utilized, the reference light generated by the reference grating module is used as the reference, and the detection light generated by the detection grating module is subjected to grating displacement detection, so that the attitude consistency of each detection grating can be ensured, the accurate displacement variation can be obtained, and the device microspur displacement measurement with high precision and small error can be realized.
Referring to fig. 2, there is shown a structure of a light source module 100 including: a number of light sources 110 for generating an initial light beam. Wherein the initial beam may be several beams. Alternatively, assuming that the light sources 110 are the first light source 111 and the second light source 112, the first light source 111 and the second light source 112 may be generated by two laser diodes with the same specification to obtain the initial light beams, respectively.
And the beam expanding lenses 120 are used for performing beam expanding processing on the initial light beams and generating initial collimated light beams. The beam expander 120 may be disposed in a number corresponding to the light sources 110; the initial collimated light beam can be a parallel light beam obtained by collimating a plurality of light sources through beam expansion processing of a beam expander. Alternatively, if the light sources are the first light source 111 and the second light source 112, the beam expander 120 may be a first beam expander 121 and a second beam expander 122, respectively. Specifically, the first beam expander 121 may collimate the light beam emitted by the first light source 111 into a parallel light beam, so as to generate a first initial collimated light beam; the second beam expander 122 may collimate the light beam from the second light source 112 into a parallel light beam to produce a second initially collimated light beam.
A plurality of diaphragms 130 for adjusting the effective area of the initially collimated beam. Wherein the effective area of the initially collimated light beam may be the area of the effective light beam of the initially collimated light beam that enters the detection system for detection. To make the detection result more accurate, the effective area of the initial collimated light beams can be adjusted to equal-diameter light beams by the diaphragm 130. Alternatively, it is assumed that the initial collimated light beams are the first initial collimated light beam and the second initial collimated light beam, respectively, and the stop 130 is set as the first stop 131 and the second stop 132, respectively. The effective area of the first initially collimated beam can be adjusted by the first aperture 131 and the effective area of the second initially collimated beam can be adjusted by the second aperture 132 so that both become a beam of constant diameter.
A trunk polarizer 140 is used to polarize the initially collimated beam and form a detection beam. Optionally, to control the transmission of the first initial collimated light beam and the second initial collimated light beam after the effective area is adjusted, polarization processing may be performed on the first initial collimated light beam and the second initial collimated light beam, and the obtained detection light beams are the first detection light beam and the second detection light beam. Specifically, as shown in fig. 2, the first initially collimated light beam may be parallel to the second initially collimated light beam after passing through the right-angle reflecting prism 150, and the right-angle reflecting prism 150 is used for changing the propagation direction of the first initially collimated light beam. The first initial collimated light beam and the second initial collimated light beam are respectively polarized by the linear polarizer 140 to obtain a first detection light beam and a second detection light beam, wherein the first detection light beam and the second detection light beam are two linearly polarized light beams with equal power, equal radius and the same polarization direction.
Through a plurality of light sources, beam expanders, diaphragms and linear polarizers in the light source module, the propagation paths, effective areas and polarization states of the first detection light beams and the second detection light beams can be effectively modulated, so that detection errors can be reduced.
Referring to fig. 3, showing the structure of the spectral module, the spectral module 200 includes:
and the polarization beam splitter prism 210 is used for splitting the detection beam to generate a plurality of first beams and a plurality of second beams. The polarization splitting prism can be arranged according to requirements. Optionally, the detection beam comprises: the first detection light beam and the second detection light beam. The first and second detection beams generated by the light source module 100 are split by the polarization splitting prism 210, for example, the first and second detection beams can be split into equal-power transmission p-light and reflection s-light. The PBS labeled in fig. 3 may be represented as a polarizing beam splitter prism. As shown in fig. 3, assuming that the detection beams are the first detection beam and the second detection beam, respectively, the first detection beam may be divided into the first transmitted p light and the first reflected s light of equal power, and the second detection beam may be divided into the second transmitted p light and the second reflected s light of equal power by the polarization beam splitter prism. The first light beam may include first reflected s-light and second reflected s-light, and the second light beam may include first transmitted p-light and second transmitted p-light. The first beam may be directed to the reference grating module 400 and the second beam may be directed to the detection grating module 500.
And the light splitting plate 220 is arranged between the polarization light splitting prism 210 and the detection grating 500 and is used for performing light splitting processing on the second light beam. Alternatively, when the light splitting plate 220 is disposed, the light splitting plate 220 may be disposed at 45 ° between the polarization beam splitter prism 210 and the detection grating 500.
The first quarter wave plate 230 is disposed between the polarization splitting prism 210 and the reference grating module 300. The first quarter-wave plate 230 is used for performing phase processing on the first light beam incident to the reference grating module 300 to adjust the polarization state of the first light beam. The first quarter-wave plate 230 may be disposed between the polarization beam splitter prism 210 and the reference grating module 300, and the first quarter-wave plate 230 is disposed parallel to the reference grating module 300, and an axial angle therebetween is 45 °. The first beam may be changed into circularly polarized light by the first quarter wave plate 230 and then directed to the reference grating module 300.
The second quarter wave plate 240 is disposed between the beam splitter plate 220 and the polarization beam splitter prism 210. The second quarter wave plate 240 may be used to perform phase processing on the second light beam emitted to the detection grating module 400 to adjust the polarization state of the second light beam. The second quarter-wave plate 240 may be disposed between the light splitting plate 220 and the polarization beam splitter prism 210, and the second quarter-wave plate 240 and the polarization beam splitter prism 210 are disposed in parallel, and an axial included angle therebetween is 45 °. The second light beam may be changed into circularly polarized light by the second quarter wave plate 240 and then directed to the detection grating module 400. Through the arrangement of the polarization beam splitter prism, the beam splitter plate, the first quarter wave plate and the second quarter wave plate in the beam splitter module, polarization beam splitting is performed to divide the polarization beam into detection beams with different polarization states, the first quarter wave plate and the second quarter wave plate perform polarization adjustment or phase modulation on the first beam and the second beam to obtain the first beam and the second beam, and the detection beams provided by the light source module can be reasonably modulated, so that the detection beams are respectively emitted to the reference grating module and the detection grating module. And the displacement variation of the detection grating is detected through the first light beam and the second light beam.
In some embodiments, before the detection system starts to detect, the beam splitting panel 220 may perform the beam splitting process on the second light beam, and the light beam position detection device performs the position detection on the incident direction of the second light beam, to determine whether the incident position of the second light beam is the central position of the beam splitting panel, so as to ensure that the second light beam is emitted to the central position of the detection grating module 400, so that the detection result is more accurate.
Referring to fig. 4, there is shown a structure of a reference grating module 300, including: the first beam is modulated with reference to a grating 310. The reference grating 310 may be used to diffract an incident beam (i.e., the first beam) at the reference grating surface and generate several diffracted beams, which are reflected at the reference grating surface. Optionally, the reference grating 310 may diffract the incident beam of the reference grating module 300 into 0-order light, two ± 1-order diffracted lights in the x direction, and two-order diffracted lights in the y direction, which are returned from the original optical path.
In some embodiments, the reference grating 310 may be a reflection grating that is: plating a layer of metal film on the metal with high reflectivity, and etching a series of parallel equal-width and equal-distance etched lines on the mirror surface metal film), and adjusting the width and distance of the etched lines to meet different precision requirements.
The plurality of right-angle reference reflecting prisms 320 include a first right-angle reference reflecting prism 321 and a second right-angle reference reflecting prism 322, the first right-angle reference reflecting prism 321 and the second right-angle reference reflecting prism 322 are disposed between the reference grating 310 and the light splitting module 200, and the first right-angle reference reflecting prism 321 and the second right-angle reference reflecting prism 322 are symmetrical with respect to a central axis of the reference grating 310. As shown in fig. 4, the first right-angle reference reflecting prism 321 and the second right-angle reference reflecting prism 322 are disposed between the reference grating 310 and the light splitting module 200, and the first right-angle reference reflecting prism 321 and the second right-angle reference reflecting prism 322 are symmetrical with respect to the central axis of the reference grating 310, so that the transmission direction of the incident first light beam can be controlled. Alternatively, the plurality of right-angle reference reflection prisms 320 may change the ± 1 st order diffracted light returned from the original optical path diffracted by the reference grating 310 into parallel beams, and finally become p-polarized light directed to the measurement module 500. The measurement module 500 may detect the p-polarized light as reference data to obtain a displacement variation. The first light beam is diffracted and reflected through a reference grating in the reference grating module, and then the light beams reflected by the reference grating are modulated through a plurality of right-angle reference reflecting prisms to obtain a plurality of parallel light beams, so that the parallel light beams are used as reference light to emit to the displacement measuring module to detect displacement variation.
Referring to fig. 5, there is shown a structure of a detection grating module 400 including:
a plurality of blocks 410 of detection gratings modulate the second light beam. The plurality of detection gratings 410 may be a plurality of tiled gratings. The plurality of detection beams 410 may be configured to diffract an incident beam (i.e., the second beam) at the surface of the tiled grating and generate a plurality of diffracted beams, which are reflected at the surface of the tiled grating. Optionally, the plurality of detection gratings 410 may diffract the incident beam of the detection grating module 400 into 0-order light, two ± 1-order diffracted lights in the x direction, and two-order diffracted lights in the y direction, which are returned from the original optical path.
In some embodiments, the detection grating 410 may be a reflection grating that is: plating a layer of metal film on the metal with high reflectivity, and etching a series of parallel equal-width and equal-distance etched lines on the mirror surface metal film), and adjusting the width and distance of the etched lines to meet different precision requirements.
The plurality of right angle detection reflecting prisms 420 include a first right angle detection reflecting prism 421 and a second right angle detection reflecting prism 422, the first right angle detection reflecting prism 421 and the second right angle detection reflecting prism 422 are disposed between the detection grating 410 and the light splitting module 200, and the first right angle detection reflecting prism 421 and the second right angle detection reflecting prism 422 are symmetrical with respect to a central axis of the detection grating 410. As shown in fig. 4, the transmission direction of the incident second light beam can be controlled by disposing the first right-angle detection reflecting prism 421 and the second right-angle detection reflecting prism 422 between the detection grating 410 and the light splitting module 200, and making the first right-angle detection reflecting prism 421 and the second right-angle detection reflecting prism 422 symmetrical with respect to the central axis of the detection grating 410. Optionally, the right-angle detection reflecting prisms 420 may change the ± 1 st order diffracted light returned from the original light path obtained by diffraction of the detection grating 410 into parallel light beams through the right-angle detection reflecting prisms 420. The obtained parallel light beam may be divided into reflected light and transmitted light by the light-dividing plate 220 again, the obtained reflected light and transmitted light may be emitted to the measurement module 500, and the measurement module 500 may compare the reflected light and transmitted light as measurement data with reference data obtained by the reference grating module 300 to obtain a displacement variation. The second light beam is diffracted and reflected through the detection grating in the detection grating module, the light beam reflected by the reference grating is modulated through the right-angle detection reflecting prisms to obtain a plurality of parallel light beams, and then the parallel light beams are subjected to light splitting processing through the light splitting flat plate and are used as detection light to irradiate the displacement measurement module for detecting displacement variation. .
Referring to fig. 6, there is shown a structure of a measurement module 500 including:
and the displacement measuring module 510 is configured to detect the coherent light and obtain a displacement. The coherent light may be obtained by interference between the reference light and the detection light. The NPBS labeled in fig. 6 can be represented as a non-polarizing beam splitter prism. The displacement may be a value of the position movement change of the detection grating 410, and the displacement may be obtained through detection processing by the displacement measurement module 510. Alternatively, the displacement measuring module 510 may detect and process the displacement amount through a plurality of photodetectors.
The angle measuring module 520 is configured to perform detection processing on the coherent light and obtain an angle value. The angle quantity may be a value of the angle change of the detection grating 410, and the angle quantity may be obtained through detection processing by the angle measurement module 510. Optionally, the angle measurement module 520 may detect and process the angle quantity through a plurality of photodetectors. Through setting up displacement measurement module and angle measurement module, detect the displacement change condition and the angle change condition of detecting the grating respectively to can obtain the displacement volume and the angle volume of detecting the grating respectively, realize detecting the displacement change volume of detecting the grating from the multidimension degree.
Referring to fig. 7, the displacement measurement module 510 includes:
the unpolarized beam splitter prism 511 is used to perform beam splitting processing on the reference light and the detection light. The non-polarizing beam splitter prism 511 may be provided as required. The NPBS labeled in fig. 7 can be represented as a non-polarizing beam splitter prism. Alternatively, the non-polarizing beam splitter prism 511 may divide the detection light and the reference light into two equal portions of light, which are respectively directed to the first photodetector 514 and the second photodetector 516.
The third quarter waveplate 512 is used for phase modulation of the reference light and the detection light. Optionally, a third quarter-wave plate may be disposed between the first photodetector 514 and the non-polarizing beam splitter prism 511, and is configured to perform phase modulation on the reference light and the detection light after the beam splitting process. Specifically, the third quarter-wave plate 0 ° may be placed between the first photodetector 514 and the non-polarization beam splitter prism 511, so that the phases of the reference light and the detection light are delayed by 90 ° after passing through the third quarter-wave plate.
The first polarizer 513 is configured to modulate the reference light and the detection light and generate a first coherent light beam. Optionally, a first polarizer 513 may be disposed between the third quarter-wave plate 512 and the first photodetector 514. After the reference light and the detection light are phase-modulated by the third quarter-wave plate 512, the reference light and the detection light may interfere at the first polarizer 513, thereby generating a first coherent light beam.
A first photodetector 514 for detecting the first coherent light beam. Alternatively, the interference signal, i.e., the first coherent light beam, may be received by the first photodetector 514, and the first coherent light beam may be detected. Specifically, assume that the beam has a current intensity I at the first photodetector 514AX+1，IAX-1，IBX+1，IBX-1，IAY+1，IAY-1，IBY+1，IBY-1Assuming three translational freedom of the detection gratingThe displacement amounts in degrees are Δ x, Δ y, Δ z, respectively, and the relationship between Δ x, Δ y, Δ z and the current intensity is as follows:
the displacement delta x, delta y and delta z can be calculated through the formulas I, II and III, the detection of the first coherent light beam is completed, and the displacement delta x, delta y and delta z of the detection grating are obtained.
And a second polarizer 515 for modulating the reference light and the detection light and generating a second coherent light beam. Alternatively, the second polarizing plate 515 may be disposed between the non-polarizing beam splitting prism 511 and the second photodetector 516. After the reference light and the detection light are split by the non-polarizing beam splitter prism 511, the reference light and the detection light may interfere with each other at the second polarizer 515, thereby generating a second coherent light beam.
And a second photodetector 516 for detecting the second coherent light beam. Alternatively, the interference signal, i.e., the second coherent light beam, may be received by the second photodetector 516, and the second coherent light beam may be detected. Specifically, assume that the beam has a current intensity I at the second photodetector 516AX+1，IAX-1，IBX+1，IBX-1，IAY+1，IAY-1，IBY+1，IBY-1If the displacements of the detection grating in the three translational degrees of freedom are respectively Δ x, Δ y, and Δ z, the relationship between Δ x, Δ y, and Δ z and the current intensity can be obtained by calculation according to the above formulas (i), (ii), and (iii), and the displacements Δ x, Δ y, and Δ z can be obtained by calculation in sequence, thereby completing the detection of the second coherent light beam and obtaining the displacement Δ of the detection gratingx，Δy，Δz。
The non-polarizing beam splitter prism is at least provided with two adjacent surfaces, including a first sub-surface and a second sub-surface, the first polarizing plate is arranged opposite to the first sub-surface, and the second polarizing plate is arranged opposite to the second sub-surface. As shown in fig. 7, of two adjacent surfaces of the non-polarizing beam splitter prism 511, a first sub-surface may correspond to the first polarizing plate 513, and a second sub-surface may correspond to the second polarizing plate 515. The light beams resulting from the light splitting process by the non-polarizing beam splitter prism 511 can thereby be modulated by the first polarizing plate 513 and the second polarizing plate 515, respectively. The displacement of the detection grating can be detected by arranging the non-polarization beam splitter prism, the third quarter wave plate, the first polarizer, the second polarizer, the first photoelectric detector and the second photoelectric detector in the displacement measurement module.
Referring to fig. 6 and 8 together, the structure of the angle measuring module 520 is shown, which includes:
a number of reflecting prisms 521 are used to adjust the propagation path of the coherent light beam. The number of the reflecting prisms 521 can be set as desired. Alternatively, if the reflecting prisms 521 may be four, the four reflecting prisms may be respectively used to adjust the propagation paths of the four coherent light beams, and if the four coherent light beams are respectively-1 st order light-1B and +1 st order light +1A, the-1 st order light-1B and the +1 st order light +1A are respectively reflected at the four right-angle reflecting mirrors 521. As shown in fig. 8, the four reflection prisms can change the propagation path of the four coherent light beams by 90 °, so that the transmission direction is deflected at a right angle.
And a plurality of focusing convex lenses 522 for focusing the coherent light beams. The number of the focusing convex lenses 522 may be set as desired. Alternatively, assuming that six coherent light beams are formed in total, six focusing concave lenses may be provided. The six coherent light beams can be focused on the corresponding photodetectors 523 by six focusing convex lenses 522. For example, six coherent light beams may pass through the focusing convex lens 522 and be focused into the photodetectors 523, respectively.
A number of third photo detectors 523 for detecting the coherent light beam and generating an angular quantity. Wherein the content of the first and second substances,the third photodetector 523 may be set according to the number of coherent light beams. Optionally, if there are six coherent light beams, six third photodetectors 523 may be correspondingly disposed, and the detection processing may be performed according to the six third photodetectors 523 respectively. Specifically, when the detection grating 410 changes in angle in three rotational degrees of freedom, the position of the light spot on the corresponding third photodetector 523 changes. The angle change of the detection grating 410 can be solved by obtaining the data of the two third photodetectors 523, such as: suppose that the angular changes in the three rotational degrees of freedom are each θx,θyAnd thetazTheta can be solved by the third photodetector 523 receiving 0-order lightxAnd thetayTheta can be solved by the third photodetector 523 receiving the 1 st order lightz. The change of the spot position on the third photodetector and the change of the three-axis angle have the following relationship:
through the formulas (i), (ii) and (iii), the angle change of the detection grating 410 in three rotational degrees of freedom can be calculated to obtain thetax,θyAnd thetazThen the angle quantities theta can be detectedx,θyAnd thetaz. Through a plurality of reflection prisms, a plurality of focusing convex lenses and a plurality of third photodetectors in the angle detection module, the angle variation of the detection grating 410 can be detected, and an accurate angle quantity can be obtained.
According to the utility model discloses the second aspect provides a grating chi, include the utility model discloses the detecting system of the first aspect. For example, the grating ruler including the detection system of the first aspect of the present invention is used in a numerical control machine tool to detect the coordinates of the tool and the workpiece, so as to observe and track the feeding error, and can play a role of compensating the motion error of the tool. By the detection system, the optical principle of the grating is utilized to work, the micro-distance displacement detection of the device can be carried out, and the detection effects of high precision and small error are achieved.
The above described system embodiments are merely illustrative, wherein the units illustrated as separate components may or may not be physically separate, i.e. may be located in one place, or may also be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (9)
1. A detection system, comprising:
the light source module is used for providing a detection light beam;
the light splitting module is used for receiving the detection light beam and performing light splitting processing to generate a plurality of first light beams and a plurality of second light beams;
the reference grating module is used for modulating the first light beam and generating reference light;
the detection grating module is used for modulating the second light beam and generating detection light;
the measuring module is used for detecting and processing coherent light generated by interference of the reference light and the detection light to obtain coherent information;
and obtaining the displacement variable quantity of the detection grating module according to the coherent information.
2. The detection system of claim 1, wherein the light source module comprises:
a plurality of light sources for generating an initial light beam;
the beam expanding lenses are used for performing beam expanding processing on the initial light beams and generating initial collimated light beams;
a plurality of diaphragms for adjusting the effective area of the initial collimated light beam;
and the linear polaroids are used for carrying out polarization processing on the initial collimated light beam and forming a detection light beam.
3. The detection system of claim 1, wherein the spectroscopy module comprises:
the polarization beam splitting prism is used for carrying out beam splitting processing on the detection light beam to generate a plurality of first light beams and a plurality of second light beams;
the light splitting flat plate is arranged between the polarization light splitting prism and the detection grating module and is used for splitting the second light beam;
the first quarter wave plate is arranged between the polarization splitting prism and the reference grating module;
and the second quarter wave plate is arranged between the light splitting flat plate and the polarization light splitting prism.
4. The detection system of claim 1, wherein the reference grating module comprises:
a reference grating that modulates the first beam;
the plurality of right-angle reference reflecting prisms comprise a first right-angle reference reflecting prism and a second right-angle reference reflecting prism, the first right-angle reference reflecting prism and the second right-angle reference reflecting prism are arranged between the reference grating and the light splitting module, and the first right-angle reference reflecting prism and the second right-angle reference reflecting prism are symmetrical about the central axis of the reference grating.
5. The system of claim 1, wherein the detection grating module comprises:
the detection gratings modulate the second light beam;
the right angle detection reflecting prisms comprise a first right angle detection reflecting prism and a second right angle detection reflecting prism, the first right angle detection reflecting prism and the second right angle detection reflecting prism are arranged between the detection grating and the light splitting module, and the first right angle detection reflecting prism and the second right angle detection reflecting prism are symmetrical about the central axis of the detection grating.
6. The detection system of claim 1, wherein the measurement module comprises:
the displacement measurement module is used for detecting and processing the coherent light and obtaining displacement;
and the angle measuring module is used for detecting and processing the coherent light and obtaining an angle quantity.
7. The detection system of claim 6, wherein the displacement measurement module comprises:
the non-polarization beam splitter prism is used for carrying out beam splitting processing on the reference light and the detection light;
a third quarter-wave plate for phase-modulating the reference light and the detection light;
the first polaroid is used for modulating the reference light and the detection light and generating a first coherent light beam;
a first photodetector for detecting the first coherent light beam;
the second polaroid is used for modulating the reference light and the detection light and generating a second coherent light beam;
a second photodetector for detecting the second coherent light beam;
the non-polarizing beam splitter prism is at least provided with two adjacent surfaces, wherein the two adjacent surfaces comprise a first sub surface and a second sub surface, the first polarizing plate is arranged opposite to the first sub surface, and the second polarizing plate is arranged opposite to the second sub surface.
8. The detection system of claim 6, wherein the angle measurement module comprises:
a plurality of reflecting prisms for adjusting a propagation path of the coherent light beam;
the focusing convex lenses are used for focusing the coherent light beams;
and the third photodetectors are used for detecting the coherent light beams and generating angle quantities.
9. Grating scale, characterized in that it comprises a detection system according to any one of claims 1 to 8.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111964587A (en) * | 2020-08-14 | 2020-11-20 | 清华大学深圳国际研究生院 | Detection system, detection method and grating scale |
| CN114001856A (en) * | 2021-10-08 | 2022-02-01 | 清华大学深圳国际研究生院 | Six-dimensional force sensor |
| WO2023155657A1 (en) * | 2022-02-21 | 2023-08-24 | 清华大学深圳国际研究生院 | Absolute six-degrees-of-freedom grating encoder |
| CN117091513A (en) * | 2023-10-19 | 2023-11-21 | 中国科学院长春光学精密机械与物理研究所 | Grating interferometry device and measurement method based on large-size light spots |
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- 2020-08-14 CN CN202021708709.4U patent/CN212747682U/en active Active
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111964587A (en) * | 2020-08-14 | 2020-11-20 | 清华大学深圳国际研究生院 | Detection system, detection method and grating scale |
| CN111964587B (en) * | 2020-08-14 | 2022-06-21 | 清华大学深圳国际研究生院 | Detection system, detection method and grating scale |
| CN114001856A (en) * | 2021-10-08 | 2022-02-01 | 清华大学深圳国际研究生院 | Six-dimensional force sensor |
| CN114001856B (en) * | 2021-10-08 | 2023-10-13 | 清华大学深圳国际研究生院 | Six-dimensional force sensor |
| WO2023155657A1 (en) * | 2022-02-21 | 2023-08-24 | 清华大学深圳国际研究生院 | Absolute six-degrees-of-freedom grating encoder |
| CN117091513A (en) * | 2023-10-19 | 2023-11-21 | 中国科学院长春光学精密机械与物理研究所 | Grating interferometry device and measurement method based on large-size light spots |
| CN117091513B (en) * | 2023-10-19 | 2024-01-02 | 中国科学院长春光学精密机械与物理研究所 | Grating interferometry device and measurement method based on large-size light spots |
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