An encoder chip offset response test system

Abstract

The present invention provides an encoder chip offset response test system, comprising: a test machine, the test machine including a fixed fixture and an offset generating device, the fixed fixture being provided with a test motor, a test light source, and a code disk; the code disk being connected to the rotating shaft of the test motor; the code disk being provided with a light-transmitting hole; the offset generating device being provided with an encoder chip, the offset generating device including a horizontal displacement stage, a pitch displacement stage, and a rotation displacement stage; light from the test light source irradiating the encoder chip when passing through the light-transmitting hole; a test circuit including a power supply and an oscilloscope; the oscilloscope being connected to the encoder chip to display a response waveform; and an offset detection device for detecting the offset value of the encoder chip, comprising a dual-path interferometer for detecting horizontal displacement, an optical flow sensor for detecting rotational displacement, and a distortion detection camera for detecting pitch displacement. The encoder chip offset response test system provided by the present invention improves the accuracy of test results by using the offset detection device.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric testing, and in particular to an encoder chip offset response testing system. Background Art

[0002] An encoder chip generates sine, cosine, or square wave electrical signals using a light source and a rotating code disk. Therefore, encoder chip testing requires both of these elements. The encoder chip's position must be precisely aligned with the light source and code disk to produce high-quality signal output. Therefore, if the encoder chip is misaligned, the output signal quality deteriorates. Therefore, it's necessary to test the impact of encoder chip misalignment on the output signal.

[0003] Prior art invention patent application number CN202211394312.6, entitled "Fiber Low-Stress Clamping and Alignment Device for Ultra-High Polarization Extinction Ratio Generation," discloses a fiber low-stress clamping and alignment device for ultra-high polarization extinction ratio generation. The device comprises a fiber sample module, an adjustable magnetic clamping module, a binocular vision system module, a coaxial adjustment and alignment module, and an angular rotation and measurement module. The fiber sample module includes a first fiber sample and a second fiber sample; the fiber adjustable magnetic clamping module includes a first adjustable magnetic clamp and a second adjustable magnetic clamp; the coaxial adjustment and alignment module includes a first coaxial adjustment and alignment module and a second coaxial adjustment and alignment module; and the binocular vision system module, second coaxial adjustment and alignment module, and angular rotation and measurement module are fixed to a marble table. This device achieves extremely low-stress clamping and precise coaxial alignment of optical fibers, offering advantages such as low clamping stress, high alignment accuracy, and a wide range of applications. It can be used in the calibration of polarization extinction ratio test instruments. However, in the technical solution disclosed in this patent, the accuracy of the test results does not meet the requirements of the encoder chip.

[0004] Therefore, it is necessary to provide an encoder chip offset response test system to effectively solve the above problems. Summary of the Invention

[0005] The present invention provides an encoder chip offset response test system. The horizontal displacement, pitch displacement, and rotational displacement of the encoder chip after the offset is generated are used as offset values ​​to test their impact on the encoder chip output signal. The horizontal displacement is obtained by a dual-path interferometer, the rotational displacement is obtained by an optical flow sensor, and the pitch displacement is obtained by a distortion detection camera, thereby improving the accuracy of the test results.

[0006] An embodiment of the present invention provides an encoder chip offset response test system, comprising:

[0007] A testing machine, comprising a fixing fixture and a deviation generating device;

[0008] The fixed fixture is provided with a test motor, a test light source and a code disk; the code disk is connected to the rotating shaft of the test motor; a light-transmitting hole is provided on the code disk, and when the code disk is rotated until the light-transmitting hole faces the test light source, light from the test light source is allowed to pass through;

[0009] The displacement generating device is provided with an encoder chip, and the displacement generating device includes a horizontal displacement stage, a pitch displacement stage, and a rotation displacement stage for adjusting the horizontal displacement, pitch displacement, and rotation displacement of the encoder chip respectively; the light of the test light source shines on the encoder chip when passing through the light-transmitting hole;

[0010] A test circuit, comprising a power supply and an oscilloscope, wherein the power supply supplies power to the test motor, the test light source, and the encoder chip; the oscilloscope is connected to the encoder chip to display a response waveform;

[0011] The deviation detection device is used to detect the deviation value of the encoder chip, including a dual-path interferometer for detecting horizontal displacement, an optical flow sensor for detecting rotational displacement, and a distortion detection camera for detecting pitch displacement.

[0012] Preferably, the horizontal displacement stage is rectangular, and the side surfaces of the horizontal displacement stage are coated with a reflective film; the dual-path interferometer has two displacement detection interference light paths, which are used to detect displacement in the X direction and displacement in the Y direction respectively;

[0013] The displacement detection interference optical path includes a laser, a dichroic mirror, and a photosensitive diode. The light beam emitted by the laser is divided into two vertically oscillating first and second light beams after passing through the dichroic mirror. The first light beam is vertically irradiated onto the reflective film, reflected onto the dichroic mirror, and then reflected onto the photosensitive diode. The second light beam is directly irradiated onto the photosensitive diode. The photosensitive diode receives a signal formed by the coherence of the first and second light beams, and calculates the displacement in the corresponding direction based on the signal received by the photosensitive diode.

[0014] Preferably, the X-direction displacement and the Y-direction displacement are calculated by the following formulas respectively:

[0015]

[0016]

[0017] Where N is the displacement in the X direction, M is the displacement in the Y direction, To detect the initial phase of the photodiode for X-direction displacement, The end phase of the photodiode for detecting the displacement in the X direction, λ X The emission wavelength of the laser for detecting displacement in the X direction;

[0018] To detect the initial phase of the photodiode for Y-direction displacement, The displacement end phase of the photodiode for detecting the displacement in the Y direction, λ Y To detect the emission wavelength of the Y-direction displacement laser;

[0019] The horizontal displacement is calculated using the following formula:

[0020]

[0021] Where R is the horizontal displacement.

[0022] Preferably, the optical flow sensor includes a detection light source and an image sensor, the light from the detection light source is irradiated onto the side of the rotational displacement stage, and the image sensor captures the light reflected back from the side of the rotational displacement stage and records a two-dimensional image matrix; the rotational displacement stage is cylindrical, and the side of the rotational displacement stage is a rough surface, so that when the rotational displacement stage is at different angles, different two-dimensional image matrices are formed on the image sensor; the rotational displacement is calculated by comparing the two-dimensional image matrices.

[0023] Preferably, the rotational displacement is calculated by the following formula:

[0024]

[0025] Where Theta is the rotational displacement, k is the number of displaced pixels of the same element in the two-dimensional image matrix at the beginning of the displacement and the two-dimensional image matrix at the end of the displacement, s is the size of the pixel unit, and radii is the distance between the image sensor and the rotation axis of the rotation stage;

[0026] The number of displacement pixels is calculated using the following formula:

[0027] A=IO(x,y)∩IE(x,y)

[0028] IO-A=P1(c1,d1)∪O(a,b)∪P(e1,f1)

[0029] IE-A=P2(c2,d2)∪O(a,b)∪P(e2,f2)

[0030] k=MAX(e2-e1,c2-c1)

[0031] Where IO(x, y) is the two-dimensional image matrix at the beginning of the displacement; IE(x, y) is the two-dimensional image matrix at the end of the displacement; a and b are the dimensional parameters of matrix A, and c1, d1, e1, f1, c2, d2, e2, and f2 are all dimensional parameters solved by the matrix.

[0032] Preferably, the pitch displacement stage is rectangular, and a standard grid is provided at the bottom of the pitch displacement stage. The intersections of the standard grid form test points arranged at equal intervals in the horizontal and vertical directions, and the test points are used to read coordinate data when the distortion detection camera takes pictures. The distortion detection camera is arranged directly opposite the bottom of the pitch displacement stage, and the pitch displacement is calculated based on the image of the standard grid taken by the distortion detection camera.

[0033] Preferably, the pitch displacement is calculated by the following formula:

[0034]

[0035] Alpha=cos- 1 (ava(ΔA n ))

[0036] Among them, Alpha is the pitch displacement, x n1 is the horizontal coordinate of the test point at the end of the first row of grids at the beginning of the displacement in the image, and x1 is the horizontal coordinate of the test point at the beginning of the first row of grids at the beginning of the displacement in the camera image; e1 is the horizontal coordinate of the test point at the end of the first row of grid in the camera image at the end of displacement, x 01 The horizontal coordinate of the test point at the beginning of the first row of grid at the end of displacement in the camera image; for each row of test points, a ΔA is calculated n , n is the number of rows.

[0037] Preferably, the horizontal displacement stage, the rotation displacement stage and the pitch displacement stage of the displacement generating device are arranged in sequence from bottom to top, the encoder chip is arranged on a test PCB board, and the test PCB board is fixed on the pitch displacement stage.

[0038] Preferably, the fixed tooling includes a measuring platform, a Z-axis travel table and a testing platform, the bottom end of the Z-axis travel table is fixed on the measuring platform, the testing platform is movably arranged on the Z-axis travel table, and the height of the testing platform is adjustable; the testing motor is installed on the testing platform, and the testing light source is fixed on the testing platform; the displacement generating device, the two-path interferometer, the optical flow sensor and the distortion detection camera are all arranged on the measuring platform.

[0039] Preferably, the test circuit further includes an ammeter, which is connected to the test light source to measure the current value of the test light source, and the test light source is an LED light source.

[0040] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0041] An encoder chip offset response test system provided by an embodiment of the present invention includes an offset generating device to adjust the horizontal, pitch, and rotational displacements of the encoder chip. The horizontal, pitch, and rotational displacements of the encoder chip after the offset are used as offset values ​​to test their impact on the encoder chip output signal, resulting in stronger test correlation and more accurate results.

[0042] Furthermore, the horizontal displacement is measured by a dual-path interferometer, the rotational displacement is measured by an optical flow sensor, and the pitch displacement is measured by a distortion detection camera, which improves the accuracy of the measurement results and further enhances the accuracy of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention, not all embodiments. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0044] Figure 1 A schematic diagram of the structure of a test machine for an encoder chip offset response test system provided by one embodiment of the present invention;

[0045] Figure 2 A schematic diagram of a test circuit for an encoder chip offset response test system provided by one embodiment of the present invention;

[0046] Figure 3 A schematic diagram showing a principle of measuring horizontal displacement using a dual-path interferometer in an encoder chip offset response test system according to an embodiment of the present invention;

[0047] Figure 4 A schematic diagram showing the principle of measuring rotational displacement using an optical flow sensor in an encoder chip offset response test system provided by one embodiment of the present invention;

[0048] Figure 5 A schematic diagram of a principle for measuring pitch displacement using a distortion detection camera in an encoder chip offset response test system provided in accordance with an embodiment of the present invention.

[0049] In the picture:

[0050] 1. Test machine; 11. Fixture fixture; 111. Measuring platform; 112. Z-axis travel platform; 113. Test platform; 12. Deflection generator; 121. Horizontal translation stage; 1211. Reflective film; 122. Rotational translation stage; 123. Pitch translation stage; 1231. Standard grid;

[0051] 2. Test circuit; 21. Test motor; 22. Test light source; 23. Code disk; 24. Encoder chip; 25. Power supply; 26. Oscilloscope; 27. Ammeter; 28. Test PCB board;

[0052] 3. Deviation detection equipment; 31. Two-way interferometer; 311. Laser; 312. Dichroic mirror; 313. Photodiode; 32. Optical flow sensor; 321. Detection light source; 322. Image sensor; 33. Distortion detection camera. DETAILED DESCRIPTION

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0054] The technical solution of the present invention is described in detail below with reference to specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0055] Based on the problems existing in the prior art, an embodiment of the present invention provides an encoder chip offset response test system, which uses the horizontal displacement, pitch displacement and rotational displacement of the encoder chip after the offset is generated as the offset value to test its impact on the output signal of the encoder chip. The horizontal displacement is obtained by a dual-path interferometer, the rotational displacement is obtained by an optical flow sensor, and the pitch displacement is obtained by a distortion detection camera, thereby improving the accuracy of the test results.

[0056] Figure 1 A schematic diagram of the structure of a test machine for an encoder chip offset response test system provided by one embodiment of the present invention; Figure 2 A schematic diagram of a test circuit for an encoder chip offset response test system provided by one embodiment of the present invention; Figure 3 A schematic diagram showing a principle of measuring horizontal displacement using a dual-path interferometer in an encoder chip offset response test system according to an embodiment of the present invention; Figure 4A schematic diagram showing the principle of measuring rotational displacement using an optical flow sensor in an encoder chip offset response test system provided by one embodiment of the present invention; Figure 5 A schematic diagram of a principle for measuring pitch displacement using a distortion detection camera in an encoder chip offset response test system provided in accordance with an embodiment of the present invention.

[0057] See now Figures 1 to 5 The embodiment of the present invention provides an encoder chip offset response test system, comprising:

[0058] The test machine 1 includes a fixed fixture 11 and a displacement generating device 12.

[0059] The fixture 11 is provided with a test motor 21, a test light source 22, and a code disk 23; the code disk 23 is connected to the rotating shaft of the test motor 21; a light-transmitting hole is provided on the code disk 23, and when the code disk 23 is rotated so that the light-transmitting hole is facing the test light source 22, light from the test light source 22 is allowed to pass through;

[0060] The displacement generating device 12 is provided with an encoder chip 24, and includes a horizontal displacement stage 121, a pitch displacement stage 123, and a rotation displacement stage 122 for adjusting the horizontal displacement, pitch displacement, and rotation displacement of the encoder chip 24, respectively. The light from the test light source 22 shines on the encoder chip 24 when passing through the light-transmitting hole.

[0061] In one embodiment, the horizontal displacement stage 121 , the rotational displacement stage 122 and the pitch displacement stage 123 of the displacement generating device 12 are arranged sequentially from bottom to top, the encoder chip 24 is arranged on the test PCB board 28 , and the test PCB board 28 is fixed on the pitch displacement stage 123 .

[0062] Test circuit 2, test circuit 2 includes a test motor 21, a test light source 22, an encoder chip 24, a power supply 25 and an oscilloscope 26. The power supply 25 supplies power to the test motor 21, the test light source 22 and the encoder chip 24; the oscilloscope 26 is connected to the encoder chip 24 to display the response waveform;

[0063] In one embodiment, the test circuit 2 further includes an ammeter 27 connected to the test light source 22 for measuring the current value of the test light source 22 . The current value corresponds to the brightness of the test light source 22 . The test light source 22 is an LED light source.

[0064] The deviation detection device 3 is used to detect the deviation value of the encoder chip 24, including a dual-path interferometer 31 for detecting horizontal displacement, an optical flow sensor 32 for detecting rotational displacement, and a distortion detection camera 33 for detecting pitch displacement.

[0065] In one embodiment, the fixed tooling 11 includes a measuring platform 111, a Z-axis travel table 112 and a testing platform 113. The bottom end of the Z-axis travel table 112 is fixed on the measuring platform 111, and the testing platform 113 is movably set on the Z-axis travel table 112. The height of the testing platform 113 is adjustable; the test motor 21 is installed on the testing platform 113, and the test light source 22 is fixed on the testing platform 113; the deviation generating device 12, the two-path interferometer 31, the optical flow sensor 32 and the distortion detection camera 33 are all arranged on the measuring platform 111.

[0066] In a specific implementation, the horizontal displacement stage 121 is rectangular, and the side of the horizontal displacement stage 121 is coated with a reflective film 1211; the dual-path interferometer 31 has two displacement detection interference light paths, which are used to detect displacement in the X direction and displacement in the Y direction respectively;

[0067] Taking the displacement detection interference optical path for detecting displacement in the X direction as an example, it includes a laser 311, a dichroic mirror 312, and a photodiode (Pd, Photo-Diode) 313. The light beam emitted by the laser 311 is divided into two vertically oscillating first and second light beams after passing through the dichroic mirror 312. The first light beam is vertically irradiated by the reflective film 1211, reflected by the dichroic mirror 312, and then reflected by the photodiode 313. The second light beam is directly irradiated by the photodiode 313. The photodiode 313 receives the signal formed by the coherence of the first and second light beams, and calculates the displacement in the X direction based on the signal received by the photodiode 313.

[0068] The displacement detection interference optical path for detecting displacement in the Y direction is similar to the displacement detection interference optical path for detecting displacement in the X direction, and will not be described in detail here.

[0069] Specifically, the X-direction displacement and the Y-direction displacement are calculated using the following formulas:

[0070]

[0071]

[0072] Where N is the displacement in the X direction, M is the displacement in the Y direction, To detect the initial phase of the photodiode 313 that is displaced in the X direction, The photodiode 313 is used to detect the end phase of the displacement in the X direction. X The emission wavelength of the laser 311 for detecting displacement in the X direction;

[0073] To detect the initial phase of the photodiode 313 that is displaced in the Y direction, The photodiode 313 is used to detect the end phase of the displacement in the Y direction. YTo detect the emission wavelength of the Y-direction displacement laser 311;

[0074] The horizontal displacement is calculated using the following formula:

[0075]

[0076] Where R is the horizontal displacement.

[0077] In a specific implementation, the optical flow sensor 32 includes a detection light source 321 and an image sensor 322. The detection light source 321 is an LED light source. The light from the detection light source 321 is irradiated onto the side of the rotational displacement stage 122. The image sensor 322 captures the light reflected back from the side of the rotational displacement stage 122 and records a two-dimensional image matrix. The rotational displacement stage 122 is cylindrical, and the side of the rotational displacement stage 122 is a rough surface, so that when the rotational displacement stage 122 is at different angles, different two-dimensional image matrices are formed on the image sensor 322. The rotational displacement is calculated by comparing the two-dimensional image matrices.

[0078] Specifically, the rotational displacement is calculated using the following formula:

[0079]

[0080] Wherein, Theta is the rotation displacement, k is the number of displaced pixels of the same element in the two-dimensional image matrix at the beginning of the displacement and the two-dimensional image matrix at the end of the displacement, s is the size of the pixel unit, and radii is the distance between the image sensor 322 and the rotation axis of the rotation stage 122;

[0081] The number of displacement pixels is calculated using the following formula:

[0082] A=IO(x,y)∩IE(x,y)

[0083] IO-A=P1(c1,d1)∪O(a,b)∪P(e1,f1)

[0084] IE-A=P2(c2,d2)∪O(a,b)∪P(e2,f2)

[0085] k=MAX(e2-e1,c2-c1)

[0086] Where IO(x, y) is the two-dimensional image matrix at the beginning of the displacement; IE(x, y) is the two-dimensional image matrix at the end of the displacement; a and b are the dimensional parameters of matrix A, and c1, d1, e1, f1, c2, d2, e2, and f2 are all dimensional parameters solved by the matrix.

[0087] In a specific implementation, the pitch displacement stage 123 is rectangular, and a standard grid 1231 is set at the bottom of the pitch displacement stage 123. The intersection of the standard grid 1231 forms test points arranged at equal intervals in the horizontal and vertical directions. The test points are used to read coordinate data when the distortion detection camera 33 takes pictures; the distortion detection camera 33 is set directly opposite the bottom of the pitch displacement stage 123, and the pitch displacement is calculated based on the image of the standard grid 1231 taken by the distortion detection camera 33.

[0088] Specifically, the pitch displacement is calculated using the following formula:

[0089]

[0090] Alpha=cos -1 (ava(ΔA n ))

[0091] Among them, Alpha is the pitch displacement, x n1 is the horizontal coordinate of the test point at the end of the first row of grids at the beginning of the displacement in the image, and x1 is the horizontal coordinate of the test point at the beginning of the first row of grids at the beginning of the displacement in the camera image; e1 is the horizontal coordinate of the test point at the end of the first row of grid in the camera image at the end of displacement, x 01 The horizontal coordinate of the test point at the beginning of the first row of grid at the end of displacement in the camera image; for each row of test points, a ΔA is calculated n , n is the number of rows.

[0092] The following is an example of an encoder chip offset response test system provided by the present invention during actual testing:

[0093] Assuming that the encoder chip 24 only produces displacement in the X direction, the phase before displacement After displacement The wavelength λ of the laser 311 used X =355nm, and the displacement of the encoder chip 24 in the X direction is calculated to be N=9370.03nm.

[0094] Assume that the encoder chip 24 only generates displacement in the rotation direction, the radius of the image sensor 322 relative to the rotation axis is radii=30mm, and the size of the pixel unit of the image sensor 322 is s=1 um, the two-dimensional image matrix IO captured by the image sensor 322 at the beginning of the displacement is [0, 1, 0, 0, 0,; 0, 1, 0, 0, 0; 0, 1, 0, 0, 0; 0, 1, 0, 0, 0; 0, 1, 0, 0, 0], and the two-dimensional image matrix IE captured by the image sensor 322 at the beginning of the displacement is [0, 0, 0, 0, 1; 0, 0, 0, 0, 1; 0, 0, 0, 0, 1; 0, 0, 0, 0, 1; 0, 0, 0, 0, 1]; according to the algorithm, the number of displacement pixels k = 3, then the rotation displacement Theta = 0.0057°.

[0095] Assume that the encoder chip 24 only generates displacement in the pitch direction, and the standard grid of the pitch stage 123 has four test points located at (1, 1), (-1, 1), (1, -1), and (-1, -1); after displacement, the four test points fall at (1.5, 1.2), (-0.2, 0.5), (-0.2, -0.5), and (1.5, -1.2); then

[0096] ΔA1=(1.5-(-0.2)) / (1-(-1))=0.85;

[0097] ΔA2=(1.5-(-0.2)) / (1-(-1))=0.85;

[0098] Alpha=31.78°.

[0099] It can be seen from the test data of the above examples in actual testing that the encoder chip offset response test system provided by the present invention improves the accuracy of the test results by using the offset detection device.

[0100] In summary, the encoder chip offset response test system provided by the embodiment of the present invention includes an offset generating device 12 for adjusting the horizontal displacement, pitch displacement, and rotational displacement of the encoder chip 24. The horizontal displacement, pitch displacement, and rotational displacement of the encoder chip 24 after the offset is generated are used as offset values ​​to test their impact on the output signal of the encoder chip 24. This provides a stronger test correlation and more accurate results.

[0101] Furthermore, the horizontal displacement is measured by a two-way interferometer 31, the rotational displacement is measured by an optical flow sensor 32, and the pitch displacement is measured by a distortion detection camera 33, thereby improving the accuracy of the measurement results and further enhancing the accuracy of the test results.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An encoder chip offset response test system, characterized in that: include: A testing machine, comprising a fixing fixture and a deviation generating device; The fixed fixture is provided with a test motor, a test light source and a code disk; the code disk is connected to the rotating shaft of the test motor; a light-transmitting hole is provided on the code disk, and when the code disk is rotated until the light-transmitting hole faces the test light source, light from the test light source is allowed to pass through; The displacement generating device is provided with an encoder chip, and the displacement generating device includes a horizontal displacement stage, a pitch displacement stage, and a rotation displacement stage for adjusting the horizontal displacement, pitch displacement, and rotation displacement of the encoder chip respectively; the light of the test light source shines on the encoder chip when passing through the light-transmitting hole; A test circuit, comprising a power supply and an oscilloscope, wherein the power supply supplies power to the test motor, the test light source, and the encoder chip; the oscilloscope is connected to the encoder chip to display a response waveform; A deviation detection device for detecting the deviation value of the encoder chip, comprising a dual-path interferometer for detecting horizontal displacement, an optical flow sensor for detecting rotational displacement, and a distortion detection camera for detecting pitch displacement; The optical flow sensor includes a detection light source and an image sensor. The light from the detection light source is irradiated onto the side of the rotational translation stage. The image sensor captures the light reflected back from the side of the rotational translation stage and records a two-dimensional image matrix. The rotational translation stage is cylindrical and has a rough surface on the side of the rotational translation stage. When the rotational translation stage is at different angles, different two-dimensional image matrices are formed on the image sensor. The rotational displacement is calculated by comparing the two-dimensional image matrices.

2. The encoder chip offset response test system according to claim 1, characterized in that: The horizontal displacement stage is rectangular, and the side of the horizontal displacement stage is coated with a reflective film; the dual-path interferometer has two displacement detection interference light paths, which are used to detect displacement in the X direction and displacement in the Y direction respectively; The displacement detection interference optical path includes a laser, a dichroic mirror, and a photosensitive diode. The light beam emitted by the laser is divided into two vertically oscillating first and second light beams after passing through the dichroic mirror. The first light beam is vertically irradiated onto the reflective film, reflected onto the dichroic mirror, and then reflected onto the photosensitive diode. The second light beam is directly irradiated onto the photosensitive diode. The photosensitive diode receives a signal formed by the coherence of the first and second light beams, and calculates the displacement in the corresponding direction based on the signal received by the photosensitive diode.

3. The encoder chip offset response test system according to claim 2, characterized in that: The X-direction displacement and the Y-direction displacement are calculated by the following formulas: Where N is the displacement in the X direction, M is the displacement in the Y direction, To detect the initial phase of the photodiode for X-direction displacement, The end phase of the photodiode for detecting the displacement in the X direction, λ X The emission wavelength of the laser for detecting displacement in the X direction; To detect the initial phase of the photodiode for Y-direction displacement, The displacement end phase of the photodiode for detecting the displacement in the Y direction, λ Y To detect the emission wavelength of the Y-direction displacement laser; The horizontal displacement is calculated using the following formula: Where R is the horizontal displacement.

4. The encoder chip offset response test system according to claim 1, characterized in that: The pitch stage is rectangular, and a standard grid is provided at the bottom of the pitch stage. The intersections of the standard grid form test points arranged at equal intervals in the horizontal and vertical directions. The test points are used to read coordinate data when the distortion detection camera takes pictures. The distortion detection camera is set directly opposite the bottom of the pitch stage, and the pitch displacement is calculated based on the image of the standard grid taken by the distortion detection camera.

5. The encoder chip offset response test system according to claim 4, characterized in that: The pitch displacement is calculated by the following formula: Alpha=cos -1 (where(ΔA n )) Among them, Alpha is the pitch displacement, x n1 is the horizontal coordinate of the test point at the end of the first row of grids at the beginning of the displacement in the image, and x1 is the horizontal coordinate of the test point at the beginning of the first row of grids at the beginning of the displacement in the camera image; e1 is the horizontal coordinate of the test point at the end of the first row of grid in the camera image at the end of displacement, x 01 The horizontal coordinate of the test point at the beginning of the first row of grid at the end of displacement in the camera image; for each row of test points, a ΔA is calculated n , n is the number of rows.

6. The encoder chip offset response test system according to claim 1, characterized in that: The horizontal displacement stage, the rotation displacement stage and the pitch displacement stage of the displacement generating device are arranged in sequence from bottom to top, the encoder chip is arranged on a test PCB board, and the test PCB board is fixed on the pitch displacement stage.

7. The encoder chip offset response test system according to claim 1, characterized in that: The fixed tooling includes a measuring platform, a Z-axis travel table and a testing platform. The bottom end of the Z-axis travel table is fixed on the measuring platform. The testing platform is movably arranged on the Z-axis travel table. The height of the testing platform is adjustable. The testing motor is installed on the testing platform. The testing light source is fixed on the testing platform. The displacement generating device, the two-path interferometer, the optical flow sensor and the distortion detection camera are all arranged on the measuring platform.

8. The encoder chip offset response test system according to claim 1, characterized in that: The test circuit further includes an ammeter, which is connected to the test light source and is used to measure the current value of the test light source. The test light source is an LED light source.

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