A non-contact method for measuring the parallelism and perpendicularity of opaque optical plane parts

Abstract

The present invention discloses a non-contact method for measuring the parallelism and perpendicularity of an opaque optical plane part. The method uses a rotating platform, an autocollimator, and a reference optical cube to measure the parallelism of the part's parallel polished surface and the perpendicularity of the perpendicular polished surface. The rotating platform can adjust its horizontality and rotation. The reference optical cube is placed on the rotating platform surface, and the autocollimator is horizontally set to one side of the reference optical cube. During measurement, the part to be measured is placed on the reference optical cube with the polished surface and the same side surface kept substantially parallel. The reflected images are simultaneously observed in the autocollimator, and the angular deviation between the two reflected images is recorded. The rotating platform is rotated, and the reflected image is again captured horizontally by the autocollimator. The angular deviation between the two reflected images is recorded. The parallelism or perpendicularity is calculated and determined based on the two angular deviations. The present invention is not affected by placement errors and does not damage the part surface.

Description

Technical Field

[0001] The invention relates to the technical field of optical detection, and in particular to a method for non-contact measurement of the parallelism and verticality of an opaque optical plane part. Background Art

[0002] When inspecting the optical surface of an opaque optical plane part, there are two inspection parameters depending on the position of the polished surface of the part. One is for the case where the two polished surfaces of the part are arranged in parallel, and parallelism measurement is required. The other is for the case where the two polished surfaces of the part are arranged in vertical arrangement, and verticality measurement is required. Usually, the existing inspection method uses precision instrument measurement, which has high inspection accuracy but is expensive.

[0003] There are also those who use autocollimators for measurement, which can control the cost of use. When using an autocollimator to measure the parallelism of an opaque optical plane part, one surface of the part is attached to the optical flat crystal and the other surface is facing upward. The autocollimator is perpendicular to the optical flat crystal. The parallel light emitted by the autocollimator is irradiated on the optical flat crystal and the surface of the part at the same time. The reflected light returns to the autocollimator to form an image. The parallel error of the part is measured based on the distance between the optical flat crystal and the reflected image of the part surface.

[0004] The defects of this measurement are: first, there is an air gap or impurities when the part is bonded to the optical flat crystal, resulting in placement errors and low measurement reliability; second, the contact between the part surface and the optical flat crystal will damage the part surface.

[0005] When measuring verticality, a standard right angle is placed on an optical flat, and then one of the right-angled surfaces of the part is placed on the optical flat. An autocollimator is used to measure the vertical deviation between the two reflected images, which corresponds to the verticality of the part. This measurement method also has the disadvantage of placement error and damage to the part surface.

[0006] Therefore, there is an urgent need for a measurement method to accurately detect the optical surface of optical plane parts. Summary of the Invention

[0007] The present invention aims to solve the above technical problems and provide a method for non-contact measurement of the parallelism and perpendicularity of an opaque optical plane part, which is not affected by placement errors and does not damage the surface of the part.

[0008] In order to solve the above technical problems, the present invention provides a method for non-contact measurement of the parallelism of opaque optical plane parts, which uses a rotating platform, an autocollimator and a reference optical cube to measure the parallelism of two parallel optical surfaces of the part. The rotating platform can adjust the horizontality and rotation. The reference optical cube is placed on the surface of the rotating platform and has four vertical reference sides. The autocollimator is horizontally arranged on one side of the reference optical cube.

[0009] During measurement, the reference optical cube is first calibrated, and the levelness of the rotating platform is adjusted so that the scale positions of the four reference surfaces in the vertical direction are consistent and located in the middle of the eyepiece field of view within the autocollimator eyepiece field of view;

[0010] Place the part to be measured on the reference optical cube, aligning the first polished surface of the part to be measured with the reference side surface on the same side. In the eyepiece field of view of the autocollimator, see the first measured reflection image of the first polished surface and the first reference reflection image of the reference side surface simultaneously. Adjust the position of the part to be measured so that the first measured reflection image is close to the first reference reflection image. Record the angular deviation between the first measured reflection image and the first reference reflection image at this time, i.e., the horizontal deviation is θx1, and the vertical deviation is θy1.

[0011] Rotate the rotating platform and use the autocollimator to measure the second polished surface of the part to be measured. In the eyepiece field of view of the autocollimator, see the second measured reflected image of the second polished surface and the second reference reflected image of the reference side surface on the same side at the same time. The second measured reflected image and the second reference reflected image are located in the middle of the eyepiece. Record the angular deviation between the second measured reflected image and the second reference reflected image at this time, that is, the horizontal deviation is θx2, and the vertical deviation is θy2;

[0012] Calculate the parallelism difference: horizontal parallelism difference θx=|θx1+θx2|, vertical parallelism difference θy=|θy1+θy2|, and finally calculate the total parallelism difference of the measured parts:

[0013]

[0014] The quality of the part is determined by the total parallelism difference of the measured part.

[0015] Furthermore, in the horizontal direction deviation, the first measured reflection image and the second measured reflection image are negative on the left and positive on the right; in the up and down direction deviation, the first measured reflection image and the second measured reflection image are negative at the bottom and positive at the top.

[0016] Furthermore, the rotating platform is connected to the horizontal adjustment platform through a rotating shaft assembly, a base plate is provided below the horizontal adjustment platform, three horizontal adjustment screws are provided between the horizontal adjustment platform and the base plate, and three base feet are provided at the bottom of the base plate.

[0017] Furthermore, the reference optical cube is bonded and fixed on the surface of the rotating platform.

[0018] Furthermore, distinguishing marks are provided on the surface of the reference optical cube and at positions close to the four sides.

[0019] A method for non-contact measurement of the verticality of an opaque optical plane part uses a rotating platform, an autocollimator, and a reference optical cube to measure the parallelism of two vertical optical surfaces of the part. The rotating platform can adjust the horizontality and rotation. The reference optical cube is placed on the surface of the rotating platform and has four vertical reference sides. The autocollimator is horizontally arranged on one side of the reference optical cube.

[0020] During measurement, the reference optical cube is first calibrated, and the levelness of the rotating platform is adjusted so that the scale positions of the four reference surfaces in the vertical direction are consistent and located in the middle of the eyepiece field of view within the autocollimator eyepiece field of view;

[0021] Place the part to be measured on the reference optical cube, aligning the first polished surface of the part to be measured with the reference side surface on the same side. In the eyepiece field of view of the autocollimator, see the first measured reflection image of the first polished surface and the first reference reflection image of the reference side surface simultaneously. Adjust the position of the part to be measured so that the first measured reflection image is close to the first reference reflection image. Record the angular deviation between the first measured reflection image and the first reference reflection image at this time, i.e., the horizontal deviation, as Ax1.

[0022] Rotate the rotating platform and use the autocollimator to measure the second polished surface of the part to be measured. In the eyepiece field of view of the autocollimator, you can see the second measured reflected image of the second polished surface and the second reference reflected image of the reference side surface on the same side. The second measured reflected image and the second reference reflected image are located in the middle of the eyepiece. Record the angular deviation between the second measured reflected image and the second reference reflected image at this time, that is, the horizontal deviation is Ax2;

[0023] Then the angle between two adjacent polished surfaces on the part to be measured is A = 90° + Ax1 - Ax2;

[0024] The quality of the part is determined by measuring the angle between the parts.

[0025] Furthermore, in the horizontal direction deviation, the reflection images of the first measured reflection image and the second measured reflection image are negative on the left and positive on the right.

[0026] Furthermore, the rotating platform is connected to the horizontal adjustment platform through a rotating shaft assembly, a base plate is provided below the horizontal adjustment platform, three horizontal adjustment screws are provided between the horizontal adjustment platform and the base plate, and three base feet are provided at the bottom of the base plate.

[0027] Furthermore, the reference optical cube is bonded and fixed on the surface of the rotating platform.

[0028] Furthermore, distinguishing marks are provided on the surface of the reference optical cube and at positions close to the four sides.

[0029] Beneficial effects of the present invention:

[0030] 1. When the method of the present invention is used for measurement, the polished surface of the measured part does not need to come into contact with other objects, thus achieving a contactless measurement effect without causing damage to the part surface.

[0031] 2. Since the reference optical cube is used as a reference, the placement error of the parts can be effectively corrected and the parallelism and verticality of the parts can be accurately measured.

[0032] 3. Even if the part is placed on an optical surface, a protective film can be added between the bottom of the part and the reference optical cube to prevent damage to the optical surface without affecting the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic structural diagram of the detection device of the present invention;

[0034] Figure 2 This invention Figure 1 Schematic diagram of the structural cross section of the middle part;

[0035] Figure 3 Schematic diagram of the present invention when performing parallelism measurement;

[0036] Figure 4 This invention Figure 3 Schematic diagram of partial structure top view during measurement;

[0037] Figure 5 Schematic diagram of the present invention when performing parallelism measurement and measuring the second surface;

[0038] Figure 6 This invention Figure 5 Schematic diagram of partial structure top view during measurement;

[0039] Figure 7 This is a schematic diagram of the present invention when performing verticality measurement;

[0040] Figure 8 This invention Figure 7 Schematic diagram of partial structure top view during measurement;

[0041] Figure 9 Schematic diagram of measuring the verticality of a second adjacent surface during the present invention;

[0042] Figure 10 This invention Figure 9 Schematic diagram of a partial top view of the structure during measurement. DETAILED DESCRIPTION

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0044] Reference Figure 1 and Figure 2 As shown, an embodiment of a method for non-contact measurement of the parallelism of an opaque optical plane part of the present invention adopts a rotating platform 1, an autocollimator 2 and a reference optical cube 3 to measure the parallelism of two parallel polished surfaces of the part. The rotating platform can adjust the horizontality and rotation. Specifically, the rotating platform is connected to the horizontal adjustment platform 5 through a rotating shaft assembly 4. A base plate 6 is provided below the horizontal adjustment platform. Three horizontal adjustment screws 7 are provided between the horizontal adjustment platform and the base plate. Three base feet 8 are provided at the bottom of the base plate. The three base feet are used to stably support the base plate. The horizontal adjustment plate adjusts the horizontality on the base plate through the three horizontal adjustment screws. During the adjustment, since the rotating platform is connected to the horizontal adjustment platform through the rotating shaft assembly, the rotating platform and the horizontal adjustment platform move synchronously. Moreover, due to the setting of the rotating shaft assembly, the rotating platform can also rotate, and rotation adjustment is performed when measuring different polished surfaces. The operation is convenient. The reference optical cube is placed on the surface of the rotating platform, and the autocollimator is horizontally set on one side of the reference optical cube. The center line of the autocollimator is on the upper surface of the reference optical cube or slightly higher.

[0045] During measurement, the autocollimator should be placed flat and aligned with the S1 surface of the reference optical cube. The center line of the autocollimator should be on the upper surface of the optical cube or slightly higher. The reference reflected image of the S1 surface should be close to the center of the field of view in the vertical direction, that is, located in the middle of the eyepiece field of view. Rotate the rotating platform to observe the reference reflected images of the S1 surface, S2 surface, S3 surface and S4 surface respectively. The vertical scales of the four reference reflected images should be consistent. If there is any deviation, adjust the horizontal adjustment screw to make the vertical scales consistent.

[0046] Reference Figure 3 and Figure 4 As shown, the part to be measured is then placed on the reference optical cube, and the first polished surface of the part to be measured is placed in the same direction as the reference side surface on the same side, that is, the surface M1 is in the same direction as the surface S1. At this time, the reflected images of the M1 surface and the S1 surface can be seen simultaneously in the autocollimator, that is, the first measured reflected image and the first reference reflected image. The direction of the M1 surface is adjusted so that the first measured reflected image of the M1 surface is close to the first reference reflected image of the S1 surface. Specifically, the close distance is controlled within two minutes to ensure measurement accuracy. The angular deviation between the two images is recorded at this time, where the horizontal deviation is recorded as θx1, and the first measured reflected image of M1 is negative on the left side of the first reference reflected image and positive on the right side; the vertical deviation is recorded as θy1, and the first measured reflected image of M1 is negative below the first reference reflected image and positive above it.

[0047] Reference Figure 5 and Figure 6 As shown, the rotating platform is rotated, and the autocollimator measures the second polished surface of the part to be measured. The second measured reflected image of the second polished surface and the second reference reflected image of the reference side surface on the same side are simultaneously seen in the eyepiece field of view of the autocollimator, that is, the reflected images of the M2 and S3 surfaces are measured. With reference to the reflected images of the M2 and S3 surfaces seen simultaneously, the angular deviation between the two images at this time is recorded. The horizontal deviation is θx2. The second measured reflected image of M2 is negative to the left of the second reference reflected image and positive to the right. The vertical deviation is θy2. The second measured reflected image of M2 is negative below the second reference reflected image and positive above it.

[0048] Calculate the parallelism error: horizontal parallelism error θx=|θx1+θx2|. When the corresponding measured reflected image is reflected on the right surface relative to the reference reflected image, the left side of the part is thicker than the right side. Vertical parallelism error θy=|θy1+θy2|. When the corresponding measured reflected image is reflected on the upper surface relative to the reference reflected image, the lower side of the part is thicker than the upper side. Finally, calculate the total parallelism error of the measured part:

[0049]

[0050] The quality of the parts is judged based on the total parallel difference of the measured parts. When the total parallel difference is within the standard value range, it indicates that the parallelism of the parts is qualified, otherwise it is unqualified.

[0051] In the above mechanism, the rotating platform surface can also be provided with a retaining groove, into which the reference optical cube is placed. This reduces movement of the reference optical cube during rotation or leveling, and facilitates replacement while retaining the position. Distinguishing markings are also provided on the surface of the reference optical cube, near its four sides, to facilitate quick identification of the first and second polished surfaces during measurement.

[0052] In one embodiment, the present invention also provides a method for measuring the verticality of two polished surfaces of a part when they are arranged adjacent to each other using a rotating platform, an autocollimator and a reference optical cube. The method uses equipment consistent with the above embodiment, that is, during measurement, the part is directly placed on the reference optical cube without the need for additional auxiliary components such as vertical triangle blocks.

[0053] During measurement, the autocollimator should be placed flat and aligned with the S1 surface of the reference optical cube. The center line of the autocollimator should be on the upper surface of the optical cube or slightly higher. The reference reflected image of the S1 surface should be close to the center of the field of view in the vertical direction, that is, located in the middle of the eyepiece field of view. Rotate the rotating platform to observe the reference reflected images of the S1 surface, S2 surface, S3 surface and S4 surface respectively. The vertical scales of the four reference reflected images should be consistent. If there is any deviation, adjust the horizontal adjustment screw to make the vertical scales consistent.

[0054] Reference Figure 7 and Figure 8 As shown, the part to be measured is then placed on the reference optical cube, and the first polished surface of the part to be measured is placed in the same direction as the reference side surface on the same side, that is, the surface M1 is in the same direction as the surface S1. At this time, the reflected images of the M1 surface and the S1 surface can be seen simultaneously in the autocollimator, that is, the first measured reflected image and the first reference reflected image. The direction of the M1 surface is adjusted so that the first measured reflected image of the M1 surface is close to the first reference reflected image of the S1 surface. Specifically, the distance between the close images is controlled within five minutes to ensure measurement accuracy. The angular deviation between the two images is recorded at this time, where the horizontal deviation is recorded as Ax1. The first measured reflected image of M1 is negative on the left side of the first reference reflected image and positive on the right side.

[0055] Reference Figure 9 and Figure 10 As shown, the rotating platform is rotated, and the autocollimator measures the second polished surface of the part to be measured. In the eyepiece field of view of the autocollimator, the second measured reflected image of the second polished surface and the second reference reflected image of the reference side surface on the same side are simultaneously seen, that is, the reflected images of the M2 and S2 surfaces are measured. With reference to the reflected images of the M2 and S2 surfaces seen simultaneously, the angular deviation between the two images is recorded. The horizontal deviation is Ax2. The second measured reflected image of M2 is negative on the left side of the second reference reflected image and positive on the right side.

[0056] Then the angle between two adjacent polished surfaces on the part to be measured is A = 90° + Ax1 - Ax2;

[0057] The quality of the part is judged by the angle between the measuring tape and the part. When the angle is within the standard value range, it indicates that the parallelism of the part is qualified, otherwise it is unqualified.

[0058] Due to the perpendicularity error between the M1 and M2 surfaces and the upper surface of the quasi-reference optical cube, the measured angles of the M1 and M2 surfaces differ from the actual angles. However, this deviation is very small. Generally, if the vertical deviation of the reflected image is 10 degrees, the resulting perpendicularity measurement error is within 2 degrees. The perpendicularity of the side surfaces of generally processed optical parts is within 5 degrees, so the perpendicularity of the measurement surface to the upper surface of the cube can be ignored.

[0059] The present invention uses a low-cost device to measure the parallelism and perpendicularity of opaque parts. The cost is less than 3% of imported goniometers and 1% of domestic goniometers, or even lower. In addition, it uses a non-contact measurement method, eliminating damage to the polished part surface.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for non-contact measurement of parallelism of opaque optical plane parts, characterized in that: The parallelism of two parallel optical surfaces of a part is measured using a rotating platform, an autocollimator, and a reference optical cube. The rotating platform can adjust the horizontality and rotation. The reference optical cube is placed on the surface of the rotating platform and has four vertical reference sides. The autocollimator is horizontally set on one side of the reference optical cube. During measurement, the reference optical cube is first calibrated, and the levelness of the rotating platform is adjusted so that the scale positions of the four reference surfaces in the vertical direction are consistent and located in the middle of the eyepiece field of view within the autocollimator eyepiece field of view; Place the part to be measured on the reference optical cube, aligning the first polished surface of the part to be measured with the reference side surface on the same side. In the eyepiece field of view of the autocollimator, see the first measured reflection image of the first polished surface and the first reference reflection image of the reference side surface simultaneously. Adjust the position of the part to be measured so that the first measured reflection image is close to the first reference reflection image. Record the angular deviation between the first measured reflection image and the first reference reflection image at this time, i.e., the horizontal deviation is θx1, and the vertical deviation is θy1. Rotate the rotating platform and use the autocollimator to measure the second polished surface of the part to be measured. In the eyepiece field of view of the autocollimator, see the second measured reflected image of the second polished surface and the second reference reflected image of the reference side surface on the same side at the same time. The second measured reflected image and the second reference reflected image are located in the middle of the eyepiece. Record the angular deviation between the second measured reflected image and the second reference reflected image at this time, that is, the horizontal deviation is θx2, and the vertical deviation is θy2; Calculate the parallelism difference: the horizontal parallelism difference θx=|θx1+θx2|, the vertical parallelism difference θy=|θy1+θy2|, and finally calculate the total parallelism difference of the part to be measured: ； The quality of the part is judged based on the total parallelism difference of the part to be measured.

2. The method for non-contact measurement of parallelism of an opaque optical plane part according to claim 1, characterized in that: In the horizontal direction deviation, the first measured reflection image and the second measured reflection image are negative on the left and positive on the right; in the up and down direction deviation, the first measured reflection image and the second measured reflection image are negative at the bottom and positive at the top.

3. The method for non-contact measurement of parallelism of an opaque optical plane part according to claim 1, characterized in that: The rotating platform is connected to the horizontal adjustment platform through a rotating shaft assembly. A base plate is provided below the horizontal adjustment platform. Three level adjustment screws are provided between the horizontal adjustment platform and the base plate. Three base feet are provided at the bottom of the base plate.

4. The method for non-contact measurement of parallelism of an opaque optical plane component according to claim 3, wherein: The reference optical cube is bonded and fixed on the surface of the rotating platform.

5. The method for non-contact measurement of parallelism of an opaque optical plane component according to claim 1, characterized in that: Distinguishing marks are set on the surface of the reference optical cube and near the four side edges.

6. A method for non-contact measurement of the verticality of an opaque optical plane part, characterized in that: The verticality of two vertical optical surfaces of a part is measured using a rotating platform, an autocollimator, and a reference optical cube. The rotating platform can adjust the horizontality and rotation. The reference optical cube is placed on the surface of the rotating platform and has four vertical reference sides. The autocollimator is horizontally set on one side of the reference optical cube. During measurement, the reference optical cube is first calibrated, and the levelness of the rotating platform is adjusted so that the scale positions of the four reference surfaces in the vertical direction are consistent and located in the middle of the eyepiece field of view within the autocollimator eyepiece field of view; Place the part to be measured on the reference optical cube, aligning the first polished surface of the part to be measured with the reference side surface on the same side. In the eyepiece field of view of the autocollimator, see the first measured reflection image of the first polished surface and the first reference reflection image of the reference side surface simultaneously. Adjust the position of the part to be measured so that the first measured reflection image is close to the first reference reflection image. Record the angular deviation between the first measured reflection image and the first reference reflection image at this time, i.e., the horizontal deviation, as Ax1. Rotate the rotating platform and use the autocollimator to measure the second polished surface of the part to be measured. In the eyepiece field of view of the autocollimator, you can see the second measured reflected image of the second polished surface and the second reference reflected image of the reference side surface on the same side. The second measured reflected image and the second reference reflected image are located in the middle of the eyepiece. Record the angular deviation between the second measured reflected image and the second reference reflected image at this time, that is, the horizontal deviation is Ax2; Then the angle between two adjacent polished surfaces on the part to be measured is A=90°+Ax1-Ax2; The quality of the part is judged based on the angle between two adjacent polished surfaces on the part to be measured.

7. The method for non-contact measurement of verticality of an opaque optical plane part according to claim 6, characterized in that: In the horizontal direction deviation, the reflected images of the first measured reflected image and the second measured reflected image are negative on the left and positive on the right.

8. The method for non-contact measurement of verticality of an opaque optical plane part according to claim 6, characterized in that: The rotating platform is connected to the horizontal adjustment platform through a rotating shaft assembly. A base plate is provided below the horizontal adjustment platform. Three level adjustment screws are provided between the horizontal adjustment platform and the base plate. Three base feet are provided at the bottom of the base plate.

9. The method for non-contact measurement of verticality of an opaque optical plane part according to claim 8, characterized in that: The reference optical cube is bonded and fixed on the surface of the rotating platform.

10. The method for non-contact measurement of verticality of an opaque optical plane part according to claim 6, characterized in that: Distinguishing marks are set on the surface of the reference optical cube and near the four side edges.

Images