Electrode Cage Electrode Opposite Area Measuring Device and Measuring Method

Abstract

The present invention relates to the technical field of geometric quantity measurement and testing, and in particular to an electrode cage electrode facing area measurement device and measurement method using interferometer beam splitting measurement; the measurement device includes an interferometer, a polarizer, a first quarter-wave plate, a polarization beam splitter prism, a second quarter-wave plate, and a reflector arranged in sequence; after the outgoing light of the interferometer passes through the polarizer and the first quarter-wave plate in sequence, it is split into a first P-polarized light and a first S-polarized light by the polarization beam splitter prism; the present invention utilizes the polarization beam splitter prism to split the light, and by reasonably designing the optical path, the in-situ high-precision measurement of the facing area of two groups of electrodes on the inner surface of the electrode cage can be realized without repeated disassembly of the measurement device and the electrode cage; in addition, compared with the conventional three-coordinate measurement means, this method adopts non-contact measurement and will not affect the surface quality of the electrodes.

Description

Technical Field

[0001] The present invention relates to the technical field of geometric quantity measurement and testing, and particularly relates to a measuring device and a measuring method for measuring the facing area of electrodes in an electrode cage by using interferometer beam splitting measurement. Background Art

[0002] The capacitive inertial sensor used for space gravitational wave detection mainly includes a test mass (TM), an electrode cage, and front-end electronics. The electrode cage contains multiple groups of symmetrically arranged capacitive plates. The distance between the test mass and the capacitive plates can be obtained by measuring the capacitance value between the test mass and the capacitive plates, and then the pose of the test mass relative to the spacecraft can be obtained. Then, a voltage is applied to the capacitive plates to generate an electrostatic force between the test mass and the capacitive plates, thereby realizing electrostatic control of multiple degrees of freedom of the test mass.

[0003] Along the sensitive axis direction of the test mass, there are two groups of symmetrically arranged capacitive plates on the electrode cage. Due to inevitable errors in the processing process, there must be an asymmetry between each group of electrodes, and the electrode asymmetry has a direct impact on the loss of the system range. The area asymmetry requirement for these two groups of electrodes is: δA < 5%. The electrodes are installed on the inner surface of the electrode cage, that is, the electrodes are located inside the electrode cage, and it is impossible to directly measure the electrode area deviation of each pair of electrodes through conventional measuring equipment.

[0004] Usually, the three-coordinate contact method is used to measure the relative position between the inner surface electrodes and the outer surface, and then the position of the electrodes on the inner surface of the electrode cage is indirectly obtained by measuring the outer surface of the electrode cage. The three-coordinate measurement method is an indirect measurement, that is, the position of the electrodes on the inner surface of the electrode cage is indirectly obtained by measuring the outer surface of the electrode cage, and the error is large. And this method uses contact measurement, which will affect the surface quality of the electrodes. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a non-contact measurement method and a corresponding measuring device that can directly measure the facing area of two groups of electrodes on the inner surface of the electrode cage.

[0006] The present invention provides a measuring device for measuring the facing area of electrodes in an electrode cage. The measuring device includes an interferometer, a polarizer, a first quarter-wave plate, a polarization beam splitter prism, a second quarter-wave plate, and a mirror arranged in sequence;

[0007] After the outgoing light of the interferometer passes through the polarizer and the first quarter-wave plate in sequence, it is split into a first P-polarized light and a first S-polarized light by the polarization beam splitter prism; the polarization beam splitter prism is arranged at 45 degrees with respect to the electrode.

[0008] The present invention also provides a method for measuring the facing area of the electrodes of an electrode cage. The measurement method is implemented by the above-mentioned device for measuring the facing area of the electrodes of the electrode cage. The inner surface of the electrode cage includes two groups of electrodes, and the two groups of electrodes include a first group of electrodes to be measured and a second group of electrodes to be measured.

[0009] Preferably, the measurement method includes the steps of:

[0010] S1. After the outgoing light of the interferometer passes through the polarizer and the first quarter-wave plate in sequence, it is split into a first P-polarized light and a first S-polarized light by the polarization beam splitter prism;

[0011] S2. The first S-polarized light is reflected by the first group of electrodes to be measured and the polarization beam splitter prism, and returns to the outgoing light path of the interferometer;

[0012] S3. After the first P-polarized light passes through the polarization beam splitter prism, it passes through the second quarter-wave plate, and then is reflected by the mirror. The first P-polarized light becomes a second S-polarized light;

[0013] S4. The second S-polarized light is reflected by the second group of electrodes to be measured and the polarization beam splitter prism, and returns to the reflection light path of the mirror;

[0014] In the reflection light path, the second S-polarized light passes through the second quarter-wave plate twice and then becomes a second P-polarized light; the second P-polarized light passes through the polarization beam splitter prism and returns to the outgoing light path of the interferometer;

[0015] S5. The first S-polarized light and the second P-polarized light converge, interfere after passing through the first quarter-wave plate and the polarizer, observe the reflected wavefront through the interferometer, and calculate the actual facing area of the first group of electrodes to be measured and the second group of electrodes to be measured by calculating the number of pixels in the interference part and the number of pixels in the non-interference part.

[0016] Preferably, the mirror is a plane mirror.

[0017] Preferably, the root mean square value RMS of the surface shape of the plane mirror is <λ / 20.

[0018] Preferably, the internal size of the electrode cage is 52mm×52mm×52mm, the outer envelope size of the electrode group is 36mm×36mm; the size of the polarization beam splitter prism is 50mm×50mm×50mm, the diameter of the first quarter-wave plate >51mm, and the diameter of the mirror >51mm.

[0019] The electrode cage electrode facing area measuring device and measuring method provided by the present invention utilize a polarization beam splitting prism for beam splitting, and by reasonably designing the optical path, the in-situ high-precision measurement of the facing area of two groups of electrodes on the inner surface of the electrode cage can be realized without repeated disassembly of the measuring device and the electrode cage. In addition, compared with the conventional three-coordinate measurement method, this method adopts non-contact measurement and will not affect the surface quality of the electrodes. Moreover, the electrode cage electrode facing area measuring device and measuring method provided by the present invention solve the problems of "difficult contact with the outer frame closure of the facing electrodes" and "in-situ measurement and calibration after installation" in the electrode cage. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 FIG. is a schematic diagram of the principle of the electrode cage electrode facing area measuring method in the specific embodiment of the present invention.

[0021] Figure 2 FIG. is a schematic diagram of the distribution of the electrodes to be measured in the electrode cage in the specific embodiment of the present invention.

[0022] Figure 3 FIG. is a schematic diagram of the original installation detection of the electrode cage electrode facing area measuring device in the specific embodiment of the present invention.

[0023] Reference numerals:

[0024] 1 interferometer; 2 polarizer; 3 first quarter-wave plate; 4 polarization beam splitting prism; 5 second quarter-wave plate; 6 plane mirror; 7 first group of electrodes to be measured; 8 second group of electrodes to be measured; 9 electrode cage; 10 six-legged displacement stage. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0026] In the specific embodiment of the present invention, an electrode cage electrode facing area measuring device is provided, as Figure 1 shown. The measuring device includes an interferometer 1, a polarizer 2, a first quarter-wave plate 3, a polarization beam splitting prism 4, a second quarter-wave plate 5 and a mirror 6 arranged in sequence. After the outgoing light of the interferometer 1 passes through the polarizer 2 and the first quarter-wave plate 3 in sequence, it is split by the polarization beam splitting prism 4 into a first P-polarized light and a first S-polarized light. The measuring device of the present invention utilizes an interferometer and a beam splitting element to divide the outgoing beam of the interferometer into two paths, which are respectively irradiated on two opposite inner surfaces, and finally the two beams of light are converged together and returned to the interferometer for interference, so as to realize the measurement of the facing area of the two electrodes on the inner surface of the electrode cage.

[0027] AsFigure 1 and Figure 2 As shown in Figure 2 , a method for measuring the facing area of electrodes in an electrode cage is provided in a specific embodiment of the present invention. The measurement method is implemented by the above-mentioned device for measuring the facing area of electrodes in an electrode cage; as Figure 2 shown in Figure 2 , it is a schematic diagram of the distribution of electrodes to be measured in an electrode cage in a specific embodiment of the present invention. The inner surface of the electrode cage includes an electrode group, and the electrode group includes a first electrode group to be measured 7 and a second electrode group to be measured 8 arranged oppositely.

[0028] In a specific embodiment, as Figure 1 shown in Figure 1 , the method for measuring the facing area of electrodes in an electrode cage provided by the present invention includes the following steps:

[0029] S1. After the outgoing light of the interferometer 1 passes through the polarizer 2 and the first quarter-wave plate 3 in sequence, it is split into a first P-polarized light and a first S-polarized light by the polarization beam splitter prism 4;

[0030] S2. The first S-polarized light is reflected by the first electrode group to be measured 7 and the polarization beam splitter prism 4, and returns to the outgoing light path of the interferometer 1;

[0031] S3. After the first P-polarized light passes through the polarization beam splitter prism 4, it passes through the second quarter-wave plate 5 and is then reflected by the mirror 6. The first P-polarized light becomes a second S-polarized light; the mirror 6 can be a plane mirror, and the root mean square value RMS of the surface shape of the plane mirror < λ / 20;

[0032] S4. The second S-polarized light is reflected by the second electrode group to be measured 8 and the polarization beam splitter prism 4, and returns to the reflection light path of the mirror 6;

[0033] In the reflection light path, the second S-polarized light passes through the second quarter-wave plate 5 twice and becomes a second P-polarized light; the second P-polarized light passes through the polarization beam splitter prism 4 and returns to the outgoing light path of the interferometer 1;

[0034] S5. The first S-polarized light and the second P-polarized light converge, and after passing through the first quarter-wave plate and the polarizer, they interfere. By observing the wavefront reflected back through the interferometer and calculating the number of pixels in the interference part and the number of pixels in the non-interference part, the actual facing area between the first electrode group to be measured 7 and the second electrode group to be measured 8 is calculated.

[0035] In a specific embodiment, in the step description of the above measurement method, after passing through S1, the outgoing light of the interferometer 1 is split into a first P-polarized light and a first S-polarized light by the polarization beam splitter prism 4. Then, both the first S-polarized light and the first P-polarized light simultaneously undergo various optical path effects. Although S2 is written first, and then S3 and S4, there is no sequential order between step S2 and step S3, while there is a sequential order between step S3 and step S4.

[0036] In a specific embodiment, the effective light-passing size of all optical elements should be larger than the electrode area. However, when the polarization beam splitter prism is arranged inside the electrode cage, its size should not be larger than the internal space size of the electrode cage. For example, the internal size of the electrode cage is 52mm × 52mm × 52mm, and the outer envelope size of the electrode group is 36mm × 36mm; the size of the polarization beam splitter prism is 50mm × 50mm × 50mm, the diameter of the first quarter-wave plate > 51mm, and the diameter of the mirror > 51mm.

[0037] The electrode cage electrode facing area measuring device and measuring method provided by the present invention utilize the polarization beam splitter prism for beam splitting and rationally design the optical path, so as to realize the in-situ high-precision measurement of the facing area of two groups of electrodes on the inner surface of the electrode cage without repeated disassembly of the measuring device and the electrode cage. In addition, compared with the conventional three-coordinate measurement means, this method uses non-contact measurement and will not affect the surface quality of the electrodes. Moreover, the electrode cage electrode facing area measuring device and measuring method provided by the present invention solve the problems of "difficult contact with the outer frame closure of the facing electrodes" and "in-situ measurement and calibration after installation" in the electrode cage.

[0038] In a specific embodiment, as Figure 3 shown, it is the original installation detection schematic diagram of the electrode cage electrode facing area measuring device in the specific embodiment of the present invention. It can be seen from the figure that when using the electrode cage electrode facing area measuring device of the present invention for measurement, the polarization beam splitter prism 4 can be installed on the hexapod displacement stage 10. By adjusting the pose of the polarization beam splitter prism 4, the outgoing light of the interferometer 1 can be vertically irradiated onto the electrode surface in the electrode cage 9. Considering the positioning accuracy of the hexapod displacement stage 10, finally, the angular error of the polarization beam splitter prism 4 is better than 2".

[0039] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0040] The specific embodiments of the present invention described above do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made according to the technical concept of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A method for measuring the facing area of electrodes of an electrode cage, characterized in that, The measurement method is implemented by an electrode cage electrode facing area measurement device. The inner surface of the electrode cage includes two groups of electrodes, and the two groups of electrodes include a first electrode group to be measured and a second electrode group to be measured; The electrode cage electrode facing area measurement device includes an interferometer, a polarizer, a first quarter-wave plate, a polarization beam splitter prism, a second quarter-wave plate, and a mirror arranged in sequence; After the outgoing light of the interferometer passes through the polarizer and the first quarter-wave plate in sequence, it is split into a first P-polarized light and a first S-polarized light by the polarization beam splitter prism; the polarization beam splitter prism is arranged at 45 degrees with the electrode; The measurement method includes the steps: S1. After the outgoing light of the interferometer passes through the polarizer and the first quarter-wave plate in sequence, it is split into a first P-polarized light and a first S-polarized light by the polarization beam splitter prism; S2. The first S-polarized light passes through the first electrode group to be measured and the reflection of the polarization beam splitter prism, and returns to the outgoing light path of the interferometer; S3. After the first P-polarized light passes through the polarization beam splitter prism, it passes through the second quarter-wave plate, and then is reflected by the mirror, and the first P-polarized light becomes a second S-polarized light; S4. The second S-polarized light passes through the second electrode group to be measured and the reflection of the polarization beam splitter prism, and returns to the reflection light path of the mirror; In the reflection light path of the second S-polarized light, after passing through the second quarter-wave plate twice, it becomes a second P-polarized light; the second P-polarized light passes through the polarization beam splitter prism and returns to the outgoing light path of the interferometer; S5. The first S-polarized light and the second P-polarized light converge, interfere after passing through the first quarter-wave plate and the polarizer, observe the reflected wavefront through the interferometer, and calculate the actual facing area between the first electrode group to be measured and the second electrode group to be measured by calculating the number of pixels in the interference part and the number of pixels in the non-interference part.

2. The method for measuring the facing area of the electrode cages as claimed in claim 1, wherein The mirror is a plane mirror.

3. The method for measuring the facing area of the electrodes of the electrode cage according to claim 2, wherein The root mean square value RMS of the surface shape of the plane mirror < λ / 20.

4. The method for measuring the electrode facing area of the electrode cage according to claim 3, characterized in that, The internal size of the electrode cage is 52mm×52mm×52mm, and the outer envelope size of the first electrode group to be measured and the second electrode group to be measured is 36mm×36mm; the size of the polarization beam splitter prism is 50mm×50mm×50mm, the diameter of the first quarter-wave plate > 51mm, and the diameter of the mirror > 51mm.

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