Apparatus and method for measuring scattering properties of an ultra-smooth surface element

Abstract

The application discloses a kind of scattering characteristic measuring devices and methods of ultra-smooth surface element, solve the detection efficiency of the scattering characteristic of ultra-smooth surface element, system complex, the problem of easily causing element surface damage.Low, specific including light source assembly, frequency shift modulation unit, integrating sphere, translation stage, image acquisition unit and data processing unit;Light source assembly emits incident light rays;Frequency shift modulation unit divides incident light rays into first light beam and second light beam with fixed frequency difference;Integrating sphere is equipped with the first incident port corresponding to first light beam, the second incident port corresponding to second light beam, the sampling port for setting the element to be measured, and first exit and second exit;Sampling port is respectively corresponding with first incident port and first exit;Translation stage is arranged at the sampling port of integrating sphere, for the element to be measured at sampling port at uniform speed translation;Image acquisition unit is arranged outside the second exit of integrating sphere;Data processing unit is electrically connected with image acquisition unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the measurement of super-smooth surface elements, and relates to a scattering characteristic measurement device and method of a super-smooth surface element. BACKGROUND

[0002] A super-smooth surface element refers to an optical element with a root mean square value (RMS) of surface roughness less than 1 nanometer, and the physical structure and surface damage degree of the optical element also have strict requirements, that is, the surface residual stress is extremely small, and has a complete lattice structure, high surface precision, low surface defects and subsurface damage.

[0003] Since the 21st century, science and technology has developed rapidly, and the field of electronics, nanometer film technology, optics and related technologies have also experienced rapid development. The status of super-smooth surface processing technology is increasingly prominent, and aerospace, high-energy laser mirrors, laser gyroscopes, nanometer film preparation and other fields have put forward extremely high requirements for super-smooth surface processing technology. In addition to processing technology, the detection technology of super-smooth surface is also an important link restricting the development of this field. For super-smooth surfaces, scattering light detection is an effective method, but super-smooth surfaces are super-precision surfaces, and the level of scattered light is extremely weak. Generally, the traditional detection method is to observe through a high-precision microscope, such as an atomic force microscope. This method mainly observes the surface shape of the element, and has low detection efficiency, complex system structure, high cost, and requires professional technical personnel to operate. At the same time, the working distance is generally short during the detection process, which is easy to cause damage to the surface of the element. SUMMARY

[0004] The purpose of the present application is to provide a scattering characteristic measurement device and method of a super-smooth surface element, to solve the technical problems of low detection efficiency, complex system structure, high cost, and the need for professional technical personnel to operate, and at the same time, the working distance is short during the detection process, which is easy to cause damage to the surface of the element.

[0005] In order to achieve the above purpose, the present application provides a scattering characteristic measurement device of a super-smooth surface element, which is characterized by comprising a light source assembly, a frequency shift modulation unit, an integrating sphere, a translation stage, an image acquisition unit and a data processing unit.

[0006] The light source assembly emits incident light;

[0007] The frequency shift modulation unit is located on the light path of the incident light, and divides the incident light into a first light beam and a second light beam with a fixed frequency difference;

[0008] The integrating sphere is provided with a first incident port corresponding to the first light beam, a second incident port corresponding to the second light beam, a sampling port for arranging the element to be measured, and a first exit port and a second exit port; the sampling port is located on the optical path of the first light beam entering the integrating sphere from the first incident port, and the first exit port is located on the optical path of the light beam after being reflected by the element to be measured;

[0009] The translation stage is arranged at the sampling port of the integrating sphere and is used to translate the component to be tested at the sampling port at a uniform speed;

[0010] The image acquisition unit is correspondingly arranged outside the second exit port of the integrating sphere;

[0011] The data processing unit is electrically connected to the image acquisition unit.

[0012] The above structural design is simple, easy to operate, and low in cost. The above measuring device can be used to perform contactless measurement without causing damage to the surface of the component to be measured.

[0013] Furthermore, in order to improve the accuracy of the test results, the present invention has made the following improvements:

[0014] Also included is a focusing lens assembly;

[0015] The focusing lens group is arranged between the second exit port of the integrating sphere and the image acquisition unit, and is used to converge and collect light.

[0016] Furthermore, the frequency shift modulation unit includes a first frequency shift modulator and a second frequency shift modulator arranged in parallel on the optical path of the incident light; the first frequency shift modulator is used to modulate a part of the incident light into a first light beam, and the second frequency shift modulator is used to modulate another part of the incident light into a second light beam.

[0017] Further, it also includes an aperture;

[0018] The aperture is arranged between the frequency shift modulation unit and the integrating sphere, and is used for filtering the first light beam and the second light beam.

[0019] Furthermore, the light source assembly includes a light source and a collimating lens group;

[0020] The light source is used to emit incident light;

[0021] The collimating lens group is arranged between the light source and the frequency shift modulation unit, and is used to collimate the incident light.

[0022] Furthermore, the image acquisition unit is a CCD camera;

[0023] The light source is a laser.

[0024] The application further provides a scattering characteristic measurement method of the super-smooth surface element, based on the scattering characteristic measurement device of the super-smooth surface element, and the method comprises the following steps:

[0025] Step 1: emitting incident light through the light source assembly

[0026] Step 2: modulating the incident light into a first light beam and a second light beam with a fixed frequency difference through the frequency shift modulation unit; the first light beam enters the integrating sphere through the first incident port of the integrating sphere, reaches the surface of the to-be-measured element at the sampling port of the integrating sphere, is reflected by the to-be-measured element to form reflected light, and is scattered by the to-be-measured element to form scattered light; the second light beam enters the integrating sphere through the second incident port of the integrating sphere; the reflected light is directly emitted out through the first exit port of the integrating sphere; the scattered light and the second light beam entering the integrating sphere interfere with each other to form interference light, and the interference light is emitted out through the second exit port of the integrating sphere;

[0027] Step 3: receiving the interference light through the image acquisition unit, obtaining a light signal image, and sending the light signal image to the data processing unit;

[0028] Step 4: moving the to-be-measured element at a constant speed through the translation stage located at the sampling port of the integrating sphere, and repeatedly executing steps 2 and 3 to push scan the surface of the to-be-measured element until the light signal image acquisition of the whole surface of the to-be-measured element is completed;

[0029] Step 5: the data processing unit receives all the light signal images obtained in the push scanning process, and calculates the surface scattering characteristic of the to-be-measured element according to all the light signal images.

[0030] Further, step 3 specifically comprises:

[0031] collecting and converging the interference light emitted out through the second exit port of the integrating sphere through the focusing lens group;

[0032] Then, the image acquisition unit receives the collected and converged interference light to obtain a light signal image, and sends the light signal image to the data processing unit.

[0033] Further, step 1 specifically comprises:

[0034] Step 1.1: emitting incident light through the light source;

[0035] Step 1.2: collimating the incident light through the collimating lens group to obtain collimated incident light.

[0036] Further, step 2 specifically comprises:

[0037] Step 2.1, modulate the collimated incident light rays into a first light beam and a second light beam with a fixed frequency difference through a frequency shift modulation unit;

[0038] Step 2.2, filter the first light beam and the second light beam respectively through an optical diaphragm;

[0039] Step 2.3, make the first light beam enter the integrating sphere through the first incident port of the integrating sphere, reach the surface of the to-be-measured element at the sampling port of the integrating sphere, form reflected light rays through reflection of the to-be-measured element, and form scattered light rays through scattering of the to-be-measured element; make the second light beam enter the integrating sphere through the second incident port of the integrating sphere; the reflected light rays directly exit through the first exit port of the integrating sphere; the scattered light rays interfere with the second light beam entering the integrating sphere to form interference light rays, and the interference light rays exit through the second exit port of the integrating sphere.

[0040] Advantages of the present application:

[0041] 1. The scattering characteristic measurement device and method of the super-smooth surface element are based on the principles of scattering light detection and laser interference, the extremely weak scattering light signal of the surface characteristics of the super-smooth surface element is enhanced through interference, the characteristics in the light signal image collected by the image acquisition unit are more obvious, so that the scattering characteristics of the super-smooth surface element are more accurately extracted by the data processing unit, and the accuracy of the measurement result is improved.

[0042] 2. The translation stage is arranged at the sampling port of the integrating sphere, the to-be-measured element can be pushed and scanned in translation, the measurement of the whole surface of the to-be-measured element is realized, manual contact with the to-be-measured element is not needed, and damage to the surface of the to-be-measured element in the measurement process can be avoided.

[0043] 3. The scattering characteristic measurement device of the super-smooth surface element is provided with a frequency shift modulation unit to modulate the same incident light rays into two light beams with a fixed frequency difference, the specific frequency difference can be set according to the measurement accuracy requirement, the application range of the measurement device is improved, and the application is more extensive.

[0044] 4. The scattering characteristic measurement device of the super-smooth surface element adopts the integrating sphere to provide a high-quality interference environment for the mutual interference of the first light beam and the scattered light rays of the surface of the to-be-measured element, various noise interferences such as low-frequency noise interference of the laser, environmental noise light interference, and wideband noise can be effectively avoided, the signal-to-noise ratio of the photoelectric signal is improved, and the measurement result is more accurate.

[0045] 5. The optical diaphragm is arranged between the integrating sphere and the frequency shift modulation unit, the first light beam and the second light beam can be filtered, the signal-to-noise ratio of the light signal is further improved, and the accuracy of the measurement result is improved.

[0046] 6、The present application sets a focusing lens group between the integrating sphere and the image acquisition unit, which can improve the comprehensiveness of image acquisition of the image acquisition unit and the efficiency of scattering characteristic measurement.

[0047] 7、The scattering characteristic measurement device of the super-smooth surface element of the present application has simple overall structure and low cost, and is suitable for wide promotion. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 is a structural schematic diagram of an embodiment of the scattering characteristic measurement device of the super-smooth surface element of the present application.

[0049] Reference numerals:

[0050] 1-light source assembly, 11-light source, 12-collimating lens group, 2-frequency shift modulation unit, 21-first frequency shift modulator, 22-second frequency shift modulator, 3-integrating sphere, 31-first entrance, 32-second entrance, 33-sampling port, 34-first exit, 35-second exit, 4-translation stage, 5-image acquisition unit; 6-data processing unit, 7-element to be measured, 8-focusing lens group, 9-diaphragm. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0052] Figure 1 is a structural schematic diagram of an embodiment of the scattering characteristic measurement device of the super-smooth surface element of the present application, as Figure 1 shown, the scattering characteristic measurement device can include a light source assembly 1, a frequency shift modulation unit 2, a diaphragm 9, an integrating sphere 3, a translation stage 4, a focusing lens group 8, an image acquisition unit 5 and a data processing unit 6; wherein the light source assembly 1 specifically includes a light source 11 and a collimating lens group 12; the frequency shift modulation unit 2 includes a first frequency shift modulator 21 and a second frequency shift modulator 22.

[0053] Specifically, the light source 11 is configured to emit incident light; in the embodiment, the light source 11 can be a laser, and the incident light is a laser beam; the collimating lens group 12 is arranged on the light path of the laser beam and is configured to collimate the laser beam emitted by the laser; the first frequency-shifting modulator 21 and the second frequency-shifting modulator 22 are arranged in parallel on the light path of the laser beam, the first frequency-shifting modulator 21 modulates a part of the collimated laser beam into a first light beam, and the second frequency-shifting modulator 22 modulates another part of the collimated laser beam into a second light beam; the first light beam and the second light beam are two light beams with a fixed frequency difference, and the range of the frequency difference is determined according to the specific measurement accuracy requirement; the diaphragm 9 is arranged behind the frequency-shifting modulation unit 2, that is, a part of the diaphragm 9 is arranged behind the first frequency-shifting modulator 21 and is configured to filter the first light beam, and another part of the diaphragm 9 is arranged behind the second frequency-shifting modulator 22 and is configured to filter the second light beam; the diaphragm 9 can be a rectangular diaphragm, and in another possible implementation, the diaphragm can also be a diaphragm with other shapes, and the principle is that the diaphragm can filter the first light beam and the second light beam at the same time; the specific shape of the diaphragm is not limited in the present application.The aperture 9 can filter out optical noise such as ambient scattered light in the first and second light beams, and only allow effective light signals to pass through; the integrating sphere 3 is arranged behind the aperture 9, and is provided with a first incident port 31 corresponding to the first light beam, a second incident port 32 corresponding to the second light beam, a sampling port 33 for setting the element to be measured 7, and a first exit port 34 and a second exit port 35; the first light beam after filtering enters the integrating sphere 3 through the first incident port 31, and irradiates the surface of the element to be measured 7 at the sampling port 33, and is reflected on the surface of the element to be measured 7 to form reflected light. The first light beam is directly emitted from the first exit port 34 of the integrating sphere 3. At the same time, the first light beam entering the integrating sphere 3 is also scattered on the surface of the component to be measured 7 to form scattered light. The second light beam after filtering enters the integrating sphere 3 through the second entrance port 32 of the integrating sphere 3, is reflected on the inner wall of the integrating sphere 3, and interferes with the scattered light formed on the surface of the component to be measured 7, so that the weak scattered light signal is enhanced to form interference light. The interference light is emitted from the second exit port 35 of the integrating sphere 3. The integrating sphere 3 can eliminate the background noise and external noise light interference, so that the two light signals are reflected in the integrating sphere. Interference is performed within the two optical signals, providing a high-quality interference environment for the two optical signals. The signal-to-noise ratio of the optical signal after interference can be greatly improved, so that the final measurement accuracy is significantly improved; the translation stage 4 is set at the sampling port 33 of the integrating sphere 3, and the element to be measured 7 can be installed on the surface of the translation stage 4, so that the element to be measured 7 moves at a uniform speed at the sampling port 33 of the integrating sphere 3; specifically, when the first light beam is irradiated on the surface of the element to be measured 7, the element to be measured 7 is moved at a uniform speed by the translation stage 4, so that the first light beam can perform high-precision push scanning on the surface of the element to be measured 7, and its detection result is more comprehensive; focusing lens The group 8 is correspondingly arranged outside the second exit port 35 of the integrating sphere 3, and is used to collect and converge the emitted interference light; the image acquisition unit 5 is arranged after the focusing lens group 8. In this embodiment, the image acquisition unit 5 can be a CCD camera, which is mainly used to receive the collected and converged interference light and convert it into a light signal image and send it to the data processing unit 6; the data processing unit 6 is electrically connected to the CCD camera. After receiving the light signal image sent by the CCD camera, the data processing unit 6 demodulates and analyzes the light signal image and calculates the scattering characteristics of the surface of the component to be measured 7.

[0054] The scattering characteristic measuring device of the super-smooth surface element provided by the application is based on the principle of scattered light detection and laser interference, and the weak scattered light of the super-smooth element surface is enhanced by the laser interference principle to highlight the light signal of the problem surface, so that the analysis and processing are more accurate, and the accuracy of the scattering characteristic measurement of the super-smooth surface element is improved. In addition, the application adopts an integrating sphere to provide a high-quality interference environment for laser interference, which can effectively avoid various noise interferences such as low-frequency noise interference of the laser, environmental noise light interference, and wideband noise, improve the signal-to-noise ratio of the photoelectric signal, realize non-contact detection, and efficiently and accurately detect the extremely weak scattered light signal of the super-smooth surface element, and the structure is simple and easy to operate.

[0055] The application further provides a scattering characteristic measurement method of a super-smooth surface element, comprising the following steps:

[0056] Step 1: emitting incident light through a light source 11; the light source 11 can be a laser;

[0057] Step 2: collimating the incident light through a collimating lens group 12 to obtain collimated incident light;

[0058] Step 3: modulating the collimated incident light into a first light beam and a second light beam with a fixed frequency difference through a frequency shift modulation unit 2; filtering the first light beam and the second light beam through a diaphragm 9 respectively; then, the first light beam enters an integrating sphere 3 through a first incident port 31 of the integrating sphere 3 until the surface of a to-be-measured element 7 at a sampling port 33 of the integrating sphere 3, forms reflected light through reflection of the to-be-measured element 7, and forms scattered light through scattering of the to-be-measured element 7; the second light beam enters the integrating sphere 3 through a second incident port 32 of the integrating sphere 3; the reflected light directly exits through a first exit port 34 of the integrating sphere 3; the scattered light and the second light beam entering the integrating sphere 3 interfere with each other to form interference light, and the interference light exits through a second exit port 35 of the integrating sphere 3;

[0059] The frequency shift modulation unit 2 specifically comprises a first frequency shift modulator 21 and a second frequency shift modulator 22 arranged in parallel on the light path of the incident light, the first frequency shift modulator 21 is used for modulating part of the incident light into the first light beam, and the second frequency shift modulator 22 is used for modulating another part of the incident light into the second light beam; the frequency difference between the first light beam and the second light beam is specifically determined according to the to-be-measured element and the measurement accuracy requirement;

[0060] Step 4: collecting and converging the interference light exiting from the second exit port 35 of the integrating sphere 3 through a focusing lens group 8;

[0061] Step 5: receiving the collected and converged interference light through an image acquisition unit 5 to obtain a light signal image, and sending the light signal image to a data processing unit 6; the image acquisition unit 5 can be a CCD camera;

[0062] Step 6, the element 7 to be measured is moved at a constant speed by the translation stage 4 located at the sampling port 33 of the integrating sphere 3, and steps 2 to 5 are repeatedly performed to push scan the surface of the element 7 to be measured until the light signal image collection of the whole surface of the element 7 to be measured is completed;

[0063] Step 7, the data processing unit 6 receives all the light signal images obtained in the push scan process, and draws a scattering characteristic curve according to the gray arrangement characteristics of each pixel in all the light signal images to obtain the surface scattering characteristics of the element 7 to be measured.

[0064] The method is simple and easy to operate, and does not require professional technicians, thereby saving costs.

[0065] Through the description of the above embodiments, those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional modules is taken as an example for illustration, and in actual application, the above functions can be completed by different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above.

[0066] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any change or replacement within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for measuring scattering characteristics of an ultra-smooth surface element based on a device for measuring scattering characteristics of an ultra-smooth surface element, characterized in that the device for measuring scattering characteristics of an ultra-smooth surface element comprises a light source assembly (1), a frequency shift modulation unit (2), an integrating sphere (3), a translation stage (4), an image acquisition unit (5), and a data processing unit (6); the light source assembly (1) emits incident light; the frequency shift modulation unit (2) is located on the light path of the incident light and divides the incident light into a first light beam and a second light beam with a fixed frequency difference; the integrating sphere (3) is provided with a first incident port (31) corresponding to the first light beam, a second incident port (32) corresponding to the second light beam, a sampling port (33) for setting the element to be measured (7), and a first exit port (34) and a second exit port (35); the sampling port (33) is located on the light path of the first light beam entering the integrating sphere (3) from the first incident port (31), and the first exit port (34) is located on the light path of the light reflected by the element to be measured (7); the translation stage (4) is arranged at the sampling port (33) of the integrating sphere (3) and used for uniformly translating the element to be measured (7) at the sampling port (33); the image acquisition unit (5) is arranged outside the second exit port (35) of the integrating sphere (3); the data processing unit (6) is electrically connected with the image acquisition unit (5); the method for measuring scattering characteristics of an ultra-smooth surface element comprises the following steps: Step 1: emitting incident light by the light source assembly (1); Step 2: modulating the incident light into a first light beam and a second light beam with a fixed frequency difference by the frequency shift modulation unit (2); the first light beam enters the integrating sphere (3) through the first incident port (31) of the integrating sphere (3), reaches the surface of the element to be measured (7) at the sampling port (33) of the integrating sphere (3), is reflected by the element to be measured (7) to form reflected light, and is scattered by the element to be measured (7) to form scattered light; the second light beam enters the integrating sphere (3) through the second incident port (32) of the integrating sphere (3); the reflected light is directly emitted out through the first exit port (34) of the integrating sphere (3); the scattered light and the second light beam entering the integrating sphere (3) interfere with each other to form interference light, and the interference light is emitted out through the second exit port (35) of the integrating sphere (3); Step 3: receiving the interference light by the image acquisition unit (5), obtaining a light signal image, and sending the light signal image to the data processing unit (6); Step 4: uniformly moving the element to be measured (7) by the translation stage (4) at the sampling port (33) of the integrating sphere (3), and repeatedly executing Step 2 and Step 3 to push scan the surface of the element to be measured (7) until the light signal image acquisition of the whole surface of the element to be measured (7) is completed; and Step 5: receiving all the light signal images obtained in the push scan process by the data processing unit (6), and calculating the scattering characteristics of the surface of the element to be measured (7) according to all the light signal images. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The method of claim 1, wherein the scattering characteristic measuring device of the ultra-smooth surface element further comprises a focusing lens group (8). The focusing lens group (8) is arranged between the second exit port (35) of the integrating sphere (3) and the image acquisition unit (5), and is used for converging and collecting the light.

3. The method of claim 2, wherein the frequency shift modulation unit (2) comprises a first frequency shift modulator (21) and a second frequency shift modulator (22) arranged in parallel on the light path of the incident light; the first frequency shift modulator (21) is used for modulating a part of the incident light into a first light beam, and the second frequency shift modulator (22) is used for modulating another part of the incident light into a second light beam.

4. The method of claim 3, wherein the scattering characteristic measuring device of the ultra-smooth surface element further comprises a diaphragm (9). The diaphragm (9) is arranged between the frequency shift modulation unit (2) and the integrating sphere (3), and is used for filtering the first light beam and the second light beam.

5. The method of claim 4, wherein the light source assembly (1) comprises a light source (11) and a collimating lens group (12). The light source (11) is used for emitting incident light. The collimating lens group (12) is arranged between the light source (11) and the frequency shift modulation unit (2), and is used for collimating the incident light. Step 3 specifically comprises: The interference light emitted from the second exit port (35) of the integrating sphere (3) is collected and converged by the focusing lens group (8); The collected and converged interference light is received by the image acquisition unit (5) to obtain a light signal image, and the light signal image is sent to the data processing unit (6). Step 1 specifically comprises:

6. The method of measuring the scattering properties of an ultra-smooth surface element according to claim 5, wherein, Step 1.1, emitting incident light by the light source (11); Step 1.2, collimating the incident light by the collimating lens group (12) to obtain collimated incident light. Step 2 specifically comprises:

7. The method of measuring the scattering properties of an ultra-smooth surface element according to claim 6, wherein, Step 2.1, modulating the collimated incident light into a first light beam and a second light beam with a fixed frequency difference by the frequency shift modulation unit (2); Step 2.2, filtering the first light beam and the second light beam by the diaphragm (9) respectively; Step 2.3, making the first light beam enter the integrating sphere (3) through the first exit port (31) of the integrating sphere (3), and reach the surface of the to-be-measured element (7) at the sampling port (33) of the integrating sphere (3), and form reflected light by reflecting on the to-be-measured element (7), and form scattered light by scattering on the to-be-measured element (7); making the second light beam enter the integrating sphere (3) through the second exit port (32) of the integrating sphere (3); the reflected light directly exits through the first exit port (34) of the integrating sphere (3); the scattered light and the second light beam entering the integrating sphere (3) interfere with each other to form interference light, and the interference light exits through the second exit port (35) of the integrating sphere (3).

8. The method of measuring the scattering properties of an ultra-smooth surface element according to claim 7, wherein, ​ ​ ​ ​ 9. The method of measuring the scattering properties of an ultra-smooth surface element according to claim 8, characterized in that: the image acquisition unit (5) is a CCD camera; the light source (11) is a laser.

Images