Aspheric optical element surface shape detection device and method

Abstract

The invention discloses an aspheric optical element surface shape detection device and method, and belongs to the technical field of optical element detection. The detection device comprises a laser light source, a first beam splitter, double CGHs, two Twyman Green interference modules and a supporting table. The detection method comprises the steps of S1, stabilizing a light source; s2, adjusting a detection device; s3, phase shifting is carried out; s4, collecting an interferogram; s5, integrating the information; and S6, switching the element to be tested. The adjustable wavelength laser is used as a laser light source, and the measurement requirements of different materials can be met by adjusting the wavelength; the double CGHs capable of generating two different wavefronts at the same time are used for meeting the surface shape measurement requirement of an optical element composed of any two aspheric surfaces. According to the invention, a double-CGH and optical fiber simplified double-channel interference system design is used, the possibility of cross interference is reduced, the optical configuration and adjustment difficulty are simplified, the surface shape measurement requirements of various materials can be met, and high-precision, high-performance and universal surface shape measurement of an optical element formed by any two aspheric surfaces can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical element detection, and in particular relates to a device and method for detecting the surface shape of an aspherical optical element. Background Art

[0002] Optical components are the core components of optical systems and occupy an important position in the development of optical technology. The improvement of optical component manufacturing technology also has a profound impact on the development and application of optical technology. Aspheric components can improve the imaging quality of the system, reduce the overall quality of the system, and thus improve the overall performance of the optical system. With the continuous development of manufacturing technology, aspheric optical components have been widely used in more and more fields, such as medical equipment, lithography equipment, camera lenses, laser beam shaping systems, etc.

[0003] The surface quality of optical components is an important factor affecting the image quality or wave aberration of optical systems. The higher the surface quality of optical parts, the closer the optical system can be to the design value. Therefore, efficient detection and manufacturing of large quantities of ultra-precision optical parts pose new challenges to current surface detection technology. At present, existing detection devices have the problem of cross-interference when simultaneously detecting optical components composed of two different aspherical surfaces, which increases the complexity of the detection device. Summary of the invention

[0004] In order to meet the measurement needs of various materials, the present invention can achieve high-precision, high-performance, and universal surface measurement of an optical element composed of any two different aspheric surfaces, improve the stability of measurement, and further propose a surface shape detection device and method for an aspheric optical element.

[0005] The technical solution adopted by the present invention is:

[0006] A non-spherical optical element surface shape detection device, comprising

[0007] A laser light source, used for emitting laser light;

[0008] Beam splitter 1, which splits the laser into two beams with exactly the same optical properties;

[0009] Dual CGH, which generates two different wavefronts from two laser beams;

[0010] Two Twyman-Green interferometer modules receive two lasers with different wavefronts through two channel optical fibers, and reflect the lasers to the corresponding two test elements;

[0011] The support table is used to place two test components.

[0012] A method for detecting the surface shape of an aspherical optical element comprises the following steps:

[0013] S1. Stabilize the light source: turn on the laser light source;

[0014] S2. Adjust the detection device: make the aspheric optical element surface shape detection device run stably;

[0015] S3. Perform phase shift: adjust the Twyman-Green interferometer module to perform phase shift;

[0016] S4. Collecting interference pattern;

[0017] S5. Integrate the information and calculate the surface information of the component to be tested;

[0018] S6. Switch the component to be tested, adjust the detection device, and continue measuring.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention uses an adjustable wavelength laser as a laser light source, and can meet the measurement requirements of different materials by adjusting the wavelength; uses a dual CGH that can simultaneously generate two different wavefronts to meet the surface measurement requirements of an optical element composed of any two aspherical surfaces; uses a dual-channel interference system design simplified by dual CGH and optical fiber to reduce the possibility of cross-interference, simplify optical configuration and adjustment difficulty,

[0021] The present invention also designs an internal adjustment mechanism of the beam splitter, which can simultaneously adjust the angle adjustment, displacement adjustment and component fixation of the beam splitter, realize optical axis alignment and splitting ratio adjustment, meet specific application requirements, adjust the angle of optical components to optimize the beam path or improve the overall performance of the system, perform precise positioning, and adapt to different experimental conditions.

[0022] The present invention can meet the surface shape measurement requirements of various materials and realize high-precision, high-performance and universal surface shape measurement for an optical element composed of any two aspherical surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the device of the present invention;

[0024] Figure 2 It is a schematic diagram of the structure of the internal adjustment fixture of the beam splitter of the present invention;

[0025] Figure 3 is a flow chart of the method of the present invention;

[0026] Among them: 1. Laser light source; 2. Beam splitter 1; 3. Dual CGH; 4. Channel optical fiber; 5. Twyman-Green interferometer module; 5-1. Collimator; 5-2. Beam splitter 2; 5-3. Phase modulator; 5-4. Reference mirror; 5-5. Image collector; 7. Component to be tested; 8. Support table; 5-2-1. Clamp arm 1; 5-2-2. Clamp arm 2; 5-2-3. Rotatable telescopic arm; 5-2-4. Support table; 5-2-5. Beam splitter holder; 5-2-6. Beam splitter; 5-2-7. Slide rail 1; 5-2-8. Slide rail 2. DETAILED DESCRIPTION

[0027] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings.

[0028] A device and method for detecting the surface shape of an aspherical optical element, which can meet the measurement requirements of various materials and realize high-precision, high-performance and universal surface shape measurement of an optical element composed of any two different aspherical surfaces.

[0029] like Figure 1 As shown, a non-spherical optical element surface shape detection device includes:

[0030] A laser light source 1, used for emitting laser light;

[0031] Beam splitter 2, which splits the laser into two beams with exactly the same optical properties;

[0032] Dual CGH 3, which generates two different wavefronts from two laser beams;

[0033] Two Twyman-Green interferometer modules 5 receive two laser beams with different wavefronts through two channel optical fibers 4, and reflect the laser beams to two corresponding detection elements 7;

[0034] The support platform 8 is used to place two test components 7.

[0035] like Figure 1 As shown, the Taiman Green interference module 5 includes

[0036] The collimator 5-1 transmits the incident light of the channel optical fiber 4 to form parallel light;

[0037] The second beam splitter 5-2 semi-reflects and semi-transmits the parallel light to form reflected light and transmitted light;

[0038] The reference mirror 5-4 reflects the reflected light back into parallel light and serves as reference light;

[0039] The phase modulator 5-3 makes the transmitted light incident on the surface of the element to be measured 7 and after reflection, it carries the surface shape information of the element to be measured 7, and interferes with the reference light in the beam splitter 2 5-2 to form an interference pattern, which is incident on the image collector 5-5.

[0040] The image collector 5-5 collects interference pattern information for analyzing and calculating the surface shape of the component to be tested 7-1.

[0041] Working process: The laser light source 1 emits laser light, which is divided into two laser beams with completely identical optical properties by a beam splitter 2 and irradiated to the dual CGH 3 that can generate two different wavefronts at the same time, and then respectively irradiated into two Twyman-Green interferometer modules 5 through a channel optical fiber 4;

[0042] In the Tyeman-Green interference module 5, the incident light of the channel optical fiber 4 is transmitted through the collimator 5-1 to form parallel light, and the parallel light is semi-reflected and semi-transmitted through the beam splitter 5-2. The reflected light is incident on the reference mirror 5-4 and the reflected parallel light is used as the reference light, and the transmitted light is used as the test light. The test light is incident on the surface of the element to be tested 7 through the phase modulator 5-3 and carries the surface shape information of the element to be tested 7 after reflection, and interferes with the reference light in the beam splitter 5-2 to form an interference pattern, which is incident on the image collector 5-5. The image collector 5-5 collects the interference pattern information for analyzing and calculating the surface shape of the element to be tested 7;

[0043] If the element to be measured 7 is made of different materials or is composed of two other aspherical surfaces, the wavelength of the laser light source is changed or the dual CGH is made to generate a specific wavefront to meet the measurement requirements.

[0044] The present invention also designs an internal adjustment fixture of the beam splitter, which can simultaneously realize the angle adjustment, displacement adjustment and component fixation of the internal beam splitter 5-2-6. When the measurement is finished, the rotatable telescopic arm 5-2-3 of the adjustment fixture can be used to realize the angle adjustment, displacement adjustment and fixation of the beam splitter 5-2-6. It can realize the alignment of the optical axis and the adjustment of the splitting ratio to meet the needs of specific applications, adjust the angle of the optical element to optimize the beam path or improve the overall performance of the system, perform precise positioning, and adapt to different experimental conditions.

[0045] The beam splitter 1 2 and the beam splitter 2 5-2 are both provided with a beam splitter internal adjustment fixture; Figure 2As shown, the internal adjustment fixture of the beam splitter includes a fixture arm 1 5-2-1, a fixture arm 2 5-2-2, a rotatable telescopic arm 5-2-3, a support table 5-2-4, a beam splitter holder 5-2-5, a beam splitter 5-2-6, a slide rail 1 5-2-7 and a slide rail 2 5-2-8; the fixture arm 1 5-2-1 and the fixture arm 2 5-2-2 are arranged in parallel, and one end of the slide rail 1 5-2-7 and the slide rail 2 5-2-8 are respectively connected to the two fixture arms 1 5-2-1 and the fixture arm 2 5-2-2, and both are along The clamp arm 5-2-1 is arranged in the length direction, and the support platform 5-2-4 is slidably mounted on the slide rail 5-2-7 and the slide rail 5-2-8. The beam splitter 5-2-6 is mounted on the support platform 5-2-4 through the beam splitter fixture 5-2-5. The beam splitter fixture 5-2-5 is mounted on the rotatable telescopic arm 5-2-3 and is driven to move by the rotatable telescopic arm 5-2-3. The rotatable telescopic arm 5-2-3 is fixed on the clamp arm 5-2-1 and the clamp arm 5-2-2 through a base.

[0046] The internal adjustment fixture of the beam splitter has three fixture arms, two fixture arms 1 5-2-1 and 2 5-2-2 connected to the slide rail 1 5-2-7 and the slide rail 2 5-2-8 fix the slide rail 1 5-2-7 and the slide rail 2 5-2-8, and the fixture arm connected to the beam splitter holder 5-2-5 is a rotatable telescopic arm 5-2-3, through which the angle adjustment, displacement adjustment and fixation of the beam splitter 5-2-6 are achieved. It can realize the alignment of the optical axis and the adjustment of the splitting ratio, meet the needs of specific applications, adjust the angle of the optical element, optimize the beam path or improve the overall performance of the system, perform precise positioning, and adapt to different experimental conditions.

[0047] The rotatable telescopic arm 5-2-3 is composed of a base, a rotating joint, a telescopic arm, a driving system, a control system and an actuator. The base serves as the supporting and fixing part of the entire rotatable telescopic arm 5-2-3, and is connected between the clamp arm 1 5-2-1 and the clamp arm 2 5-2-2. The rotating joint is installed between the base and the telescopic arm. The beam splitter 5-2-6 is installed on the telescopic arm. The rotating joint allows the telescopic arm to rotate in the horizontal direction, and the telescopic arm realizes the telescopic change of the arm length and controls the horizontal position of the beam splitter 5-2-6.

[0048] The drive system provides power to drive the rotation of the rotary joint and the extension and retraction of the telescopic arm. The control system is used to control the movement and posture of the rotatable telescopic arm. The actuator is used to execute the rotation and retraction of the rotatable telescopic arm.

[0049] The swivel joint uses high-precision swivel joints that allow rotation without affecting the length of the telescopic part. The telescopic arm uses a telescopic mechanism with multiple nested parts so that the telescopic process does not affect the positioning of the swivel joint.

[0050] The angle of the beam splitter 5-2-6 is adjusted by a rotating switch, and the displacement of the beam splitter 5-2-6 is adjusted by a telescopic arm.

[0051] The laser light source 1 is a wavelength-tunable laser, which allows the system to perform interference at different wavelengths and meet the surface shape measurement requirements of different materials.

[0052] The dual CGH 3 can generate two different wavefronts at the same time. The dual CGH 3 can generate two different aspheric wavefronts at the same time, and can also generate specific wavefronts according to needs to meet the surface measurement needs of optical components composed of any two aspheric surfaces.

[0053] The channel optical fiber 4 is a single-mode optical fiber.

[0054] like Figure 3 As shown, a method for detecting the surface shape of an aspherical optical element comprises the following steps:

[0055] S1. Stabilize the light source: Turn on the laser light source 1 and adjust the light source to stabilize the wavelength of the emitted light;

[0056] S2. Adjust the detection device: make the aspheric optical element surface shape detection device run stably;

[0057] After placing the beam splitter 2 in the optical path of the laser light source 1, the beam splitter 2 divides the outgoing light into two laser beams with completely the same optical characteristics, which are injected into the double CGH3 that can generate two different wavefronts at the same time. The double CGH3 generates two different aspherical wavefronts. The output end of the double CGH3 is connected to the input end of the channel optical fiber 4, and the position and direction of the channel optical fiber 4 are adjusted so that it can accurately receive the light beam from the double CGH3. The wavefront identical to the corresponding component to be measured 7 is incident into the corresponding Tyeman-Green interferometer module 5 through the channel optical fiber 4. The aspherical component to be measured 7 is placed on the support table 8, and the optical path is adjusted so that the measurement range of the Tyeman-Green interferometer module 5 covers the component to be measured 7, so that the image collector 5-5 collects the interference pattern information.

[0058] S3. Phase shift: adjust the Tighman-Green interference module 5 to perform phase shift;

[0059] The two phase modulators 5 - 3 are simultaneously set to a 0 phase state, and then the phase states of the two phase modulators 5 - 3 are simultaneously adjusted, each time the phase is adjusted to π / 2, and a five-step phase shift is performed.

[0060] S4. Collecting interference pattern:

[0061] The two phase modulators 5-3 are controlled to perform five-step phase shift at the same time. Each time the phase shift is performed, the two image collectors 5-6 collect an interference pattern respectively. The two image collectors 5-6 collect five interference patterns in total. The interference patterns collected by one image collector 5-6 are recorded as I1.1, I1.2, ... I1.5; the interference patterns collected by the other image collector 5-6 are recorded as I2.1, I2.2, ... I2.5.

[0062] S5. Integrate the information and calculate the surface information of the component under test 7;

[0063] Based on the Kalman filtering method, the data are integrated and the surface shape PV value is finally calculated to improve the accuracy and comprehensiveness of the aspheric shape measurement, evaluate the surface shape of the component to be measured 7, and thus obtain the surface shape information of the entire optical component.

[0064] S6. Switch the test element 7, adjust the detection device, and continue measuring;

[0065] If the element to be measured 7 is made of different materials or is composed of two other aspherical surfaces, the wavelength of the laser light source 1 is changed or the dual CGH3 is made to generate a specific wavefront to meet the measurement requirements; then the optical axis is aligned by adjusting the fixture inside the beam splitter, and steps S1 to S5 are repeated to achieve high-precision, high-performance, and universal surface measurement.

[0066] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A device for detecting the surface shape of an aspherical optical element, characterized in that: include A laser light source (1), used for emitting laser light; A beam splitter (2) that splits the laser into two laser beams with exactly the same optical properties; Dual CGH (3), which generates two different wavefronts from two laser beams; Two Tighman-Green interferometer modules (5) receive two laser beams with different wavefronts respectively through two channel optical fibers (4), and reflect the laser beams to two corresponding detection elements to be measured (7); The support platform (8) is used to place two test components (7).

2. The device for detecting the surface shape of an aspherical optical element according to claim 1, characterized in that: The T.M.G. interference module (5) comprises A collimator (5-1) transmits incident light from the channel optical fiber (4) to form parallel light; Beam splitter 2 (5-2) semi-reflects and semi-transmits the parallel light to form reflected light and transmitted light; A reference mirror (5-4) reflects the reflected light back into parallel light and serves as a reference light; The phase modulator (5-3) causes the transmitted light to be incident on the surface of the element to be measured (7) and to carry the surface shape information of the element to be measured (7) after reflection, and to interfere with the reference light in the beam splitter 2 (5-2) to form an interference pattern, which is incident on the image collector (5-5). The image collector (5-5) collects interference pattern information for analyzing and calculating the surface shape of the component to be measured (7-1).

3. The device for detecting the surface shape of an aspherical optical element according to claim 1, characterized in that: The beam splitter 1 (2) and the beam splitter 2 (5-2) are both provided with a beam splitter internal adjustment fixture; the beam splitter internal adjustment fixture comprises a fixture arm 1 (5-2-1), a fixture arm 2 (5-2-2), a rotatable telescopic arm (5-2-3), a support platform (5-2-4), a beam splitter fixer (5-2-5), a beam splitter (5-2-6), a slide rail 1 (5-2-7) and a slide rail 2 (5-2-8); the fixture arm 1 (5-2-1) and the fixture arm 2 (5-2-2) are arranged in parallel, and one end of the slide rail 1 (5-2-7) and the slide rail 2 (5-2-8) are respectively connected to the two fixture arms 1 (5-2-1) and the fixture arm 2 (5-2-2). The support platform (5-2-4) is slidably mounted on the slide rail (5-2-7) and the slide rail (5-2-8). The beam splitter (5-2-6) is mounted on the support platform (5-2-4) via a beam splitter holder (5-2-5). The beam splitter holder (5-2-5) is mounted on a rotatable telescopic arm (5-2-3) and is driven to move by the rotatable telescopic arm (5-2-3). The rotatable telescopic arm (5-2-3) is fixed on the clamp arm (5-2-1) and the clamp arm (5-2-2) via a base.

4. The device for detecting the surface shape of an aspherical optical element according to claim 1, characterized in that: The laser light source (1) is a wavelength-tunable laser.

5. The device for detecting the surface shape of an aspherical optical element according to claim 1, characterized in that: The channel optical fiber (4) is a single-mode optical fiber.

6. A method using the aspheric optical element surface shape detection device according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Stabilize the light source: turn on the laser light source (1); S2. Adjust the detection device: make the aspheric optical element surface shape detection device run stably; S3. Perform phase shift: adjust the Tighman-Green interferometer module (5) to perform phase shift; S4. Collecting interference pattern; S5. Integrate the information and calculate the surface information of the component to be tested (7); S6. Switch the component to be tested (7), adjust the detection device, and continue measuring.

7. A method for detecting the surface shape of an aspherical optical element according to claim 6, characterized in that: In S2, the specific steps of adjusting the detection device are: After a beam splitter (2) is placed in the optical path of a laser light source (1), the beam splitter (2) splits the emitted light into two laser beams with completely identical optical characteristics, which are injected into a double CGH (3) capable of simultaneously generating two different wavefronts. The double CGH (3) generates two different aspheric wavefronts. The output end of the double CGH (3) is connected to the input end of a channel optical fiber (4). The position and direction of the channel optical fiber (4) are adjusted so that the light beam from the double CGH (3) can be accurately received. The wavefront identical to the corresponding component to be measured (7) is incident into the corresponding Tighman-Green interference module (5) through the channel optical fiber (4). The aspheric component to be measured (7) is placed on a support table (8). The optical path is adjusted so that the measurement range of the Tighman-Green interference module (5) covers the component to be measured (7), and the image collector (5-5) collects interference pattern information.

8. The method for detecting the surface shape of an aspherical optical element according to claim 6, characterized in that: In S3, the specific process of performing the phase shift is: setting the two phase modulators (5-3) to a 0 phase state at the same time, and then adjusting the phase states of the two phase modulators (5-3) at the same time, each time adjusting the phase to π / 2, and performing a five-step phase shift.

9. The method for detecting the surface shape of an aspherical optical element according to claim 6, characterized in that: In S4, the specific process of collecting the interference pattern is: simultaneously controlling the two phase modulators (5-3) to perform five-step phase shift, each time the phase shift is performed, the two image collectors (5-6) respectively collect an interference pattern, and the two image collectors (5-6) respectively collect a total of five interference patterns.

10. The method for detecting the surface shape of an aspherical optical element according to claim 6, characterized in that: In S6, the specific process of switching the element to be measured (7), adjusting the detection device, and continuing the measurement is as follows: if the element to be measured (7) is made of different materials or is composed of two other aspherical surfaces, the wavelength of the laser light source (1) is changed or the dual CGH (3) is made to generate a specific wavefront to meet the measurement requirements; then the optical axis is aligned by adjusting the fixture inside the beam splitter, and S1 to S5 are repeated.

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