Lens detection device

Abstract

The application relates to a lens detection device, which comprises a coherent light source, an optical fiber, a first optical fiber coupler and an analysis module. The first optical fiber coupler is connected with the optical fiber and the coherent light source. Light output by the coherent light source is transmitted to the first optical fiber coupler through the optical fiber and is divided into two beams. One beam is transmitted to a measuring light path through the optical fiber, and the other beam is transmitted to a reference light path through the optical fiber. The measuring light path is provided with a lens to be measured. The analysis module is connected with the optical fiber and the first optical fiber coupler. The first optical fiber coupler is used for coupling a measuring beam reflected back by the measuring light path and a reference beam reflected back by the reference light path into the optical fiber connected with the analysis module. The analysis module is used for receiving interference information generated by the measuring beam and the reference beam and analyzing a center deviation of the lens to be measured. The lens detection device provided by the application realizes the measurement of the center deviation of the lens to be measured through the optical fiber connection, has the characteristics of small occupied volume and high reliability.

Description

Technical Field

[0001] This application relates to the technical field of optical inspection, specifically to a lens inspection device. Background Technology

[0002] Lenses are primarily used for optical imaging and precision measurement in semiconductor equipment, serving as crucial components for ensuring the equipment's functionality. However, in actual manufacturing processes, discrepancies can exist between the lens's specifications and image quality, potentially affecting the normal operation of the equipment. Therefore, it is necessary to test the lens's actual specifications. Existing lens testing equipment, however, is space-consuming and easily affected by environmental factors. Summary of the Invention

[0003] The main technical problem addressed by this application is to provide a lens inspection device to improve inspection reliability.

[0004] This application provides a lens detection device, including:

[0005] Coherent light source; optical fiber; The first fiber coupler is connected to the coherent light source via the optical fiber. The light output from the coherent light source is transmitted to the first fiber coupler via the optical fiber and split into two beams. One beam is transmitted to the measurement optical path via the optical fiber, and the other beam is transmitted to the reference optical path via the optical fiber. The measurement optical path is equipped with a lens under test. An analysis module is connected to the optical fiber and the first optical fiber coupler. The first optical fiber coupler is used to couple the measurement beam reflected back from the measurement optical path and the reference beam reflected back from the reference optical path into the optical fiber connected to the analysis module. The analysis module is used to receive the interference information generated by the measurement beam and the reference beam and analyze it to obtain the center deviation of the lens under test.

[0006] According to one embodiment of this application, the reference optical path is provided with a reflector and a displacement sensor. The reflector is disposed on the displacement sensor. The reflector can move along the length direction of the displacement sensor during the measurement process. The displacement sensor is used to record the position information of the reflector at each moment during the movement. The analysis module is used to combine the position information and the interference information to obtain the mirror spacing of the lens under test.

[0007] According to one embodiment of this application, the measurement optical path is provided with a first fiber optic lens, which is connected to the first fiber optic coupler via the fiber optic cable. The first fiber optic lens is used to incident the light output from the first fiber optic coupler onto the surface of the lens under test and receive the reflected measurement beam. The reference optical path is provided with a second fiber optic lens, which is connected to the first fiber optic coupler via the fiber optic cable. The second fiber optic lens is used to incident the light output from the first fiber optic coupler onto the surface of the reflector and receive the reflected reference beam.

[0008] According to one embodiment of this application, the displacement sensor is a grating ruler.

[0009] According to one embodiment of this application, the lens detection device further includes a focusing lens, which is located between the first fiber optic lens and the lens to be tested.

[0010] According to one embodiment of this application, the lens testing device further includes an adjustment platform, on which the lens to be tested is disposed, and the adjustment platform is used to adjust the position and angle of the lens to be tested.

[0011] According to one embodiment of this application, the lens detection device further includes an indicator light source and a second fiber optic coupler. The indicator light source is connected to the second fiber optic coupler via the optical fiber. The coherent light source is connected to the second fiber optic coupler via the optical fiber. The second fiber optic coupler is connected to the first fiber optic coupler via the optical fiber. The second fiber optic coupler is used to couple the light output by the coherent light source and the light output by the indicator light source into the optical fiber connected to the first fiber optic coupler.

[0012] According to one embodiment of this application, the second fiber coupler is a 1×2 fiber coupler.

[0013] According to one embodiment of this application, the first fiber coupler is a 2×2 fiber coupler.

[0014] According to one embodiment of this application, the analysis module includes a detector and a processor. The detector is used to receive interference information generated by the measurement beam and the reference beam, and the processor is used to analyze and obtain the center deviation and mirror spacing of the lens under test.

[0015] The lens testing device provided in this application measures the center deviation of the lens under test through optical fiber connection, and features small size and high reliability. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of an embodiment of the lens detection device of this application; Figure 2 This is a schematic diagram of another embodiment of the lens detection device of this application.

[0018] The attached diagram lists the components represented by each number as follows: Lens testing device 10, coherent light source 110, indicator light source 111, optical fiber 120, first optical fiber coupler 130, second optical fiber coupler 131, analysis module 140, detector 141, processor 142, measurement optical path 150, first optical fiber lens 151, focusing lens 152, lens under test 153, adjustment stage 154, adjustment platform 1541, electric turntable 1542, reference optical path 160, second optical fiber lens 161, reflector 162, displacement sensor 163, base 170. Detailed Implementation

[0019] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the application. Similarly, the following embodiments are only some, not all, embodiments of the present application, and all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present application.

[0020] The terms "first," "second," and "third" used in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movement of components in a specific posture (as shown in the figures). If the specific posture changes, the directional indication will also change accordingly. The terms "comprising" and "having," and any variations thereof, in the embodiments of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or components inherent to these processes, methods, products, or devices.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] This application provides a lens detection device 10, such as... Figure 1 and Figure 2As shown, the lens testing device 10 includes a coherent light source 110, an optical fiber 120, a first optical fiber coupler 130, and an analysis module 140. The first optical fiber coupler 130 is connected to the coherent light source 110 via the optical fiber 120. The light output from the coherent light source 110 is transmitted through the optical fiber 120 to the first optical fiber coupler 130 and split into two beams. One beam is transmitted through the optical fiber 120 to the measurement optical path 150, and the other beam is transmitted through the optical fiber 120 to the reference optical path 160. The measurement optical path 150 is equipped with the lens under test 153. The analysis module 140 is connected to the first optical fiber coupler 130 via the optical fiber 120. The first optical fiber coupler 130 is used to couple the measurement beam reflected back from the measurement optical path 150 and the reference beam reflected back from the reference optical path 160 into the optical fiber 120 connected to the analysis module 140. The analysis module 140 is used to receive the interference information generated by the measurement beam and the reference beam and analyze it to obtain the center deviation of the lens under test 153. This application uses an optical fiber 120 to form an interferometric system to measure the center deviation of the lens 153 under test. Compared with the interferometric system composed of traditional optical elements (beam splitters, etc.), the lens detection device 10 of this application is more adaptable to detection in complex environments, has higher system integration, and a compact structure, which helps to reduce space occupation and improve detection accuracy and reliability.

[0023] In some embodiments, the reference optical path 160 is provided with a reflector 162 and a displacement sensor 163. The reflector 162 is disposed on the displacement sensor 163. The reflector 162 can move along the length direction of the displacement sensor 163 during the measurement process. The displacement sensor 163 is used to record the position information of the reflector 162 at each moment during the movement. The analysis module 140 is used to combine the position information and interference information to obtain the mirror spacing of the lens 153 under test.

[0024] In processes requiring precision measurement, such as semiconductor manufacturing, the lens assembly process is mainly affected by the center deviation and mirror spacing errors of individual mirror surfaces, in addition to the manufacturing errors of the processed parts themselves. Currently, there are separate detection methods for center deviation and mirror spacing. The lens inspection device 10 of this application can simultaneously detect center deviation and mirror spacing, thereby achieving simultaneous measurement of center deviation and mirror spacing and avoiding the inconvenience and systematic errors caused by tooling switching.

[0025] In some embodiments, the light transmitted from the first fiber optic coupler 130 to the measurement optical path 150 is reflected by the surface of the lens under test 153 to form a measurement beam. The measurement beam interferes with the reference beam, and the center deviation of the lens under test 153 can be accurately calculated by obtaining the interference fringes.

[0026] In some embodiments, the analysis module 140 includes a detector 141 and a processor 142. The detector 141 is used to receive interference information generated by the measurement beam and the reference beam, and the processor 142 is used to analyze and obtain the center deviation and mirror spacing of the lens 153 under test.

[0027] In some embodiments, detector 141 is a photodetector that can convert optical signals into electrical signals.

[0028] In some embodiments, during measurement, the lens detection device 10 performs a linear scan of the reflector 162 of the reference optical path 160, records the position of the reflector 162 at various times using a displacement sensor 163, and collects and records the amplitude of the electrical signal generated by the detector 141 at various times during the scan using a processor 142. The peak value of the electrical signal indicates that the optical coherence signal generated at the position of the reflector 162 at that moment is the strongest, and the optical path difference between the measurement optical path 150 and the reference optical path 160 is zero. That is, the position of the reflector 162 at the signal peak point can be used to represent the vertex position of the mirror surface of the lens 153 under test. During the linear scan of the reflector 162 of the reference optical path 160, the collected electrical signal will have multiple peak values. The positions of the reflector 162 corresponding to these peak points represent the positions of the vertices of the mirror surface of the lens 153 under test, respectively. The difference ΔL between the readings of the displacement sensor 163 corresponding to two adjacent peak points is equal to the optical path S of the corresponding two vertices of the measured optical surfaces. If the two optical mirrors being measured are two surfaces of the same lens, then the thickness of the lens is equal to the difference ΔL between the readings of displacement sensor 163 divided by the refractive index of the lens; if the two optical mirrors being measured are not two surfaces of the same lens, then the air gap between the vertices of the two optical mirrors being measured is equal to the difference ΔL between the readings of displacement sensor 163.

[0029] In some embodiments, the light output from the coherent light source 110 is transmitted via optical fiber 120 to the first optical fiber coupler 130 and split into two beams. One beam is transmitted via optical fiber 120 to the measurement optical path 150, where it is reflected by the surface of the lens under test 153 to form a measurement beam. The other beam is transmitted via optical fiber 120 to the reflector 162 of the reference optical path 160, where it is reflected by the reflector 162 to form a reference beam. The reference beam and the measurement beam interfere with each other, and the analysis module 140 can then acquire an interference fringe image. By calculating and analyzing the interference information, the deviation of the center of the lens under test 153 can be derived. By measuring the centers of the two surfaces of the lens under test 153, the center deviation of a single lens under test 153 can be obtained.

[0030] In some embodiments, since the reflected light from both the front and rear surfaces of the lens under test 153 interferes with the reference beam, two independent concentric interference fringes appear on the detector 141. The position of the center point of the interference fringe is related to the center deviation of the front and rear surfaces of the lens under test 153. By analyzing the position of the center point of the interference ring, the center deviation of the lens under test 153 can be measured.

[0031] In some embodiments, the light output from the coherent light source 110 is transmitted via optical fiber 120 to the first fiber coupler 130 and split into two beams. One beam reaches the surface of the lens under test 153, is reflected, and then returns along the original path. The other beam reaches the surface of the reflector 162, is reflected, and also returns along the original path. These two reflected beams return to the first fiber coupler 130 and converge on the target surface of the detector 141. During the measurement process, the reflector 162 of the reference optical path 160 performs a linear scan along the displacement sensor 163, analyzes the amplitude of the output signal of the detector 141, and finds the point with the largest amplitude, which is the maximum coherence value. The displacement sensor 163 of the reference optical path 160 can be used to locate the vertex of the lens under test 153. The two adjacent points with the strongest coherence correspond to the two adjacent vertexes of the mirror. The displacement of the reflector 162 is read by the displacement sensor 163, which is the air gap between the two vertexes of the mirror.

[0032] In some embodiments, the space between the two mirror surfaces of the lens under test 153 is a glass medium. Without considering the influence of glass dispersion, the thickness of the lens under test 153 is equal to the displacement of the reflector 162 divided by the refractive index of the glass medium.

[0033] In some embodiments, the displacement sensor 163 is a grating ruler. A grating ruler, also known as a grating ruler displacement sensor (grating ruler sensor), is a measurement feedback device that works using the optical principle of a grating. Grating rulers are frequently used in closed-loop servo systems of CNC machine tools and can be used for the detection of linear or angular displacement. Its measurement output signal is a digital pulse, featuring a large detection range, high detection accuracy, and fast response speed.

[0034] In some other embodiments, the displacement sensor 163 may be an inductive sensor, a capacitive sensor, a laser interferometer, etc.

[0035] In some embodiments, the coherent light source 110 is a short coherent light source superluminescent diode (SLD).

[0036] In some embodiments, the measurement optical path 150 is provided with a first fiber optic lens 151, which is connected to a first fiber optic coupler 130 via an optical fiber 120. The first fiber optic lens 151 is used to incident the light output from the first fiber optic coupler 130 onto the surface of the lens under test 153 and receive the reflected measurement beam.

[0037] In some embodiments, the reference optical path 160 is provided with a second fiber optic lens 161, which is connected to the first fiber optic coupler 130 via an optical fiber 120. The second fiber optic lens 161 is used to incident the light output from the first fiber optic coupler 130 onto the surface of the reflector 162 and receive the reflected reference beam.

[0038] In some embodiments, the first fiber optic lens 151 is a fiber optic collimator. The light output from the first fiber optic coupler 130 is converted into an approximately parallel beam by the first fiber optic lens 151 and emitted to the surface of the lens under test 153. The beam is reflected by the surface of the lens under test 153 and returns along the original path.

[0039] In some embodiments, the second fiber optic lens 161 is a fiber optic collimator. The light output from the first fiber optic coupler 130 is converted into an approximately parallel beam by the second fiber optic lens 161 and emitted. The beam reaches the surface of the reflector 162 and is reflected back along the original path.

[0040] In some embodiments, the lens detection device 10 further includes a focusing lens 152, which is disposed in the measurement optical path 150 and located between the first fiber optic lens 151 and the lens to be tested 153.

[0041] In some embodiments, the optical axis of the focusing lens 152 coincides with the optical axis of the first fiber optic lens 151.

[0042] In some embodiments, the lens testing device 10 further includes an adjustment platform 154, on which the lens to be tested 153 is disposed. The adjustment platform 154 is used to adjust the position and angle of the lens to be tested 153 so that the optical axis of the lens to be tested 153 coincides with the optical axis of the first fiber optic lens 151.

[0043] In some embodiments, the adjustment stage 154 includes an adjustment platform 1541 and an electric turntable 1542. The lens testing device 10 also includes a base 170. The electric turntable 1542 is disposed on the base 170, and the adjustment platform 1541 is disposed on the side of the electric turntable 1542 opposite to the base 170. The lens 153 to be tested is mounted on the side of the adjustment platform 1541 opposite to the electric turntable 1542. The electric turntable 1542 can be used to adjust the rotation angle of the lens 153 to be tested, and the adjustment platform 1541 is used to adjust the pitch angle of the lens 153 to be tested.

[0044] In some embodiments, the adjustment stage 154 includes an adjustment platform 1541 and an electric displacement stage. The electric displacement stage is located on the side of the adjustment platform 1541 away from the lens 153 under test, and is used to adjust the position of the lens 153 under test.

[0045] In some embodiments, the lens detection device 10 further includes an indicator light source 111 and a second fiber optic coupler 131. The indicator light source 111 is connected to the second fiber optic coupler 131 via an optical fiber 120. The coherent light source 110 is connected to the second fiber optic coupler 131 via an optical fiber 120. The second fiber optic coupler 131 is connected to the first fiber optic coupler 130 via an optical fiber 120. The second fiber optic coupler 131 is used to couple the light output from the coherent light source 110 and the light output from the indicator light source 111 into the optical fiber 120 connected to the first fiber optic coupler 130.

[0046] In some embodiments, the indicator light source 111 can be a visible light LED light source. The light output from the indicator light source 111 is transmitted through the optical fiber 120, passes through the first optical fiber lens 151, and is incident on the surface of the lens 153 under test to indicate the position of the measurement point. During the measurement process, the indicator light source 111 can be turned off, and the photosensitive light source 110 can be turned on.

[0047] In some embodiments, the second fiber coupler 131 is a 1×2 fiber coupler. A fiber coupler is an optical device that distributes or combines optical signal power between different optical fibers. It is constructed by utilizing the mutual exchange of guided wave energy in the fiber core regions adjacent to different fiber surfaces. According to the type of fiber used, it can be classified into multimode fiber, single-mode fiber, and polarization-maintaining fiber couplers, etc. Fiber couplers are also called splitters, connectors, adapters, or fiber optic flanges. This application, by setting the second fiber coupler 131, ensures that the light output from the indicator light source 111 and the light output from the coherent light source 110 are at the same exit position from the first fiber optic lens 151, thereby facilitating the positioning of the beam emitted by the coherent light source 110.

[0048] In some embodiments, the first fiber coupler 130 is a 2×2 fiber coupler.

[0049] In some embodiments, the lens testing device 10 operates as follows: The indicator light source 111 is turned on, generating an indicator light spot on the surface of the lens under test 153. If this indicator light spot deviates from the center of the lens under test 153, the adjustment stage 154 is adjusted until the indicator light spot is located at the center of the lens under test 153. Then, the indicator light source 111 is turned off, and the coherent light source 110 is turned on. The beam emitted by the coherent light source 110 passes through the optical fiber 120 and the second optical fiber coupler 131, then enters the first optical fiber coupler 130 and is split into two paths. One beam enters the measurement optical path 150, and the other beam enters the reference optical path 160. The beam entering the measurement optical path 150 passes through the first optical fiber lens 151, is converted into an approximately parallel beam, and exits to various surfaces of the lens under test 153. The beam is reflected by various surfaces of the lens under test 153 and returns along the original path in reverse. The light beam entering the reference optical path 160 is converted into an approximately parallel beam and emitted, reaching the surface of the reflector 162. After being reflected, the beam returns along the original path. The beams reflected back from the measurement optical path 150 and the reference optical path 160 are coupled into the optical fiber 120 through the first optical fiber lens 151 and the second optical fiber lens 161, respectively. These two beams then pass through the first optical fiber coupler 130 and are coupled into the same optical fiber 120, and transmitted to the target surface of the detector 141. The detector 141 converts the optical signal into an electrical signal.

[0050] During the measurement process of the lens inspection device 10, the reflector 162 of the reference optical path 160 performs a linear scan along the direction parallel to the optical axis. The displacement sensor 163 records the position of the reflector 162 at each moment during the scan. Simultaneously, the processor 142 acquires and records the amplitude of the electrical signal generated by the detector 141 at each moment during the scan. The peak value of the electrical signal indicates that the optical coherence signal generated by the measuring optical path 150 and the reference optical path 160 is strongest at the position of the reflector 162 at that moment. At this time, the optical path difference between the measuring optical path 150 and the reference optical path 160 is zero, that is, the position of the reflector 162 corresponding to the signal peak point represents the vertex position of the mirror surface of the lens 153 under test. During the linear scan of the reflector 162 of the reference optical path 160, the acquired signal of the detector 141 will have multiple peak values. The positions of the reflector 162 corresponding to these peak points represent the vertex positions of each mirror surface of the lens 153 under test. The processor 142 combines the position information of the reflector 162 and the interference information to perform calculation and analysis, and can simultaneously obtain the center deviation and mirror spacing of the lens 153 under test.

[0051] The lens inspection device 10 provided in this application can simultaneously measure the center deviation and mirror spacing of the lens 153 under test. The lens inspection device 10 has a compact structure, a simple measurement process, and features small size and high reliability, which is beneficial to improving inspection efficiency and accuracy.

[0052] The above description is only a part of the embodiments of this application and does not limit the scope of protection of this application. Any equivalent device or equivalent process transformation made based on the content of this application specification and drawings, or direct or indirect application in other related technical fields, are similarly included in the patent protection scope of this application.

Claims

1. A lens inspection device, characterized in that, include: Coherent light source; optical fiber; The first fiber coupler is connected to the coherent light source via the optical fiber. The light output from the coherent light source is transmitted to the first fiber coupler via the optical fiber and split into two beams. One beam is transmitted to the measurement optical path via the optical fiber, and the other beam is transmitted to the reference optical path via the optical fiber. The measurement optical path is equipped with a lens under test. An analysis module is connected to the optical fiber and the first optical fiber coupler. The first optical fiber coupler is used to couple the measurement beam reflected back from the measurement optical path and the reference beam reflected back from the reference optical path into the optical fiber connected to the analysis module. The analysis module is used to receive the interference information generated by the measurement beam and the reference beam and analyze it to obtain the center deviation of the lens under test.

2. The lens inspection device according to claim 1, characterized in that, The reference optical path is equipped with a reflector and a displacement sensor. The reflector is mounted on the displacement sensor and can move along the length direction of the displacement sensor during the measurement process. The displacement sensor is used to record the position information of the reflector at each moment during the movement. The analysis module is used to combine the position information and the interference information to obtain the mirror spacing of the lens under test.

3. The lens inspection device according to claim 2, characterized in that, The measurement optical path is provided with a first fiber optic lens, which is connected to the first fiber optic coupler via the fiber optic cable. The first fiber optic lens is used to incident the light output from the first fiber optic coupler onto the surface of the lens under test and receive the reflected measurement beam. The reference optical path is provided with a second fiber optic lens, which is connected to the first fiber optic coupler via the fiber optic cable. The second fiber optic lens is used to incident the light output from the first fiber optic coupler onto the surface of the reflector and receive the reflected reference beam.

4. The lens inspection device according to claim 2, characterized in that, The displacement sensor is a grating ruler.

5. The lens inspection device according to claim 3, characterized in that, The lens testing device further includes a focusing lens, which is located between the first fiber optic lens and the lens under test.

6. The lens inspection device according to claim 1, characterized in that, The lens testing device also includes an adjustment platform, on which the lens to be tested is placed, and the adjustment platform is used to adjust the position and angle of the lens to be tested.

7. The lens inspection device according to claim 1, characterized in that, The lens detection device further includes an indicator light source and a second fiber optic coupler. The indicator light source is connected to the second fiber optic coupler via the optical fiber. The coherent light source is connected to the second fiber optic coupler via the optical fiber. The second fiber optic coupler is connected to the first fiber optic coupler via the optical fiber. The second fiber optic coupler is used to couple the light output by the coherent light source and the light output by the indicator light source into the optical fiber connected to the first fiber optic coupler.

8. The lens inspection device according to claim 7, characterized in that, The second fiber optic coupler is a 1×2 fiber optic coupler.

9. The lens inspection device according to claim 1, characterized in that, The first fiber optic coupler is a 2×2 fiber optic coupler.

10. The lens inspection device according to claim 2, characterized in that, The analysis module includes a detector and a processor. The detector is used to receive interference information generated by the measurement beam and the reference beam, and the processor is used to analyze and obtain the center deviation and mirror spacing of the lens under test.

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