Lens testing system and lens testing method

Abstract

A lens testing system includes a variable object distance optical system, a testing platform, and a collimating lens. The variable object distance optical system includes a light source and a photoelectric sensor. The testing platform includes a heater, a movable platform, and a reflector. The heater is used to support and heat the lens to be tested. The reflector is located on the movable platform and below the heater. The collimating lens is disposed between the variable object distance optical system and the testing platform. Light emitted by the light source passes through the collimating lens, the lens to be tested, and the reflector. After being reflected by the reflector, it passes through the lens to be tested and the collimating lens. The photoelectric sensor can receive the light reflected by the reflector. The variable object distance optical system and the movable platform can both move up and down along the optical axis of the collimating lens. The lens testing system of the present invention can identify lens variations in advance and compensate for them in advance. The present invention also relates to a lens testing method.

Description

Technical Field

[0001] The present invention relates to the technical field of lens detection technology, and in particular to a lens testing system and a lens testing method. Background Art

[0002] Currently, fixed-focus camera modules experience lens variations when the ambient temperature rises. These variations, such as changes in focal length and the main image plane, can reduce camera resolution and impact the user experience. Furthermore, it is difficult for designers to identify the various factors that cause lens variation. Summary of the Invention

[0003] In view of this, the present invention provides a lens testing system that can identify lens variations in advance and compensate in advance, which is beneficial to improving product quality and user experience.

[0004] A lens testing system, comprising:

[0005] A variable object distance optical system, including a light source and a photoelectric sensor;

[0006] The test platform includes a heater, a mobile platform, and a reflector. The heater is used to carry and heat the lens to be tested. The reflector is located on the mobile platform and below the heater.

[0007] Collimating lens: The collimating lens is set between the variable object distance optical system and the test platform. The light emitted by the light source passes through the collimating lens, the lens to be tested and the reflector. After being reflected by the reflector, it passes through the lens to be tested and the collimating lens. The photoelectric sensor can receive the light reflected by the reflector.

[0008] The variable object distance optical system and the moving platform can both move up and down along the optical axis direction of the collimating lens.

[0009] In an embodiment of the present invention, the variable object distance optical system further includes a cross-reticle plate, and the light source and the cross-reticle plate are disposed opposite to each other vertically along the optical axis of the collimating lens.

[0010] In an embodiment of the present invention, the variable object distance optical system further includes a dichroic prism, the light source and the dichroic prism are arranged opposite to each other up and down along the optical axis of the collimating lens, the photoelectric sensor is arranged on one side of the dichroic prism, and the light reflected by the reflector is reflected by the dichroic prism and then incident on the photoelectric sensor.

[0011] In an embodiment of the present invention, the variable object distance optical system further includes a mounting frame, on which the light source, the cross-reticle, the beam splitter prism, and the photoelectric sensor are mounted. In an embodiment of the present invention, the variable object distance optical system further includes a first displacement actuator, to which the mounting frame is connected, the first displacement actuator being configured to drive the mounting frame to move up and down along the optical axis of the collimating lens.

[0012] In an embodiment of the present invention, the test platform further includes a second displacement driver, and the second displacement driver is used to drive the test platform to move up and down along the optical axis of the collimating lens.

[0013] In an embodiment of the present invention, the movable platform further comprises a third displacement driver, and the third displacement driver is used to drive the reflecting mirror to move up and down along the optical axis of the collimating lens.

[0014] In an embodiment of the present invention, the heater includes a carrying platform for carrying the lens to be tested, and the carrying platform is arranged perpendicular to the optical axis of the collimating lens.

[0015] In an embodiment of the present invention, the reflective mirror, the movable platform and the optical axis of the collimating lens are arranged perpendicularly.

[0016] The present invention also relates to a lens testing method, which utilizes the lens testing system described above and comprises:

[0017] When the temperature is T1, the focal length F1 of the lens to be tested is tested. The testing steps include: first, adjusting the position of the variable object distance optical system so that the variable object distance optical system generates parallel light; then, adjusting the position of the reflector so that a clear cross is displayed on the photoelectric sensor, and recording the scale Y1 of the movable platform; then, adjusting the position of the variable object distance optical system so that the lens to be tested generates a first object distance X1, adjusting the position of the reflector again so that a clear cross is displayed on the photoelectric sensor, and recording the scale Y2 of the movable platform; the focal length F1 of the lens to be tested = (X1·(Y2-Y1)) 1 / 2 ;

[0018] The focal length F2 of the lens under test is tested during heating. The testing steps include: first, heating the lens under test from temperature T1 to temperature T2 using the heater, adjusting the position of the variable object distance optical system so that the variable object distance optical system generates parallel light; then, adjusting the position of the reflector so that a clear cross is displayed on the photoelectric sensor, and recording the scale Y3 of the movable platform; then, adjusting the position of the variable object distance optical system so that the lens under test generates a second object distance X2, adjusting the position of the reflector again so that a clear cross is displayed on the photoelectric sensor, and recording the scale Y4 of the movable platform; the focal length F2 of the lens under test = (X2·(Y4-Y3)). 1 / 2 .

[0019] In an embodiment of the present invention, after the temperature of the lens under test changes from T1 to T2, the front focal length of the lens under test changes to F2-F1; after the temperature of the lens under test changes from T1 to T2, the back focal length of the lens under test changes to Y3-F1; and after the temperature of the lens under test changes from T1 to T2, the movement amount of the image-side principal surface of the lens under test is (Y3-F2)-(Y1-F1).

[0020] The lens testing system of the present invention can detect the variation of the lens in a high-temperature environment (the difference between the lens in a normal temperature environment and a high-temperature environment). For example, the variation of the lens includes the front focal length, back focal length and change in the main surface of the image side. When the camera module factory produces fixed-focus cameras, the lens variation can be identified in advance and compensation can be made in advance, which provides a compensation basis for the camera module factory, which is conducive to improving product quality and user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the lens testing system of the present invention. DETAILED DESCRIPTION

[0022] The present application provides a lens testing system.

[0023] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0024] To facilitate understanding by those skilled in the art, the present application describes the specific implementation process of the technical solution provided by the present application through the following embodiments.

[0025] Figure 1 Schematic diagram of the lens testing system of the present invention. Figure 1 As shown, the lens testing system includes a variable object distance optical system 10, a testing platform 20 and a collimating lens 30;

[0026] The variable object distance optical system 10 includes a light source 12 and a photoelectric sensor 15;

[0027] The test platform 20 includes a heater 21, a movable platform 22, and a reflector 23. The heater 21 is used to carry and heat the lens 40 to be tested. The reflector 23 is located on the movable platform 22 and below the heater 21.

[0028] Collimating lens 30, which is used to align a light beam in a specific direction to form collimated or parallel light. Collimating lens 30 is disposed between variable object distance optical system 10 and test platform 20. Light emitted by light source 12 passes through collimating lens 30, lens 40 to be tested, and reflector 23. After being reflected by reflector 23, light passes through lens 40 to be tested and collimating lens 30. Photoelectric sensor 15 can receive the light reflected by reflector 23.

[0029] Both the variable object distance optical system 10 and the moving platform 22 can move up and down along the optical axis of the collimating lens 30 .

[0030] The lens testing system of the present invention can detect the variation of the lens in a high-temperature environment (the difference between the lens in a normal temperature environment and a high-temperature environment). For example, the variation of the lens includes the front focal length, back focal length and change in the main surface of the image side. When the camera module factory produces fixed-focus cameras, the lens variation can be identified in advance and compensation can be made in advance, which provides a compensation basis for the camera module factory, which is conducive to improving product quality and user experience.

[0031] Furthermore, the variable object distance optical system also includes a cross-reticle plate 13. The light source 12 and the cross-reticle plate 13 are arranged opposite to each other along the optical axis of the collimating lens 30. The light emitted by the light source 12 passes through the cross-reticle plate 13 and the collimating lens 30 in sequence.

[0032] Furthermore, the variable object distance optical system also includes a beam splitter prism 14. The light source 12 and the beam splitter prism 14 are arranged vertically opposite each other along the optical axis of the collimating lens 30. A photoelectric sensor 15 is disposed on one side of the beam splitter prism 14. Light reflected by the reflector 23 is then reflected by the beam splitter prism 14 and incident on the photoelectric sensor 15. A crosshair plate 13 is positioned between the light source 12 and the beam splitter prism 14. Light emitted by the light source 12 sequentially passes through the crosshair plate 13, the beam splitter prism 14, and the collimating lens 30. After being reflected by the reflector 23, the light passes through the test lens 40, the collimating lens 30, and the beam splitter prism 14. Finally, after being reflected by the beam splitter prism 14, it is received by the photoelectric sensor 15. In this embodiment, the dichroic prism 14 is a semi-transparent and semi-reflective prism. When the light emitted by the light source 12 passes through the dichroic prism 14, 50% of the light is reflected, and the other 50% of the light passes through the dichroic prism 14 to reach the collimating lens 30. The light reflected back by the reflector 23 reaches the dichroic prism 14, 50% of which is reflected to reach the photoelectric sensor 15, and the other 50% passes through the dichroic prism 14.

[0033] Furthermore, the variable object distance optical system further includes a mounting frame 11 , on which the light source 12 , the cross-reticle 13 , the beam splitter prism 14 and the photoelectric sensor 15 are mounted.

[0034] Furthermore, the variable object distance optical system 10 includes a first displacement actuator (not shown). The mounting frame 11 is connected to the first displacement actuator and is configured to move the mounting frame 11 up and down along the optical axis of the collimating lens 30. When the first displacement actuator moves the mounting frame 11 and positions the upper focal point of the collimating lens 30 at the center of the crosshair reticle 13, light passing through the collimating lens 30 forms parallel light. In this embodiment, the first displacement actuator is, for example, a high-precision motor, but is not limited thereto.

[0035] Furthermore, the test platform 20 includes a second displacement actuator (not shown) that is used to move the test platform 20 up and down along the optical axis of the collimating lens 30. Specifically, the second displacement actuator can move the test platform 20 toward or away from the collimating lens 30. The second displacement actuator is a highly precise displacement actuator. In this embodiment, the second displacement actuator adjusts the position of the test platform 20 to maintain a constant distance between the lower vertex of the collimating lens 30 and the upper vertex of the lens under test.

[0036] Furthermore, the mobile platform 22 includes a third displacement actuator (not shown) that is used to move the reflective mirror 23 up and down along the optical axis of the collimating lens 30. The third displacement actuator is a highly precise displacement actuator. In this embodiment, the third displacement actuator adjusts the position of the reflective mirror 23 so that the cross displayed by the photoelectric sensor 15 changes from blurred to clear. When the photoelectric sensor 15 displays a clear cross, the third displacement actuator stops driving.

[0037] Furthermore, the heater 21 includes a supporting platform (not shown) for supporting the lens 40 to be tested. The supporting platform is arranged perpendicular to the optical axis of the collimating lens 30 .

[0038] Furthermore, the reflective mirror 23 , the movable platform 22 and the optical axis of the collimating lens 30 are arranged perpendicularly.

[0039] Furthermore, the movable platform 22 has a scale for checking the displacement of the movable platform 22 .

[0040] Furthermore, the photoelectric sensor 15 is, for example, a CCD charge coupled device, but is not limited thereto.

[0041] Furthermore, when the lens testing system tests the lens 40 to be tested, the lens 40 to be tested needs to be placed in the heater 21. The top and bottom of the heater 21 are both light-transmissive, that is, the light emitted by the light source 12 can pass through the heater 21 and the lens 40 to be tested therein. The heater is preferably a heating box, and the heating box is provided with light holes on the top and bottom to allow the light emitted by the light source to pass through. The temperature of the heating box can be adjusted to a specified temperature as needed. The supporting platform for placing the lens 40 in the heating box is made of a material that is not easily deformed by heat, such as titanium alloy.

[0042] Furthermore, the collimating lens 30 may be composed of a single lens or multiple lenses, which can be freely selected according to actual needs.

[0043] Furthermore, when the lens testing system is not heated at the temperature T1, the steps of testing the focal length F1 of the lens 40 to be tested include:

[0044] In step 1, the heater 21 is not operated, and the position of the variable object distance optical system 10 is adjusted, that is, by adjusting the position of the mounting frame 11, so that the variable object distance optical system 10 generates parallel light. Specifically, the mounting frame 11 is driven to move by the first displacement driver until the light passing through the collimating lens 30 forms parallel light.

[0045] Step 2: Adjust the position of the reflective mirror 23 so that a clear cross is displayed on the photoelectric sensor 15, and record the scale Y1 of the movable platform 22. Specifically, adjust the position of the reflective mirror 23 by the third displacement driver until the photoelectric sensor 15 displays a clear cross, then stop driving. At this time, record the position scale Y1 of the movable platform 22.

[0046] Step 3: Adjust the position of the variable object distance optical system 10 by adjusting the position of the mounting bracket 11, so that the lens 40 to be tested has a first object distance X1. The position of the reflector 23 is then adjusted again so that a clear crosshair is displayed on the photoelectric sensor 15, and the scale Y2 on the movable platform 22 is recorded. The focal length F1 of the lens 40 to be tested is (X1·(Y2-Y1)).1 / 2 Specifically, the mounting frame 11 is driven to move a certain distance by the first displacement driver so that the lens 40 to be tested generates a first object distance X1. Then, the position of the reflector 23 is adjusted by the third displacement driver so that the photoelectric sensor 15 stops driving when it can display a clear cross. At this time, the position scale Y2 of the movable platform 22 is recorded.

[0047] Furthermore, when the lens testing system is heated from temperature T1 to temperature T2, the step of testing the focal length F2 of the lens to be tested 40 includes:

[0048] Step 1: After the lens 40 to be tested is heated from temperature T1 to temperature T2 by the heater 21, the position of the mounting frame 11 is adjusted so that the variable object distance optical system 10 generates parallel light. Specifically, after the lens 40 to be tested is heated from temperature T1 to temperature T2 by the heater 21, the mounting frame 11 is driven to move by the first displacement actuator until the light passing through the collimating lens 30 forms parallel light.

[0049] Step 2: Adjust the position of the reflective mirror 23 so that a clear cross is displayed on the photoelectric sensor 15, and record the scale Y3 of the movable platform 22. Specifically, adjust the position of the reflective mirror 23 by the third displacement driver until the photoelectric sensor 15 displays a clear cross, then stop driving. At this time, record the position scale Y3 of the movable platform 22.

[0050] Step 3: Adjust the position of the mounting bracket 11 so that the lens 40 to be tested has a second object distance X2. Adjust the position of the reflector 23 again so that a clear cross is displayed on the photoelectric sensor 15. Also, record the scale Y4 on the movable platform 22. The focal length F2 of the lens 40 to be tested is (X2·(Y4-Y3)). 1 / 2 Specifically, the mounting frame 11 is driven to move a certain distance by the first displacement driver so that the lens 40 to be tested produces a second object distance X2. Finally, the position of the reflector 23 is adjusted by the third displacement driver so that the photoelectric sensor 15 stops driving when it can display a clear cross. At this time, the position scale Y4 of the movable platform 22 is recorded.

[0051] Furthermore, after the temperature of the lens 40 under test changes from T1 to T2, the front focal length of the lens 40 under test changes to F2-F1; after the temperature of the lens 40 under test changes from T1 to T2, the back focal length of the lens 40 under test changes to Y3-F1; and after the temperature of the lens 40 under test changes from T1 to T2, the movement of the image-side principal surface of the lens 40 under test is (Y3-F2)-(Y1-F1). In this embodiment, the lens testing system can detect changes in the front focal length F2-F1, back focal length Y3-F1, and image-side principal surface (Y3-F2)-(Y1-F1) of the lens under high temperature environments, providing a compensation basis for camera module manufacturers, thereby improving product quality and user experience.

[0052] The present invention also relates to a lens testing method, which utilizes the above-mentioned lens testing system and comprises:

[0053] At S1, when the temperature is T1, the focal length F1 of the lens under test 40 is tested. The test steps include: first, adjusting the position of the variable object distance optical system 10 so that the variable object distance optical system 10 generates a parallel beam; then, adjusting the position of the reflector 23 so that a clear cross is displayed on the photoelectric sensor 15, and recording the scale Y1 on the movable platform 22; then, adjusting the position of the mounting frame 11 so that the lens under test 40 produces a first object distance X1; then adjusting the position of the reflector 23 again so that a clear cross is displayed on the photoelectric sensor 15, and recording the scale Y2 on the movable platform 22; the focal length F1 of the lens under test 40 = (X1·(Y2-Y1)). 1 / 2 .

[0054] Specifically, first, the mounting frame 11 is driven to move by the first displacement driver until the light passing through the collimating lens 30 forms parallel light, and the driving is stopped;

[0055] Afterwards, the position of the reflective mirror 23 is adjusted by the third displacement driver, and the driving is stopped when the photoelectric sensor 15 can display a clear cross. At this time, the position scale Y1 of the movable platform 22 is recorded.

[0056] Next, the first displacement actuator drives the mounting frame 11 to move a certain distance, so that the lens 40 to be tested has a first object distance X1. The third displacement actuator then adjusts the position of the reflector 23 until the photoelectric sensor 15 displays a clear cross. The actuator then stops driving and records the position Y2 of the movable platform 22. The focal length F1 of the lens 40 to be tested is (X1·(Y2-Y1)). 1 / 2 ;

[0057] S2, testing the focal length F2 of the lens under test 40 during heating. The testing steps include: first, heating the lens under test 40 from temperature T1 to temperature T2 using the heater 21, then adjusting the position of the variable object distance optical system 10 so that the variable object distance optical system 10 generates a parallel beam; then, adjusting the position of the reflector 23 so that a clear cross is displayed on the photoelectric sensor 15, and recording the scale Y3 on the movable platform 22; then, adjusting the position of the variable object distance optical system 10 so that the lens under test 40 generates a second object distance X2, and again adjusting the position of the reflector 23 so that a clear cross is displayed on the photoelectric sensor 15, and recording the scale Y4 on the movable platform 22; the focal length F2 of the lens under test 40 = (X2·(Y4-Y3)). 1 / 2 .

[0058] Specifically, first, the heater 21 is used to heat the lens 40 to be tested from the temperature T1 to the temperature T2, and then the first displacement driver is used to drive the mounting frame 11 to move until the light passing through the collimating lens 30 forms parallel light, and then the driving is stopped;

[0059] Afterwards, the position of the reflective mirror 23 is adjusted by the third displacement driver, and the driving is stopped when the photoelectric sensor 15 can display a clear cross. At this time, the position scale Y3 of the movable platform 22 is recorded.

[0060] Next, the first displacement actuator drives the mounting frame 11 to move a certain distance, causing the lens 40 to have a second object distance X2. Finally, the third displacement actuator adjusts the position of the reflector 23 until the photoelectric sensor 15 displays a clear cross. The actuator then stops driving and records the position Y4 of the movable platform 22. The focal length F2 of the lens 40 is (X2·(Y4-Y3)). 1 / 2 .

[0061] Furthermore, after the temperature of the lens 40 under test changes from T1 to T2, the front focal length of the lens 40 under test changes to F2-F1; after the temperature of the lens 40 under test changes from T1 to T2, the back focal length of the lens 40 under test changes to Y3-F1; and after the temperature of the lens 40 under test changes from T1 to T2, the movement amount of the image-side principal surface of the lens 40 under test is (Y3-F2)-(Y1-F1).

[0062] The lens testing method of the present invention can detect the variation of the lens in a high-temperature environment. For example, the variation of the lens includes the front focal length, back focal length and the change in the main surface of the image side. When the camera module factory produces fixed-focus cameras, the variation of the lens back focal length can be identified in advance and compensation can be performed in advance, which provides a compensation basis for the camera module factory and is conducive to improving product quality and user experience.

[0063] The present application is not limited to the specific details in the above-mentioned embodiments. Within the scope of the technical concept of the present application, a variety of simple variations can be made to the technical solution of the present application, and these simple variations all fall within the scope of protection of the present application. The various specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner unless there is any contradiction. In order to avoid unnecessary repetition, the present application will not further describe various possible combinations.

Claims

1. A lens testing system, characterized in that: include: A variable object distance optical system, including a light source and a photoelectric sensor; The test platform includes a heater, a movable platform, and a reflector, wherein the heater is used to carry and heat the lens to be tested, and the reflector is located on the movable platform and below the heater; A collimating lens, the collimating lens being arranged between the variable object distance optical system and the test platform, wherein the light emitted by the light source passes through the collimating lens, the lens to be tested, and the reflector, and then is reflected by the reflector before passing through the lens to be tested and the collimating lens, and the photoelectric sensor can receive the light reflected by the reflector; The variable object distance optical system and the movable platform can both move up and down along the optical axis of the collimating lens; The variable object distance optical system further includes a cross-reticle plate, and the light source and the cross-reticle plate are arranged vertically and oppositely along the optical axis of the collimating lens; When the temperature is T1, test the focal length of the lens to be tested , adjust the position of the variable object distance optical system so that the variable object distance optical system generates a parallel light; adjust the position of the reflector so that a clear cross is displayed in the photoelectric sensor, and record the scale of the moving platform ; Adjust the position of the variable object distance optical system again so that the lens to be tested produces a first object distance , adjust the position of the reflector again so that a clear cross is displayed on the photoelectric sensor, and record the scale of the moving platform ; The focal length of the lens to be tested ; Testing the focal length of the lens under test while heating After heating the lens to be tested from temperature T1 to temperature T2 using the heater, the position of the variable object distance optical system is adjusted so that the variable object distance optical system generates a parallel light; the position of the reflector is adjusted so that a clear cross is displayed on the photoelectric sensor, and the scale of the moving platform is recorded. ; Adjust the position of the variable object distance optical system again so that the lens to be tested produces a second object distance , adjust the position of the reflector again so that a clear cross is displayed on the photoelectric sensor, and record the scale of the moving platform ; The focal length of the lens to be tested ; After the temperature of the lens to be tested changes from T1 to T2, the front focal length of the lens to be tested changes to After the temperature of the lens to be tested changes from T1 to T2, the back focal length of the lens to be tested changes to After the lens under test changes from temperature T1 to temperature T2, the movement amount of the main surface of the image side of the lens under test is .

2. The lens testing system according to claim 1, wherein: The variable object distance optical system also includes a dichroic prism. The light source and the dichroic prism are arranged opposite to each other up and down along the optical axis of the collimating lens. The photoelectric sensor is arranged on one side of the dichroic prism. The light reflected by the reflector is reflected by the dichroic prism and then enters the photoelectric sensor.

3. The lens testing system according to claim 2, wherein: The variable object distance optical system further includes a mounting frame, and the light source, the cross-reticle, the beam splitter prism, and the photoelectric sensor are mounted on the mounting frame.

4. The lens testing system according to claim 3, wherein: The variable object distance optical system further includes a first displacement driver, the mounting frame is connected to the first displacement driver, and the first displacement driver is used to drive the mounting frame to move up and down along the optical axis of the collimating lens.

5. The lens testing system according to claim 1 or 4, wherein: The test platform further includes a second displacement driver, which is used to drive the test platform to move up and down along the optical axis of the collimating lens.

6. The lens testing system according to claim 5, wherein: The moving platform further includes a third displacement driver, which is used to drive the reflecting mirror to move up and down along the optical axis of the collimating lens.

7. The lens testing system according to claim 1, wherein: The heater includes a carrying platform for carrying the lens to be tested, and the carrying platform is arranged perpendicular to the optical axis of the collimating lens.

8. The lens testing system according to claim 1, wherein: The reflector, the movable platform and the optical axis of the collimating lens are arranged perpendicularly.

9. A lens testing method, characterized in that: The method utilizes the lens testing system according to any one of claims 1 to 8, and the method comprises: When the temperature is T1, test the focal length of the lens to be tested The test steps include: first, adjusting the position of the variable object distance optical system so that the variable object distance optical system generates a parallel light; then, adjusting the position of the reflector so that a clear cross is displayed in the photoelectric sensor, and recording the scale of the moving platform. Then, adjust the position of the variable object distance optical system so that the lens to be tested produces a first object distance , adjust the position of the reflector again so that a clear cross is displayed on the photoelectric sensor, and record the scale of the moving platform ; The focal length of the lens to be tested ; Testing the focal length of the lens under test while heating The test steps include: first, using the heater to heat the lens to be tested from temperature T1 to temperature T2, adjusting the position of the variable object distance optical system so that the variable object distance optical system generates a parallel light; then, adjusting the position of the reflector so that a clear cross is displayed on the photoelectric sensor, and recording the scale of the moving platform. Then, adjust the position of the variable object distance optical system so that the lens to be tested produces a second object distance , adjust the position of the reflector again so that a clear cross is displayed on the photoelectric sensor, and record the scale of the moving platform ; The focal length of the lens to be tested ; After the temperature of the lens to be tested changes from T1 to T2, the front focal length of the lens to be tested changes to After the temperature of the lens to be tested changes from T1 to T2, the back focal length of the lens to be tested changes to After the lens under test changes from temperature T1 to temperature T2, the movement amount of the main surface of the image side of the lens under test is .

Images