Imaging lens based on double-hole diaphragm

Abstract

The imaging lens is characterized in that the imaging lens comprises a first lens group, a second lens group, a diaphragm and a switchable shielding device, the first lens group and the second lens group form a double-Gaussian structure, the diaphragm comprises two diaphragm holes, the circle centers of the two diaphragm holes are located on the diameter of the diaphragm, and the switchable shielding device is arranged on the diaphragm. And the switchable shielding device alternately shields one of the diaphragm holes by taking the circle center of the diaphragm as a symmetric point. The device has the advantages of light and compact structure, flexibility in use, high measurement precision and the like, and can effectively improve the stability and accuracy of a measurement result. Through the advantages of the switchable shielding device, the problem of imaging jitter easily caused by movement of the imaging device in laser speckle dynamic measurement is solved, and the device can be suitable for various optical test scenes such as laser speckle measurement, optical element detection, image sensor calibration, scientific research optical experiments and the like.

Description

Technical Field

[0001] The invention relates to an optical testing device, in particular to an imaging lens based on a double-aperture diaphragm. Background Art

[0002] In the field of laser speckle measurement, different optical testing equipment has different effects on improving the accuracy of speckle measurement. The small displacement imaging device and the method of rotating the glass sheet to change the optical path adopted in "CN202111523480.6 A test method and test device for dynamic speckle in laser display" developed by the applicant can effectively overcome the situation that the laser speckle test method is easily affected by the screen microstructure, image pixel unit structure, and brightness uniformity, and improve the accuracy of speckle measurement. However, during use, it was found that the method of small displacement imaging equipment will cause imaging jitter problems of optical measuring equipment; the method of rotating the glass sheet to change the optical path will cause pixel alignment difficulties due to the thickness of the glass sheet. How to solve the above difficulties has become a roadblock to the application and promotion of this technology.

[0003] As we all know, in the field of optical testing, imaging lenses are a crucial component. With the continuous development of optical testing technology, technical problems such as the accuracy and aberration of imaging lenses have been effectively solved.

[0004] The double Gauss structure is a classic lens design, proposed by German mathematician and physicist Carl Friedrich Gauss in the early 19th century and improved by British optical designer Paul Rudolph in 1896. Its typical structure is symmetrical or nearly symmetrical, usually consisting of two symmetrical or nearly symmetrical meniscus lens groups in front and behind, with the aperture placed between the two lens groups. This symmetrical structure enables the double Gauss lens to correct various aberrations, especially distortion and coma, to obtain high-quality imaging effects. Due to its excellent performance, the double Gauss structure is widely used in various photographic lenses, especially large aperture standard lenses.

[0005] The double Gaussian structure is usually composed of two symmetrical or nearly symmetrical meniscus lens groups, and the aperture is located between the two lens groups. The front lens group converges the incident light to make it tend to be parallel; the rear lens group then converges these tending to be parallel light to the focus. In a dynamic test method and test device for speckle in a laser display, since it needs to collect two images, "the test device collects the first image, keeps the vertical distance between the test device and the screen unchanged, uses a moving device to make the image of the screen image on the test device move, and then the test device collects the second image". Traditional single-aperture aperture lenses have been widely used in optical imaging tests. When they are applied to "a dynamic test method and test device for speckle in a laser display", they cannot solve the existing imaging jitter caused by displacement of the technology; the use effect is not good. Summary of the invention

[0006] In view of the above problems and the structural characteristics of the double Gaussian lens, the present invention provides an imaging lens based on a double aperture diaphragm to give full play to the advantages of the double Gaussian lens. Two images can be collected without displacement to solve the problem of optical measurement imaging jitter caused by equipment displacement, thereby obtaining high-quality imaging effects.

[0007] The technical solution adopted by the present invention is: an imaging lens based on a double-aperture diaphragm, the main point of which is that it includes: a first lens group, a second lens group, an diaphragm and a switchable shielding device, wherein the first lens group and the second lens group constitute a double Gaussian structure, the diaphragm includes two diaphragm holes, the centers of the two diaphragm holes are located on the diameter of the diaphragm, and the center of the diaphragm is used as a symmetry point, and the switchable shielding device alternately blocks one of the diaphragm holes.

[0008] The present invention creatively improves the double Gauss lens by changing the traditional single-aperture diaphragm into a double-aperture diaphragm, the centers of which are , The double-aperture structured aperture and the switchable shielding device are arranged on the parallel light beam path, and their position design ensures that the incident light beam will not affect the size of the object image of the imaging system after passing through the structure. The double-aperture aperture is located on the X-axis or Y-axis of the aperture, and one of the aperture holes is covered by the switchable shielding device, so that only one aperture hole is working at a time, maintaining the unique advantages of the double Gaussian lens. Since the two aperture holes are misaligned on the X-axis or Y-axis, the displacement of light can be achieved without moving the optical test equipment, and two collected images can be obtained. The distance moved is the center distance between the two aperture holes, which is recorded as .

[0009] Specifically, the switchable blocking device is placed in front of the aperture or behind the aperture, and the device can switch the blocking state and selectively switch to block one of the aperture holes.

[0010] The switchable shielding device of the present invention aims to selectively shield one of the aperture holes so that the light beam passes only through one of the aperture holes, while the other aperture hole is completely covered and opaque, thereby achieving light movement and image movement.

[0011] Further design: The switchable shielding device is a turntable, in which a semicircular hole is opened in half of the disk surface, and the intersection points of the line connecting the center of the aperture circle o and the centers of the two aperture holes and the two aperture holes are: a, b, c, d respectively, the radius of the semicircular hole is greater than oa and od, and the vertical distance between the straight edge of the semicircular hole and the center of the aperture circle o is less than ob and oc.

[0012] The switchable shielding device is a rotating disk, in which a hole is opened in half of the disk surface, and the smallest opening of the hole is larger than the diameter of the aperture hole.

[0013] The above two switchable shielding devices are designed with holes on the switchable shielding devices that are not smaller than the aperture hole, so that the light beam can pass through the aperture hole and the switchable shielding device without obstacles to reach the imaging device.

[0014] The switchable shielding device is a rotatable shielding sheet, the area of ​​which can completely cover a single aperture, but not another aperture. The switchable shielding device completely covers one aperture, allowing the light beam to pass through the other aperture.

[0015] The first lens group, the aperture and the second lens group are rigidly connected. Through the rigid connection among the three, the problem that the method of a small displacement imaging device may cause imaging jitter of the optical measurement device is solved.

[0016] The diameter of the diaphragm is D, the diameter of the diaphragm hole is 0.1-0.4D, and the distance between the nearest adjacent points of two diaphragm holes is 0.1-0.5D.

[0017] Method of using the above device in conjunction with optical testing equipment:

[0018] (a) installing an imaging lens based on a double aperture stop onto an optical testing device, calibrating the optical axes of the first lens group and the second lens group, and ensuring that the optical axes of the first lens group and the second lens group are aligned;

[0019] (b) starting the light source and the switchable shielding device, and making the switchable shielding device shield one of the aperture holes, and using an imaging device or an image acquisition unit to record the imaging result;

[0020] (c) The switchable blocking device is driven to block another aperture and the imaging result is recorded.

[0021] The first lens group is mainly used to initially converge light, reduce aberrations, and improve optical imaging quality. This lens group effectively reduces spherical aberration and coma by combining lenses with different curvature radii.

[0022] The second lens group further corrects the remaining aberrations and forms a clear optical image in the focal plane. Together with the first lens group, this lens group forms a double Gaussian structure, which effectively compensates for chromatic aberration and field curvature.

[0023] The two symmetrical aperture circular holes of the double aperture aperture are used to achieve the effect of imaging displacement through a double light path design while maintaining imaging symmetry.

[0024] Further design: there is a filter turntable at the rear end of the second lens group, and behind the filter turntable is the imaging device, the filter turntable includes a Y filter, an Xr filter, an Xb filter, and a Z filter, and the optical path of the light is the first lens group, a shading plate, an aperture, the second lens group, the filter turntable, and the imaging device, wherein the positions of the shading plate and the aperture are interchangeable.

[0025] When the present invention is used for a test method and a test device for dynamic speckle in a laser display in CN202111523480.6, since the switchable shielding device of the present invention can realize light movement and image movement, the present invention replaces the moving device and the testing device in CN202111523480.6, solves the problem that the method of a small displacement imaging device may cause imaging jitter of the optical measuring device and the method of changing the optical path by rotating the glass sheet may cause difficulty in pixel alignment due to the thickness of the glass sheet, thereby allowing CN202111523480.6 to be promoted and applied.

[0026] The specific improvements and application methods are as follows:

[0027] A testing device for speckle in laser display is composed of a screen, a laser display device, an imaging lens based on a double-aperture diaphragm (the present invention), a filter wheel, an image acquisition unit, and a computer. The image acquisition unit is connected to the computer by signals, and the image captured by the image acquisition unit is transmitted to the computer. The computer stores a calculation formula, and the computer controls the image acquisition unit to capture the speckle pattern. A filter wheel and an imaging lens based on a double-aperture diaphragm are arranged in sequence in front of the image acquisition unit from near to far. After the light projected by the laser display device is projected onto the screen, it is reflected through the imaging lens based on the double-aperture diaphragm and the filter wheel to enter the image acquisition unit. The image formed by the screen image on the image acquisition unit is moved by a switchable shielding device in the imaging lens based on the double-aperture diaphragm, so that the image acquisition unit captures two images with the same test area and different observation positions. The testing steps are as follows:

[0028] (a) placing the device under test at a preset projection position as required, and projecting a test image onto a screen; installing an imaging lens based on a dual aperture diaphragm onto an optical test device, calibrating the optical axes of the first lens group and the second lens group, and ensuring that the optical axes of the first lens group and the second lens group are aligned;

[0029] (b) The test position should be the same as the observation position; the test distance depends largely on the device under test; for full HD projectors, the test distance used is 1.5-3 times the screen height; for cinema projectors, the test distance is 4-6m; the photosensitive surface of the image acquisition unit should be placed on the conjugate image plane of the screen;

[0030] (c) The projected image of the device under test is spatially uniform; when the device under test is a multi-primary color system, all primary color speckles should be tested and the image size should be larger than the field of view of the optical measurement device;

[0031] (d) The filter wheel is placed to filter out unnecessary optical noise signals; the monochromatic filter in the filter wheel should have high transmittance for the main primary color light of the projected image; for the test of different primary colors, the filter with a larger transmittance for the primary color should be selected to obtain a larger image dynamic range;

[0032] (e) starting the switchable shielding device and adjusting one of the aperture holes to be shielded, and adjusting the focal length of the optical testing device so that the captured image is clearly imaged on the optical testing device;

[0033] (f) Adjust the exposure time and make sure that the exposure time should avoid saturation of the imaging device signal. The exposure time should be set between 50 and 200 ms, which is the visual persistence time of the human eye. 100 ms is preferred. If the image brightness is too high and the exposure time is too short, a neutral filter can be used to reduce the image brightness.

[0034] (g) capturing a first image; driving the switchable shielding device to shield another aperture and capturing a second image;

[0035] (h) Perform differential operation on the corresponding positions in the two images and calculate the standard deviation of the speckle using the formula ;

[0036] (i) Calculate the average light intensity of the first and second images and take the average as the average light intensity in the calculation ;

[0037] (j) Speckle contrast is calculated by the formula .

[0038] The present invention creatively improves the double Gaussian lens, changes the traditional single-aperture diaphragm into a double-aperture diaphragm, and the switchable shielding device is arranged on the parallel light beam path, and its position design ensures that the incident light beam will not affect the object image size of the imaging system after passing through the structure. The double-aperture diaphragm is located on the X-axis or Y-axis of the diaphragm, and one of the diaphragm holes is covered by the switchable shielding device, so that only one diaphragm hole is working at a time, maintaining the unique advantages of the double Gaussian lens. Since the two diaphragm holes are misaligned on the X-axis or Y-axis, the movement of light can be achieved without moving the optical testing equipment, thereby realizing the two images generated by the small displacement required by CN202111523480.6 A test method for dynamic speckle in laser display and its test device, which solves the problem that the method of small displacement imaging equipment will cause imaging jitter of the optical measuring equipment, and the first lens group, the diaphragm and the second lens group are rigidly connected, which further improves the problem of imaging jitter.

[0039] The present invention has the advantages of light and compact structure, flexible use, high measurement accuracy, etc., and can effectively improve the stability and accuracy of the measurement results. Through the switchable shielding device, selective shielding can be performed according to the test requirements, and different optical paths can be freely switched. It can be applied to various optical test scenarios such as laser speckle measurement, optical component detection, image sensor calibration, and scientific research optical experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Attached Figure 1 A schematic structural diagram of an imaging lens based on a double aperture diaphragm according to Embodiment 1 of the present invention

[0041] Attached Figure 2 Schematic diagram of the double aperture diaphragm structure of the present invention

[0042] Attached Figure 3 A schematic diagram of the structure of a switchable shielding device according to Embodiment 1 of the present invention

[0043] Attached Figure 4 A schematic diagram of the structure of an imaging lens based on a double aperture diaphragm according to Embodiment 2 of the present invention

[0044] Attached Figure 5 Schematic diagram of the switchable shielding device structure of embodiment 2 of the present invention

[0045] Attached Figure 6 Schematic diagram of the structure of a speckle testing device based on a double aperture diaphragm according to embodiment 3 of the present invention

[0046] Attached Figure 7 A schematic diagram of the principle of a dynamic speckle testing device in laser display based on the present invention

[0047] Among them: 1 imaging lens based on double aperture diaphragm, 101 first lens group, 102 second lens group, 103 diaphragm, 104 switchable shielding device, 105 hole, 106 limit point, 107 rotatable shading plate, 201 left hole of diaphragm, 202 right hole of diaphragm, 601 filter turntable, 602 Y filter, 603 Xr filter, 604 Xb filter, 605 Z filter, 606 image acquisition unit, 7 screen, 8 laser display device. DETAILED DESCRIPTION

[0048] The present invention is described in detail below in conjunction with the drawings so that those skilled in the art can better understand the present invention.

[0049] Embodiment 1, as Figure 1-3 As shown, an imaging lens based on a double-aperture diaphragm is composed of a first lens group 101, a second lens group 102, an aperture 103 and a switchable shielding device 104, which are coaxially arranged.

[0050] The first lens group and the second lens group are symmetrically arranged to form a classic double Gauss lens structure to reduce aberration. The first lens group 101 is mainly used to initially converge light, reduce aberration, and improve optical imaging quality. The lens group effectively reduces spherical aberration and coma by combining lenses with different curvature radii.

[0051] The second lens group 102 further corrects the residual aberration and forms a clear optical image on the focal plane. This lens group and the first lens group together form a double Gaussian structure, thereby effectively compensating for chromatic aberration and field curvature.

[0052] As attached Figure 2 As shown, the aperture 103 is a double-hole structured aperture plate, and its outer diameter is 30 mm. Two aperture circular holes are set on the aperture plate, which are symmetrical with respect to the optical axis. The center of the left aperture hole 201 is , the center of the right aperture 202 is The centers of the two aperture holes are located on the diameter of the aperture, which are generally set on the X-axis or the Y-axis, and the center of the aperture is the symmetry point. In the figure, the two aperture holes are on the X-axis, with the Y-axis as the symmetry axis. The diameters of the two aperture holes are both 9mm, and the distance between the centers of the two holes is 15mm, that is, The switchable shielding device 104 is placed in front of or behind the aperture, and can selectively block one aperture hole, alternately block one aperture hole, the aperture left hole 201 or the aperture right hole 202, to achieve flexible switching of the dual light paths. Through the dual light path structure designed in this way, the imaging displacement effect can be achieved while maintaining the imaging symmetry to achieve different optical imaging requirements. The images collected by the two aperture holes are displaced on the X-axis to obtain two collected images. The distance moved is the center distance between the two aperture holes, which is 15 mm.

[0053] As attached Figure 3 As shown, the switchable shielding device 104 is in the form of a rotating disk, and its surface is anti-reflective treated so that the reflectivity of the device is less than 1%. A hole 105 (a semicircular hole in the figure) is opened in half of the disk surface, and the maximum opening of the hole is larger than the diameter of the aperture hole (9mm), that is, at least one position does not block one of the aperture holes, the center of the semicircular hole is coaxial with the center of the aperture o, and the intersection points of the line connecting the center of the aperture and the centers of the two aperture holes with the two aperture holes are: a, b, c, d, respectively, the radius of the semicircular hole is larger than oa and od, and the vertical distance between the straight edge of the semicircular hole and the center of the aperture o (1-2.5mm) is smaller than ob and oc. During the rotation of the turntable, there is at least one position where the light beam from one of the aperture holes can pass through completely without obstruction, while the other half of the closed structure completely covers the other aperture hole, making it opaque. As can be seen from the above, the straight-line distance between a, d and the outer circle of the aperture is 3 mm, so the size of the ring formed by the hole 105 and the outer edge is not greater than 3 mm.

[0054] The switchable shielding device is a rotating disk with a hole in half of the disk surface. The semicircular hole can be designed to be a hole of any shape, such as round, square, diamond, etc. As long as the opening of the hole is larger than the diameter of the aperture hole, the light beam of one of the aperture holes can pass through without obstruction, while the other half of the closed structure completely covers the other aperture hole and blocks light.

[0055] When the imaging position needs to be adjusted, an aperture hole is blocked by a switchable blocking device to achieve different effects of imaging positions of different optical channels.

[0056] As Example 1 of the present invention, the specific operation steps of using the optical testing device to perform testing are as follows:

[0057] (a) installing the imaging lens of Example 1 on an optical testing device, calibrating the optical axes of the first lens group and the second lens group to ensure that the optical axes of the first lens group and the second lens group are aligned;

[0058] (b) starting the switchable shielding device and adjusting it to shield one of the aperture holes, and using an imaging device or an image acquisition unit to record the imaging result;

[0059] (c) Drive the rotating sheet to block the other aperture and record the imaging result.

[0060] The optical testing equipment may be:

[0061] Embodiment 2, as attached Figure 4 As shown in FIG. 1 , an imaging lens based on a double aperture diaphragm is shown. Compared with Embodiment 1, the switchable shielding device 104 of this embodiment adopts an additional Figure 5 The rotatable shading sheet 107 shown in the figure can completely cover a single aperture without blocking another aperture. The limit points 106 at both ends are used to ensure the end point of the movement of the shading sheet. The shading sheet 107 realizes the aperture selection by swinging. The other devices are the same as those in the first embodiment.

[0062] Embodiment 3, as attached Figure 6 , 7 As shown, a dynamic speckle test device based on a double aperture diaphragm. This embodiment is a specific practical application of embodiment 1 in combination with a filter turntable 601 and an image acquisition unit 606 in dynamic speckle measurement. That is, it is an improved CN202111523480.6, a test device for dynamic speckle in laser display, in which the moving device is eliminated and the present invention is adopted. Specifically: A testing device for speckle in laser display is composed of a screen, a laser display device, an imaging lens based on a double-aperture aperture (the present invention), a filter wheel, an image acquisition unit, and a computer. The image acquisition unit is connected to the computer by signal, and the image captured by the image acquisition unit is transmitted to the computer. The computer stores a calculation formula, and the computer controls the image acquisition unit to capture the speckle pattern. A filter wheel and an imaging lens based on a double-aperture aperture are arranged in sequence in front of the image acquisition unit from near to far. After the light projected by the laser display device is projected onto the screen, it is reflected through the imaging lens based on the double-aperture aperture and the filter wheel to enter the image acquisition unit. The image formed by the screen image on the image acquisition unit is moved by a switchable shielding device in the imaging lens based on the double-aperture aperture, so that the image acquisition unit captures two images with the same test area and different observation positions.

[0063] As attached Figure 6As shown, the first lens group 101 and the second lens group 102 are the specific structures of the classic double Gaussian lens. A switchable shielding device 104 and a double-aperture aperture are arranged between the first lens group 101 and the second lens group 102. A filter wheel 601 is arranged behind the second lens group 102. An image acquisition unit 606 is placed behind the filter wheel for speckle imaging and measuring the speckle contrast value. The filter wheel 601 includes a Y filter 602, an Xr filter 603, an Xb filter 604, and a Z filter 605, and its function is to make the spectral response curve of the test equipment consistent with the visual matching function curve of the human eye.

[0064] The test should be performed as follows:

[0065] (a) placing the device under test at a preset projection position as required, and projecting a test image onto a screen; installing an imaging lens based on a dual aperture diaphragm (the present invention) onto an optical test device, calibrating the optical axes of the first lens group and the second lens group, and ensuring that the optical axes of the first lens group and the second lens group are aligned;

[0066] (b) The test position should be the same as the observation position; the test distance depends largely on the device under test; for full HD projectors, the recommended test distance is 1.5-3 times the screen height; for cinema projectors, a test distance of 4-6m is recommended; the photosensitive surface of the image acquisition unit should be placed on the conjugate image plane of the screen;

[0067] (c) The projected image of the device under test is spatially uniform (typically a primary color image: red, green or blue); when the device under test is a multi-primary system, all primary color speckles should be tested and the image size should be larger than the field of view of the optical measurement device;

[0068] (d) The filter wheel is placed to filter out unnecessary optical noise signals; the most suitable filter on the filter wheel 601 is selected to filter out unnecessary optical noise signals, and the monochromatic filter in the filter wheel should have a high transmittance for the main primary color light of the projected image; for the test of different primary colors, a filter with a larger transmittance for the primary color should be selected to obtain a larger image dynamic range;

[0069] (e) starting the switchable shielding device and adjusting one of the aperture holes to be shielded, and adjusting the focal length of the optical testing device so that the captured image is clearly imaged on the optical testing device;

[0070] (f) Adjust the exposure time and make sure that the exposure time should avoid saturation of the imaging device signal. The exposure time should be set between 50 and 200 ms, which is the visual persistence time of the human eye. 100 ms is preferred. If the image brightness is too high and the exposure time is too short, a neutral filter can be used to reduce the image brightness.

[0071] (g) capturing a first image; driving the rotating sheet to block another aperture and capturing a second image;

[0072] (h) Perform a differential operation on the corresponding positions in the two images and calculate the standard deviation of the speckle as follows ;

[0073]

[0074] Where:

[0075] ——The total number of pixels of the pattern being tested;

[0076] ——The intensity of the i-th pixel of the first measured pattern;

[0077] ——The intensity of the i-th pixel of the second measured pattern;

[0078] (i) Calculate the average light intensity of the first and second images and take the average as the average light intensity in the calculation ;

[0079] (j) The speckle contrast is calculated using Equation 2.

[0080]

[0081] Where:

[0082] ——standard deviation of the speckle pattern intensity;

[0083] ——The average light intensity of the speckle pattern.

[0084] The present invention adopts a double-hole structured aperture and a switchable shielding device, which can significantly reduce the interference of factors such as screen microstructure, image pixel unit structure and brightness uniformity on the test results, thereby obtaining more universal and accurate test data. The present invention also effectively avoids the problems of imaging jitter and difficulty in pixel alignment caused by the small-displacement imaging device and the method of rotating the glass sheet to change the light path used in the patent "CN202111523480.6 A test method and test device for dynamic speckle in laser display". In addition, the double-hole structured aperture and the switchable shielding device have a light and thin structure, which has little impact on the overall optical test equipment during rotation, further improving the stability and reliability of the system.

Claims

1. An imaging lens based on a double aperture diaphragm, characterized in that: It includes: A first lens group, a second lens group, an aperture and a switchable shielding device, wherein the first lens group and the second lens group form a double Gaussian structure, the aperture comprises two aperture holes, the centers of the two aperture holes are located on the diameter of the aperture, and the center of the aperture is used as a symmetry point, and the switchable shielding device alternately blocks one of the aperture holes.

2. The imaging lens based on a dual aperture stop according to claim 1, characterized in that: The switchable shielding device is placed in front of the aperture or behind the aperture, and the device can switch the shielding state and selectively switch to shield one of the aperture holes.

3. The imaging lens based on a dual aperture stop according to claim 2, characterized in that: The switchable shielding device is a rotating disk, in which a semicircular hole is opened in half of the disk surface, the center of the semicircular hole is coaxial with the center of the aperture o, the intersection points of the line connecting the center of the aperture and the centers of the two aperture holes and the two aperture holes are: a, b, c, d respectively, the radius of the semicircular hole is greater than oa and od, and the vertical distance between the straight edge of the semicircular hole and the center of the aperture o is less than ob and oc.

4. The imaging lens based on a dual aperture stop according to claim 2, characterized in that: The switchable shielding device is a rotating disk, in which a hole is opened in half of the disk surface, and the smallest opening of the hole is larger than the diameter of the aperture hole.

5. The imaging lens based on a dual aperture stop according to claim 2, characterized in that: The switchable shielding device is a rotatable shading sheet, the area of ​​which can completely cover a single aperture but not cover another aperture.

6. The imaging lens based on a dual aperture stop according to claim 1, characterized in that: The first lens group, the aperture and the second lens group are rigidly connected.

7. The imaging lens based on a dual aperture stop according to claim 1, characterized in that: The diameter of the diaphragm is D, the diameter of the diaphragm hole is 0.1-0.4D, and the distance between the nearest adjacent points of two diaphragm holes is 0.1-0.5D.

8. The imaging lens based on a dual aperture stop according to claim 1, characterized in that: There is a filter turntable at the rear end of the second lens group, and behind the filter turntable is the imaging device. The filter turntable includes a Y filter, an Xr filter, an Xb filter, and a Z filter. The optical path of the light is the first lens group, a shading plate, an aperture, the second lens group, the filter turntable, and the imaging device, wherein the positions of the shading plate and the aperture are interchangeable.

9. A method for using a dual-aperture diaphragm imaging lens according to any one of claims 1 to 7, characterized in that: (a) installing an imaging lens based on a double aperture stop onto an optical testing device, calibrating the optical axes of the first lens group and the second lens group, and ensuring that the optical axes of the first lens group and the second lens group are aligned; (b) Start the light source and the switchable shielding device, and make the switchable shielding device shield one of the aperture holes, and use an imaging device or an image acquisition unit to record the imaging result; (c) Drive the switchable shielding device to shield the other aperture hole and record the imaging result.

10. The method for testing dynamic speckle in laser display using an imaging lens based on a double aperture diaphragm according to claim 8, characterized in that: The testing device for speckle in laser display is composed of a screen, a laser display device, an imaging lens based on a double-aperture diaphragm, a filter wheel, an image acquisition unit, and a computer. The image acquisition unit is connected to the computer by signal, and the image captured by the image acquisition unit is transmitted to the computer. The computer stores a calculation formula, and the computer controls the image acquisition unit to capture the speckle pattern. The filter wheel and the imaging lens based on the double-aperture diaphragm are arranged in sequence in front of the image acquisition unit from near to far. After the light projected by the laser display device is projected onto the screen, it is reflected through the imaging lens based on the double-aperture diaphragm and the filter wheel to enter the image acquisition unit. The image formed by the screen image on the image acquisition unit is moved by the switchable shielding device in the imaging lens based on the double-aperture diaphragm, so that the image acquisition unit captures two images with the same test area and different observation positions. The test steps are as follows: (a) placing the device under test at a preset projection position as required, and projecting a test image onto a screen; installing an imaging lens based on a dual aperture diaphragm onto an optical test device, calibrating the optical axes of the first lens group and the second lens group, and ensuring that the optical axes of the first lens group and the second lens group are aligned; (b) The test position should be the same as the observation position; the test distance depends largely on the device under test; for full HD projectors, the test distance used is 1.5-3 times the screen height; for cinema projectors, the test distance is 4-6m; the photosensitive surface of the image acquisition unit should be placed on the conjugate image plane of the screen; (c) The projected image of the device under test is spatially uniform; when the device under test is a multi-primary color system, all primary color speckles should be tested and the image size should be larger than the field of view of the optical measurement device; (d) The filter wheel is placed to filter out unnecessary optical noise signals; the monochromatic filter in the filter wheel should have high transmittance for the main primary color light of the projected image; for the test of different primary colors, the filter with a larger transmittance for the primary color should be selected to obtain a larger image dynamic range; (e) starting the switchable shielding device and adjusting one of the aperture holes to be shielded, and adjusting the focal length of the optical testing device so that the captured image is clearly imaged on the optical testing device; (f) Adjust the exposure time and make sure that the exposure time should avoid saturation of the imaging device signal. The exposure time should be set between 50 and 200 ms, which is the visual persistence time of the human eye. 100 ms is preferred. If the image brightness is too high and the exposure time is too short, a neutral filter can be used to reduce the image brightness. (g) capturing a first image; driving the switchable shielding device to shield another aperture, and capturing a second image; (h) Perform differential operation on the corresponding positions in the two images and calculate the standard deviation of the speckle using the formula ; (i) Calculate the average light intensity of the first image and the second image and take the average as the average light intensity in the calculation ; (j) Speckle contrast is calculated by the formula .

Images