Dual-aperture mask-based imaging lens

Abstract

The present invention relates to a dual-aperture mask-based imaging lens, comprising: a first lens group, a second lens group, a mask, and a switchable light-blocking unit, wherein the first lens group and the second lens group form a double Gaussian structure, the mask comprises two mask apertures, centers of the two mask apertures lie on a diameter of the mask, and a center of the mask serves as a symmetry point, and the switchable light-blocking unit alternately blocks one of the mask apertures. The present invention offers advantages such as a lightweight, compact structure, flexible use, and high measurement accuracy, and can effectively improve stability and accuracy of measurement results. A switchable light-blocking unit alternately blocks an aperture, thereby achieving the advantage of allowing two micro-displacement images to be obtained without requiring a mobile device, resolving imaging jitter in dynamic laser speckle measurement caused by mobile imaging apparatuses, and being applicable to various optical testing scenarios such as laser speckle measurement, optical element testing, image sensor calibration, and scientific optical experimentation.

Description

An imaging lens based on a dual aperture stop Technical Field

[0001] This invention relates to an optical testing device, and more particularly to an imaging lens based on a dual-aperture aperture. Background Technology

[0002] In the field of laser speckle measurement, different optical testing equipment has varying impacts on improving the accuracy of speckle measurement. The small-displacement imaging device and the method of changing the optical path by rotating the glass plate, as described in the applicant's paper "CN202111523480.6 A Test Method and Test Device for Dynamic Speckle in Laser Displays," effectively overcome the susceptibility of laser speckle testing methods to the influence of screen microstructure, image pixel unit structure, and brightness uniformity, thus improving speckle measurement accuracy. However, during use, it was found that the small-displacement imaging device method causes imaging jitter in the optical measurement equipment; and the method of changing the optical path by rotating the glass plate causes pixel alignment difficulties due to the thickness of the glass plate. Solving these difficulties has become a major obstacle to the widespread application of this technology.

[0003] As is well known, imaging lenses are a crucial component in the field of optical testing. With the continuous development of optical testing technology, technical challenges such as the accuracy and aberrations of imaging lenses have been effectively addressed.

[0004] The double Gaussian lens design is a classic lens design proposed in the early 19th century by German mathematician and physicist Carl Friedrich Gauss 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, with the aperture stop placed between the two lens groups. This symmetrical structure allows double Gaussian lenses to effectively correct various aberrations, especially distortion and coma, resulting in high-quality imaging. Due to its excellent performance, the double Gaussian design is widely used in various photographic lenses, especially large-aperture standard lenses.

[0005] A double-Gaussian structure typically consists of two symmetrical or nearly symmetrical meniscus lens groups, with an aperture stop located between the two groups. The front lens group converges the incident light rays, making them tend to be parallel; the rear lens group then converges these tended-to-parallel rays to the focal point. In a dynamic testing method and apparatus for speckle in laser displays, since it needs to acquire two images, "the testing apparatus acquires the first image, keeping the perpendicular distance between the testing apparatus and the screen constant, and after the image formed on the testing apparatus by the moving device is moved, the testing apparatus acquires the second image." Traditional single-aperture lenses are widely used in optical imaging testing. However, when applied to "a dynamic testing method and apparatus for speckle in laser displays," they cannot solve the existing imaging jitter caused by displacement; the results are not good. Summary of the Invention

[0006] To address the aforementioned problems and the structural characteristics of dual-Gaussian lenses, this invention provides an imaging lens based on a dual-aperture stop, which fully leverages the advantages of dual-Gaussian lenses. It can acquire two images without displacement, thus solving the problem of optical measurement and imaging jitter caused by device displacement, thereby obtaining high-quality imaging results.

[0007] The technical solution adopted in this invention is as follows: an imaging lens based on a dual aperture, comprising: a first lens group, a second lens group, an aperture, and a switchable blocking device, wherein the first lens group and the second lens group constitute a double Gaussian structure, the aperture includes two aperture holes, the centers of the two aperture holes are located on the diameter of the aperture, and are symmetrical about the center of the aperture, and the switchable blocking device alternately blocks one of the aperture holes.

[0008] This invention creatively improves upon the double Gaussian lens by replacing the traditional single-aperture diaphragm with a double-aperture diaphragm, with centers o1 and o2 respectively. The double-aperture diaphragm and switchable blocking device are positioned on the parallel beam path, and their placement ensures that the incident beam does not affect the 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 apertures is blocked by the switchable blocking device, ensuring that only one aperture is active at any given time. This maintains the unique advantages of the double Gaussian lens. Because the two apertures are misaligned on the X-axis or Y-axis, light displacement can be achieved without moving the optical testing equipment, resulting in two acquired images. The distance moved is the center distance between the two apertures, denoted as |o2-o1|.

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

[0010] The purpose of the switchable blocking device of the present invention is to selectively block one of the apertures, so that the light beam passes through only one aperture while the other aperture is completely blocked and opaque, thereby realizing light movement and image movement.

[0011] Further design: The switchable blocking device is a turntable, with a semi-circular hole in one half of the turntable. The intersection points of the line connecting the center o of the aperture and the centers of the two aperture holes with the two aperture holes are a, b, c, and d, respectively. The radius of the semi-circular hole is greater than oa and od, and the perpendicular distance between the straight edge of the semi-circular hole and the center o of the aperture is less than ob and oc.

[0012] The switchable blocking device is a turntable with a hole in one half of its surface. The minimum opening of the hole is larger than the diameter of the aperture.

[0013] Both of the aforementioned switchable blocking devices have holes designed on them that are no smaller than the aperture, allowing the light beam to pass unobstructed through the aperture and the switchable blocking device to reach the imaging device.

[0014] The switchable blocking device is a rotatable light-blocking plate whose area can completely cover a single aperture without blocking the other aperture. The switchable blocking device completely covers one aperture, allowing the light beam to pass through the other aperture.

[0015] The first lens group, the aperture stop, and the second lens group are rigidly connected. This rigid connection among the three solves the problem of imaging jitter in optical measurement equipment caused by methods involving small displacement imaging devices.

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

[0017] The above device is used in conjunction with optical testing equipment as follows: (a) Install the imaging lens based on the dual aperture diaphragm onto the optical testing equipment, calibrate the optical axes of the first lens group and the second lens group, and ensure that the optical axes of the first lens group and the second lens group are aligned; (b) Activate the light source and the switchable blocking device, and block one of the apertures with the switchable blocking device, and use the imaging equipment or image acquisition unit to record the imaging result; (c) Drive the switchable blocking device to block the other aperture, and record the imaging result.

[0018] The first lens group is mainly used to initially converge light rays, reduce aberrations, and improve optical imaging quality. This lens group effectively reduces spherical aberration and coma by combining lenses with different radii of curvature.

[0019] The second lens group further corrects residual aberrations and forms a clear optical image at the focal plane. This lens group, together with the first lens group, forms a double Gaussian structure, thereby effectively compensating for chromatic aberration and field curvature.

[0020] The two symmetrical apertures of the dual-aperture system are designed to achieve imaging displacement while maintaining imaging symmetry through a dual-optical-path design.

[0021] Further design: There is a filter turntable at the rear end of the second lens group, and the imaging device is behind the filter turntable. The filter turntable includes a Y filter, an Xr filter, an Xb filter, and a Z filter. The light path passes through the first lens group, the light shield, the aperture, the second lens group, the filter turntable, and the imaging device in sequence. The positions of the light shield and the aperture can be interchanged.

[0022] When this invention is applied to CN202111523480.6, a test method and test device for dynamic speckle in laser display, the switchable blocking device of this invention can realize light movement and image movement. Therefore, this invention replaces the moving device and test device in CN202111523480.6, solving the problem that the method of small displacement imaging device will cause imaging jitter in optical measurement equipment and the problem that the method of rotating glass plate to change the optical path will cause pixel alignment difficulties due to the thickness of the glass plate. This allows CN202111523480.6 to be widely applied.

[0023] The specific improvements and application methods are as follows: The speckle testing device in laser display consists of a screen, a laser display device, the imaging lens based on a dual-aperture aperture of this invention, a filter turntable, an image acquisition unit, and a computer. The image acquisition unit is connected to the computer via a signal connection, transmitting the images captured by the image acquisition unit to the computer. The computer stores calculation formulas and controls the image acquisition unit to capture speckle patterns. A filter turntable and a dual-aperture aperture-based imaging lens are arranged sequentially in front of the image acquisition unit from near to far. After the light projected from the laser display device is projected onto the screen, it is reflected and enters the image acquisition unit through the dual-aperture aperture-based imaging lens and the filter turntable. A switchable blocking device in the dual-aperture aperture-based imaging lens causes the image formed on the image acquisition unit to move, thereby allowing the image acquisition unit to acquire two images with the same test area but different observation positions. The testing steps are as follows: (a) Place the device under test (DUT) in the preset projection position as required, and project the test image onto the screen; install the dual-aperture imaging lens onto the optical testing equipment, calibrate the optical axes of the first and second lens groups, and ensure that the optical axes of the first and second lens groups are aligned; (b) The test position should be the same as the observation position; the test distance largely depends on the DUT; for full HD projectors, the test distance is 1.5-3 times the screen height; for cinema projectors, a test distance of 4m-6m is used; 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 DUT is spatially uniform; when the DUT is a multi-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 equipment; (d) The filter turntable is placed to filter out unnecessary optical noise signals; the monochromatic filter in the filter turntable should have high transmittance of the main primary color light of the projected image; for testing different primary colors, a filter with a large transmittance of that primary color should be selected to obtain a larger image dynamic range; (e) Activate the switchable occlusion device and adjust the occlusion of one of the apertures to adjust the focal length of the optical testing equipment, so that the captured image is clearly imaged on the optical testing equipment; (f) Adjust the exposure time, ensuring that the exposure time avoids signal saturation of the imaging equipment. The exposure time should be set between 50ms and 200ms, ideally between 100ms and 50ms, which is the persistence of vision in the human eye. If the image brightness is too high and the exposure time is too short, a neutral density filter can be used to reduce the image brightness; (g) Acquire the first image; drive the switchable occlusion device to block the other aperture and acquire the second image; (h) Perform a difference operation on the corresponding positions in the two images and calculate the standard deviation σ of the speckle using the formula; (i) Calculate the average light intensity of the first image and the second image, and take the average value as the average light intensity in the calculation. (j) The speckle contrast C is calculated using the formula.

[0024] This invention creatively improves upon the double Gaussian lens by replacing the traditional single-aperture stop with a double-aperture stop. A switchable blocking device is positioned on the parallel beam path, and its placement ensures that the incident beam does not affect the image size of the imaging system after passing through this structure. The double-aperture stop is located on either the X-axis or Y-axis of the aperture, and one of the aperture holes is blocked by the switchable blocking device, ensuring that only one aperture hole is active at any given time. This maintains the unique advantages of the double Gaussian lens. Because the two aperture holes are misaligned on the X-axis or Y-axis, light movement can be achieved without moving the optical testing equipment. This achieves the two images generated by the small displacement required by CN202111523480.6, a method and device for testing dynamic speckle in laser displays. This solves the problem of imaging jitter in optical measurement equipment caused by small displacement imaging devices. Furthermore, the rigid connection between the first lens group, the aperture, and the second lens group further improves the imaging jitter problem.

[0025] This invention boasts advantages such as lightweight and compact structure, flexible use, and high measurement accuracy, effectively improving the stability and accuracy of measurement results. Through a switchable blocking device, selective blocking can be achieved according to testing requirements, allowing for free switching between different optical paths. It is applicable to various optical testing scenarios, including laser speckle measurement, optical component inspection, image sensor calibration, and scientific optical experiments. Attached Figure Description

[0026] Figure 1 is a schematic diagram of an imaging lens based on a dual-aperture aperture according to Embodiment 1 of the present invention; Figure 2 is a schematic diagram of the dual-aperture aperture structure of the present invention; Figure 3 is a schematic diagram of the switchable blocking device according to Embodiment 1 of the present invention; Figure 4 is a schematic diagram of an imaging lens based on a dual-aperture aperture according to Embodiment 2 of the present invention; Figure 5 is a schematic diagram of the switchable blocking device according to Embodiment 2 of the present invention; Figure 6 is a schematic diagram of a speckle testing device based on a dual-aperture aperture according to Embodiment 3 of the present invention; Figure 7 is a schematic diagram of the principle of a dynamic speckle testing device in laser display based on the present invention. Among them: 1. Imaging lens based on dual aperture, 101. First lens group, 102. Second lens group, 103. Aperture, 104. Switchable blocking device, 105. Aperture, 106. Limiting point, 107. Rotatable light shield, 201. Left aperture of aperture, 202. Right aperture of aperture, 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 Implementation

[0027] The present invention will now be described in detail with reference to the views, so that those skilled in the art can better understand the present invention.

[0028] Example 1, as shown in Figures 1-3, is an imaging lens based on a dual-aperture diaphragm, which consists of a first lens group 101, a second lens group 102, an aperture 103, and a switchable blocking device 104, all four of which are arranged coaxially.

[0029] The first lens group 101 and the second lens group 102 are symmetrically arranged to form a classic double-Gaussian lens structure, reducing aberrations. The first lens group 101 is mainly used for initial convergence of light rays, reducing aberrations and improving optical imaging quality. This lens group effectively reduces spherical aberration and coma by combining lenses with different radii of curvature.

[0030] The second lens group 102 further corrects residual aberrations and forms a clear optical image at the focal plane. This lens group, together with the first lens group 101, forms a double Gaussian structure, thereby effectively compensating for chromatic aberration and field curvature.

[0031] As shown in Figure 2, the aperture 103 is a double-hole aperture plate with an outer diameter of 30mm. Two aperture holes symmetrical about the optical axis are provided on this aperture plate. The center of the left aperture 201 is O1, and the center of the right aperture 202 is O2. The centers of the two aperture holes are located on the diameter of the aperture 103, generally on the X-axis or Y-axis, and are symmetrical about the center of the aperture 103. In the figure, the two aperture holes are on the X-axis with the Y-axis as the axis of symmetry. The diameter of both aperture holes is 9mm, and the distance between the centers of the two holes is 15mm, i.e., |O2-O1| is 15mm. A switchable blocking device 104 is placed in front of or behind the aperture 103, selectively blocking one aperture and alternately blocking one aperture, such as alternately blocking the left aperture 201 or the right aperture 202, to achieve flexible switching between the two optical paths. This dual-optical-path structure maintains imaging symmetry while achieving image displacement to meet different optical imaging needs. The images acquired through the two apertures are displaced along the X-axis, resulting in two acquired images. The distance moved is the center distance between the two apertures, which is 15mm.

[0032] As shown in Figure 3, the switchable blocking device 104 is in the form of a turntable, and its surface is treated with anti-reflection to reduce the reflectivity of the device to less than 1%. A hole 105 (a semi-circular hole in the figure) is opened in one half of the turntable. The maximum opening of this hole 105 is larger than the diameter of the aperture (9mm), meaning that at least one position is unobstructed by one of the apertures. The center of the semi-circular hole is coaxial with the center o of the aperture. The intersection points of the line connecting the center of the aperture and the centers of the two apertures with the two apertures are a, b, c, and d, respectively. The radius of the semi-circular hole is greater than oa and od. The perpendicular distance (1mm-2.5mm) between the straight edge of the semi-circular hole and the center o of the aperture is less than ob and oc. During the rotation of the turntable, at least one position can completely allow the light beam from one of the apertures to pass through without obstruction, while the other semi-closed structure completely covers the other aperture, making it opaque. As can be seen above, the straight-line distance between a, d and the outer circle of the aperture is 3mm, so the size of the ring formed by the aperture 105 and the outer edge is no greater than 3mm.

[0033] The switchable blocking device 104 is a turntable with a hole 105 in one half of the disc. In other embodiments, the semi-circular hole can be replaced with any shape, such as a circle, a square, or a rhombus, as long as the opening of the hole 105 is larger than the diameter of the aperture, the light beam from one aperture can pass through without obstruction, while the other semi-closed structure completely covers the other aperture, making it opaque.

[0034] When the imaging position needs to be adjusted, a switchable blocking device 104 can block one aperture to achieve different imaging positions for different optical channels.

[0035] As an embodiment 1 of the present invention, the specific operation steps for testing using the optical testing equipment are as follows: (a) Install the imaging lens of embodiment 1 onto the optical testing equipment, calibrate the optical axes of the first lens group 101 and the second lens group 102, and ensure that the optical axes of the first lens group 101 and the second lens group 102 are aligned; (b) Activate the switchable blocking device 104 and adjust to block one of the apertures, and use the imaging equipment or image acquisition unit to record the imaging result; (c) Drive the switchable blocking device 104 to block the other aperture and record the imaging result.

[0036] The optical testing equipment can be: Example 2, as shown in Figure 4, an imaging lens based on a dual-aperture aperture. Compared with Example 1, the switchable blocking device 104 adopts the rotatable light-blocking plate 107 shown in Figure 5. The area of ​​the light-blocking plate 107 can completely cover a single aperture without blocking the other aperture. The movement endpoint of the light-blocking plate is ensured by the limiting points 106 at both ends. The light-blocking plate 107 achieves aperture selection by swinging. Other devices are the same as in Example 1.

[0037] Example 3, as shown in Figures 6 and 7, is a dynamic speckle testing device based on a dual-aperture aperture. This example is a practical application of Example 1, combining a filter turntable 601 and an image acquisition unit 606 in dynamic speckle measurement. It is an improved version of CN202111523480.6, a testing device for dynamic speckle in laser displays, which eliminates the moving device and incorporates the present invention. Specifically, the speckle testing device in laser display consists of a screen 7, a laser display device 8, an imaging lens 1 based on a dual-aperture aperture of this invention, a filter turntable 601, an image acquisition unit 606, and a computer. The image acquisition unit 606 is connected to the computer via a signal connection, transmitting the images captured by the image acquisition unit 606 to the computer. The computer stores calculation formulas and controls the image acquisition unit 606 to capture speckle patterns. The filter turntable 601 and the imaging lens 1 based on a dual-aperture aperture are arranged sequentially from near to far in front of the image acquisition unit 606. The light projected by the laser display device 8 is projected onto the screen 7 and reflected through the imaging lens 1 based on a dual-aperture aperture and the filter turntable 601 before entering the image acquisition unit 606. The switchable blocking device 104 in the imaging lens 1 based on a dual-aperture aperture causes the image formed on the image acquisition unit 606 to move, thereby allowing the image acquisition unit 606 to acquire two images with the same test area but different observation positions.

[0038] As shown in Figure 6, the first lens group 101 and the second lens group 102 are the specific structures of a classic double Gaussian lens. A switchable blocking device 104 and a double-aperture stop are arranged between the first lens group 101 and the second lens group 102. Behind the second lens group 102 is a filter turntable 601. The image acquisition unit 606 is placed behind the filter turntable 601 for speckle imaging and measuring the speckle contrast value. The filter turntable 601 includes a Y filter 602, an Xr filter 603, an Xb filter 604, and a Z filter 605, the function of which is to make the spectral response curve of the test equipment consistent with the visual matching function curve of the human eye.

[0039] The test should be performed according to the following steps: (a) Place the device under test in the preset projection position as required, and project the test image onto the screen; install the imaging lens 1 based on the dual aperture of the present invention onto the optical testing equipment, calibrate the optical axes of the first lens group 101 and the second lens group 102, and ensure that the optical axes of the first lens group 101 and the second lens group 102 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 recommended test distance is 1.5-3 times the screen height; for cinema projectors, a test distance of 4m-6m is recommended; 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 (typically a primary color image: red, green, or blue); 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 measuring equipment; (d) The filter turntable 601 is placed to filter out unnecessary optical noise signals. Select the most suitable filter on the filter turntable 601 to filter out unnecessary optical noise signals. The monochromatic filter in the filter turntable 601 should have high transmittance of the main primary color light of the projected image. For testing different primary colors, a filter with a large transmittance of that primary color should be selected to obtain a larger image dynamic range. (e) Activate the switchable blocking device 104 and adjust the blocking of one of the apertures to adjust the focal length of the optical testing equipment so that the captured image is clearly imaged on the optical testing equipment. (f) Adjust the exposure time to ensure that the exposure time avoids signal saturation of the imaging equipment. The exposure time should be set as close as possible to 50ms to 200ms of the human eye's visual persistence time, with 100ms being optimal. If the image brightness is too high and the exposure time is too short, a neutral density filter can be used to reduce the image brightness. (g) Acquire the first image; drive the switchable blocking device 104 to block the other aperture and acquire the second image. (h) Perform a difference operation on the corresponding positions in the two images, and calculate the standard deviation σ of the speckle as follows;

[0040] Where: N r —Total number of pixels in the measured image; I 1i —The intensity of the i-th pixel in the first measured image; I 2i —The intensity of the i-th pixel in the second image being tested; (i) Calculate the average light intensity of the first image and the second image, and take the average value as the average light intensity in the calculation. (j) The speckle contrast is calculated using Equation 2.

[0041]

[0042] Where: σ—standard deviation of speckle pattern intensity; —The average light intensity of the speckle pattern.

[0043] This invention, by employing a dual-aperture structure and a switchable blocking device 104, significantly reduces the interference of factors such as screen microstructure, image pixel unit structure, and brightness uniformity on test results, thereby obtaining more universal and accurate test data. This invention also effectively avoids the imaging jitter and pixel alignment problems caused by the small-displacement imaging device and the method of changing the optical path by rotating the glass plate, as described in patent CN202111523480.6, "A Test Method and Test Device for Dynamic Speckle in Laser Displays." Furthermore, the dual-aperture structure and switchable blocking device have a thin and lightweight structural feature, which minimizes the impact on the overall optical testing equipment during rotation, further improving the stability and reliability of the system.

Claims

1. An imaging lens based on a dual-aperture stop, characterized in that, It includes: The system comprises a first lens group, a second lens group, an aperture, and a switchable blocking device. The first lens group and the second lens group form a double Gaussian structure. The first lens group, the aperture, and the second lens group are rigidly connected. The aperture itself remains stationary. The aperture includes two aperture holes, the centers of which are located on the diameter of the aperture. The switchable blocking device is driven with the center of the aperture as the symmetrical point. The switchable blocking device alternately blocks one of the aperture holes.

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

3. An imaging lens based on a dual-aperture stop according to claim 2, characterized in that, The switchable blocking device is a turntable with a semi-circular hole in one half of the turntable. The center of the semi-circular hole is coaxial with the center of the aperture circle o. The intersection points of the line connecting the center of the aperture circle and the centers of the two aperture holes with the two aperture holes are a, b, c, and d, respectively. The radius of the semi-circular hole is greater than oa and od, and the perpendicular distance between the straight side of the semi-circular hole and the center of the aperture circle o is less than ob and oc.

4. An imaging lens based on a dual-aperture stop according to claim 2, characterized in that, The switchable blocking device is a turntable with a hole in one half of its surface. The minimum opening of the hole is larger than the diameter of the aperture.

5. An imaging lens based on a dual-aperture stop according to claim 2, characterized in that, The switchable blocking device is a rotatable light-blocking plate. The area of ​​the light-blocking plate can completely cover a single aperture without blocking the other aperture.

6. An imaging lens based on a dual-aperture stop according to claim 1, characterized in that, The two apertures have the same diameter.

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

8. An imaging lens based on a dual-aperture stop according to claim 1, characterized in that, At the rear end of the second lens group is a filter turntable, 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 light path passes sequentially through the first lens group, a light shield, an aperture, the second lens group, the filter turntable, and the imaging device. The positions of the light shield and the aperture can be interchanged.

9. A method of using an imaging lens based on a dual-aperture stop according to any one of claims 1 to 7, characterized in that, (a) Install the imaging lens based on the dual aperture onto the optical testing equipment, calibrate the optical axes of the first lens group and the second lens group, and ensure that the optical axes of the first lens group and the second lens group are aligned. (b) Activate the light source and the switchable occlusion device, and make the switchable occlusion device block one of the apertures, and use the imaging device or image acquisition unit to record the imaging result; (c) drive the switchable occlusion device to block the other aperture and record the imaging result.

10. The method for testing dynamic speckle in laser displays using an imaging lens based on a dual-aperture aperture according to claim 8, characterized in that, The speckle test device in laser display consists of a screen, a laser display device, an imaging lens based on a dual-aperture aperture, a filter turntable, an image acquisition unit, and a computer. The image acquisition unit is connected to the computer, transmitting the images captured by the image acquisition unit to the computer. The computer stores calculation formulas and controls the image acquisition unit to capture speckle patterns. A filter turntable and a dual-aperture aperture imaging lens are arranged sequentially in front of the image acquisition unit from near to far. Light projected from the laser display device is reflected off the screen and passes through the dual-aperture aperture imaging lens and the filter turntable before entering the image acquisition unit. A switchable blocking device in the dual-aperture aperture imaging lens causes the image formed on the image acquisition unit to shift, thus allowing the image acquisition unit to acquire two images with the same test area but different observation positions. The test steps are as follows: (a) Place the device under test in the preset projection position and project the test image onto the screen; install the imaging lens based on the dual aperture onto the optical test equipment, calibrate the optical axes of the first lens group and the second lens group, and ensure that the optical axes of the first lens group and the second lens group are aligned. (b) The test position is the same as the observation position; the test distance depends on the device under test; for full HD projectors, the test distance is 1.5-3 times the screen height; for cinema projectors, the test distance is 4m-6m; the photosensitive surface of the image acquisition unit is 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-color system, all primary color speckles are tested, and the image size is larger than the field of view of the optical measuring device. (d) The filter turntable is placed to filter out unnecessary optical noise signals; the monochromatic filter in the filter turntable has high transmittance for the main primary color light of the projected image; for testing different primary colors, a filter with high transmittance for that primary color is selected in order to increase the dynamic range of the obtained image. (e) Activate the switchable occlusion device and adjust the occlusion of one of the apertures to adjust the focal length of the optical testing equipment so that the captured image is clearly imaged on the optical testing equipment. (f) Adjust the exposure time to ensure that the exposure time avoids signal saturation of the imaging device. Set the exposure time between 50ms and 200ms, which is the persistence of vision of the human eye, and further to 100ms. If the image brightness is too high and the exposure time is too short, a neutral density filter can be used to reduce the image brightness. (g) Acquire the first image; drive the switchable occlusion device to block the other aperture and acquire the second image; (h) Perform difference operations on the corresponding positions in the two images, and calculate the standard deviation σ of the speckle using the formula; (i) Calculate the average light intensity of the first image and the second image, and take the average value as the average light intensity in the calculation. (j) The speckle contrast C is calculated using the formula.

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