Device and method for testing halo of low-light night vision camera

Abstract

The invention discloses a halo testing device and a halo testing method for a low-light night vision camera, belongs to the technical field of night vision detection imaging, and aims to overcome the defects that a traditional halo detection method is high in requirement for the light environment of a laboratory, large in occupied area and generally incapable of meeting detection of long-focus and wide-angle cameras at the same time. According to the visible light-near infrared digital camera halo testing device and method based on technologies such as precise motion control, optical target simulation and image processing, the testing efficiency is improved, the size of the whole system is reduced, the construction cost is reduced, and the testing capacity of low-light night vision cameras with different focal lengths and view fields is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of night vision detection imaging, and in particular relates to a halo testing device and a testing method for a low-light-level night vision camera. Background Art

[0002] Pilot night vision systems are widely used in fighters, helicopters, bombers, drones and other platforms. As the eyes of the aircraft platform, pilot night vision systems can effectively improve the pilot's ability to fly aircraft and perform combat missions in night sky light environments such as dusk, dawn, moonlight, and starlight, thereby improving the night vision and night combat capabilities of combat aircraft. As an important part of the pilot's night vision system, the low-light night vision camera uses the night sky light spectrum such as moonlight, starlight, and atmospheric glow reflected by the target and background, and performs photoelectric conversion and enhancement processing through the low-light sensor, and outputs video signals to the display system, so that the pilot can find and identify the target and background. When the low-light night vision camera is in use, when there are high-brightness targets such as city lights and interfering light sources in the shooting picture, the night vision camera will have local area and local time accumulated charge oversaturation, and the excess charge overflows and affects the surrounding pixels, generating a halo. This affects the detection and identification capabilities of the low-light night vision camera to the target, so it is necessary to test and analyze the halo effect of the low-light night vision camera.

[0003] The traditional halo detection method requires the construction of a professional darkroom, a large-sized transmission target plate, and the target plate requires a uniform illumination light source of the same size. The construction cost of the whole system is high and the floor space is large. In addition, due to the size limitation of the laboratory, the close-up night vision camera with a large relative aperture and a long shooting distance cannot focus correctly. The night vision camera with a large field of view may not be able to fill the field of view. Therefore, a method and equipment with high integration, low requirements for the laboratory light environment, and strong compatibility with the night vision camera test of different focal lengths and fields of view are required, which reduces the efficiency of the night vision camera halo test. Summary of the invention

[0004] In view of this, the present invention provides a low-light-level night vision camera halo testing device and testing method, which improves testing efficiency, reduces the volume of the entire system and reduces construction costs, and improves the testing capability of low-light-level night vision cameras with different focal lengths and fields of view.

[0005] A low-light-level night vision camera halo test device is provided, which uses a low-light-level night vision camera as a test object to perform halo test, including a light source, an adjustable aperture, an integrating sphere, a switchable graticule and an adjustable focus collimator, wherein:

[0006] The light source is a halogen tungsten lamp light source, and the light source is sequentially processed through an adjustable aperture and an integrating sphere and irradiates the switchable graticule, wherein the adjustable aperture is used to adjust the luminous flux of the light source, and the adjusted light source is uniformly processed through an integrating sphere;

[0007] The switchable graticule plate includes a focus test target plate and an adjustable rectangular aperture target plate, a numerically controlled motor and a guide rail, wherein the focus test target plate is used to assist the focus of the test piece, and the adjustable rectangular aperture target plate is used to dynamically simulate the target source during the halo test;

[0008] The numerically controlled motor and the guide rail, the focus test target plate is adjacent to the adjustable rectangular aperture target plate and is movably mounted on the guide rail, wherein the output end of the numerically controlled motor is respectively connected to the focus test target plate and the adjustable rectangular aperture target plate, and can drive the focus test target plate and the adjustable rectangular aperture target plate to switch positions on the guide rail, and the numerically controlled motor is controlled by a controller; the light source transmits light to the focusable collimator through the switchable graticule;

[0009] The switchable graticule is located at the focal plane position of the adjustable focus collimator, the adjustable focus collimator collimates or projects the target sources of the focus test target plate and the adjustable rectangular aperture target plate into parallel light, the parallel light is transmitted to the object to be tested, the adjustable focus collimator can focus along the optical axis of the adjustable focus collimator, and transmit the target sources of the focus test target plate and the adjustable rectangular aperture target plate to different distances, so as to simulate targets at different object distances;

[0010] The light outlet of the focusable collimator is in mechanical optical communication with the dark box.

[0011] Secondly, a method for testing the halo of a low-light-level night vision camera is provided. Using the above-mentioned device for testing the halo of a low-light-level night vision camera, the testing method comprises:

[0012] Step 1: The device to be tested is installed in a dark box, the lens end of the device to be tested is aligned with the light outlet of the focusable collimator, the device to be tested is electrically connected to the controller, and the controller is electrically connected to the light source, the adjustable aperture, the integrating sphere, the switchable graticule and the focusable collimator respectively;

[0013] Step 2: Switch to the focus test target board, the controller obtains the image captured by the test piece, and adjusts the size of the adjustable diaphragm opening to a preset range so that the image of the test piece is not overexposed, and the adjustable focus collimator is used to focus, and the clarity of the image or picture captured by the test piece is adjusted;

[0014] Step 3: Switch the focus test target plate to the adjustable rectangular aperture target plate, and adjust the rectangular window or light hole of the adjustable rectangular aperture target plate to the preset magnification of the shooting picture of the test piece according to the parameters of the test piece;

[0015] Step 4: The light flux of the light source is adjusted through the adjustable aperture to a point where the halo signal intensity at the boundary of the adjustable rectangular aperture target plate is a preset percentage of the white signal of the adjustable rectangular aperture target plate, and the illuminance L1 of the integrating sphere is recorded; an illuminance meter is installed at a preset position of the integrating sphere, and the collected value of the illuminance meter is fed back to the controller;

[0016] Step 5: reducing the opening size of the adjustable diaphragm until the white signal of the adjustable rectangular diaphragm target plate image taken by the test piece drops to 100%, and recording the illuminance L2 of the integrating sphere;

[0017] Step 6: Calculate the actual halo value of the object to be tested according to the values ​​of the illuminance L1 and the illuminance L2, and output it.

[0018] The technical beneficial effects of the present invention are:

[0019] In view of the shortcomings of traditional halo detection methods, such as high requirements on laboratory light environment, large floor space, and usually inability to simultaneously meet the detection requirements of telephoto and wide-angle cameras, a visible light-near-infrared digital camera halo testing device and method based on precision motion control, optical target simulation, image processing and other technologies are provided, which can improve test efficiency, reduce the volume of the entire system, reduce construction costs, and improve the test capability of low-light-level night vision cameras with different focal lengths and fields of view. A low-light-level night vision camera halo testing device and method based on precision motion control, optical target simulation, image processing and other technologies can improve test efficiency, reduce the volume of the entire system, reduce construction costs, and improve the test capability of low-light-level night vision cameras with different focal lengths and fields of view. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 It is a schematic diagram of the structure of the present invention;

[0022] Figure 2 It is a schematic diagram of a focus test target plate of a switchable reticle of the present invention;

[0023] Figure 3 It is a schematic diagram of the adjustable rectangular aperture target plate of the switchable graticule plate of the present invention. DETAILED DESCRIPTION

[0024] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0025] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0026] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0027] like Figures 1 to 3 The halo test device for low-light-level night vision cameras shown in the figure uses a low-light-level night vision camera as a test object to perform halo test, and includes a light source, an adjustable aperture, an integrating sphere, a switchable graticule, and an adjustable focus collimator, wherein:

[0028] The light source is a halogen tungsten light source with a color temperature of 3100K±100K, and the light source is processed by an adjustable aperture and an integrating sphere in sequence and illuminates a switchable graticule, wherein the adjustable aperture is used to adjust the luminous flux of the light source, and the adjusted light source is uniformly processed by an integrating sphere;

[0029] The switchable graticule plate includes a focus test target plate and an adjustable rectangular aperture target plate, a CNC motor and a guide rail, wherein the focus test target plate is used to assist the focus of the test piece, and the adjustable rectangular aperture target plate is used to dynamically simulate the target source of the halo test, such as a rectangular window or light hole with adjustable size, which plays the role of letting light in. The CNC motor and the guide rail, the focus test target plate and the adjustable rectangular aperture target plate are adjacent and are installed on the guide rail in a movable manner, and the output end of the linear CNC motor is respectively connected to the focus test target plate and the adjustable rectangular aperture target plate, which can drive the focus test target plate and the adjustable rectangular aperture target plate to switch positions on the guide rail, so as to realize the switching of the target source functions of the test piece auxiliary focus and the dynamic simulation halo test, or the rotational switching method or other switching methods in the prior art can also be used. The CNC motor is controlled by the controller, and the light source transmits light to the adjustable focus collimator through the switchable graticule plate;

[0030] The switchable graticule is located at the focal plane position of the focusable collimator. The focusable collimator collimates or projects the target sources of the focus test target plate and the adjustable rectangular aperture target plate into parallel light, and the parallel light is transmitted to the object to be tested. In actual use, the object to be tested is placed in a dark box to prevent ambient light from interfering with the parallel light or the test process. The focusable collimator includes a group of focusing lenses, which can be focused along the optical axis of the focusable collimator to transmit the target sources of the focus test target plate and the adjustable rectangular aperture target plate to different distances, so as to simulate targets at different object distances.

[0031] The light outlet of the focusable parallel light tube is connected to the dark box mechanical light.

[0032] like Figures 2 to 3 The low-light-level night vision camera halo test method shown uses the above-mentioned low-light-level night vision camera halo test device, and the test method includes:

[0033] Step 1: The device under test is installed in a dark box, the lens end of the device under test is aligned with the light outlet of the focusable collimator, the device under test is electrically connected to the controller, and the controller is electrically connected to the light source, the adjustable aperture, the integrating sphere, the switchable graticule and the focusable collimator respectively;

[0034] Step 2: Switch to the focus test target board, the controller obtains the image captured by the DUT, and adjusts the size of the adjustable diaphragm opening to a preset range (the preset range value is determined according to the model and characteristics of the DUT), so that the image of the DUT (the DUT, for example, is a low-light night vision camera) is not overexposed, and the adjustable focus collimator is used for focusing to adjust the clarity of the image or picture captured by the DUT;

[0035] Step 3: Switch the focus test target plate to the adjustable rectangular aperture target plate, and adjust the rectangular window or light hole of the adjustable rectangular aperture target plate to 0.3 times the shooting picture of the test piece according to the parameters of the test piece;

[0036] Step 4: Adjust the light flux emitted from the light source to the adjustable rectangular aperture target plate through the adjustable aperture, until the signal intensity at the white signal boundary of the adjustable rectangular aperture target plate photographed by the test piece is 50% of the white signal of the adjustable rectangular aperture target plate (the brightness of the boundary of the aperture target plate is half of its central area), and record the illuminance L1 of the integrating sphere; an illuminance meter is installed at the preset position of the integrating sphere, and the collected value of the illuminance meter is fed back to the controller;

[0037] Step 5: Reduce the opening of the adjustable iris until the signal intensity at the white signal of the adjustable rectangular iris target plate photographed by the test piece drops to 100%, that is, the image at the white signal of the adjustable rectangular iris target plate is just not overexposed, and record the illuminance L2 of the integrating sphere;

[0038] Step 6: According to the values ​​of illuminance L1 and illuminance L2, calculate the actual halo value of the test piece and output it.

[0039] Example

[0040] Step 1: Install the low-light-level night vision camera to be tested in a dark box, align the lens end with the light outlet of the adjustable-focus collimator, and connect the low-light-level night vision camera to the computer with a data cable;

[0041] Step 2: Start the light source controller, light source, illuminance meter and other lower computers through the computer built-in test software;

[0042] Step 3: Switch the switchable reticle to the focus test target plate, collect the focus test target plate image taken by the low-light night vision camera through the computer, calculate the gray value of the white area of ​​the image, and determine whether the image is overexposed. If it is overexposed, control the adjustable iris to reduce the opening size of the adjustable iris. If the image is too dark, control the adjustable iris to increase the opening size of the adjustable iris to make the image in a better exposure state. The switchable reticle includes an adjustable rectangular iris target plate. The target plate is opaque on all sides and a rectangular light hole is set in the center. The horizontal and vertical dimensions of the rectangular light hole can be adjusted independently.

[0043] Step 4: Use the focus controller to adjust the focus state of the adjustable focus collimator forward and backward to simulate different object distances, collect the images taken by the low-light night vision camera in real time, calculate the edge sharpness of the image, determine whether the image is in the best focus state, and adjust repeatedly until the image reaches the best focus state;

[0044] Step 6: Switch the switchable graticule to the adjustable rectangular aperture target through the graticule controller, calculate the size of the rectangular light-transmitting area of ​​the rectangular aperture target captured by the low-light night vision camera, and adjust the horizontal and vertical opening sizes of the rectangular aperture so that the horizontal size of the opening in the picture is 0.3 times the total horizontal pixels, and the vertical size is 0.3 times the total vertical pixels.

[0045] Step 7: Control the size of the adjustable aperture opening through the light source controller, collect the low-light night vision camera image in real time, calculate the gray value of the halo image at the boundary of the central light-transmitting area of ​​the adjustable rectangular aperture target plate through the software to be 50% of the central light-transmitting area, and collect the illumination value L1 of the light-emitting surface of the integrating sphere monitored by the illumination meter through the illumination probe;

[0046] Step 8: Reduce the size of the adjustable aperture opening through the light source controller, collect the low-light night vision camera image in real time, make the grayscale value of the central light-transmitting area of ​​the adjustable rectangular aperture target plate lower than 100%, and then increase the size of the adjustable aperture opening so that the grayscale value of the central light-transmitting area of ​​the adjustable rectangular aperture target plate is just at 100%, and collect the current integrating sphere light output illuminance L2 through the illuminometer;

[0047] Step 9: Quantify the camera's vignetting value by the following formula, expressed as,

[0048]

[0049] In view of the shortcomings of traditional halo detection methods, such as high requirements for laboratory light environment, large footprint, and usually inability to simultaneously meet the detection of telephoto and wide-angle cameras, this paper improves the test efficiency based on precision motion control, optical target simulation, image processing and other technologies, reduces the size of the entire system, reduces construction costs, and improves the test capabilities of low-light night vision cameras with different focal lengths and fields of view.

[0050] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A halo test device for a low-light-level night vision camera, which performs halo test on a low-light-level night vision camera as a test object, characterized in that: It includes a light source, an adjustable aperture, an integrating sphere, a switchable graticule and a focusable collimator, wherein: The light source is a halogen tungsten lamp light source, and the light source is sequentially processed through an adjustable aperture and an integrating sphere and irradiates the switchable graticule, wherein the adjustable aperture is used to adjust the luminous flux of the light source, and the adjusted light source is uniformly processed through an integrating sphere; The switchable graticule plate includes a focus test target plate and an adjustable rectangular aperture target plate, a numerically controlled motor and a guide rail, wherein the focus test target plate is used to assist the focus of the test piece, and the adjustable rectangular aperture target plate is used to dynamically simulate the target source during the halo test; The numerically controlled motor and the guide rail, the focus test target plate is adjacent to the adjustable rectangular aperture target plate and is movably mounted on the guide rail, wherein the output end of the numerically controlled motor is respectively connected to the focus test target plate and the adjustable rectangular aperture target plate, and can drive the focus test target plate and the adjustable rectangular aperture target plate to switch positions on the guide rail, and the numerically controlled motor is controlled by a controller; the light source transmits light to the focusable collimator through the switchable graticule; The switchable graticule is located at the focal plane position of the adjustable focus collimator, the adjustable focus collimator collimates or projects the target sources of the focus test target plate and the adjustable rectangular aperture target plate into parallel light, the parallel light is transmitted to the object to be tested, the adjustable focus collimator can focus along the optical axis of the adjustable focus collimator, and transmit the target sources of the focus test target plate and the adjustable rectangular aperture target plate to different distances, so as to simulate targets at different object distances; The light outlet of the focusable collimator is in mechanical optical communication with the dark box.

2. The halo test device for low-light-level night vision cameras according to claim 1, characterized in that: The color temperature of the light source is 3100K±100K.

3. A method for testing halo of a low-light-level night vision camera, characterized in that: Using the halo test device for low-light-level night vision cameras as described in claim 1 or 2, the test method comprises: Step 1: The device to be tested is installed in a dark box, the lens end of the device to be tested is aligned with the light outlet of the focusable collimator, the device to be tested is electrically connected to the controller, and the controller is electrically connected to the light source, the adjustable aperture, the integrating sphere, the switchable graticule and the focusable collimator respectively; Step 2: Switch to the focus test target board, the controller obtains the image captured by the test piece, and adjusts the size of the adjustable diaphragm opening to a preset range so that the image of the test piece is not overexposed, and the adjustable focus collimator is used to focus, and the clarity of the image or picture captured by the test piece is adjusted; Step 3: Switch the focus test target plate to the adjustable rectangular aperture target plate, and adjust the rectangular window or light hole of the adjustable rectangular aperture target plate to the preset magnification of the shooting picture of the test piece according to the parameters of the test piece; Step 4: Use the adjustable aperture to adjust the light flux emitted by the light source to the adjustable rectangular aperture target plate until the signal intensity at the white signal boundary of the adjustable rectangular aperture target plate photographed by the test piece is 50% of the white signal at the adjustable rectangular aperture target plate, and record the illuminance L1 of the integrating sphere; Step 5: Reduce the opening of the adjustable iris until the signal intensity at the white signal of the adjustable rectangular iris target plate photographed by the test piece drops to 100%, so that the image at the white signal of the adjustable rectangular iris target plate is not overexposed, and record the illuminance L2 of the integrating sphere; Step 6: Calculate the actual halo value of the object to be tested according to the values ​​of the illuminance L1 and the illuminance L2, and output it.

4. The testing method according to claim 3, characterized in that: According to the parameters of the test piece, the rectangular window or light hole of the adjustable rectangular aperture target plate is adjusted to 0.3 times the shooting picture of the test piece.

5. The testing method according to claim 3, characterized in that: The light flux of the light source is adjusted by the adjustable aperture so that the halo signal intensity at the border of the adjustable rectangular aperture target plate is 50% of the white signal intensity at the adjustable rectangular aperture target plate.

Images