Compact type infrared laser aperture-dividing on-line axis calibration system

Abstract

The invention discloses a compact infrared laser aperture-dividing online axis calibration system, and belongs to the technical field of optical axis calibration of photoelectric detection systems. Comprising a composite light source, a target plate, an optical light pipe and an infrared optical sensor of a detected photoelectric detection device which are sequentially arranged along a light path; the optical light pipe comprises a primary mirror, a secondary mirror and a third mirror which adopt an off-axis three-mirror design, and the primary mirror faces an infrared optical sensor of the detected photoelectric detection equipment; the target plate serves as a test system reference, the surface of the target plate is coated with a laser infrared optical conversion material, energy irradiated by laser can be absorbed and converted, an infrared observable point image is formed, and a circular through hole is engraved in the center of the target plate to serve as a zero reference of an axis calibration system; and a beam combining prism is arranged between the optical light pipe and the infrared optical sensor, the inner end of the beam combining prism is arranged in the clear aperture of the primary mirror, and the outer end of the beam combining prism is aligned with the direction of the measured laser and is used for combining infrared and laser aperture-splitting light rays. The problem that the optical axis of each optical channel is difficult to calibrate is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of optical axis calibration of a photoelectric detection system, and in particular relates to a compact infrared laser aperture-based online axis calibration system. Background Art

[0002] With the continuous development of optoelectronic detection technology, multifunctional integrated optoelectronic detection systems such as laser ranging and infrared imaging are widely used in various modern equipment platforms. Such as airborne optoelectronic radars, optoelectronic pods, vehicle-mounted optoelectronic aiming equipment, etc. In modern optoelectronic weapons and equipment, multiple optical channels such as infrared and laser are generally included, which can complete the functions of searching, detecting, identifying, observing, aiming and laser irradiation of targets. In the application of equipment, due to the influence of factors such as temperature changes and platform vibration, the aiming lines of each optical channel of the optoelectronic detection equipment will change, causing optical axis deviation and aiming error. Therefore, it is necessary not only to detect the consistency of the optical axis during ground maintenance, but also to calibrate the consistency of the optical axis in real time during the use of the platform.

[0003] Photoelectric detection equipment often contains multiple discrete optical channels, such as the MX series of photoelectric products of L-3Wescam in the United States, the Spectro XR photoelectric turret in Israel, etc. At the same time, it is difficult to calibrate the optical axis of each optical channel. The required axis calibration system diameter includes the optical channel aperture, and the volume is huge, making it difficult to work in real time with the platform. How to achieve discrete aperture optical axis calibration at a small volume cost is the primary problem currently faced. Summary of the invention

[0004] Technical issues to be solved:

[0005] In order to avoid the shortcomings of the prior art, the present invention provides a compact infrared laser sub-aperture online axis calibration system, which images the point target image of the target plate onto the infrared sensor of the photoelectric detection device under test through an off-axis three-reflection optical light tube, and performs self-inspection and optical alignment on the photoelectric detection device under test; a beam combining prism is arranged in front of the optical light tube to realize the beam combining of infrared and laser sub-aperture light; a composite light source is located on the rear end face of the target plate as the light source of the axis calibration system; the present invention has the characteristics of high calibration accuracy, full band, miniaturization, light weight, easy installation and adjustment, and heat difference elimination, solves the problem of difficult optical axis calibration of each optical channel, and is an effective way for ground maintenance of photoelectric detection equipment and real-time calibration of the platform.

[0006] The technical solution of the present invention is: a compact infrared laser sub-aperture online axis calibration system, characterized in that: it comprises a composite light source, a target plate, an optical light pipe, and an infrared optical sensor of a photoelectric detection device to be measured, which are arranged in sequence along an optical path; the optical light pipe comprises a primary mirror, a secondary mirror, and a third mirror adopting an off-axis three-mirror design, and the primary mirror faces the infrared optical sensor of the photoelectric detection device to be measured; the target plate is used as a reference of the test system, and its surface is sprayed with laser infrared optical conversion material, which can absorb and convert the energy irradiated by the laser to form an infrared observable point image, and a circular through hole is engraved in the center of the target plate as a zero position reference of the axis calibration system;

[0007] A beam combining prism is arranged between the optical light pipe and the infrared optical sensor, the inner end of the beam combining prism is placed in the light aperture of the main mirror, and the outer end is aligned with the direction of the laser to be measured, so as to combine the infrared and laser light of different apertures.

[0008] A further technical solution of the present invention is: the optical parameters of the optical light pipe are: the primary mirror is a quadratic surface with a curvature radius of -91.2 mm and a k value of -1.0784; the secondary mirror is an aspherical surface with a curvature radius of -41.33 mm, an A value of 5.7489e-6, a B value of -1.98e-9, a C value of 1.798e-12, and a D value of -5.2447e-16; the third mirror is a plane reflector; the optical distance from the primary mirror to the secondary mirror is 30 mm, the optical distance from the secondary mirror to the third mirror is 32.4 mm, and the optical distance from the third mirror to the target plate is 31.17 mm.

[0009] A further technical solution of the present invention is that the primary mirror, the secondary mirror and their structural support members are made of the same metal material, and the three mirrors are made of quartz material.

[0010] A further technical solution of the present invention is that the beam combining prism is made of sapphire material.

[0011] A further technical solution of the present invention is that the target plate is a circular or square thin metal sheet with a thickness of ≤3 mm; the size range of the central through hole diameter D must meet the following conditions:

[0012]

[0013] Among them, f 校轴系统 is the optical focal length of the axis calibration system, f 被测产品 is the infrared optical focal length of the photoelectric detection device under test, and M is the pixel size of the infrared detector of the photoelectric detection device under test.

[0014] A further technical solution of the present invention is that the optimal thickness of the target plate is 1±0.3 mm.

[0015] A further technical solution of the present invention is that the laser infrared optical conversion material sprayed on the surface of the target plate is phenolic resin or polyimide.

[0016] A further technical solution of the present invention is that a starry sky or four-bar target pattern is engraved around the circular through hole of the target plate for rough alignment of the photoelectric detection device to be tested with the axis calibration system.

[0017] A further technical solution of the present invention is: the composite light source has a thermoluminescence function and can radiate a wide-spectrum light wave of 0.4μm-14μm; as the light source of the calibration system, it is set closely to the target plate, and by irradiating the target plate, a point image or a starry sky or a four-bar target pattern is formed as a reference for the calibration system.

[0018] A calibration method for a compact infrared laser aperture-dividing online axis calibration system, characterized by the following specific steps:

[0019] Aim the infrared optical aperture of the photoelectric detection device under test to the aperture of the primary mirror, and use the infrared sensor of the photoelectric detection device under test to observe the target plate in the calibration system, and perform self-inspection and optical alignment through the engraved pattern on the target plate, that is, adjust the observed point target image to the center of the observation field of view through the product posture;

[0020] Aim the laser emitted by the laser channel of the photoelectric detection device to be tested at the outer end of the beam combining prism, and transmit the laser into the aperture of the primary mirror through the beam combining prism; focus the laser on the target plate through the primary mirror, the secondary mirror, and the third mirror in sequence, and absorb and convert the laser infrared optical conversion material on the surface of the target plate to form an infrared observable target point;

[0021] The actual deviation between the target at the observation point of the photoelectric detection device under test and the center of the observation field of view is measured to obtain the error of the laser and infrared optical axis of the photoelectric detection device under test, and then the photoelectric detection device under test realizes the optical axis calibration.

[0022] Beneficial Effects

[0023] The beneficial effects of the present invention are:

[0024] 1. The target plate used in the present invention is a photoelectric conversion target, which realizes absorption and conversion through the laser infrared conversion material on its surface to form an infrared observable target point; a circular hole is engraved in the center of the target plate, and a starry sky or four-bar target pattern is engraved around the circular hole as a reference for the axis calibration system; the laser image spot can be homogenized to reduce the optical axis consistency deviation caused by poor beam quality;

[0025] 2. The present invention adopts a total reflection optical design. The primary mirror and the secondary mirror are made of the same material as their structural support. The three mirrors are made of quartz material, which can further reduce the physical size of the system, reduce the difficulty of installation and adjustment, and achieve the working capacity of the full temperature range and the full spectrum range;

[0026] 3. The present invention adopts an off-axis three-reflection design, which is easy to install and adjust. It has the characteristics of miniaturization and lightness, and can meet the needs of online axis calibration and ground calibration maintenance of the optoelectronic load platform;

[0027] 4. When calibrating the consistency of the optical axes of the laser and infrared optical sensor of the photoelectric detection equipment, the present invention aims the infrared optical aperture of the photoelectric detection equipment under test at the aperture of the primary mirror, performs self-inspection and optical alignment through the engraved pattern on the target plate, and realizes aiming at the center; the laser channel of the photoelectric detection equipment under test emits the laser and aims at the outer end of the beam-combining prism, and transmits the laser into the aperture of the primary mirror through the beam-combining prism; the laser is focused on the target plate through the primary mirror, the secondary mirror, and the tertiary mirror in turn, and the special surface material of the target plate is absorbed and converted to form an infrared observable target point. The actual deviation between the target at the observation point of the photoelectric detection equipment under test and the center of the observation field can be used to obtain the error of the laser and infrared optical axis of the product itself, and then the optical axis calibration is realized. The calibration process is simple and easy to operate, and the calibration accuracy is high. It can be carried on the photoelectric detection equipment for online optical axis calibration, and can also be used to check the consistency of the product optical axis under offline maintenance.

[0028] 5. As Figure 2 As shown in the figure, the MTF of each field of view is close to the diffraction limit, which ensures that high-resolution image information can be obtained with high axis alignment accuracy. Figure 3 It can be seen that the maximum RMS diameter of the diffuse spot in each field of view does not exceed 10 μm, ensuring that the infrared image converted by the laser is smaller than a single image pixel, thereby improving the calibration accuracy.

[0029] 6. The present invention can be widely used in military and civilian optoelectronic radars, optoelectronic turrets, optoelectronic pods and other optoelectronic detection products equipped with multiple optical sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the principle diagram of the compact infrared laser aperture-based online axis calibration system of the present invention.

[0031] Figure 2 This is the MTF diagram of the compact infrared laser aperture-based online axis calibration system of the present invention.

[0032] Figure 3 This is a point diagram of the compact infrared laser aperture-based online axis calibration system of the present invention.

[0033] Explanation of the accompanying reference numerals: 1. beam combining prism, 2. primary mirror, 3. secondary mirror, 4. tertiary mirror, 5. target plate, 6. composite light source. DETAILED DESCRIPTION

[0034] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0035] Based on the problem that the current photoelectric detection equipment includes multiple discrete optical channels, but it is difficult to calibrate the optical axis of each optical channel at the same time, the present invention provides a compact infrared laser sub-aperture online axis calibration system, including a composite light source, a target plate, an optical light pipe, and an infrared optical sensor of the photoelectric detection device to be measured, which are arranged in sequence along the optical path; the optical light pipe includes a primary mirror, a secondary mirror, and a tertiary mirror adopting an off-axis three-reflection design, and the primary mirror faces the infrared optical sensor of the photoelectric detection device to be measured; the target plate serves as a reference for the test system, and its surface is sprayed with laser infrared optical conversion material, which can absorb and convert the energy irradiated by the laser to form an infrared observable point image, and a circular through hole is engraved in the center as a zero position reference of the axis calibration system; a beam combining prism is arranged between the optical light pipe and the infrared optical sensor, and the inner end of the beam combining prism is placed in the light aperture of the primary mirror, and the outer end is aligned with the direction of the laser to be measured, so as to combine the infrared and laser sub-aperture light.

[0036] Specifically, the optical parameters of the optical light pipe are: the primary mirror is a quadratic surface with a curvature radius of -91.2 mm and a k value of -1.0784; the secondary mirror is an aspherical surface with a curvature radius of -41.33 mm, an A value of 5.7489e-6, a B value of -1.98e-9, a C value of 1.798e-12, and a D value of -5.2447e-16; the third mirror is a plane reflector; the optical distance from the primary mirror to the secondary mirror is 30 mm, the optical distance from the secondary mirror to the third mirror is 32.4 mm, and the optical distance from the third mirror to the target plate is 31.17 mm.

[0037] The above technical solution is further described below in conjunction with the accompanying drawings:

[0038] Reference Figure 1 As shown, the compact infrared laser sub-aperture online axis calibration system of this embodiment includes: a beam combining prism 1, a primary mirror 2, a secondary mirror 3, a tertiary mirror 4, a target plate 5 and a composite light source 6. The primary mirror 2, the secondary mirror 3 and the tertiary mirror 4 adopt an off-axis three-mirror design and are fixed by structural supports to together constitute an optical light pipe of the axis calibration system; the beam combining prism 1 is located in front of the optical light pipe, the inner end of which is located in the light-clearing aperture of the primary mirror 2, and the outer end is aligned with the direction of the laser to be measured, so as to realize the beam combining of infrared and laser sub-aperture light; the target plate 5 is located at the focal plane of the optical lens, and the composite light source 6 is located behind the target plate 5 and is arranged close to the target plate 5; the target plate 5 serves as a reference for the test system, and its surface is sprayed with laser infrared conversion material, which can absorb and convert the energy of laser irradiation to form an infrared observable point image; a circular through hole is engraved in the center of the target plate 5 as a zero position reference for the axis calibration device.

[0039] The beam combining prism 1 is made of sapphire material.

[0040] The primary mirror 2, secondary mirror 3 and tertiary mirror 4 form an optical light tube of the axis correction system with a focal length of 186 mm; and the primary mirror 2 and secondary mirror 3 are made of the same material as their structural support members, and the tertiary mirror 4 is made of quartz material.

[0041] The primary mirror 2 and the secondary mirror 3 are made of optical mirror surfaces using a diamond turning process, and the materials are metals or composite materials that can be used as optical reflectors.

[0042] The target plate 5 is used as the reference of the axis calibration system, and is a round or square thin metal sheet with a thickness of ≤3mm, and the optimal thickness is 1±0.3mm; its surface is sprayed with laser infrared optical conversion material, such as phenolic resin or polyimide, which can absorb and convert the energy of laser irradiation to form an infrared observable point image;

[0043] The target plate 5 is engraved with a circular through hole in the center as the zero reference of the axis calibration system; the through hole diameter D size range must meet the following requirements:

[0044]

[0045] Among them, f 校轴系统 is the optical focal length of the axis calibration system, f 被测产品 is the infrared optical focal length of the photoelectric detection device under test, and M is the pixel size of the infrared detector of the photoelectric detection device under test. A starry sky or four-bar target pattern is engraved around the circular hole of the target plate 5, which is used for the rough alignment of the photoelectric detection device under test with the axis calibration system.

[0046] The composite light source 6 is typically made of thermal resistance wire, which can radiate 0.4μm-14μm wide-spectrum light waves. As the light source of the calibration system, the target plate 5 is irradiated to form a point image or a starry sky or a four-bar target pattern, which serves as the reference of the calibration system.

[0047] The axis calibration system described in this embodiment can be used to calibrate the consistency of the optical axes of laser and infrared optical sensors of photoelectric detection equipment, and the photoelectric detection equipment includes photoelectric radars, photoelectric pods, photoelectric turrets, and vehicle-mounted photoelectric aiming equipment.

[0048] The specific steps of the optical axis calibration method of the axis calibration system in this embodiment are as follows:

[0049] Step 1: The product under test emits a laser pulse and aims at the outer end of the beam combining prism 1, and transmits the laser into the aperture of the primary mirror 2 through the beam combining prism 1; it is reflected to the target plate 5 through the primary mirror 2, the secondary mirror 3, and the tertiary mirror 4 in sequence, and the laser infrared optical conversion material coated on the surface of the target plate 5 converts the laser light source into an infrared radiation image of 3μm-14μm;

[0050] Step 2: The infrared detection sensor of the tested product is aligned with the aperture of the primary mirror 2 of the sub-aperture online axis calibration system, and the position information of the laser conversion image in the imaging area is recorded by observing the infrared radiation image converted by the laser on the target plate 5;

[0051] Step 3: The tested product is calibrated through software to correct the deviation between the laser converted image and the center of the theoretical image.

[0052] Figure 2 This is the transfer function MTF diagram of the compact infrared laser aperture online calibration system of the present invention. Figure 2 As shown, the MTF of each field of view is close to the diffraction limit, which ensures that high-resolution image information can be obtained with high axis alignment accuracy.

[0053] Figure 3 This is a point diagram of the compact infrared laser aperture-based online axis calibration system of the present invention. Figure 3 It can be seen that the maximum RMS diameter of the diffuse spot in each field of view does not exceed 10 μm, ensuring that the infrared image converted by the laser is smaller than a single image pixel, thereby improving the calibration accuracy.

[0054] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A compact infrared laser aperture-based online axis calibration system, characterized in that: It includes a composite light source, a target plate, an optical light pipe, and an infrared optical sensor of the photoelectric detection device to be tested, which are arranged in sequence along the optical path; the optical light pipe includes a primary mirror, a secondary mirror, and a tertiary mirror adopting an off-axis three-mirror design, and the primary mirror faces the infrared optical sensor of the photoelectric detection device to be tested; the target plate is used as a reference of the test system, and its surface is sprayed with laser infrared optical conversion material, which can absorb and convert the energy irradiated by the laser to form an infrared observable point image, and a circular through hole is engraved in the center as a zero reference of the axis calibration system; A beam combining prism is arranged between the optical light pipe and the infrared optical sensor, the inner end of the beam combining prism is placed in the light aperture of the main mirror, and the outer end is aligned with the direction of the laser to be measured, so as to combine the infrared and laser light of different apertures.

2. According to claim 1, a compact infrared laser aperture-based online axis calibration system is characterized by: The optical parameters of the optical light pipe are as follows: the primary mirror is a quadratic surface with a curvature radius of -91.2 mm and a k value of -1.0784; the secondary mirror is an aspherical surface with a curvature radius of -41.33 mm, an A value of 5.7489e-6, a B value of -1.98e-9, a C value of 1.798e-12, and a D value of -5.2447e-16; the third mirror is a plane reflecting mirror; the optical distance from the primary mirror to the secondary mirror is 30 mm, the optical distance from the secondary mirror to the third mirror is 32.4 mm, and the optical distance from the third mirror to the target plate is 31.17 mm.

3. According to claim 1, a compact infrared laser aperture-based online axis calibration system is characterized by: The primary mirror, secondary mirror and their structural support are made of the same metal material, and the three mirrors are made of quartz material.

4. According to claim 1, a compact infrared laser aperture-based online axis calibration system is characterized by: The beam combining prism is made of sapphire material.

5. According to claim 1, a compact infrared laser aperture-based online axis calibration system is characterized by: The target plate is a circular or square thin metal sheet with a thickness of ≤3mm; the diameter D of the central through hole must meet the following conditions: Among them, f 校轴系统 is the optical focal length of the axis calibration system, f 被测产品 is the infrared optical focal length of the photoelectric detection device under test, and M is the pixel size of the infrared detector of the photoelectric detection device under test.

6. According to claim 5, a compact infrared laser aperture-based online axis calibration system is characterized by: The optimal thickness of the target plate is 1±0.3 mm.

7. According to claim 1, a compact infrared laser aperture-based online axis calibration system is characterized by: The laser infrared optical conversion material sprayed on the surface of the target plate is phenolic resin or polyimide.

8. According to claim 1, a compact infrared laser aperture-based online axis calibration system is characterized by: A starry sky or four-bar target pattern is engraved around the circular through hole of the target plate, which is used for coarse alignment of the photoelectric detection device to be tested with the axis calibration system.

9. According to claim 1, a compact infrared laser aperture-based online axis calibration system is characterized by: The composite light source has a thermoluminescent function and can radiate a wide-spectrum light wave of 0.4 μm-14 μm. As the light source of the axis calibration system, it is arranged closely to the target plate, and forms a point image or a starry sky or a four-bar target pattern by irradiating the target plate, which serves as a reference for the axis calibration system.

10. A method for calibrating a compact infrared laser aperture-based online axis calibration system, which is implemented based on the method for calibrating a compact infrared laser aperture-based online axis calibration system according to any one of claims 1 to 9, characterized in that The specific steps are as follows: Aim the infrared optical aperture of the photoelectric detection device under test to the aperture of the primary mirror, and use the infrared sensor of the photoelectric detection device under test to observe the target plate in the calibration system, and perform self-inspection and optical alignment through the engraved pattern on the target plate, that is, adjust the observed point target image to the center of the observation field of view through the product posture; Aim the laser emitted by the laser channel of the photoelectric detection device to be tested at the outer end of the beam combining prism, and transmit the laser into the aperture of the primary mirror through the beam combining prism; focus the laser on the target plate through the primary mirror, the secondary mirror, and the third mirror in sequence, and absorb and convert the laser infrared optical conversion material on the surface of the target plate to form an infrared observable target point; The actual deviation between the target at the observation point of the photoelectric detection device under test and the center of the observation field of view is measured to obtain the error of the laser and infrared optical axis of the photoelectric detection device under test, and then the photoelectric detection device under test realizes the optical axis calibration.

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