Reflection target for optoelectronic system calibration, calibration method and target preparation method

Abstract

The present invention discloses a reflective target for photoelectric system calibration, a calibration method, and a reflective target preparation method. The reflective target includes a substrate and a reflective target material disposed on the substrate. The reflective target material is formed by mixing 15-25 parts of upconversion material powder, 50-70 parts of aluminum oxide powder, and 15-25 parts of thermal conductive adhesive in a weight ratio and then sintering. After the reflective target is irradiated by a 1μm laser, the upconversion material emits visible light for axial calibration of a visible light camera. Simultaneously, the temperature of the laser reaching the reflective target rises to tens to hundreds of degrees. An infrared spectrum is simultaneously generated at the laser irradiation position, which performs axial calibration of the infrared thermal imager. Therefore, the reflective target conveniently realizes the axial calibration of the optical axes of a laser rangefinder, a visible light camera, and an infrared thermal imager in a single irradiation. Compared with similar products, the reflective target has the advantages of high hardness, resistance to laser damage, high thermal conductivity, and small spot dispersion, meeting the requirements of online self-calibration and engineering testing.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoelectric testing equipment and application, and relates to a reflective target for calibration and detection of a photoelectric system in a photoelectric pod, a calibration method and a preparation method thereof. Background Art

[0002] Electro-optical pods are increasingly being used in the aviation and aerospace sectors. Their optoelectronic systems integrate three devices: a visible light camera, an infrared thermal imager, and a laser rangefinder. The laser rangefinder uses a high-power 1064nm near-infrared laser to emit laser light at a target, while the visible light camera and infrared thermal imager are used to image the target. Applications require the optical axes of all three devices to remain parallel. However, parallelism calibration of the three devices presents a technical challenge in the production and application of electro-optical pods. Typically, large-aperture collimators are used to incorporate visible and infrared light sources for parallelism calibration and testing. However, due to the bulk and weight of the calibration equipment and the high site requirements, it cannot meet the requirements of online self-calibration and engineering testing. Summary of the Invention

[0003] (1) Purpose of the invention

[0004] The purpose of the present invention is to provide a reflective target for photoelectric system calibration, a calibration method and a reflective target preparation method. After the reflective target is irradiated by a 1μm laser, the upconversion material emits visible light, which is used for axial calibration of a visible light camera. At the same time, after the laser reaches the reflective target, the temperature rises to tens of degrees to hundreds of degrees. The laser irradiation position also generates an infrared spectrum, which performs axial calibration of the infrared thermal imager.

[0005] (2) Technical solution

[0006] In order to solve the above technical problems, the present invention provides a reflective target for calibrating a photoelectric system, which includes a substrate 5 and a reflective target material arranged on the substrate 5, wherein the reflective target material is sintered after mixing 15-25 parts by weight of upconversion material powder, 50-70 parts by weight of aluminum oxide powder and 15-25 parts by weight of thermal conductive adhesive.

[0007] Preferably, the reflective target is a circular target with a thickness of 2-3 mm and a diameter of 10-20 mm.

[0008] Preferably, a cross mark is processed at the center of the reflective target, and the depth of the cross mark is 0.5-1 mm.

[0009] Preferably, the substrate is an aluminum plate, and the reflective target is bonded to the substrate by thermally conductive adhesive.

[0010] Preferably, the up-conversion material is the rare earth up-conversion luminescent material NaYF4.

[0011] Preferably, the reflective target is formed by mixing 15 parts of up-conversion material powder, 70 parts of aluminum oxide powder and 15 parts of thermally conductive silver paste in a weight ratio and then sintering the mixture.

[0012] Preferably, the reflective target is formed by mixing 25 parts of up-conversion material powder, 50 parts of aluminum oxide powder and 25 parts of thermally conductive silver paste in a weight ratio and then sintering the mixture.

[0013] Preferably, the reflective target is formed by mixing 20 parts by weight of up-conversion material powder, 60 parts by weight of aluminum oxide powder and 20 parts by weight of thermally conductive silver paste and then sintering the mixture.

[0014] The present invention also provides a method for calibrating an optoelectronic system using a reflective target, comprising the following steps:

[0015] Step 1: The laser rangefinder of the optoelectronic system transmits an infrared laser to a reflective target placed at a set distance. The conversion material on the reflective target emits visible light, and the temperature of the target rises to generate infrared radiation.

[0016] Step 2: The visible light camera and infrared thermal imager of the optoelectronic system respectively obtain the visible light spot and infrared thermal imaging spot of the laser;

[0017] Step 3: Adjust the optical axis of the optoelectronic system so that both the visible light spot and the infrared thermal imaging spot are imaged at the set center of the image sensor to eliminate the axial angle deviation.

[0018] The present invention further provides a method for preparing a reflective target for photoelectric system calibration, comprising the following steps:

[0019] Step 1: 15-25 parts by weight of upconversion material powder, 50-70 parts by weight of aluminum oxide, and 15-25 parts by weight of thermal conductive silver paste are thoroughly and evenly mixed and ball-milled into powder;

[0020] Step 2: Using vacuum sintering method, sintering at a temperature of 150-200° for 8-10 hours to form a block material;

[0021] Step 3: Processing the bulk material into the set reflective target size;

[0022] Step 4: Draw a cross mark on the front of the reflective target;

[0023] Step 5: Bond the reverse side of the reflective target to the substrate using thermally conductive adhesive.

[0024] (3) Beneficial effects

[0025] The reflective target, calibration method, and reflective target preparation method for photoelectric system calibration provided by the above technical solution have the following beneficial effects:

[0026] (1) The present invention mixes and sinters alumina powder, upconversion material powder and thermal conductive adhesive to form a reflective target. During calibration, the laser rangefinder of the photoelectric system emits 1 μm laser. After the reflective target is irradiated by the 1 μm laser, the upconversion material emits visible light, which is used for axial calibration of the visible light camera. At the same time, after the reflective target is irradiated by the high-power laser, the temperature rise reaches tens of degrees to hundreds of degrees. The laser irradiation spot position generates an infrared spectrum, and the infrared thermal imager is axially calibrated at the same time. Therefore, a reflective target can conveniently realize the axial calibration of the optical axes of the laser rangefinder, the visible light camera and the infrared thermal imager in one irradiation.

[0027] (2) The present invention processes cross-marks on the reflective target material. During calibration, the laser rangefinder aligns the light spot with the cross-marks and illuminates them. At the same time, the visible light camera and the infrared thermal imager form an image of the cross-marks, providing a position reference for the image and further improving the calibration accuracy.

[0028] (3) When preparing the reflective target of the present invention, the upconversion material powder is used to convert the near-infrared laser into visible light, and the alumina powder provides a hard substrate with relatively stable heat generation and good durability. The material has the characteristics of high hardness and high thermal conductivity, which meets the imaging calibration requirements of the optoelectronic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the composition of the photoelectric system and the axial alignment principle of the present invention.

[0030] In the figure: 1- optoelectronic pod; 2- visible light camera; 3- rangefinder; 4- infrared thermal imager; 5- substrate; 6- reflective target; 7- crosshairs; 8- light spot; 9- optoelectronic system. DETAILED DESCRIPTION

[0031] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below with reference to the accompanying drawings and examples.

[0032] like Figure 1 As shown, the optoelectronic system 9 of the optoelectronic pod 1 integrates three devices: a visible light camera 2, an infrared thermal imager 4, and a laser rangefinder 3. The laser rangefinder 3 uses a high-power near-infrared laser at 1064 nm. During calibration, a reflective target 6 is positioned several hundred meters to several kilometers away from the optoelectronic system. The laser rangefinder 3 then emits a laser beam towards the reflective target 6, and the visible light camera 2 and infrared thermal imager 4 are used to capture an image of the reflective target 6.

[0033] Reflective target 6 includes a substrate 5 and a reflective target material disposed on substrate 5. The reflective target material is formed by sintering a mixture of 15-25 parts by weight of upconversion material powder, 50-70 parts by weight of aluminum oxide powder, and 15-25 parts by weight of thermally conductive adhesive. The optoelectronic system's laser rangefinder emits a 1μm laser. When irradiated by the 1μm laser, the upconversion material in the reflective target material emits visible light, which is used for axial alignment of the visible light camera 2. Simultaneously, the temperature of the reflective target material rises by tens to hundreds of degrees Celsius after exposure to the high-power laser. The laser irradiation spot 8 generates an infrared spectrum, which simultaneously calibrates the infrared thermal imager 4. Therefore, a single reflective target facilitates axial alignment of the optical axes of the laser rangefinder 3, visible light camera 2, and infrared thermal imager 4 in a single exposure.

[0034] The reflective target is a circular target with a thickness of 2-3mm and a diameter of 10-20mm. A crosshair is machined into the center of the target, with a depth of 0.5-1mm. During calibration, the laser rangefinder 3 aligns its beam spot with the crosshairs, while the visible light camera 2 and the infrared thermal imager 4 simultaneously capture images of the crosshairs, providing a positional reference for the image and further improving calibration accuracy.

[0035] In this embodiment, the substrate is an aluminum plate, and the reflective target is bonded to the substrate by thermally conductive adhesive.

[0036] In this embodiment, the reflective target material preferably has three compositions: (1) the reflective target material is formed by mixing 15 parts by weight of up-conversion material powder, 70 parts by weight of aluminum oxide powder, and 15 parts by weight of thermally conductive silver paste, and then sintering; (2) the reflective target material is formed by mixing 25 parts by weight of up-conversion material powder, 50 parts by weight of aluminum oxide powder, and 25 parts by weight of thermally conductive silver paste, and then sintering; (3) the reflective target material is formed by mixing 20 parts by weight of up-conversion material powder, 60 parts by weight of aluminum oxide powder, and 20 parts by weight of thermally conductive silver paste, and then sintering.

[0037] In this embodiment, the upconversion material is a rare earth upconversion luminescent material NaYF4, which has a high upconversion efficiency. The thermal conductive adhesive is a high thermal conductivity and conductive silver adhesive, which is commonly used for bonding materials in high-power and heat dissipation components, chips, and other high-temperature environments.

[0038] Based on the above-mentioned reflective target, the method for calibrating the optoelectronic system includes the following steps:

[0039] 【1】The laser rangefinder of the optoelectronic system transmits infrared laser to a reflective target hundreds of meters to kilometers away. The conversion material on the reflective target emits visible light, and at the same time, the temperature rise of the target generates infrared radiation.

[0040] 【2】The visible light camera and infrared thermal imager of the optoelectronic system respectively obtain the visible light spot and infrared thermal imaging spot of the laser;

[0041] 【3】Adjust the optical axis of the optoelectronic system so that both the visible light spot and the infrared thermal imaging spot are imaged at the center of the set image sensor, eliminating the axial angle deviation.

[0042] The method for preparing the reflective target comprises the following steps:

[0043] 【1】15-25 parts by weight of upconversion material powder, 50-70 parts by weight of aluminum oxide, and 15-25 parts by weight of thermal conductive silver paste are thoroughly mixed and ball-milled into powder;

[0044] 【2】Use vacuum sintering method, sintering at a temperature of 150-200° for 8-10 hours to make block material;

[0045] 【3】Processing the bulk material into the specified reflective target size;

[0046] 【4】Draw a cross mark on the front of the reflective target;

[0047] 【5】The reverse side of the reflective target is bonded to the substrate using thermally conductive adhesive.

[0048] The preparation example of the reflective target is as follows:

[0049] Example 1

[0050] An embodiment of the present invention provides a material and preparation method for laser spectrum conversion. 15 grams of upconversion material, 70 grams of Al2O3, and 15 grams of thermally conductive silver paste are taken. The above materials are fully and evenly mixed in proportion and ball-milled, loaded in a quartz crucible, and sintered in a vacuum furnace at a sintering temperature of 200 degrees and a sintering time of 8 hours.

[0051] Example 2

[0052] An embodiment of the present invention provides a material and preparation method for laser spectrum conversion. 20 grams of upconversion material, 60 grams of Al2O3, and 20 grams of thermally conductive silver paste are taken. The above materials are fully and evenly mixed in proportion and ball-milled, loaded in a quartz crucible, and sintered in a vacuum furnace at a sintering temperature of 200 degrees and a sintering time of 8 hours.

[0053] Example 3

[0054] An embodiment of the present invention provides a material and preparation method for laser spectrum conversion. 25 grams of upconversion material, 50 grams of Al2O3, and 25 grams of thermally conductive silver paste are taken. The above materials are fully and evenly mixed in proportion and ball-milled, loaded in a quartz crucible, and sintered in a vacuum furnace at a sintering temperature of 200 degrees and a sintering time of 8 hours.

[0055] The material prepared according to the above process converts the absorbed energy into visible light and infrared light spots of 0.3-0.75μm after being excited by a 1-micron laser. The material also has the characteristics of high hardness and high thermal conductivity, meeting the needs of online self-calibration and engineering testing of optoelectronic systems.

[0056] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A reflective target for calibrating an optoelectronic system, characterized in that: The reflective target is formed by mixing 15-25 parts by weight of upconversion material powder, 50-70 parts by weight of aluminum oxide powder, and 15-25 parts by weight of thermal conductive adhesive, and then sintering the mixture. The reflective target is a circular target with a thickness of 2-3 mm and a diameter of 10-20 mm; The center of the reflective target is processed with a cross-marked line, and the depth of the cross-marked line is 0.5-1mm; The substrate is an aluminum plate, and the reflective target is bonded to the substrate by thermally conductive adhesive; The up-conversion material is a rare earth up-conversion luminescent material NaYF4; The optoelectronic system includes a laser rangefinder, a visible light camera and an infrared thermal imager with parallel optical axes. The laser rangefinder emits laser light to a reflective target arranged at a set distance. The upconversion material of the reflective target emits visible light for optical axis calibration of the visible light camera.

2. The reflective target for photoelectric system calibration according to claim 1, wherein: The reflective target material is formed by mixing 15 parts of up-conversion material powder, 70 parts of aluminum oxide powder and 15 parts of heat-conducting silver paste in a weight ratio and then sintering the mixture.

3. The reflective target for photoelectric system calibration according to claim 1, wherein: The reflective target material is formed by mixing 25 parts of up-conversion material powder, 50 parts of aluminum oxide powder and 25 parts of heat-conducting silver paste in a weight ratio and then sintering the mixture.

4. The reflective target for photoelectric system calibration according to claim 1, wherein: The reflective target material is formed by mixing 20 parts of up-conversion material powder, 60 parts of aluminum oxide powder and 20 parts of heat-conducting silver paste in a weight ratio and then sintering the mixture.

5. A method for calibrating a photoelectric system using the reflective target for calibrating a photoelectric system according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: The laser rangefinder of the optoelectronic system transmits an infrared laser to a reflective target placed at a set distance. The conversion material on the reflective target emits visible light, and the temperature of the target rises to generate infrared radiation. Step 2: The visible light camera and infrared thermal imager of the optoelectronic system respectively obtain the visible light spot and infrared thermal imaging spot of the laser; Step 3: Adjust the optical axis of the optoelectronic system so that both the visible light spot and the infrared thermal imaging spot are imaged at the set center of the image sensor to eliminate the axial angle deviation.

6. The method for preparing a reflective target for photoelectric system calibration according to claim 1, characterized in that: The following steps are involved: Step 1: 15-25 parts by weight of upconversion material powder, 50-70 parts by weight of aluminum oxide, and 15-25 parts by weight of thermal conductive silver paste are thoroughly and evenly mixed and ball-milled into powder; Step 2: Using vacuum sintering method, sintering at a temperature of 150-200° for 8-10 hours to form a block material; Step 3: Processing the bulk material into the set reflective target size; Step 4: Draw a cross mark on the front of the reflective target; Step 5: Bond the reverse side of the reflective target to the substrate using thermally conductive adhesive.

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