Infrared target background noise analysis and suppression method in low-temperature nitrogen cold cabin

Abstract

The invention provides an infrared target background noise analysis and suppression method in a low-temperature nitrogen cold cabin. The analysis method comprises the steps that an optical system model is established in zemax software, ray tracing software is imported, a low-temperature nitrogen cold cabin model is established, spontaneous radiation sources are established for all objects, object surface attributes are set, and finally full-link ray tracing is completed to obtain background noise. According to the suppression method, background noise is effectively suppressed by means of optimizing an optical system model, reducing the temperature of a radiation source, modifying surface attributes of an inner wall material of the low-temperature nitrogen cold cabin and the like in combination with re-light tracing judgment. According to the method, the background noise of the low-temperature target system can be rapidly analyzed and effectively suppressed, the fidelity and credibility of an infrared target simulation system are improved, and the background noise analysis requirements of different research and development stages of a complex system are met.

Description

Technical Field

[0001] The invention relates to the technical field of infrared target background noise analysis, and in particular to an infrared target background noise analysis and suppression method in a low-temperature nitrogen cold chamber. Background Art

[0002] The target simulator background noise is one of the important indicators for judging the simulation capability of the infrared target simulation system. In the design and evaluation process of the infrared target simulation system, accurate analysis and effective suppression of background noise are crucial. The lower the background noise, the higher the fidelity and credibility of the target simulator when simulating infrared targets, which is of great significance to improving the overall performance of the system.

[0003] At present, the analysis of simulation systems and suppression of target simulator background noise at home and abroad are mainly carried out under normal temperature environment. However, with the continuous development of aerospace technology, the demand for infrared target simulation in low-temperature nitrogen cold chamber environment is becoming increasingly urgent. In this environment, due to the complexity of temperature, material properties and optical system design, the source and characteristics of background noise are significantly different from those in normal temperature environment.

[0004] Specifically, in a cryogenic nitrogen cold chamber environment, all objects can be regarded as spontaneous radiation sources. The light radiated outward by them may eventually reach the detector surface and form background noise after being refracted by the optical system. In addition, the surface properties of materials in a low-temperature environment (such as absorption, reflection, refraction, transmission, and diffraction) will also change, further affecting the simulation results of background noise. Therefore, the traditional background noise analysis and suppression methods in a normal temperature environment cannot be directly applied to a cryogenic nitrogen cold chamber environment.

[0005] A method and system for analyzing the dynamic range of infrared target energy in a cryogenic nitrogen cold chamber is disclosed in a patent document with publication number CN117490855A, including: establishing an equivalent black body detection model at the entrance pupil of the tested product, and obtaining the corresponding relationship between the equivalent black body temperature at the entrance pupil and the detector irradiance; establishing a background stray radiation analysis model for the target simulation system in the cryogenic nitrogen cold chamber, and calculating the background stray irradiance of the target simulation system; calculating the minimum target irradiance that the target system can simulate based on the product's minimum signal-to-noise ratio and the target system's background stray irradiance; calculating the corresponding relationship between the radiation source temperature and the equivalent black body temperature at the entrance pupil of the tested product, and obtaining the maximum target irradiance that the target system can simulate based on the maximum temperature of the radiation source; and calculating the dynamic range of infrared target energy in a cryogenic nitrogen cold chamber based on the maximum target irradiance and the minimum target irradiance. However, the invention does not have a target background noise analysis method in a cryogenic nitrogen cold chamber environment, nor does it form an effective suppression method.

[0006] At present, there is no method for analyzing target background noise in a cryogenic nitrogen cold chamber environment, nor is there an effective suppression method. This results in the inability to accurately evaluate the impact of background noise during the early performance demonstration of the cryogenic target system, which in turn affects the design and optimization of the system. Therefore, developing an infrared target background noise analysis and suppression method suitable for a cryogenic nitrogen cold chamber environment is of great significance for improving the performance of the infrared target simulation system.

[0007] Therefore, it is necessary to propose a new technical solution to improve the above technical problems. Summary of the invention

[0008] In view of the defects in the prior art, the object of the present invention is to provide a method for analyzing and suppressing background noise of infrared targets in a low-temperature nitrogen cold chamber.

[0009] According to a method for analyzing background noise of infrared targets in a low-temperature nitrogen cold chamber provided by the present invention, the method comprises the following steps:

[0010] Step S1: construct the initial model of the collimating optical system and the converging optical system in the zemax software, and check the imaging quality;

[0011] Step S2: Import the optical system model into the ray tracing software, and further construct a three-dimensional model of the cryogenic nitrogen cold chamber and related structures in the software to obtain the background noise of the infrared target system by tracing.

[0012] Preferably, the method further comprises step S3: establishing a spontaneous radiation source model for all constituent elements, including the optical system, the cryogenic nitrogen cold chamber and the mechanical structure, in the ray tracing software to simulate the radiation characteristics of these elements in a cryogenic environment.

[0013] Preferably, the process of establishing the spontaneous radiation source model includes: determining the surfaces of each constituent element that have an impact on the background noise, calculating the spontaneous radiation luminous area of ​​these surfaces, estimating their temperature, and calculating their respective radiation intensities using the Planck formula, and finally establishing a spontaneous radiation source of the corresponding band for each surface in the ray tracing software.

[0014] Preferably, the surface properties of all constituent elements are set in the ray tracing software in combination with the actual characteristics of various materials, including absorption, reflection, refraction, transmission and diffraction, to simulate the interaction between light and these surfaces.

[0015] Preferably, the method further includes establishing a detector as a surface receiver, and calculating and acquiring background noise data of the target simulator through full-link ray tracing.

[0016] The present invention also provides a method for suppressing background noise of infrared targets in a low-temperature nitrogen cold chamber, the method comprising the following steps:

[0017] Step 1: Optimize the optical system model to reduce background noise;

[0018] Step 2: Verify the optimization effect through ray tracing. If it does not meet the requirements, repeat step 1.

[0019] Step 3: Reduce the temperature of the radiation source to further reduce the background noise;

[0020] Step 4: Verify the reduction effect through ray tracing. If it does not meet the requirements, repeat step 3.

[0021] Preferably, step 5 is also included: modifying the surface properties of the inner wall material of the cryogenic nitrogen cold chamber to reduce background noise, specifically including selecting high reflectivity or high emissivity materials according to actual simulation results, and selecting the optimal material in combination with the existing material library to reduce the self-radiation energy of background stray light or weaken its intensity reflected to the detector surface.

[0022] Preferably, the method further comprises step 6: after re-ray tracing, determining whether the background noise caused by the cryogenic nitrogen cooling chamber meets the requirement, and if not, repeating step 5.

[0023] Preferably, the process of optimizing the optical system model in step 1 includes finely adjusting the surface shape and curvature parameters of the lens in the optical system until the background stray light does not converge to the detector surface through the lens.

[0024] Preferably, the process of reducing the temperature of the radiation source in step 3 includes adding a liquid nitrogen refrigeration mechanism to the lens and aperture structure to reduce the self-radiation energy of the background stray light from the source.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention provides a background noise analysis method in a low-temperature nitrogen environment. Through simulation and calculation, the background noise in the environment can be quantified, which is helpful to carry out background noise suppression work in a targeted manner, thereby improving the performance of the infrared target simulation system;

[0027] 2. The background noise suppression method provided by the present invention starts from multiple aspects, including optimizing the optical system model, reducing the temperature of the radiation source, and modifying the surface properties of the inner wall material of the cryogenic nitrogen cold chamber. These measures work together to effectively reduce the infrared background noise in the cryogenic nitrogen environment and improve the fidelity and credibility of the target simulator.

[0028] 3. The method of the present invention can not only be applied to infrared target simulators in cryogenic nitrogen cold chambers, but also meet the background noise analysis requirements of complex systems at different research and development stages. Background noise suppression can run through the entire process of complex target simulator system development, and can provide effective support from the initial design to later optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0030] Figure 1 This is a schematic diagram of a semi-physical simulation system of a low-temperature nitrogen cold chamber of the present invention;

[0031] Figure 2 This is a flow chart of the infrared target background noise analysis method in the low-temperature nitrogen cold chamber of the present invention;

[0032] Figure 3 This is a flow chart of the method for suppressing background noise of infrared targets in a cryogenic nitrogen cold chamber of the present invention;

[0033] Figure 4 Schematic diagram of the external cold plate structure. DETAILED DESCRIPTION

[0034] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0035] Embodiment 1:

[0036] Reference Figure 1 and Figure 2 According to a method for analyzing background noise of infrared targets in a low-temperature nitrogen cold chamber provided by the present invention, the method comprises the following steps:

[0037] Step S1: construct the initial model of the collimating optical system and the converging optical system in the zemax software, and check the imaging quality;

[0038] Step S2: Import the optical system model into the ray tracing software, and further construct a three-dimensional model of the cryogenic nitrogen cold chamber and related structures in the software to obtain the background noise of the infrared target system by tracing.

[0039] Step S3: In the ray tracing software, a spontaneous radiation source model is established for all constituent elements, including the optical system, the cryogenic nitrogen cold chamber and the mechanical structure, to simulate the radiation characteristics of these elements in a cryogenic environment.

[0040] The process of establishing a spontaneous radiation source model includes: determining the surfaces of each component that have an impact on the background noise, calculating the spontaneous radiation luminous area of ​​these surfaces, estimating their temperature, and calculating their respective radiation intensities through Planck's formula, and finally establishing a spontaneous radiation source of the corresponding band for each surface in the ray tracing software.

[0041] A method for analyzing background noise of infrared targets in a cryogenic nitrogen cold chamber also includes combining the actual characteristics of various materials, setting the surface properties of all constituent elements in ray tracing software, including absorption, reflection, refraction, transmission and diffraction, and simulating the interaction between light and these surfaces.

[0042] A method for analyzing background noise of an infrared target in a cryogenic nitrogen cold chamber also includes establishing a detector as a surface receiver, and calculating and acquiring background noise data of a target simulator through full-link ray tracing.

[0043] Reference Figure 3 The present invention also provides a method for suppressing background noise of infrared targets in a low-temperature nitrogen cold chamber, the method comprising the following steps:

[0044] Step 1: Optimize the optical system model to reduce background noise. The process of optimizing the optical system model includes modifying the surface shape and curvature parameters of key lenses in the ZEMAX software, changing the light transmission path of the background stray light, so that most of the background stray light will not converge on the detector surface and will not be detected, thereby reducing the background noise.

[0045] Step 2: Verify the optimization effect through ray tracing. If it does not meet the requirements, repeat step 1.

[0046] Step 3: Lower the temperature of the radiation source to further reduce background noise; the process of lowering the temperature of the radiation source includes adding a liquid nitrogen refrigeration mechanism to the lens and aperture structure to reduce the self-radiation energy of background stray light from the source. Taking the aperture structure as an example, a cold plate structure is added to the back of the aperture. The upper and lower ends of the cold plate are designed with liquid nitrogen inlet and outlet joints. Liquid nitrogen enters through the liquid nitrogen inlet and flows out from the liquid nitrogen outlet after circulation in the flow channel. After temperature conduction between the liquid nitrogen and the radiation panel, the radiation panel obtains a uniform and stable cold source background.

[0047] Step 4: Verify the reduction effect through ray tracing. If it does not meet the requirements, repeat step 3.

[0048] Step 5: Modify the surface properties of the inner wall material of the cryogenic nitrogen cold chamber to reduce background noise, including selecting high reflectivity or high emissivity materials based on actual simulation results, and selecting the optimal material based on the existing material library to reduce the self-radiation energy of background stray light or weaken its intensity reflected to the detector surface.

[0049] Step 6: After re-ray tracing, determine whether the background noise caused by the cryogenic nitrogen cold chamber meets the requirements. If not, repeat step 5.

[0050] Embodiment 2:

[0051] The invention provides a target background noise analysis method for an infrared target simulator in a cryogenic nitrogen cold chamber, comprising: step 1: establishing collimating optical system and converging optical system models in ZEMAX software, and completing optical system optimization design; step 2: importing the optical system model into ray tracing software, and establishing models of a cryogenic nitrogen cold chamber and other structures; step 3: establishing a spontaneous radiation source for all objects such as the optical system, the cryogenic nitrogen cold chamber and a mechanical structure in the ray tracing software; step 4: combining various material properties, setting the surface properties of all objects in the ray tracing software; step 5: establishing a detector as a surface receiver, completing full-link ray tracing, and obtaining the background noise of the target simulator. At the same time, the present invention also provides a method for suppressing target background noise of an infrared target simulator in a low-temperature nitrogen cold chamber, comprising: step 1: optimizing the optical system model, thereby reducing background noise; step 2: determining whether the background noise caused by the optical system meets the requirements after re-ray tracing, and repeating step 1 if not; step 3: reducing the temperature of the radiation source, thereby reducing background noise; step 4: determining whether the background noise caused by the radiation source meets the requirements after re-ray tracing, and repeating step 3 if not; step 5: modifying the surface properties of the inner wall material of the low-temperature nitrogen cold chamber, thereby reducing background noise; step 6: determining whether the background noise caused by the low-temperature nitrogen cold chamber meets the requirements after re-ray tracing, and repeating step 5 if not. The method provided by the present invention can quickly analyze and effectively suppress the background noise of the low-temperature target system, and improve the fidelity and credibility of the infrared target simulation system.

[0052] The present invention provides a method for analyzing and suppressing background noise of infrared targets in a low-temperature nitrogen cold chamber, comprising:

[0053] Analysis method: Step 1: Establish collimating optical system and converging optical system models in ZEMAX software, and complete the optimization design of the optical system; Step 2: Import the optical system model into the ray tracing software, and establish the cryogenic nitrogen cold chamber and other structural models; Step 3: Establish spontaneous radiation sources for all objects such as the optical system, cryogenic nitrogen cold chamber and mechanical structure in the ray tracing software. Because in a low-temperature environment, all objects can be regarded as a spontaneous radiation source, and the light radiating outward will eventually reach the detector surface after refraction by the optical system to form background noise. Step 4: Combined with various material properties, set the surface properties of all objects in the ray tracing software; Step 5: Establish the detector as a surface receiver, complete the full-link ray tracing, and obtain the background noise of the target simulator; The number of traced rays should be set to be sufficient to ensure the credibility of the simulation background noise results.

[0054] The step of establishing a spontaneous radiation source includes the following steps: determining the surface of each object that affects the background noise of the target system; calculating the spontaneous radiation luminous area of ​​each surface respectively; estimating the temperature of each surface respectively; calculating the spontaneous radiation intensity of each surface by Planck's formula; and establishing a spontaneous radiation source of a corresponding band for each surface in a ray tracing software.

[0055] The setting of the object surface properties includes but is not limited to absorption, reflection, refraction, transmission and diffraction, etc., and needs to be set according to the actual characteristics of the material. Different surface properties have different effects on light, affecting the simulation background noise result.

[0056] Suppression method: Step 1: Optimize the optical system model to reduce the background noise; Step 2: After re-ray tracing, determine whether the background noise caused by the optical system meets the requirements. If not, repeat step 1; Step 3: Reduce the temperature of the radiation source to reduce the background noise; Step 4: After re-ray tracing, determine whether the background noise caused by the radiation source meets the requirements. If not, repeat step 3; Step 5: Modify the surface properties of the inner wall material of the cryogenic nitrogen cold chamber to reduce the background noise; Step 6: After re-ray tracing, determine whether the background noise caused by the cryogenic nitrogen cold chamber meets the requirements. If not, repeat step 5.

[0057] The optimization of the optical system model includes but is not limited to modifying the surface shape and curvature of the lens in the optical system so that the background stray light will not converge to the detector surface through the lens, thereby suppressing the infrared target background noise.

[0058] The lowering of the radiation source temperature includes, but is not limited to, adding a liquid nitrogen refrigeration mechanism to structures such as lenses and apertures, thereby reducing the self-radiation energy of background stray light from the source, thereby suppressing the background noise of the infrared target.

[0059] The modification of the surface properties of the inner wall material of the cryogenic nitrogen cold chamber requires the selection of high reflectivity or high emissivity materials based on actual simulation results, and the selection of the optimal material in combination with actual existing materials to reduce the self-radiation energy of the background stray light or weaken the background stray light reflected on the detector surface, thereby suppressing the background noise of the infrared target.

[0060] By using the method provided by the present invention to calculate background noise, the background noise in a low-temperature nitrogen environment can be quantified, which is beneficial to the targeted background noise suppression; by using the method provided by the present invention to suppress background noise, the infrared background noise in a low-temperature nitrogen environment can be effectively reduced, and the suppression method is implemented from multiple aspects to ensure that the noise is suppressed to the greatest extent; by using the method provided by the present invention to analyze and suppress background noise, the background noise analysis requirements of different research and development stages of complex systems can be met, so that background noise suppression can run through the entire process of complex target simulator system development.

[0061] Those skilled in the art may understand this embodiment as a more specific description of Embodiment 1.

[0062] Those skilled in the art know that, in addition to realizing the system and its various devices, modules, and units provided by the present invention in a purely computer-readable program code, it is entirely possible to realize the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered as a hardware component, and the devices, modules, and units included therein for realizing various functions can also be regarded as structures within the hardware component; the devices, modules, and units for realizing various functions can also be regarded as both software modules for realizing the method and structures within the hardware component.

[0063] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for analyzing background noise of infrared targets in a low-temperature nitrogen cold chamber, characterized in that: The method comprises the following steps: Step S1: construct the initial model of the collimating optical system and the converging optical system in the zemax software, and check the imaging quality; Step S2: Import the optical system model into the ray tracing software, and further construct a three-dimensional model of the cryogenic nitrogen cold chamber and related structures in the software to obtain the background noise of the infrared target system by tracing.

2. The method for analyzing infrared target background noise in a cryogenic nitrogen cold chamber according to claim 1 is characterized in that: The method further includes step S3: establishing a spontaneous radiation source model for all constituent elements, including the optical system, the cryogenic nitrogen cold chamber and the mechanical structure, in the ray tracing software to simulate the radiation characteristics of these elements in a cryogenic environment.

3. The method for analyzing infrared target background noise in a cryogenic nitrogen cold chamber according to claim 2, characterized in that: The process of establishing the spontaneous radiation source model includes: determining the surfaces of each component element that have an impact on the background noise, calculating the spontaneous radiation luminous area of ​​these surfaces, estimating their temperature, and calculating their respective radiation intensities using the Planck formula, and finally establishing a spontaneous radiation source of the corresponding band for each surface in the ray tracing software.

4. The method for analyzing infrared target background noise in a cryogenic nitrogen cold chamber according to any one of claims 1 to 3, characterized in that: It also includes combining the actual characteristics of various materials, setting the surface properties of all constituent elements in the ray tracing software, including absorption, reflection, refraction, transmission and diffraction, and simulating the interaction between light and these surfaces.

5. The method for analyzing infrared target background noise in a cryogenic nitrogen cold chamber according to any one of claims 1 to 4, characterized in that: It also includes establishing a detector as a surface receiver and calculating and obtaining the background noise data of the target simulator through full-link ray tracing.

6. A method for suppressing background noise of infrared targets in a low-temperature nitrogen cold chamber, characterized in that: The method comprises the following steps: Step 1: Optimize the optical system model to reduce background noise; Step 2: Verify the optimization effect through ray tracing. If it does not meet the requirements, repeat step 1. Step 3: Reduce the temperature of the radiation source to further reduce the background noise; Step 4: Verify the reduction effect through ray tracing. If it does not meet the requirements, repeat step 3.

7. The method for suppressing background noise of infrared targets in a cryogenic nitrogen cold chamber according to claim 6, characterized in that: It also includes step 5: modifying the surface properties of the inner wall material of the cryogenic nitrogen cold chamber to reduce background noise, specifically including selecting high reflectivity or high emissivity materials according to actual simulation results, and selecting the optimal material in combination with the existing material library to reduce the self-radiation energy of background stray light or weaken its intensity reflected to the detector surface.

8. The method for suppressing background noise of infrared targets in a cryogenic nitrogen cooling chamber according to claim 7, characterized in that: The step 6 is also included: after re-ray tracing, it is determined whether the background noise caused by the cryogenic nitrogen cold chamber meets the requirements, and if not, step 5 is repeated.

9. The method for suppressing background noise of infrared targets in a cryogenic nitrogen cold chamber according to claim 6, characterized in that: The process of optimizing the optical system model in step 1 includes modifying the surface shape and curvature parameters of key lenses in the ZEMAX software and changing the light transmission path of the background stray light.

10. The method for suppressing background noise of infrared targets in a cryogenic nitrogen cooling chamber according to claim 6, characterized in that: The process of reducing the temperature of the radiation source in step 3 includes adding a liquid nitrogen refrigeration mechanism to the lens and aperture structure to reduce the self-radiation energy of the background stray light from the source.

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