Abstract:Type-II superlattice infrared detectors usually use mesa junctions to detect infrared radiation, in which the preparation process of metal electrodes is crucial. The control of physical etching and chemical etching on the morphology of superlattice detector electrode holes and the influence on the etching rate in the inductively coupled plasma (ICP) etching system are studied in depth. By adjusting parameters such as ICP ion source power, radio frequency power, and etching gas flow, the balance between physical etching and chemical etching in the etching system is broken, and the process control of the inclination angle of the electrode hole sidewall from 70° to 90° is achieved. This method can obtain smooth electrode hole sidewalls and suitable inclination angles, providing optimal deposition conditions for the growth of metal electrodes.

Abstract:Dewar window is one of the core components of infrared detectors. Its welding quality has a decisive influence on the vacuum maintenance time and long-term operation stability of the detector. In this experiment, two preformed solder rings are introduced for vacuum brazing to replace the traditional manual SAC305 solder paste soft soldering process, and the appearance quality, airtightness, void rate and welding strength of the dewar window are studied. The experimental results show that when the SnAgCu composite solder ring with an intermediate layer of Ni skeleton structure is used for vacuum brazing, the leakage rate of the dewar window can reach a high airtightness requirement of less than 1×10^-12 Pa·m³/s, and the void rate can be reduced to 1%. The tensile strength of the dewar window is tested. The results show that when the process parameters are 250 ℃, 5 min, and 0.32 MPa, the tensile strength reaches a maximum value of 66.73 MPa; compared with the traditional manual SAC305 solder paste soft soldering joint, it increases by 10.19%. At the same time, this method can improve the consistency of the process and greatly improve the production efficiency, which has a certain guiding significance for the mass production process of the dewar windows.

Abstract:Dual-band infrared focal plane detectors are one of the future development trends and are being used in more and more scenarios. Aiming at the design of the driving circuit for the mid- and long-wave dual-band infrared focal plane detector, the design method proposed includes a dual-mode driving circuit, an independent dynamic range adjustment circuit, a low analog signal conditioning circuit, a dual-substrate switching circuit, a power driving circuit and distributed integration. The driving circuit can effectively transform the analog signal output by the sensitive element of the infrared focal plane detector, and provide the required bias voltage and driving timing to the infrared focal plane detector. The driving circuit of the mid- and long-wave dual-band infrared focal plane detector designed in this paper has a good imaging effect after the mid-wave and long-wave images are fused.

Abstract:Infrared system calibration is an important task in measuring the infrared characteristics of targets, and its accuracy will directly affect the accuracy of the final measurement results. In order to reduce the influence of temperature drift on calibration accuracy, a field calibration method for refrigerated infrared systems considering ambient temperature changes is proposed, and the relation formula between pixel gray response and target radiance considering ambient temperature is derived. The feasibility and accuracy of this method are verified through field calibration experiments on a domestic cooled infrared system. The results show that compared with the traditional calibration method, the proposed method reduces the mean error of the inversion of the temperature points involved in the fitting by 0.57%, and the root mean square error by 0.03. For extended temperature points, the mean error of the inversion is reduced by 1.63%, and the root mean square error is reduced by 0.93. This method offers higher calibration accuracy across the entire frame and significantly improves the accuracy of target characteristic inversion, providing a useful reference for the practical engineering application of infrared system calibration.

Abstract:The infrared seeker is the core component of the weapon guidance system to identify and track the target, and determines whether the missile can successfully and accurately hit the target. The combat conditions of modern warfare are complex and changeable, with interference factors such as clouds, smoke, point source decoys, laser suppression, camouflage, and multi-wave strikes. It is a very challenging task for the infrared seeker to identify the target characteristics and maintain continuous tracking under various interference conditions. Various interference factors in the battlefield environment are summarized and sorted out, and the interference mechanisms and their impacts on the performance of the infrared seeker are analyzed. Several anti-interference technologies currently used are introduced, and then their design principles and workflows are analyzed, and the anti-interference effect of the infrared seeker in various application scenarios is demonstrated. This study has a certain reference significance for the formulation of anti-interference strategies for infrared seekers.

Abstract:The dual-comb ranging system has shown great potential in the field of long-distance and high-precision measurement due to its fast measurement speed and high ranging accuracy. Usually, the complex hardware is required to lock the dual-comb system to ensure the stability of the system. This has a negative impact on the practical application of the dual-comb system. Therefore, the free-running dual-comb system is used as the light source, and the software correction algorithms (mainly the cross-ambiguity function) are used to extract the distance of the target, which greatly simplifies the complexity of the experimental system. The experimental results show that when the target distance is about 1 m, the laser repetition frequency is about 100 MHz, and the repetition frequency difference between the combs is about 774 Hz, the single-shot ranging accuracy of the free-running dual-comb system is about 3.56 μm, and the measurement results have good linearity. This study has accumulated a certain foundation for the practical field application of the dual-comb system.

Abstract:A butterfly-shaped terahertz waveguide sensor based on the plasmon effect is proposed. The resonance characteristics of the terahertz waveguide at a specific frequency are used to detect changes in solution concentration. By analyzing the S₁₁ reflection parameters of the terahertz waveguide sensor, it is observed that at a frequency of 53.28 GHz, a resonance dip with a Q-value of 82.28 appears in the waveguide structure. When different concentrations of analytes are set in the butterfly-shaped region of the waveguide, dual resonance dips are generated and frequency shifts occur; the resonance frequency exhibits a blue shift with the increase of solution concentration, indicating that the dielectric constant of the solution affects the electromagnetic field distribution in the waveguide. The simulation results verify the frequency shift law of the S₁₁ reflection parameters of lactose solutions at different concentrations, and the sensitivity can reach 0.075 GHz/(g/L). Compared with traditional sensor detection methods, this sensor can provide higher sensitivity, accurately reflecting small changes in the concentration of trace solutions.