Gas detection is an important application area in industry. The detection of CO2 plays a crucial role in environmental protection. However, the primary challenges in achieving atmospheric CO2 and other detection of other gases revolve around developing instrumentation featuring a broad detection range, heightened sensitivity, and dynamic real-time capabilities. To address these challenges, a four-channel multi-spectral imaging device utilizing a superpixel filter array (SFA) for simultaneous detection of multiple gases in the mid-infrared (MIR) is introduced in this work. The device demonstrates selective transmittance at wavelengths of 3.92, 4.08, 4.29, and 4.40 mu m, achieving a spectral resolution (delta lambda/lambda) of 1%. The SFA's narrowband filtering capability facilitates real-time imaging detection of multiple gases by its high spectral selectivity of each super-pixel unit. Multi-channel spectral detection capability means that our detectors can detect multiple target gases simultaneously according to the specific spectral channel of each unit. Finally, the great potential of this technique for CO2 detection was verified by a demonstration experiment. (c) 2024 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

Objective Infrared detection technology is widely used in the aerospace industry owing to its strong anti-interference capabilities and wide detection ranges. This enables comprehensive and large-scale continuous monitoring of land and oceans. Notable examples include the successful launch of the Ocean No.1(HY-1A) and Fengyun sequence satellites, both of which are equipped with an infrared payload. However, infrared detection is challenging because of weak target signals and the need for increased detector sensitivity. To address this issue, infrared focal plane detectors such as mercury cadmium telluride (MCT) operate at lower temperatures, necessitating sufficient cooling capacity provided by refrigerators. Currently, most MCT detectors used in space applications employ mechanical refrigeration. These detectors are typically packaged in a metal Dewar to meet low-temperature working requirements and are coupled with the refrigerator through the Dewar cold finger. Hence, the Dewar design directly affects the refrigeration efficiency. Additionally, strict stray light analysis and suppression are essential for satisfying the high-performance requirements of infrared remote-sensing loads. This is crucial for ensuring the accurate quantitative inversion and image quality of infrared remote sensing data. A notable example is the temporary shutdown of the EU Meteosat-5/7 series imager owing to stray light interference. Infrared remote sensing detection systems, particularly those operating at long wavelengths, rely heavily on the suppression of internal stray light radiation to enhance image quality. To reduce the infrared component background radiation, the infrared component barrel, lens, and Dewar window are often low-temperature optically processed, ensuring the infrared optical component cooling capacity in a limited space becomes the key to component design. Methods To suppress stray light in the system, the veiling glare index (VGI) is calculated based on the functional relationship between the point source transmittance (PST) and the VGI (Fig.2). In addition, the VGI and noise signal ratio (NSR) are used as indicators to investigate methods for suppressing external stray light and background radiation. This study aims to optimize the design of a Dewar cold screen and window. Initially, the effectiveness of the cold optical design for reducing the background radiation of the system is compared (Figs.3 and 4). Refrigeration is essential for the cold optical design and proper functioning of the Dewar detector.The impact of the Dewar cold screen and window design parameters on the Dewar heat loss is examined (Tables 1 and 3). By fitting the experimental data, the relationship between the Dewar heat leakage and chiller power consumption is defined (Fig.6).Subsequently, a cold-screen design with low cooling power consumption is proposed (Fig.8), and the values of the system VGI and Dewar NSR are calculated through simulations. Results and Discussions The results indicate that the cold optical design effectively reduces stray light from background radiation in the system. The NSR of the three bands operating in the system decreases significantly from above 4.5 to below 0.35(Fig.4).Theoretical calculations demonstrate that as the distance between the cold screen and window decreases, there is an increase in the Dewar heat leakage and power consumption of the refrigerator (Table 1). Furthermore, the relationship between the Dewar heat leakage and power consumption follows an E-exponential function (Fig.6). By utilizing the new cold-screen design (Fig.8), it is possible to reduce the power consumption of the refrigerator while simultaneously improving the external and Dewar background radiation stray lights (Figs.9 and 10). Conclusions With the improvements in the detection accuracy of space remote sensing loads, stray light suppression design has become a key technology in space remote sensing. The infrared optical load benefits from the low-temperature optical design, which effectively suppresses the background radiation of the infrared system. The refrigeration of the refrigerator is crucial for the normal operation of the detector and the low temperature optical design. Therefore, it plays a key role in ensuring an efficient stray-light-suppression design within the limited refrigeration resources of refrigerators. This study utilizes the functional relationship between the PST and VGI to calculate the VGI. It investigates the impact of the Dewar cold screen and window design on the external stray light, system background radiation, and power consumption of the refrigerator using the VGI and NSR as indicators. This study establishes a preliminary system for a Dewar cold screen and window design, encompassing stray light suppression and Dewar heat leakage designs. A cold screen design that achieves both low cooling power consumption and high stray light suppression is proposed.Under these design conditions, the Dewar heat leakage is 1.7 W, the chiller power consumption is 103.72 W, VGI is reduced from 1.95% to 1.92%, and the energy proportion of the window radiation stray light is reduced by 60%, meeting the project design requirements. This study addresses issues related to low-temperature optical design, refrigerator power consumption, and stray light suppression, providing valuable insights for the design and engineering applications of infrared Dewar refrigeration components.

The main factor affecting the vacuum life of the infrared detector Dewar is the internal material outgassing. The Langmuir adsorption model outgassing equation is used to calculate the vacuum lifetime due to the outgassing mechanism and the long-term degassing procedure of the Dewar. An innovative method of changing the temperature at the end of the degassing procedure was proposed to obtain the outgassing activation energy. The outgassing rate was measured at different temperatures while simultaneously removing the influence of coverage on the outgassing rate. The out gassing rates at storage temperature and the rule of outgassing rate changing over time were deduced. The difference among the three Dewar outgassing activation energies obtained in different conditions was 8. 8%. The heat load of the Dewar was tracked for two years to verify the method. The estimated error of Dewar's vacuum lifetime was 7. 2%. It is a non-destructive testing estimation method for the vacuum life of small and diverse Dewar.

Objective Most current advanced optical systems employ low-temperature optical technology to cool the optical lens to a lower temperature level to reduce optomechanical radiation and enhance the detection sensitivity and dynamic range of remote sensing instruments, which helps to enhance the detection performance of optical remote sensing instruments. This research focuses on the packaging technologies that are required for the engineering application of multiband long-wave infrared detectors for cryogenic optics, including multimodule splicing and multiband integrated filter low-temperature registration, support and heat insulation of low-temperature optical windows of modules, and coupling stress between detectors and refrigerators. Through systematic investigation, the multiband long-wave infrared detector' s Dewar for low-temperature optics has been successfully developed, and it has been confirmed by a series of space environment adaptability tests. Methods 1. Low-temperature module splicing registration and four three-band integrated filters. The filter was designed based on the imaging optical path. The closer the filter was to the chip, the smaller the non-uniformity, stray radiation energy, and the detector image surface' s stray ratio. To enhance the detector image plane's uniformity, the filter in the Dewar package should be as close to the chip as possible (Fig. 5). Detectors and filters were packaged as follows: 1) four three-band detectors were spliced and cemented on the ceramic substrate, and the flatness of the cemented surface of the ceramic substrate detector' s gemstone was controlled to be less than 5 mu m; 2) the four integrated filters were preliminarily bonded to the filter holder, and the splicing accuracy was controlled in the range from - 3 mu m to + 3 mu m; 3) the filter holder was aligned with the detector's center, ensuring the alignment accuracy was in the range from 5 tan to + 5 tan. 2. The design of the flexible bellows shell' s thermal insulation structure. We proposed a Dewar flexible bellows shell structure for the infrared detector assembly employed in the low-temperature optical system. By increasing the heat transfer path, reducing heat leakage, and increasing thermal insulation, the heat transfer area of the transfer link can be reduced. 3. The design of a cold platform for physical isolation of coupled stress. In this research, based on the detector's coupling characteristics and the refrigerator's cold finger, an arc-shaped isolation groove of a specific shape was designed and processed on the cold platform. The groove width is H, (Fig. 8). On the heat transfer capacity's premise needed by a certain heat load, the heat conduction link's physical isolation and the coupling stress transfer channel were achieved. Results and Discussions Through the positioning and integration design of four three-band integrated filters, the alignment error between three -band integrated filter and detector back cover is less than 10 mu m. By implementing the Dewar flexible bellows shell structure, the thermal isolation between the infrared detector Dewar refrigeration assembly's low-temperature shell and the refrigerator expander or pulse tube is achieved, as well as the infrared detector Dewar assembly flexible corrugated shell's 101 mW thermal insulation (Table 1). During the thermal vacuum test, at the operating temperature of 55 K, the temperatures of the compressor's cooling surface and the pulse tube's cooling surface increased immediately, and there was no visible response to the Dewar temperature ( Fig. 7). We measured the cold platform' s surface deformation after slotting and compared it with the cold platform' s surface deformation without slotting (Fig. 9). During the implementation of the Dewar' s full coupling and the refrigerator, the unslotted cold platform' s surface deformation increases sharply and stabilizes at around 40 m/m, while the cold platform' s surface deformation after grooving does not change, and stabilizes at about 8 m/m, and the deformation decreases by about 80 %. From this, it can be deduced that the cold platform's surface stress is reduced by 80 % after grooving. Conclusions The challenges of packaging multiband long-wave infrared detectors are examined to meet the requirements of spliced multiband long-wave IRFPA in cryogenic optics. It is proposed that the three-band integrated filter and the detector's back cover can be aligned with a misalignment of fewer than 10 mu m, and the Dewar flexible corrugated housing 101 mW heat insulation is realized. Simultaneously, measures including a multilayer thermal layer structure that physically isolates the coupled stress are designed on the Dewar cold platform. It addresses essential technologies like low light string, low background radiation, low power consumption, high-temperature uniformity of cold platform, and high reliability of multiband long-wave infrared detector components. A 12. 5 mu m three -band 2000 x 12 element detector component for cryogenic optics was successfully developed and a series of space environment adaptation tests were implemented, and the test results indicate that the Dewar assembly meets the criteria of engineering application.

目的 探索高效的冷屏黑化技术,获得石墨烯环氧胶混合喷涂与化学镀镍黑化后的红外探测器冷屏的光学特性、真空放气特性.方法 采用傅里叶光谱仪对比测试不同粗糙度的基底,以及基底经过化学镀镍、石墨烯喷涂黑化后的样品在2.5～15μm波段内的镜面反射率,利用扫描电子显微镜观察分析黑化表面形貌.采用小孔流导法测试对比不同粗糙度基底250℃除气前后的放气规律,以及除气后基底、化学镀镍、石墨烯喷涂黑化样品的出气率.结果 化学镀镍黑化反射率受基底粗糙度的影响大,若在喷砂面黑化,镜面反射率低于2％.石墨烯喷涂的黑化涂层厚,吸收率不受基底表面粗糙度影响,镜面反射率低于0.4％,但镀层的表面结合力受到基底粗糙度的影响.对放气特性进行分析发现,高温除气可以去除化学吸附气体分子,再次暴露大气吸附的气体多为物理吸附.黑化层对出气率的影响远大于基底粗糙度,石墨烯黑化层的微孔洞结构使初始出气率大于镀黑镍约1个数量级.结论 石墨烯与环氧胶混合喷涂黑化的消杂散光能力显著优于化学镀镍黑化,但总放气量高,采用适当的低出气率处理,改进其真空性能是在红外组件应用中的关键.

为了满足低温光学系统低背景、低功耗和红外探测器制冷组件高环境适应性的要求,提出了探测器制冷组件杜瓦主体(窗口、窗口帽和引线盘)200 K低温保持,与制冷机膨胀机或脉管散热面柔性绝热连接的设计思想.针对低温光学用杜瓦柔性外壳工程应用中的特点,文中以某低温光学用长波12.5μm2 000元红外探测器杜瓦组件以例,提出了波纹管作为绝热连接的柔性外壳,重点阐述杜瓦柔性波纹管隔热、力学和相关漏热的设计,并开展不同热负载条件下波纹管热特性验证,可实现最小温度梯度为37.22 K,绝热热阻为1142K/W,误差在37％.为综合评价低温光学用柔性外壳结构杜瓦组件的性能,对某低温光学用长波12.5 μm 2 000元探测器柔性外壳杜瓦组件开展热真空和鉴定级的力学试验考核验证,试验结果表明实现了 200K低温窗口,探测器60K工作,杜瓦漏热为544 mW,低温工况工作时相对于常温工况制冷机的功耗下降了 53％,并通过了 4g的随机力学考核,验证了低温光学用杜瓦柔性波纹管外壳模型合理可行,对于后续低温光学用杜瓦柔性外壳结构工程应用提供了重要参考.

为了解决空间红外相机的高分辨率、高成品率及可维修性等问题,提出了先将6个线列探测器子模块拼接在一个“Z”字型的子基板上,再将多个(N≥5)这样的“Z”字型子基板通过精密拼接的方法以形成空间超长线列红外焦平面探测器.基于由多个子基板拼接形成的超长冷平台与单点冷源耦合以实现热交换的特点,针对超长冷平台温度均匀性小于1K及其与单点冷源间温度梯度小于5K的要求,建立了冷量传输通道的热网络模型,分析了影响冷量传输效率的主要因素,提出了优化各部件及不同部件螺接的接触热阻的方法,设计了两个“树状”柔性冷链实现了冷量向多基板冷平台高效传输.通过对加载不同总焦耳热时超长冷平台的温度均匀性及其与单点冷源间的温度梯度等热特性进行仿真和实验验证,结果表明超长冷平台温度均匀性误差小于0.05 K,温度梯度误差小于0.55 K,验证了由多个子基板拼接而成的超长冷平台与单点冷源间冷量传输模型合理可行,对于后续多基板精密拼接的工程应用提供重要参考.

针对超长线列红外探测器杜瓦具有容积大、零部件种类多、材料放气源多,特别是集成式超长线列杜瓦与内充3 MPa高压氦气的直线脉管冷指封装集成等特点,基于材料解析放气及渗透理论,建立了超长线列杜瓦组件真空寿命评估模型,对分置式与集成式超长线列杜瓦的真空寿命进行了计算,其真空寿命预计值均可以达到2年.设计了一种杜瓦真空度在线监测结构对这两类杜瓦的真空度进行了实时监测,分置式及集成式杜瓦真空寿命预计值与实测值相对误差分别为5.8％和6.96％.因集成式杜瓦真空寿命估算较为困难,对其热负载通过制冷性能进行实验验证,其热负载2年后未发生明显变化.

The 256×2 HgCdTe focal plane array consists of two 256×1 sub-modules and two photovoltaic silicon readout integrated circuits in parallel and symmetrical configuration.Two different narrowband filters are separately assembled by filter pier.The long wave 256×2 long linear HgCdTe focal plane array is assembled in a metal Dewar.The key technologies of 12.5 μm long linear HgCdTe focal plane array Dewar are solved,which include high accuracy assembly,thermal mismatch design for long linear HgCdTe focal plane array and high reliability package.A series of technologies are used for the suppression of the stray light,the reduction of background radiation and reliability enhancement,which made HgCdTe focal plane array detector performs much better.Some space environmental tests are carried out.Results show that the main performances do not change.The IRFPA detector satisfies the requirements of space application.

Compared with a cooled infrared detector,an uncooled infrared detector has the advangtages of small size,low weight and low power consumption because it has not any cooler.To improve the encapsulation process of an uncooled infrared detector after exhaustion and achieve its configuration optimization and reliability enhancement,a technical scheme to use laser welding to encapsulate the uncooled infrared detector in high vacuum is proposed.The test result shows that the uncooled infrared detector assembly has not apparent variation in performance and can meet the requirements for actual application.

Highly hermetical laser sealing is a packaging technology which can be used for metal packages.It can achieve the sealing of a small hole of the metal package containing an infrared detector in a high vacuum environment.Thus,both the exhaust process and the sealing process of the infrared detector assembly can be finished at the same time.According to the structure and material of a micro package,the relation of the current and pulse width of a laser welding equipment to welding energy and the influence of the current,pulse width and defocusing distance on welding quality are analyzed.Proper laser welding parameters are obtained for Kovar materials.With those parameters,the laser sealing of a hole of the metal package containing an infrared detector is achieved.The test result shows that its leak rate is better than 1×10~(_10)Torr·1/s.

The infrared focus plane micro-dewar must have vacuum high air-sealed properties in order to be able to stand up to the demanding of vacuum longevity.In the manufacture course of infrared focus micro-dewar,laser welding is among crucial processes for the sake of obtaining low integral leakage.This paper reports on laser welding process characteristics of the infrared focus micro-dewar.

With the development of ceramics fabrications, some transparent oxide ceramics have been synthesized for laser gain hosts. So the new application of transparent polycrystalline ceramics would be exploited as laser ceramics. The fabrications and developments of transparent laser ceramics were reviewed in this paper.

According to package characteristics of long linear HgCdTe IRFPA detector,difficulties of the metal split micro dewar manufacture are discussed in the paper.During the course of the manufacture for packaging 2000 pixel HgCdTe IRFPA wafer,some crucial techniques are solved,such as the design of the button stem structures with inclined dragging wires applied in cryogenic platform,the optimization of long linear IRFPA detector's signal wires layouts,the implement of a fanout board having thin film gold metalization for defining the required electrical conductors and a method of hermetically sealed vacuum enclosure of large dimension windows,etc.The research and development of packaging technics are important to advance application of long linear IRFPA detector.