40 K双波段长波探测器冷箱封装技术研究

Research on packaging technology for 40 K dual-band long-wave detectors

冷光学技术是弱目标及多光谱红外探测的重要支撑技术。为了实现低温光学系统温度精确控制和防污染,一般多将低温光学与探测器集成在冷箱内。某高光谱相机需要1个320×64量子阱探测器和1个320×64 II类超晶格探测器共面拼接,集成双波段微型滤光片,形成长波双波段探测杜瓦组件,探测器工作所需的40 K低温环境由脉管制冷机提供。杜瓦采用无窗口设计,并通过柔性波纹管将杜瓦外壳与冷箱外壳集成,以实现气密性集成和光校调节。针对40 K温区双波段探测器封装的三维拼接、探测器及滤光片的低应力封装、制冷机与探测器的高效热传输等难点,对探测器的三维拼接、40 K温区高效热传输、探测器低应力集成的热层结构、低应力滤光片支撑、杜瓦与制冷机耦合等进行研究,创新性提出了三点Z向调节拼接方法、探测器Al2O3载体复合钼基板和钼冷平台的热层结构、双波段滤光片集成的钼支撑结构、带应力隔离的冷平台与制冷机过盈装配的耦合方法,最终实现了40 K温区下双波段探测器平面度优于±2.06μm(RMS)、探测器的低温应力小于22.06 MPa、双波段滤光片低温形变小于8.55μm、探测器与制冷机温度梯度为2.6 K。40 K长波双波段红外探测器冷箱杜瓦组件经过2000 h通电老练和300次开关机试验验证,试验前后组件性能未发生明显变化,满足工程化应用的要求。

Objective Cryogenic optical technology is a crucial support technology for weak target and multispectral infrared detection.In order to achieve precise temperature control and prevent contamination in the cryogenic optical system,it is common to integrate the cryogenic optics with the detectors inside a cryocooler.Methods A specific hyperspectral camera requires the integration of a 320×64 quantum well detector and a 320×64 type II superlattice,co-planarly assembled with dual-band micro-filters to create a long-wave dual-band detection dewar assembly.The required operating temperature for the detector is 40 K,and it is achieved using a pulse tube cryocooler.The dewar adopts a windowless design and is integrated with the cryogenic optical system cryocooler using flexible bellows for hermetic sealing and precise alignment adjustments.Results and Discussions Addressing the challenges of three-dimensional assembly of the dual-band detector at 40 K,low-stress assembly of the detector and filters,and efficient heat transfer between the cryocooler and detector,this study investigates the three-dimensional assembly of the detector(Fig.4-6),a heat layer structure for efficient heat transfer at 40 K with low-stress integration with the detector(Fig.7),low-stress filter support(Fig.15),and the coupling between the dewar and the cryocooler(Fig.12).Innovative approaches such as a threepoint Z-axis adjustment assembly method,an Al2O3 carrier composite molybdenum substrate for the detector,a molybdenum support structure for the integrated dual-band filters,and a coupling method with stress isolation for the cryocooler and detector are proposed.Conclusions Ultimately,this research achieves a detector flatness better than±2.06μm(RMS)at 40 K(Fig.6),low-temperature stress of the detector less than 22.06 MPa(Fig.8),low-temperature deformation of the dual-band filter membrane less than 8.55μm,and a temperature gradient of 2.6 K(Fig.14)between the detector and the cryocooler.The dewar assembly with a 40 K long-wave dual-band infrared detector has been verified through 2000 hours of continuous operation and 300-on/off cycles,with no significant change in component performance before and after testing,meeting the requirements for engineering applications(Fig.16).