无基底焦平面阵列的红外成像性能分析

利用提出的光学读出非制冷红外成像系统，先后制作了单元尺寸各不相同的单层膜无基底焦平面阵列(focal plane array，FPA)，获得了室温物体的热图像.分析发现，当FPA的单元尺寸从200μm逐渐减小到60μm时，基于恒温基底模型的理论响应与实验结果的偏差逐渐增大.通过有限元分析方法，模拟分析了不同尺寸的微梁单元在无基底FPA中的热学行为，发现了当单元尺寸逐渐减小时恒温基底模型偏差逐渐增大的原因，即无基底FPA的支撑框架不满足恒温基底条件，受热辐射后支撑框架的温升从基底上抬高了单元的温升.论文还分 关键词： 光学读出 非制冷红外成像 焦平面阵列 无基底

Performance analysis of the substrate-free focal plane array in infrared imaging

Based on the proposed optical readout uncooled infrared (IR) imaging system，several batches of the substrate-free focal plane array (FPA) with different pitches have been successively fabricated，and by using these fabricated FPAs，the thermal images were obtained at room temperature. However，the theoretical analysis indicates that the deviation between the theoretical model assuming constant temperature of the supporting frames of the FPAs and the experimental results gradually increases with the decreasing pitch size of from 200μm to 60μm. Based on the finite element method，the thermal characteristic of those FPAs was simulated and the reason for the deviation is found to be that the temperature-constant assumption is not quite appropriate for the substrate-free FPA，and the absorption of the thermal radiation will obviously result in the temperature rise of the supporting frame，which would increase the temperature of the adjacent pixels. The imaging performance of the substrate-free FPA is also analyzed. Compared with the substrate FPA with the same pitch, the thermal detection sensitivity of the substrate-free FPA with 60μm pitch increases by about one order of magnitude.