Performance Analysis and Optimization of Optical-Readout of Microcantilever Array Infrared Imaging
光学读出微梁阵列红外成像性能分析与优化

Sensor responsivity is a key performance parameter of IR (Infrared) imaging using bimaterial microcantilever focal plane array (FPA) and optical readout method. For the optical readout method using knife-edge filtering technique, the optical sensitivity, an important part of the sensor responsivity, is closely related to the length of the mirror, and is seriously affected by the undesired deformation of the mirror. The deformation always exists due to the imbalanced residual stress induced by fabrication process. The deformation curvature radius is determined by the thicknesses of the films. In this paper, the influence of the length and deformation of the mirror on the optical sensitivity is discussed, and then a theoretical sensitivity model is established and validated. According to the model, the relation between the sensor responsivity and the length of the mirror is analyzed. The analysis is validated by experiment. It is demonstrated that, reducing the thickness of SiNx film and making the length of the mirror be the optimum length not only can increase the sensor responsivity, but also can improve the spatial resolution.