Design of Diffractive Microlens Arrays Integration with Focal Plane Arrays

摘要

The IR spectrum from 3 to 5mum has numerous applications in both military and civil industries. High performance at high operating temperature is often importatn in these applications. Conventional Focal Plane Arrays(FPAs) without integration with concentrator such as microlens have poor sensitivity and low signal-to-noise ratio because of their lower fill factor. The binary optics microlens arrays reported in this paper are designed for integration with FPAs. Thus, the FPAs' fill factor, sensitivity, and signal-to-noise ratio can be improved while retaining a given image resolution and optical collection area~1. In the paper, we discussed the 256(Horizontal)x290(Vertical) microlens arrays designed for a center wavelength of 4mum, with 50mum(Horizontal)x33mum(vertical) quadrate pixel dimension and a speed (F number) of F/1.96. PtSi FPAs were fabricated on the front side of a 400-mum-thick Si substrate. The designed diffractive microlens arrays will be etched on the back side of the same wafer in a register fashion and it will be reported in other paper. considering the diffraction efficiency, 8-phase-level approximation is enough. For the diffraction efficiency of 8-phase-level diffractive microlens reaches 95