A windowless low-temperature surface profile measurement method for tiled detectors

As the core sensor component of infrared remote sensing systems, the cryogenic coplanarity of tiled detectors focal plane is important for system imaging quality, making its precise measurement highly significant. However, current testing methods are constrained by interference from test windows, rendering accurate cryogenic coplanarity measurements challenging. This study proposes an innovative low-temperature surface profile testing method for tiled detector assemblies. The method analyzes influencing factors in surface profile measurement, revealing that transmission wavefront distortion caused by window manufacturing errors and atmospheric pressure when the structure is a vacuum chamber, structural deformation induced by both window assembly and atmospheric pressure collectively alter the focal plane profile, thereby introducing errors in surface measurement results. Through simulation, this research quantified the surface variation of tiled detectors caused by window assembly (0.24μm) and atmospheric pressure (0.57μm). These factors are subsequently eliminated from actual test data to accurately obtain windowless cryogenic coplanarity. Results demonstrate that uncorrected low-temperature coplanarity is 10.16μm, while window-effect-removed measurements is 12.39μm, showing a significant 2.74μm discrepancy. This substantial difference underscores the necessity of eliminating window effects during cryogenic coplanarity testing of focal planes.