A custom IR spot scanning experiment was constructed to project subpixel spots on a mercury cadmium telluride focal plane array (FPA). The hardware consists of an FPA in a liquid nitrogen cooled Dewar, high precision motorized stages, a custom aspheric lens, and a 1.55 and 3.39 μm laser source. By controlling the position and intensity of the spot, characterizations of cross talk, saturation, blooming, and (indirectly) the minority carrier lifetime were performed. In addition, a Monte-Carlo-based charge diffusion model was developed to validate experimental data and make predictions. Results show very good agreement between the model and experimental data. Parameters such as wavelength, reverse bias, and operating temperature were found to have little effect on pixel crosstalk in the absorber layer of the detector. Saturation characterizations show that these FPAs, which do not have antiblooming circuitry, exhibit an increase in cross talk due to blooming at ∼39% beyond the flux required for analog saturation.
Thin-shelled composite mirrors have been recently proposed as both deformable mirrors for aberration correction and as variable radius-of-curvature mirrors for adaptive optical zoom. The requirements on actuation far surpass those for other MEMS or micro-machined deformable mirrors. We will discuss recent progress on developing the actuation for these mirrors, as well as potential applications.
Iris recognition utilizes distinct patterns found in the human iris to perform identification. Image acquisition is a critical first step towards successful operation of iris recognition systems. However, the quality of iris images required by standard iris recognition algorithms puts hard constraints on the imaging optical systems which have resulted in demonstrated systems to date requiring a relatively short subject stand-off distance. In this paper, we study long-range iris recognition at distances as large as 200 meters, and determine conditions the imaging system must satisfy for identification at longer stand-off distances.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.