快照(计算机存储)
旋光法
计算机科学
光学
遥感
散射
物理
地质学
操作系统
作者
Shanalyn A. Kemme,Alvaro Augusto Cruz-Cabrera,Prabal Nandy,Robert R. Boye,Joel R. Wendt,T. R. Carter,S. Samora
摘要
We report on the design, fabrication, and simulation of a four-state pixelated subwavelength optical device that
enables mid-wave infrared (MWIR) or long-wave infrared (LWIR) snapshot polarimetric imaging. The
polarization information can help to classify imaged materials and identify objects of interest for remote sensing
and military applications. The fabricated pixelated polarizers have measured extinction ratios larger than 100:1
for pixel sizes greater than 9 microns by 9 microns, with transmitted signals greater than 50%. That exceeds, by
7 times, previously reported device extinction ratios for 15 micron by 15 micron pixels.
Traditionally, sequential polarimetric imaging sensors produce scenes with polarization information through a
series of assembled images. Snapshot polarimetric imaging collects the spatial distribution of all four Stokes'
parameters simultaneously. In this way any noise due to scene movement from one frame to the next is
eliminated.
In this paper, we will quantify near-field and diffractive effects of the finite pixel apertures upon detection. We
have designed and built an experimental setup that models a pixel within a focal plane array (FPA) to measure
crosstalk from adjacent gold wiregrid micropolarizers. This configuration simulates a snapshot polarization
imaging device where the two substrates are stacked; micropolarizer array substrate on top of an FPA. Modeling
and measured data indicate crosstalk between the adjacent pixels up to a few microns behind the polarizer plane.
Crosstalk between adjacent pixels increases uncertainty in the measured polarization states in a scene of interest.
Measured and simulated data confirm that the extinction ratio of a micropolarizer pixel in a super-cell will be
reduced by 17% when moving the FPA from 0.5 microns to 1.0 microns away from the polarizer. These
changes in extinction ratio are significant since typical glue separation is on the order of 10 microns.
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