Proposed standard for infrared focal plane array nonuniformity measurements

Abstract

The staring infrared focal-plane array (IRFPA), once a novelty, has now evolved into an important technology being used in a variety of imaging systems. These systems frequently include schemes for nonuniformity correction (NUC) that reduce artifacts caused by lack ofdetector uniformity within the IREPA. The effect of these artifacts is a fixed-pattern that interferes with the desired image of the scene. Although the resulting imagery can be substantially improved using NUC, significant residual fixed-pattern noise (RFPN) typically remains. As IRFPAs become more standard in designs for missile seekers, measurement methods related to RFPN should be standardized. This paper introduces an improved method with which the IRFPA fixed pattern noise can be measured both before and after NUC algorithms have been applied. The proposed standard provides two key benefits: 1) consistent quanhification of the specific characteristics of the inherent spatial noise or residual post-NUC RFPN that significantly impact system performance; and 2) a standardized process that facilitates IRFPA and NUC comparisons and measures progress toward design improvement. The approach considers the 3-D noise modeling technique proposed for FUR systems and modifies the technique to account for the spalial scale and power spectrum of the RFPN. The resulting characterization is called the Simplified Power Spectrum (SPS). Residual low-frequency nonuniformities such as gradients across the entire array may not be as important as high-frequency, uncorrelated variations; the SPS allows differentiation ofthese RFPN effects. The algorithms and test procedures required for the standard are presented in the paper.

A non-uniformity correction method of infrared hyperspectral image based on spectral channel

“…According to the linear or nonlinear characteristics of pixel response, the commonly used non-uniformity correction methods mainly include one-point correction method, two-point correction method, multi-point piecewise correction method and so on [4][5][6][7] ,and the definitions of these methods are not described in detail here.…”

“…When the energy distribution of blackbody on each spectral channel is uniform, the coefficient obtained by formula (5) can be used to correct the non-uniformity between channels, and the spectral curve of the target will not be destroyed. However, the energy distribution of blackbody on each spectral channelis actually uneven, which is equivalent to add a variable i V ∆ to V , and the i V ∆ of each channel is different.Therefore, formula ( 5) is rewritten as:…”