Spatial Noise In Staring IR Focal Plane Arrays

Abstract

Problems with nonuniformity correction algorithms due to nonlinear pixel response and 1/f noise have been shown previously to cause spatial noise which can be significantly greater than temporal noise. The residual spatial noise after correction cannot be reduced with time averaging. Because of spatial noise the sensitivity of staring FPA sensors is often less than predicted on the basis of the temporal noise of the individual elements.A review is given of methods for measuring and analyzing spatial noise (after nonuniformity correction) in staring infrared focal plane arrays. Automated measurement techniques are described briefly, including necessary equipment and data reduction procedures. An example of spatial noise measurements is given using a staring InSb Charge Injection Device(CID) array.

Performance of BF focal plane array 320x256 InSb detectors

“…This large dynamic range in the BF FPP is equivalent to a temperature background range of 5-100°C, which compares to typical values of the order of 15-45°C in other detectors 1,3,4,6 . These results were achieved by the use of only one set of two-point corrections, which enables the user to save on look-up tables in the image processing electronics.…”

Nonuniformity correction algorithm based on adaptive filter for infrared focal plane arrays

“…In fact, the response characteristic of the infrared detector changes with operating time inherently, that is to say, the gain and the offset of the detector drift slowly with operating time temporally [1][2][3]. The origin of that include three aspects mainly: (1) fluctuation in working temperature of IRFPA, (2) instability in the drive electrocircuit of IRFPA, and (3) the inherent drift caused by the detector itself, such as performance instability of the detector and its readout circuit.…”

“…The nonuniformity is due to the pixel-to-pixel gain and offset variations in IRFPA. The nonuniformity results in a fixed-pattern-noise superimposed on the true infrared image, which can considerably degrade the quality of the infrared image [1][2][3]. The nonuniformity drifts temporally, as a result of variations in the IRFPA working conditions, make this problem even more complicated.…”

“…The nonuniformity drifts temporally, as a result of variations in the IRFPA working conditions, make this problem even more complicated. Such drifts require a real-time correction for IRFPA's response when the IRFPA imaging system is operating [1][2][3][4]. Under this scope, nonuniformity correction (NUC) is a necessary and unavoidable task to reduce the undesirable fixed-pattern-noise in order to achieve higher-quality infrared images.…”

Improvement in adaptive nonuniformity correction method with nonlinear model for infrared focal plane arrays

“…Even more, what makes the matter worse is that the spatial nonuniformity drifts slowly over time, which results in the failure of traditional reference-based NUC methods. In order to solve this problem, many scene-based NUC techniques have been developed recently [1][2][3].…”