US 6,184,529 B2 · Methods and apparatus for performing scene based uniformity correction in imaging systems

Abstract

Methods and apparatus for generating uniform reference sources for use in calibrating multiple-detector imaging devices. In exemplary embodiments, a plano-plano reference lens is inserted at a non-focusing position in the optics path of a multiple-detector imaging device. The reference lens includes a highly polished side coated with a semi-reflective film and a rough polished side coated with an anti-reflective coating. The smooth polished side causes the detector array to see a reflected image of itself and a portion of the incoming scene energy simultaneously. The energy emitted by the detector array thus mixes with the scene energy to create a detected photon flux level which is dependent upon, but deviates in a controlled manner from, that of the scene energy alone. At the same time, the rough polished side and the thickness of the reference lens blur the detected image to eliminate scene structure and to provide a uniform photon flux level at each detector in the array. Since the detected flux is uniform and dependent upon the scene energy, the inserted reference lens effectively provides a reference source suitable for detector calibration. Additional reference lenses of varying reflectivity can be successively inserted to provide additional calibration points. Advantageously, the reference source levels vary automatically and passively with the viewed scene flux, and the present invention eliminates many of the drawbacks associated with conventional calibration techniques.

Claims65

Dependent claims

An imaging device, comprising:

a plurality of radiation detectors positioned in an optical path of said imaging device;
a plano-plano reference lens;
and
a lens carrier supporting said reference lens and configured to selectively position said reference lens within and without the optical path.

1 more element

A method for correcting non-uniformities among a plurality of radiation detectors in an imaging device, said plurality of radiation detectors being positioned in a focal plane of an optical path of said imaging device, comprising the steps of:

positioning a piano-plano reference lens within the optical path to provide the plurality of radiation detectors with a uniform level of radiation;
computing an offset value for each of the plurality of radiation detectors based on values output by the plurality of radiation detectors when the reference lens is positioned within the optical path;
removing the reference lens from the optical path;
and
computing a corrected output value for each of the plurality of radiation detectors based on the computed offset values and on values output by the plurality of radiation detectors when the reference lens is removed from the optical path.

2 more elements

Dependencies are inferred from the claim text.

Methods and apparatus for performing scene based uniformity correction in imaging systems

Life of this patent

Methods and apparatus for performing scene based uniformity correction in imaging systems

Life of this patent

Abstract

Claims65