An apparatus for controlling the exposure of a solid state image sensor array monitors the semiconductor substrate current produced as charge signal accumulates during an exposure of the array to radiant energy. The exposure of the array is controlled in response to an output signal representative of the total substrate current.

Apparatus for controlling exposure of a solid state image sensor array

A method and system for testing the performance of at least one electro-optical test device, comprising constructing an electro-optical system (10) having a light source (15), a test target (14), a lens (13) and an imaging device (12) as required in combination with the test devices. A respective identity code of a plurality of pre-calibrated devices together with corresponding electro-optical performances are stored in a database and the imaging device is aligned to the test target so as to produce a focused image thereof. Pre-calibrated devices are selected from the database and the focussed image is digitized and stored so as to produce a digitized image which is analyzed so as to determine an electro-optical performance representative of the performance of the electro-optical system which is equal to the product of component electro-optical performances of each of the electro-optical test devices and each of the additional pre-calibrated devices. This permits determination of the product of component electro-optical performances of each of the electro-optical test devices.

Method and system for testing the performance of at least one electro-optical test device

Spatial light modulators which use a substrate having a buried channel charge-coupled device (CCD) formed therein, wherein the amount of charge in the charge storage wells associated with the electrodes of the CCD is controlled by an electrically or optically addressed data signal. The level of charge in such charge storage wells controls the electric field beneath the electrodes so that the intensity of electromagnetic energy (e.g., light) directed through The CCD is spatially modulated by the charge levels in the charge storage wells in accordance with the Franz-Keldysh electroabsorption effect.

Spatial light modulator

The present system provides a thermal imaging device including a detector array responsive to thermal infrared radiation. The detector array has a linearly-arrayed plurality of spaced-apart detector elements defining cooperatively a length dimension for the detector array. Each of the plurality of detector elements provides a corresponding individual electrical signal indicative of the thermal infrared radiation incident thereon. The detector elements vary from one another in the plurality of detector elements, and the thermal imaging device responsively provides a visible-light image replicating a viewed scene. The thermal imaging device includes a scanning device scanning the viewed scene across the plurality of detector elements in a direction generally perpendicular to the length dimension. The scanning device includes a first portion scanning the viewed scene across the entire plurality of the plurality of detector elements, and a second portion scanning the viewed scene across the plurality of detector elements with transposition of the viewed scene such that a portion of the viewed scene scanned by the first portion across a certain detector element is scanned across a detector element next-adjacent to the certain detector element.

Thermal imaging device

An infrared line-scanning imager includes a scanner having an optical system, infrared linear photoconductive detector providing an analog image signal, cooler, and conversion electronics for converting the image signal from the detector to digital electrical and digitally-encoded optical formats, all on a moving scanning platform of the scanner. The digitally-encoded optical format of the image signal takes the form of an encoded light beam which is beamed off of the moving scanning platform to a receiver on the stationary portion of the scanner. From the scanner, the image signal is transmitted in the optical format over a fiber optic cable to a reformatting, processing, analysis, and display portion of the imager. This latter portion of the imager allows the image signal to be converted once again to digital electronic format for processing, pattern recognition, image enhancement, storage, delayed display and comparison, and display in near-real time if desired.

Miniature infrared line-scanning imager

An automatic responsivity compensator for correcting video output signals om a CCD multiplexer in a cryogenic dewar in IR imaging systems wherein the CCD multiplexer must operate with fixed gain inputs from a plurality of linear detector channels. The automatic responsivity compensator is comprised of a signal reference that is normalized with what the output voltage should be when looking at a fixed temperature source in the field of view of the detectors and which further provides a voltage reference for automatic gain adjustment for each detector channel to normalize and equalize the responsivity of the detectors. The automatic responsivity compensator may be either a feedback system as a direct gain control means of a controllable gain amplifier or may be a feedback system operating on the output from a constant gain amplifier wherein either feedback system equalizes the responsivity of the detectors.

Automatic responsivity compensator in an IR imaging system

An analog computer method provides modulation transfer functions (MTF) expressions or graphs for arbitrary shaped detectors in an arbitrary scan direction. Fraunhofer diffraction calculations or measurements given for specific shaped apertures are used for calculating detector MTFs of similarly shaped detectors. In an analog measuring device, an aperture in an opaque screen may be made the shape of a detector whose MTF is to be calculated. The aperture is flooded with laser light which produces a Fraunhofer irradiance pattern at an observing screen which is parallel with the opaque screen, for measuring the irradiance in the Fraunhofer plane at the observing screen. A sensor, which has a detector small compared with the diffraction pattern, is moved along the chosen thermal imager scan direction, in the Fraunhofer plane. The analog pattern of the irradiance along the x'-axis is digitized by a digitizer, has the square root of the irradiance versus distance along the x'-axis plotted and normalized so that at x'=0 the square root of the irradiance equals one (1). By relabeling the square root of the irradiance with MTF and relabeling the x'-axis with spatial frequency a detector MTF curve is shown in appropriate units of spatial frequency.

Max L. Harwell

Papers

Automatic responsivity compensator in an IR imaging system

Analog and analytical computation method for determining detector MTF