Xedar Corporation

Ball Brothers Research Corporation

Hans R Bucher

Donald E Hodd

Jack A Bamberg

John G Bultena

A scan-type X-ray imaging system and method are disclosed. Image detection is effected by use of a fixed phosphor converter screen covering the entire field of view so that X-rays passed through an object, or a body portion, positioned at a scan area, are received at the converter screen and light signals, proportional to the received X-rays, are coupled through a movable coupler, having an input portion movably engaging the converter screen, to a movable sensor that converts received light signals to electrical output signals indicative of the object, or body portion, then at the scan area. The input face of the coupler, preferably a fiber optic coupler, is held in positive engagement with the converter screen throughout movement of the coupler relative to the converter screen by a force, such as by an air cushion between the object, or body portion, positioner and the converter screen, by establishing a vacuum between the input face of the coupler and the converter screen, and/or by springs biasing the coupler face plate toward engagement with the converter screen.

Scan-type X-ray imaging with fixed converter

A system and method are disclosed for pyroelectric camera signal processing, which processing includes multi-parameter automatic signal level adjustment to compensate for the effects of pedestal level variations. The pyroelectric vidicon tube generates an electrical output signal component indicative of target signal information based upon the sensed thermal energy emitted from the target, and also generates a pedestal component around which the target signal information is centered, and this information is processed to provide field video signals which are utilized to provide a composite video output. An automatic adjustment control unit, responsive to the field video signal, provides automatic adjustment of gain, balance, and offset to thereby allow the pyroelectric camera to operate at an optimized signal-to-noise ratio.

Pyroelectric camera signal processing having interrelated

A system and method are disclosed for pyroelectric camera signal processing, which processing includes compensating for the effects of pedestal level variations. The pyroelectric videcon tube generates an electrical output signal component indicative of target signal information based upon the sensed thermal energy emitted from the target, and also generates a pedestal component around which the target signal information is centered. A line-by-line DC restorer is provided to re-establish the DC level of the video signal, with the DC level of the restorer being automatically controlled to thereby compensate for variations in pedestal levels due to drift, tube aging, and/or generated by shutter to scene temperature differences.

Pyroelectric camera signal processing having pedestal signal level

A system and method are disclosed for initiating target crossover recovery in a pyroelectric camera by electronically detecting crossover and automatically initiating recovery in response thereto. The video signal appearing at the output of the video amplifier during readout of the vidicon tube is coupled to a level detector to detect crossover by sensing a positive signal having an amplitude greater than any such signal producible during readout arising from an optical input to the video amplifier, with reliability of detection being enhanced by use of an automatic balancing circuit providing a stable reference. The output from the level detector, indicative of sensed crossover of an area (or all) of the target of the pyroelectric tube, is either directly used to trigger an automatic target poling circuit which returns the pyroelectric tube back to normal operation, or is coupled to a time delay for delaying repoling of the target to allow an image to continue for a period of time after an area of the target has been crossed over in order to avoid loss of information.

Automatic initiation of target crossover recovery in a pyroelectric

A signal processing system is disclosed for a pyroelectric camera having a mechanical chopper in the optical path for causing information sensed by the camera to appear as dynamic information. The pyroelectric camera includes a pyroelectric vidicon tube which senses thermal energy emitted by a target and provides an electrical output signal indicative of the received thermal information. The output signal developed by the pyroelectric vidicon tube includes a relatively large pedestal signal component that is established during flyback due to secondary electron generation and a slightly wider but relatively small pedestal signal that is established due to differences in temperature sensed by the pyroelectric vidicon tube, which pedestal signal is timewise aligned with the relatively large pedestal signal generated due to secondary electron generation. Removal of the pedestal signals avoids saturation of the system amplifiers and limiting of the dynamic range of the camera by thus enabling processing of only the signal components indicative of sensed thermal energy from the target. Background flicker is also eliminated, or reduced, by adding signals of adjacent fields.

Signal processing system for chopper type pyroelectric camera

A plurality of range increments are sequentially pulse-illuminated and energy reflected therefrom is received by a gated light amplifier. Timing circuitry sequentially varies the range viewed, by adjusting the time between illumination and gating on of the light amplifier to achieve enhancement, suppression or apparent uniform illumination of preselected range increments such that all ranges of interest are viewed by the light amplifier within a single integration period of a recording device.

Growing community of inventors

Boulder, CO, United States of America

Hans R Bucher