Abstract: An imaging detector includes a collimator, a scintillator and a photodiode array. The collimator directs radiation to scintillator segments having apertures substantially matched to collimator apertures. Optical reflectors and heavy metal septa between the segments reduce light and radiation scatter between the segments, respectively. Photodiode array elements with active areas substantially matched to the scintillator segment apertures detect light generated when the radiation interacts with the scintillator. A cooler, a low noise photodiode array and readout electronics improve the signal-to-noise ratio of the imaging system in specific embodiments.

Abstract: Mercuric iodide detector systems are made less power consumptive and smaller by employing a single Peltier cooler rather than the two required by prior art systems. The optimal temperature requirements (and thus leakage current conditions) for the two critical temperature sensitive components for such a system are met by cooling the components to a reference temperature using a single cooler and by illuminating the detector to achieve the required operating performance. The elimination of the extra cooler not only conserves power and reduces maintenance requirements, but also reduces size. The use of light to achieve the required detector and FET leakage current relation for optimum operation is permitted by the implementation of a feedback loop for automatic control of the operation.

Abstract: A small, rugged photomultiplier tube is achieved by closely spacing a large area avalanche "photodetector" with respect to a photocathode in an opaque casing having a window for incident light. The photocathode and the avalanche photodetector have comparable areas and are closely spaced. The avalanche photodetector includes a PN junction which as to be close to the surface of the detector to maximize the response to electrons and reduce any direct response to light. The need for an electrostatic lens to focus electrons onto the small target characteristic of prior art photomultiplier tubes is obviated.

Abstract: Mercuric Iodide X-RAY detectors are made to exhibit high energy resolution characteristics, reduced background level in the x-ray spectra, enhanced sensitivity to low energy x-rays and significantly improved long term stability and reliability. The above improvements has been achieved through specific changes in the detector construction and passivation/encapsulation techniques. Specifically, the introduction of a guard ring structure and collimating shield improved the electric field distribution in the detector, reduced the surface leakage current, lowered effective capacitance and eliminated current injections. A special Parylene-C and Parylene-N deposition onto the detector surface insured excellent long term detector stability and reliability.

Abstract: Large area semiconductor photodiodes are made free of microcracks by forming on the incident light surface of the device a ring-shaped electrode structure. The electrode structure adds rigidity to the device when the edge surface of the device is later bevelled, a process which creates microcracks normally.

Abstract: Apparatus and method for detecting light involve applying a substantially uniform electrical potential difference between first and second spaced surfaces of a body of mercuric iodide, exposing the first surface to light and measuring an electrical current passed through the body in response to the light. The mercuric iodide may be substantially monocrystalline and the potential may be applied between a substantially transparent conductive layer at the first surface and a second conductive layer at the second surface. In a preferred embodiment, the detector is coupled to a scintillator for passage of light to the mercuric iodide in response to ionizing radiation incident on the scintillator.