Abstract: Sensing in an elevated-temperature environment is provided using a sensor system having a sensor housing with an exterior wall with a window-support region having an outwardly facing external face, and a window through the window-support region of the exterior wall and affixed to the exterior wall. A sensor unit contained within the sensor housing receives an input signal through the window. A thermal-insulation layer is on the external face of the window-support region of the exterior wall at a location immediately adjacent to the window. The sensor system is operated in an environment wherein the window-support region of the exterior wall is heated to a temperature of greater than about 100° C. in the event that no thermal-insulation layer is present. In a typical application, the sensor system is attached to an aircraft such that the external face is in a forward-facing orientation, and the aircraft is operated such that the external face is heated by aerodynamic heating.

Abstract: A wide-angle IR imaging system (1A) has an entrance aperture (40) for admitting IR from a scene and a dewar (4A) that contains a coldshield (3) that encloses a cooled IR detector (2) disposed at an image plane (2A). The dewar includes a dewar window (4), and an optical axis of the IR imaging system passes through the dewar window and the image plane. The IR imaging system further includes a plurality of uncooled optical elements (22, 24, 26, 28) disposed along the optical axis between the entrance aperture and the dewar window, and a plurality of generally annular reflector segments (18A, 18B) disposed around the optical axis between the dewar window and the entrance aperture. Each of the reflector segments has a reflective surface that faces the dewar window.

Abstract: A window mounting system for optical sensors including a removable connection for window replacement, an alignment system to assure precision registration of the window or dome with the sensor internal optics, and thermal insulation to limit heat transfer from the window to the optics housing and sensor. The removable connection maintains precise optical alignment of curved domes with significant optical power, yet also is effective with simple flat windows.

Abstract: A method and system of time-to-intercept determination for a radiation source using passively-sensed irradiance data. The invention provides a plurality of noise reduction features to reduce the noise present in the data and improve the accuracy of the time-to-intercept computation. The method includes reducing data noise by defining an acceptable noise level and eliminating any excessively noisy data from the time-to-intercept computation. The method further includes constantly updating the time-to-intercept computation by using irradiance values that are advanced in time. Other features of the present invention includes averaging of irradiance values over a time interval, filtering of the irradiance data received by the method, and triggering at a predetermined time-to-intercept. The invention also includes a time-to-intercept system and processor implementing the above method.

Abstract: A radiation shield 40 is mounted to an uncooled portion, such as an outer case 14, of an IR detector assembly 10 such that it surrounds a thermoelectric cooler 16 and a radiation detector 18. The shield 40 has a curved reflective upper surface 42 having the shape of a toric segment and cylindrical or rectangular reflective sidewalls 44 for imaging the detector 18 and the upper cooler stage upon the tops and sides of lower and slightly warmer cooler stages, which absorb and eliminate radiative energy. This beneficially reduces the heat load upon the coldest stage by excluding hotter surfaces from its view, and by inhibiting reflective couplings of unwanted energy admitted by aperture 46. An aperture 46 defines the effective coldstop for the detector 18.

Abstract: An infrared detector assembly (10) of the type used in munitions and night vision systems having improved coldfinger dewar tube (22). Such detectors include a tubular coldfinger which is surrounded by a vacuum and has a cold end (24) which supports the infrared detector array (30) and related components, and an opposite warm end (26). In accordance with this invention, the coldfinger tube is a two-material composite structure having plastic (44) and metal (42) layers. The plastic layer provides the necessary bending stiffness to support the cold end components while minimizing heat transfer rate between the warm and cold ends of the tube. The metal film layer provides a gas seal to preserve the integrity of the dewar vacuum, but is sufficiently thin to provide a minimal increase in thermal conductivity. The compositie coldfinger tube in accordance with this invention features lower overall heat conductivity thus minimizing cryogenic cooling requirements while providing the necessary bending stiffness.

Abstract: Two broad blackbody sources (24, 26) having a constantly maintained temperature differential therebetween are alternately directed via a chopper (40) onto a detector array (12) for testing same.

Abstract: A warmshield reflector for a cryogenically cooled radiation detector has a reflective surface of toroidal shape. The surface has geometric properties which cause a ray emanating from the detector to be reflected such that a ray is imaged as a defocused ring outside of and surrounding the active detector area. Several such segments are located in front of a small, cryogenically cooled detector shield, to provide an overall detector shielding effect similar to that of a larger, cryogenically cooled shield.