Patent ID: 8674308
Filing Date: 2014-03-18
Classification: G01J,G02B

Abstract:
1. A dewar assembly for use in an optical IR detection system including an IR detector unit, said dewar assembly comprising: a base comprising radiation absorbing regions and arranged for defining a light collecting region of the dewar assembly associated with a designated location for the IR detector; and a warm shield unit having an optical window through which incident light enters the dewar assembly and having a reflective inner surface, said warm shield unit forming a thermal shield configured as a sole shield structure configured to optically enclose the base and the light collecting region defined thereby, wherein: the reflective inner surface and an outer surface of said warm shield unit have low emissivity not exceeding few percents in wavelengths, to which said IR detector is sensitive, thereby reducing the amount of radiation absorbed by said surfaces and reducing the amount of radiation emitted from said inner surface under given temperature conditions; and a shape of the reflective inner surface is configured to reflect light portions propagating through said optical window and impinging thereon towards regions outside said light collecting region.