Cold-shielded infrared dispersive spectrometer with all ambient optics
AssigneeRaytheon Company
InventorLacy G. Cook
Life of this patent
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Abstract
A dispersive infrared spectrometer in which only a minimum number of optical components, for example, the detector sub-system only, are housed within a cold/cryogenic dewar and the remaining optical components are at ambient temperature during operation of the spectrometer. In one example, the spectrometer includes a slit substrate with a highly reflective surface, and the optical components of the spectrometer are configured and arranged such that for all in-band wavelengths, substantially all off-slit optical paths in the detector field of view are retro-reflected off the reflective surface of the slit substrate into the cryogenic dewar.
Claims15
A dispersive infrared spectrometer comprising:
- a substrate defining at least one slit, the substrate having a first reflective surface;
- telecentric flat-field foreoptics configured to direct light rays through the at least one slit;
- a telecentric flat-field collimator positioned facing the first reflective surface of the substrate and configured to collimate the light rays from the at least one slit to provide collimated light rays;
- a dispersive element optically coupled to the telecentric flat-field collimator, the telecentric flat-field collimator being positioned between the substrate and the dispersive element, the dispersive element configured to receive and spectrally disperse the collimated light rays to provide dispersed light;
- a detector housed within a cryogenic dewar;
- and
- a flat-field relayed imager positioned between the dispersive element and the detector and configured to receive the dispersed light from the dispersive element and to image the dispersed light onto the detector;
- wherein the substrate, the telecentric flat-field foreoptics, the dispersive element, the telecentric flat-field collimator and the flat-field relayed imager are located outside the cryogenic dewar and, during operation of the spectrometer, are at ambient temperature.
A method of controlling thermal noise in an infrared spectrometer, the method comprising:
- providing a cryogenic dewar containing a detector;
- providing a substrate defining at least one slit and having a planar reflective mirror surface, the substrate being located outside of the cryogenic dewar;
- and
- retro-reflecting a field of view of the detector from the reflective minor surface through a dispersive element and a telecentric collimator positioned between the substrate and the dispersive element into the cryogenic dewar, the dispersive element and the telecentric collimator being located outside of the cryogenic dewar.
Dependencies are inferred from the claim text.