Cooled echelle grating spectrometer

摘要

A cooled echelle grating spectrometer for detecting wavelengths between one micron and fifteen microns. More specifically, a spectrometer is disclosed having a cross-dispersing grating for ordering infrared energy, and an echelle grating for further ordering of the infrared energy. Means are disclosed to direct infrared energy to the cross- dispersing grating and then to the echelle grating. Ordered radiation from the echelle grating is sensed by a detecting means. Means are also disclosed for cooling the cross-dispersing grating, the echelle grating and the detecting means so that background radiation can be minimized. In a specific embodiment the cross-dispersing grating and echelle grating are in separate enclosed volumes having access to each other through a single intermediate aperture, reflected energy from the cross-dispersing grating being focused so as to pass through the intermediate aperture and then collimated and directed to the echelle grating for further ordering. Also disclosed is use of a Schmidt camera for focusing the further ordered radiation from the echelle grating onto a detector array having individual detectors dispersed on a plane which substantially corresponds to a curved focal plane of the Schmidt camera. A spectrometer constructed according to the teachings of the present invention will continuously cover the spectrum between one micron and fifteen microns and have a resolution of 0.1 cm..sup.-1.