Scannable detector system for echelle grating spectrometers

A scannable detector system for echelle grating spectrometric comprising in combination:

• a. an echelle diffraction grating for separating radiation input energy into a spectrum of mixed orders;
• b. optical dispersing means for further separating said orders into a spectral array of discrete monochromatic wavelength segments;
• c. imaging means to image said spectral array in a focal plane;
• d. a first aperture plate positioned in said focal plane, said plate having a plurality of apertures corresponding to focal positions of said segments of said array;
• e. at least one scannable photodetector positioned behind said plate to receive and sense any of said wavelength segments transmitted by said plate;
• f. means to scan said detector from aperture to aperture to measure individual wavelength segments in a selected sequence;
• g. a photodetector array mounted behind said first aperture plate;
• h. means to remove said scannable detector from the field of said plate;
• i. a second masking aperture plate having fewer apertures than said first aperture plate;
• and
• j. mounting means for mounting said second aperture plate between said photodetector array and said first aperture plate, said mounting means arranged such that said apertures in said second plate align with said apertures in said first plate.