# US 4,391,523 A · Scannable detector system for echelle grating spectrometers

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- Number: US 4,391,523 A
- Document ID: US4391523A
- Status: Granted
- Kind: A
- Application number: 06/246,716
- Filed: 1981-03-23
- Granted: 1983-07-05
- Earliest claimed: 1980-11-13
- Assignees: Leeman Labs Inc.
- Inventors: Karl J. Hildebrand; John Leeman
- Web page: https://patentgrep.com/patent/US4391523A

## CPC

- G01J 3/32: Investigating bands of a spectrum in sequence by a single detector
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)

## Abstract

A scannable detector system for echelle grating spectrometers is disclosed in which a photodetector is positioned behind an aperture plate having a plurality of apertures corresponding to focal positions of the spectral array eminating from the grating. The detector is arranged to scan from aperture to aperture to measure the presence of individual wavelengths in the array. Additionally, the detector may be removed from the field of the plate to permit the substitution of a non-scannable array of detectors and an associated masking aperture plate to simultaneously measure the presence of a plurality of wavelengths in the spectral array.

## Claims

### Claim 1

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.

### Claim 2 (depends on 1)

The apparatus of claim 1 wherein said mounting means for said second aperture plate comprises slide means to raise and lower said second plate between said first plate and said detector array.

### Claim 3 (depends on 2)

The apparatus of claim 2 wherein said slide means comprises a plurality of sleeves attached to said array and an equivalent plurality of rods slideably positioned in said sleeves and attached to said second aperture plate.

### Claim 4 (depends on 1, 2)

The apparatus of claim 1, 2, or 3 wherein said imaging means comprises a lens possessing chromatic aberration and said focal plane forms an oblique angle with the axis of said lens.