Optics: measuring and testing – By dispersed light spectroscopy – Utilizing a spectrophotometer
Patent
1985-10-28
1988-02-23
McGraw, Vincent P.
Optics: measuring and testing
By dispersed light spectroscopy
Utilizing a spectrophotometer
356411, 356246, G01J 342, G01N 2105
Patent
active
047266805
ABSTRACT:
To reduce noise in an absorbance monitor in which the light source is a deuterium lamp, an aspheric condensing mirror focuses light from an approximately 0.6 mm-high by 2 mm-wide part of the central bright spot in the deuterium lamp through a slit in an aperture plate which blocks all other light and an aspheric monochromator mirror focuses the light onto a plane reflective diffraction grating, which: (1) is mounted for orbiting about an axis parallel to the longitudinal axis of the slit; and (2) adjusted so that, as it orbits it reflects a selected wavelength of light to a beam splitter. Each beam is focused upon and transmitted through a different one of two equal oval apertures optically at least as large as the height of the image of the aperture near the lamp. The beams are converted to an electrical signal by silicon diode photosensors, thus using only light: (1) focused in both transverse planes and originating from the same spot on the central bright spot; and (2) with the same relative geometric weighting for light propagating in various directions from various subparts of the central bright spot. To reduce noise originating from flow-related refraction effects in the flow cell, the flow cell has reflective walls and a large collecting mirror focuses light entry in a large cone from the flow cell into a measuring photocell. This large cone has a wider angle than the cone of light entering the flow cell.
REFERENCES:
patent: 3120608 (1964-02-01), Bird
patent: 3591801 (1971-07-01), Watson
patent: 4053236 (1977-10-01), Atwood et al.
patent: 4192614 (1980-03-01), de Mey, II et al.
Chupp et al "Coma Cancelling Monochromator with No Slit Mismatch" Applied Optics, vol. 8, No. 5, May 1969.
Rudberg "Spectrophotometer with Linear Output" IBM Tech. Disc. Bulletin, vol. 20, #7, Dec. 1977, pp. 2767-2769.
Carney Vincent L.
Isco, Inc.
McGraw Vincent P.
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