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US 4,726,680 AGranted
Absorbance monitor
AssigneeIsco, Inc.
InventorRobert W. Allington
Life of this patent
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AssigneeIsco, Inc.
InventorRobert W. Allington
Estimating the term…
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.
An absorbance monitor having a deuterium lamp as a light source, a diffraction grating for selecting certain frequencies of light from the light emitted by said deuterium lamp, a reference photocell, a measuring photocell, a beam splitter for developing a measuring beam of light and a reference beam of light from light of frequencies selected by said diffraction grating, a flow cell having a liquid channel and a light channel which intersect each other and a comparator whereby the measuring beam of light is transmitted through the light channel of the flow cell to the measuring photocell and the reference beam of light is transmitted to the reference photocell, with signals from the reference and measuring photocells being compared by the comparator, wherein the improvement comprises the combination of:
An absorbance monitor having a deuterium lamp as a light source, a diffraction grating for selecting certain frequencies of light from the light emitted by said deuterium lamp, a reference photocell, a measuring photocell, a beam splitter for developing a measuring beam of light and a reference beam of light from light of frequencies selected by said diffraction grating, a flow cell having a liquid channel and a light channel which intersect each other and a comparator whereby the measuring beam of light is transmitted through the light channel of the flow cell to the measuring photocell and the reference beam of light is transmitted to the reference photocell, with signals from the references and measuring photocells being compared by the comparator, wherein the improvement comprises the combination of:
Dependencies are inferred from the claim text.