Back to results
US 6,643,016 B2Granted
Multiple pathlength spectrophotometer
AssigneeAlberta Research Council
InventorsTheodore M. Garver, David G. Jenkins, Andrew Riser
Life of this patent
Estimating the term…
Abstract
A spectrometer or multiple wavelength absorbance detection method and apparatus providing improved accuracy for an array of measurements at different wavelengths. The spectrometer utilizes a multiple wavelength illumination system with an array of independent detectors with different pathlength cells, where each cell is illuminated with predominately monochromatic light after separation by a light dispersing element. Each sample cell has an optical pathlength, optics and photodetection device that are optimized for its particular wavelength to accurately measure absorbance through an expected substance.
Claims34
A method of measuring light absorption by a fluid sample comprising the steps of:
- a) providing polychromatic light along an initial optical path;
- b) dispersing the polychromatic light in dependence upon wavelength:
- to direct light at a first predetermined wavelength along a first optical path having a first path length through the fluid sample;
- and,
- to direct light at a second other predetermined wavelength along a second other optical path having a second other path length through the fluid sample;
- c) detecting an intensity of light at the first predetermined wavelength after it has propagated the first optical path length through the fluid sample using a first light detector disposed within the first optical path and supporting a first range of detected values;
- and,
- d) detecting an intensity of light at the second other predetermined wavelength after it has propagated the second optical path length through the fluid sample using a second other light detector disposed within the second other optical path and supporting a second range of detected values,
- wherein the first path length is selected in dependence upon the first wavelength and the fluid sample such that a detected first value is within a portion of the first range wherein substantial variations in optical intensity result in substantial changes in the first value, and,
- wherein the second path length is selected in dependence upon the second other wavelength and the fluid sample such that a detected second value is within a portion of the second range wherein substantial variations in optical intensity result in substantial changes in the second value, and,
- wherein the first light detector is angularly disposed along an arc section of a Rowland circle in dependence upon the first wavelength of light and the second other light detector is angularly disposed along a same arc section of a same Rowland circle in dependence upon the second other wavelength of light.
8 more elements
A method of measuring light absorption by a fluid sample including a light absorbing species comprising the steps of:
- a) providing polychromatic light along an initial optical path;
- b) dispersing the polychromatic light in dependence upon wavelength:
- to direct light at a first predetermined wavelength along a first optical path having a first path length through the fluid sample;
- and,
- to direct light at a second other predetermined wavelength along a second other optical path having a second other path length through the fluid sample;
- c) detecting an intensity of light at the first predetermined wavelength after it has propagated the first optical path length through the fluid sample using a first light detector disposed within the first optical path and supporting a first range of detected values;
- and,
- d) detecting an intensity of light at the second other predetermined wavelength after it has propagated the second optical path length through the fluid sample using a second other light detector disposed within the second other optical path and supporting a second other range of detected values,
- wherein the first path length is selected in dependence upon the first wavelength and the fluid sample such that a detected first value is within a portion of the first range wherein substantial variations in optical intensity result in substantial changes in the first value, and,
- wherein the second path length is selected in dependence upon the second other wavelength and the fluid sample such that a detected second value is within a portion of the second range wherein substantial variations in optical intensity result in substantial changes in the second value.
7 more elements
An apparatus for measuring light absorption by a fluid sample comprising:
- at least a light source for providing polychromatic light along an initial optical path;
- a light separating element disposed within the initial optical path for receiving the polychromatic light from the at least a light source and for dispersing the polychromatic light in dependence upon wavelength to direct light at each of a plurality of different predetermined wavelengths along one of a plurality of different secondary optical paths, including a signal at a first predetermined wavelength of light propagating along a first secondary optical path and a signal at a second other predetermined wavelength of light propagating along a second other secondary optical path;
- a first channel detector disposed within the first secondary optical path comprising:
- a) a first sample cell for containing a fluid sample within a containing portion thereof and having at least a light transmissive endface;
- and,
- b) a first light detector disposed for receiving light at the first predetermined wavelength from one of the at least a light transmissive endface of the first sample cell, light at the first predetermined wavelength propagating a first optical path length through the containing portion of the first sample cell;
- a second channel detector disposed within the second other secondary optical path comprising:
- a) a second other sample cell for containing a fluid sample within a containing portion thereof and having at least a light transmissive endface;
- and,
- b) a second other light detector disposed for receiving light from one of the at least a light transmissive endface of the second other sample cell, light at the second other predetermined wavelength propagating a second different optical path length through the containing portion of the second other sample cell;
- wherein the light separating element defines a Rowland circle, the first channel detector and the second other channel detector being angularly disposed along an arc section of the Rowland circle in dependence upon the first predetermined wavelength of light and the second other predetermined wavelength of light, respectively.
8 more elements
Dependencies are inferred from the claim text.