Method and apparatus for improvement of spectrometer stability, and multivariate calibration transfer
First Claim
1. A method of producing an interferogram from a reference signal and a spectroscopic signal obtained from a spectroscopic instrument, comprising:
- (a) determining from a plurality of measurements of a digital reference signal, each taken at one of a plurality of different times, a functional relationship that relates optical path difference and time over a set of times that are between the times of at least two of the measurements in the plurality of measurements of the digital reference signal;
(b) determining from the functional relationship one or more times that correspond to a predetermined set of optical path differences; and
(c) determining the value of the spectroscopic signal at the determined times to produce the interferogram.
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Abstract
The present invention provides improved methods and apparatuses for accurate measurements using interferometers. A functional relationship between the optical path difference and time is determined from a reference signal from an interferometer. The times at which the interferometer had specific optical path differences can be determined from the functional relationship. Those times can then be used to select times at which the spectroscopic signal from the interferometer was produced at the specific optical path differences. The invention can be applied, as examples, to maintain instrument calibration, and to transfer or compare calibrations or measurements across different interferometers.
29 Citations
27 Claims
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1. A method of producing an interferogram from a reference signal and a spectroscopic signal obtained from a spectroscopic instrument, comprising:
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(a) determining from a plurality of measurements of a digital reference signal, each taken at one of a plurality of different times, a functional relationship that relates optical path difference and time over a set of times that are between the times of at least two of the measurements in the plurality of measurements of the digital reference signal; (b) determining from the functional relationship one or more times that correspond to a predetermined set of optical path differences; and (c) determining the value of the spectroscopic signal at the determined times to produce the interferogram. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method of producing an interferogram from a reference signal and a spectroscopic signal obtained from a spectroscopic instrument, comprising:
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(a) storing a plurality of measurements of a digital reference signal, each taken at one of a plurality of different times; (b) determining from the stored plurality of measurements a functional relationship that relates optical path difference and time over a set of times that are between the times of at least two of the stored measurements; (c) determining from the functional relationship one or more times that correspond to a predetermined set of optical path differences; and (d) determining the value of the spectroscopic signal at the determined times to produce the interferogram. - View Dependent Claims (25, 26, 27)
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Specification