Time resolved raman spectroscopy
First Claim
1. A method for determining the composition of a sample, comprising:
- providing a controller and a source of pulsed light and a sensor receiving photons and providing an electrical signal corresponding to each received photon;
repetitiously illuminating the sample with a pulse of light from the source, wherein some of the source photons from each pulse are scattered by the sample;
substantially eliminating the elastically scattered photons and collecting the Raman-shifted inelastically scattered photons;
preparing a time histogram of the number of collected Raman-shifted photons, the histogram dividing a predetermined period of time into a plurality of counting bins arranged in sequential order, each bin containing a natural number corresponding to the number of Raman-shifted photons collected during the corresponding time interval, one of the bins having the largest natural number; and
determining by the controller the composition of the sample by analyzing the photons collected earlier in time than the one bin and ignoring the photons collected later in time than the one bin.
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Accused Products
Abstract
System, method, and apparatus for determining the composition of a sample of material. In one embodiment, the method pertains to the counting of photons that were inelastically scattered by the sample, and for minimizing the effects of fluorescent or phosphorescent photons. In yet another embodiment of the invention, a sample is illuminated by a repetitive pulse of monochromatic light, and the resultant scattered photons from the samples are collected and counted during a predetermined integration period. Yet other embodiments pertain to a low-cost, computer-controlled system for repetitively counting inelastically scattered photons so as to create a Raman histogram and a Raman spectrogram of the photons.
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Citations
29 Claims
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1. A method for determining the composition of a sample, comprising:
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providing a controller and a source of pulsed light and a sensor receiving photons and providing an electrical signal corresponding to each received photon; repetitiously illuminating the sample with a pulse of light from the source, wherein some of the source photons from each pulse are scattered by the sample; substantially eliminating the elastically scattered photons and collecting the Raman-shifted inelastically scattered photons; preparing a time histogram of the number of collected Raman-shifted photons, the histogram dividing a predetermined period of time into a plurality of counting bins arranged in sequential order, each bin containing a natural number corresponding to the number of Raman-shifted photons collected during the corresponding time interval, one of the bins having the largest natural number; and determining by the controller the composition of the sample by analyzing the photons collected earlier in time than the one bin and ignoring the photons collected later in time than the one bin. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for determining the composition of a sample comprising:
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a repetitive source of pulsed light at a source wavelength; a chamber for receiving the sample; a probe for directing the pulsed light onto the sample and collecting the photons scattered by the sample; a controllable photon filter receiving the collected photons and substantially eliminating photons not within a selectable frequency band defined between a first selectable lower frequency and a second selectable higher frequency, the photon filter substantially eliminating photons at the source wavelength; an electrical filter having an intensity threshold; a photon counting sensor for receiving Raman-shifted inelastically scattered photons from said photon filter and providing a plurality of electrical signals each in response to a different one of the corresponding plurality of received photons, said sensor further counting only the photons within the frequency band having corresponding electrical signals that exceed the intensity threshold of the electrical filter; and a controller having a plurality of memory bins and being operably connected to said source, said filter, and said sensor; wherein said controller receives the count of photons from a first pulse, stores the count as a first count signal in a first memory bin associated with the first frequency band. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification