Raman instrument for measuring weak signals in the presence of strong background fluorescence
First Claim
1. A method of measuring the level of a selected molecule in a target sample, comprising:
- illuminating the target with light of a first wavelength F1;
illuminating the target with light of a second wavelength F2 adjacent to the first wavelength F1;
receiving from the target emitted light resulting from each of the illuminations at wavelengths F1 and F2 and sampling the intensity of the emitted light at a range of wavelengths including a characteristic Raman emission wavelength Fc associated with the selected molecule and each of the illumination wavelengths;
developing a first set of sampled intensity values for emitted light resulting from the illumination for wavelength F1, said sample including a value at or near the characteristic emission wavelength Fc associated with the selected molecule and wavelength F1, at least one sample adjacent the characteristic wavelength Fc but sufficiently displaced below that wavelength to exclude Raman emissions resulting from the illumination for wavelength F1 and at least one sample adjacent the characteristic wavelength Fc but sufficiently displaced above that wavelength to exclude Raman emissions resulting from the illumination for wavelength F1;
developing a second set of sampled intensity values for emitted light resulting from the illumination for wavelength F2, said sample including a value at or near the characteristic emission wavelength Fc associated with the selected molecule and wavelength F2, at least one sample adjacent the characteristic wavelength Fc but sufficiently displaced below that wavelength to exclude Raman emissions resulting from the illumination for wavelength F2 and at least one sample adjacent the characteristic wavelength Fc but sufficiently displaced above that wavelength to exclude Raman emissions resulting from the illumination for wavelength F2; and
deriving from ratios of corresponding values in the first and second sets of sampled intensity values an interpolated intensity value for emitted light between the characteristic wavelength Fc associated with each of F1 and F2 that removes the intensity value component due to non-Raman emissions, said interpolated intensity value derived from ratios of corresponding values in the first and second sets representing a measurement of the level of the selected molecule in the target sample.
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Abstract
A method for measuring a chemical concentration in tissue has two measurement steps. A portion of tissue is illuminated with a first generated light and a second generated light. A first Raman scattered light, corresponding to the first generated light, and a second Raman scattered light, corresponding to the second generated light, are directed to a plurality of light sensors, each light sensor measuring light at a different wavelength, that wavelength being proximate to a wavelength of an expected Raman shift wavelength for the chemical in the tissue. A measurement is obtained from each light sensor, each measurement being specific to the first scattered light and/or the second reflected light to that light sensor. The measurements of the first scattered light and the measurements of the second scattered light are used to calculate a concentration of the chemical in the tissue.
32 Citations
33 Claims
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1. A method of measuring the level of a selected molecule in a target sample, comprising:
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illuminating the target with light of a first wavelength F1; illuminating the target with light of a second wavelength F2 adjacent to the first wavelength F1; receiving from the target emitted light resulting from each of the illuminations at wavelengths F1 and F2 and sampling the intensity of the emitted light at a range of wavelengths including a characteristic Raman emission wavelength Fc associated with the selected molecule and each of the illumination wavelengths; developing a first set of sampled intensity values for emitted light resulting from the illumination for wavelength F1, said sample including a value at or near the characteristic emission wavelength Fc associated with the selected molecule and wavelength F1, at least one sample adjacent the characteristic wavelength Fc but sufficiently displaced below that wavelength to exclude Raman emissions resulting from the illumination for wavelength F1 and at least one sample adjacent the characteristic wavelength Fc but sufficiently displaced above that wavelength to exclude Raman emissions resulting from the illumination for wavelength F1; developing a second set of sampled intensity values for emitted light resulting from the illumination for wavelength F2, said sample including a value at or near the characteristic emission wavelength Fc associated with the selected molecule and wavelength F2, at least one sample adjacent the characteristic wavelength Fc but sufficiently displaced below that wavelength to exclude Raman emissions resulting from the illumination for wavelength F2 and at least one sample adjacent the characteristic wavelength Fc but sufficiently displaced above that wavelength to exclude Raman emissions resulting from the illumination for wavelength F2; and deriving from ratios of corresponding values in the first and second sets of sampled intensity values an interpolated intensity value for emitted light between the characteristic wavelength Fc associated with each of F1 and F2 that removes the intensity value component due to non-Raman emissions, said interpolated intensity value derived from ratios of corresponding values in the first and second sets representing a measurement of the level of the selected molecule in the target sample. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for measuring a chemical concentration in tissue comprising:
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generating a first light and illuminating a portion of the tissue with the first light; capturing a first reflected light from the tissue; directing the first reflected light to a plurality of light sensors, each light sensor measuring light at a different wavelength, that wavelength being proximate to a wavelength of an expected Raman shift wavelength for the chemical in the tissue; obtaining a measurement from each of the light sensors, each measurement being specific to the first scattered light to that light sensor; generating a second light different in frequency from the first light and illuminating a portion of the tissue with the second light; capturing a second reflected light from the tissue; directing the second scattered light to the plurality of light sensors, each light source measuring light at a different wavelength that wavelength being proximate to a wavelength of an expected Raman shift wavelength for the chemical in the tissue; obtaining a measurement from each of the light sensor; and
each measurement being specific to the second scattered light to that light source; andusing a ratio of the measurements of the first scattered light to the corresponding measurements of the second scattered light to calculate a concentration of the chemical in the tissue. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification