Method and system for examining biological materials using low power CW excitation raman spectroscopy
First Claim
1. A method of examining an object, said method comprising the steps of:
- (a) irradiating the object with a first pump beam at a first wavelength, whereby the object produces a spontaneous Raman emission at a second wavelength;
(b) substantially simultaneously with step (a), irradiating the object with a first probe beam at a third wavelength, whereby the intensity of said first probe beam emitted from the object at said third wavelength increases if said third wavelength is equal to said second wavelength;
(c) detecting the intensity of said first probe beam emitted from the object at said third wavelength following steps (a) and (b), whereby an increase in intensity of said first probe beam at said third wavelength indicates the presence of a Raman mode for the object at said first wavelength;
(d) irradiating the object with a second pump beam at a fourth wavelength, whereby the object produces a spontaneous Raman emission at a fifth wavelength, said fourth wavelength not being equal to said first wavelength;
(e) substantially simultaneously with step (d), irradiating the object with said first probe beam at said third wavelength, whereby the intensity of said first probe beam emitted from the object at said third wavelength increases if said third wavelength is equal to said fifth wavelength; and
(f) detecting the intensity of said first probe beam emitted from the object at said third wavelength following steps (d) and (e), whereby an increase in intensity of said first probe beam at said third wavelength indicates the presence of a Raman mode for the object at said fourth wavelength.
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Abstract
A method and system for examining biological materials using low-power cw excitation Raman spectroscopy. In accordance with the teachings of the invention, a low-power continuous wave (cw) pump laser beam and a low-power cw Stokes (or anti-Stokes) probe laser beam simultaneously illuminate a biological material and traverse the biological material in collinearity. The pump beam, whose frequency is varied, is used to induce Raman emission from the biological material. The intensity of the probe beam, whose frequency is kept constant, is monitored as it leaves the biological material. When the difference between the pump and probe excitation frequencies is equal to a Raman vibrational mode frequency of the biological material, the weak probe signal becomes amplified by one or more orders of magnitude (typically up to about 104 -106) due to the Raman emission from the pump beam. In this manner, by monitoring the intensity of the probe beam emitted from the biological material as the pump beam is varied in frequency, one can obtain an excitation Raman spectrum for the biological material tested. The present invention may be applied to in the in vivo and/or in vitro diagnosis of diabetes, heart disease, hepatitis, cancers and other diseases by measuring the characteristic excitation Raman lines of blood glucose, cholesterol, serum glutamic oxalacetic transaminase (SGOT)/serum glutamic pyruvic tansaminase (SGPT), tissues and other corresponding Raman-active body constituents, respectively. For example, it may also be used to diagnose diseases associated with the concentration of Raman-active constituents in urine, lymph and saliva It may be used to identify cancer in the breast, cervix, uterus, ovaries and the like by measuring the fingerprint excitation Raman spectra of these tissues. It may also be used to reveal the growing of tumors or cancers by measuring the levels of nitric oxide in tissue.
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Citations
22 Claims
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1. A method of examining an object, said method comprising the steps of:
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(a) irradiating the object with a first pump beam at a first wavelength, whereby the object produces a spontaneous Raman emission at a second wavelength; (b) substantially simultaneously with step (a), irradiating the object with a first probe beam at a third wavelength, whereby the intensity of said first probe beam emitted from the object at said third wavelength increases if said third wavelength is equal to said second wavelength; (c) detecting the intensity of said first probe beam emitted from the object at said third wavelength following steps (a) and (b), whereby an increase in intensity of said first probe beam at said third wavelength indicates the presence of a Raman mode for the object at said first wavelength; (d) irradiating the object with a second pump beam at a fourth wavelength, whereby the object produces a spontaneous Raman emission at a fifth wavelength, said fourth wavelength not being equal to said first wavelength; (e) substantially simultaneously with step (d), irradiating the object with said first probe beam at said third wavelength, whereby the intensity of said first probe beam emitted from the object at said third wavelength increases if said third wavelength is equal to said fifth wavelength; and (f) detecting the intensity of said first probe beam emitted from the object at said third wavelength following steps (d) and (e), whereby an increase in intensity of said first probe beam at said third wavelength indicates the presence of a Raman mode for the object at said fourth wavelength. - 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 system for examining an object, said system comprising:
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(a) means for producing a first low-power pump beam at a first wavelength; (b) means for producing a second low-power pump beam at a second wavelength, said second wavelength differing from said first wavelength; (c) means for producing a first low-power probe beam at a third wavelength, said third wavelength differing from each of said first and second wavelengths; (d) optics for combining said first low-power probe beam and said first low-power pump beam into a first combined beam focused on the object and for combining said first low-power probe beam and said second low-power pump beam into a second combined beam focused on the object; and (e) means for detecting the intensity of light emitted from the object at said third wavelength. - View Dependent Claims (22)
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Specification