| CPC G01N 21/65 (2013.01) [G01J 3/06 (2013.01); G01J 3/10 (2013.01); G01J 3/44 (2013.01); G01J 2003/064 (2013.01); G01J 2003/102 (2013.01); G01J 2003/4424 (2013.01); G01N 2021/655 (2013.01); G01N 2201/0691 (2013.01)] | 21 Claims |
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1. A system for high gain stimulated Raman spectroscopy comprising:
a first continuous wave laser having a first output beam at a tunable optical frequency which is modulated at a first RF modulation frequency (f1) and a first average power of laser radiation;
a second continuous wave laser having a second output beam at an optical frequency which is modulated at a second RF modulation frequency (f2) and a second average power of laser radiation, wherein the first and second RF modulation frequencies (f1, f2) are selected such that their difference or sum beat notes (f1−f2; f1+f2) represent a Raman resonance frequency;
a dual-beam rasterizing probe (R-probe) including first and second photosensors and coupled to the first and second continuous wave laser output beams, the R-probe including a rasterizer that is configured to scan the first and second continuous wave laser output beams onto a sample over an exposure area, wherein the scanned sample exposure area is exposed to an average power of laser radiation that is reduced relative to first and second average powers of laser radiation and in response thereto is stimulated by the laser beams to emit Raman radiation signals, the R-probe further directing Raman signals emitted from the sample to the first and second photosensors, the first and second photosensors having respective first and second outputs responsive to the first and second continuous wave laser output beams and the Raman signals emitted from the sample; and
a differential amplifier coupled to outputs of the first and second photosensors of the R-probe that is configured to provide sensitivity and gain to signals at the beat note resonant frequency (f1−f2) and to filter out signals at other frequencies so as to output the Raman radiation signals with gain.
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