Patent ID: 8111394

Claim:
A Raman spectrometer comprising: a laser source emitting a laser beam; a lens having a lens focal length and being disposed approximately one lens focal length away from a silicon substrate and operable to focus said laser beam onto said silicon substrate at an angle at least approximately 60 degrees from a line normal to said silicon substrate, wherein said focused laser beam at least partially reflects from said silicon substrate and diverges toward a first concave mirror; said first concave mirror having a first mirror focal length and being disposed approximately two first mirror focal lengths away from said silicon substrate, said first concave mirror operable to focus said laser beam onto said silicon substrate, wherein said focused laser beam at least partially reflects from said silicon substrate and diverges toward a second concave mirror; said second concave mirror having a second mirror focal length and being disposed approximately two second mirror focal lengths away from said silicon substrate, said second concave mirror operable to focus said laser beam onto said silicon substrate, said silicon substrate, said first concave mirror, and said second concave mirror together comprising a multi-pass Raman cell; at least one lens operable to collect Raman light from said silicon substrate and provide an image of said Raman light to a spectrograph operable to separate said Raman light according to wavelength; and a filter operable to remove at least a portion of Rayleigh scattered light from said Raman light.