Apparatus for measuring Raman spectra over optical fibers

An optical probe useful for conducting Raman spectroscopy remotely over optical fibers with minimal interference from Raman scattering and or luminescence within said fibers comprising

• a first optical fiber transmissive at the wavelength used for Raman excitation for transmitting the Raman excitation light to the sample
• a probe head assembly of optical elements said assembly having the functions of delivering light from the end of said first optical fiber to the sample, of collecting Raman scattered light from the sample and of focusing said Raman scattering light into a second optical fiber
• said second optical fiber transmitting said Raman scattering light to a detector means for measuring the intensity and or spectral distribution of said Raman scattered light
• said probe head optical assembly also having the geometric configuration such that the input and output fibers are colinear and are connected to the proximal end of the probe and the sample is illuminated from the distal end of the probe head wherein
• said probe head assembly comprising
• a first lens or lens assembly spaced from the exit of said first optical fiber for collimating the light exiting said first optical fiber, followed in the optical path by
• a primary optical filter that is tuned to pass said Raman excitation wavelengths, but that is rejecting of light of other wavelengths generated within said first optical fiber by said excitation light
• said primary optical filter being arranged at approximately 45.degree. with respect to the light path, followed in the optical path by
• a second lens or lens assembly for focusing the light
• said second lens or lens assembly directing the Raman excitation light onto the sample
• the scattered light from the sample being collected and collimated by the same second lens or lens assembly used for focusing the exciting light
• said collimated scattered light impinging onto the back face of said angled primary optical filter
• said primary filter admitting light of said Raman excitation wavelengths while reflecting the remaining light at approximately 90.degree., said remaining light containing the desired Raman spectrum, followed in the optical path by
• a second reflecting element inserted at approximately 45.degree. with respect to the light path
• said second reflecting element reflecting the light at approximately 90.degree. thus returning the light on a path approximately parallel, but in reverse direction to the input light, said second reflecting element being followed in the optical path by
• a third lens or lens assembly for focusing said reflected light into the end aperture of said second optical fiber or fiber bundle, approximately parallel to said first optical fiber or fiber bundle and transmissive at the wavelengths of the Raman scattered light
• said second optical fiber transmitting said Raman scattering light to a detector means for measuring the intensity and or spectral distribution of said Raman scattered light.