Diamond detection using coherent anti-stokes raman spectroscopy

摘要

The invention concerns a method and apparatus for detecting diamonds using the phenomenon of coherent anti-Stokes Raman spectroscopy (CARS). Each particle (46) which is to be analysed is irradiated by a focused particle irradiating beam (44) of laser light formed by combining initial laser beams (35, 36) having frequencies differing from one another by a value characteristic for diamond. Components of the initial laser beams are coherently phase-matched to produce, in diamond particles, a CARS signal characteristic of diamond. The scattered signal from the particle is then collected and analysed for the presence of the characteristic CARS signal. The irradiating beam and/or at least one of the initial laser beams is focused by a lens system including a cylindrical lens. This feature has been found to give an enhanced result compared to conventional CARS analysis.