to a laser side collimator lens 107 the collimated laser beam then passes through a laser line filter 104 in the integrated optics module to ensure the spectral purity of the laser beam before projecting onto a dichroic beam splitter mirror 101 the dichroic beam splitter transmits the majority of the laser beam into the sending receiving fiber 108 through the sending receiving collimator 109 probe side optical fiber 108 may be connected to a fiber in a multiple fiber probe not shown such a multi fiber intravascular catheter to deliver the laser beam to a target and at the same time to collect scattering light from the target the scattered light transmitted back from the target through probe side optical fiber 108 is then projected onto the same dichroic beam splitter mirror 101 after passing through the sample side collimator lens 109 the dichroic beam splitter is selected to at least predominantly transmit the emission wavelength of the laser but reflect raman scattered light as received back from a target in a wavelength range of interest accordingly beam splitter 101 then reflects the raman signals received from the target toward spectrometer side collimator lens 111 and spectrometer side optical fiber 110 the.