System for generating raman vibrational analysis signals- WO2010013118

A system for generating signals for Raman vibrational analysis, particularly for a CARS microscope or spectroscope of an external specimen, the system comprising a a laser source apt to emit at least one fundamental optical pulse in a first band of fundamental frequencies comprising at least one first (?f1) and one second (?f2) fundamental frequencies; a second-harmonic (SH) generating system comprising at least one nonlinear optical crystal for converting said at least one fundamental optical pulse into at least two second-harmonic optical pulses, i.e. a first second-harmonic pulse at a first second-harmonic frequency (?p) of the first fundamental frequency (?f1) and a second second-harmonic pulse at a second second-harmonic frequency (?s) of the second fundamental frequency (?f2), said second second-harmonic frequency being other than the first second-harmonic frequency, and a Raman vibrational analysis apparatus apt to receive said first and second second-harmonic pulses and direct them toward said specimen. According to an embodiment, the SH system comprises two nonlinear optical crystals, each including a ferroelectric crystal with periodic space-modulation of the sign of the optical susceptibility. In a different embodiment, the SH system comprises a ferroelectric crystal with aperiodic space-modulation of the sign of nonlinear optical susceptibility, with a period varying along the optical path of said at least one fundamental optical pulse, said crystal being apt to generate said first and second second-harmonic pulses.