Spectroscopy method using coherent, periodic radiation pulses aims two beams with different repetition frequencies

摘要

The method involves a radiation source (52) emitting a periodically pulsed beam (A) with a repetition frequency omega and a second source (51) emitting one with a repetition frequency omega + delta (B), delta being smaller than omega. Both beams are directed at a material specimen (6) and are combined with each other either before or after the specimen. The beam emerging from the specimen is directed to a receiver (7) which determines the amplitudes delta, 2 x delta,... of the frequency components. A visible laser beam may be added to the beam path.