MEASUREMENT OF THE OPTICAL COHERENCE OF A FEMTOSECOND PULSED-LASER BYSHEARING INTERFEROMETRY WITH A DOUBLE-FREQUENCY GRATING

Shearing interferometry of an ion-etched holographic double-frequency grating is used to measure the optical coherence of femtosecond pulsed lasers. The experimental results show that the optical coherence of t he femtosecond light beam is not only related to the spectral width an d size of the light source but is also related to the pulse duration a nd mode-locked laser state. The results of theoretical analysis and nu merical calculation are also given. Application of this research is al so discussed.