OPTICAL PULSE STRETCHING AND COMPRESSING

摘要

Ablative material removal with a series of high-power, ultra-short (e.g., sub-picosecond) optical pulses is especially useful for a number of purposes (including medical) as the ablation is essentially non-thermal and applies essentially no pressure to the surface. In order to amplify the pulse to a reasonable power level, ablative pulses are created by generating low-power, ultra-short pulses, which are then stretched, amplified, and compressed back to ultra-short durations. The present invention provides a method for temporally stretching or compressing optical pulses containing a band of wavelengths by inputting a tilted collimated beam (56), spatial-spreading the beam (56), spatial-narrowing the beam (56), spatial-spreading the beam (56), spatial-narrowing the beam (56), and collimating the output beam (52), wherein path length and delay vary by wavelength and the pulses are temporally modified, and wherein the tilt causes the beam (56) to hit at least one of the gratings (54) more than once at a different line or point.