Pulse compression using segmented grating in Gekko MII system, ILE

A segmented (tiled) grating array is now investigated as a new compressor system for the reason of manufacturing cost of large aperture single grating. However the considerable freedom of motion of segment arises new difficulties on pulse compression and focusing. We constructed a real compressor system using a segmented grating for 15cm aperture laser beam at Gekko MII 100TW laser system, ILE, for investigating several alignment techniques. In order to produce clean pulse shape and focused pattern generated by misalignments or line density mismatching between segment gratings, we applied the image rotation technique as a compressor arrangement. In addition to reduce uncertainness of motion of all optics, we introduced several sensor/detector such as laser level meter or position sensor. It is also shown that a capacitance detector can keep the perfect flatness of segmented grating surface. Using these techniques we demonstrated pulse compression close to Fourier transform limit.