[OPTICAL REVIEW Vol. 5, No. 4 (1998) 234-241]

Study of Serrated Aperture for a Cassegrain Booster Amplifier

Thierry BONTOUX, Taku SAIKI, Tadashi KANABE, Hisanori FUJITA and Masahiro NAKATSUKA

Institute of laser Engineering, Osaka University, 2-6, Yamada-oka, Suita, Osaka, 565-0871 Japan

(Received May 30, 1998; Accepted June 17, 1998)

The upgrade of the actual large laser facilities (GEKKO XII in our case) implies an increase of filling-factor, but avoiding the generation of spatial high frequencies. To reach that purpose we intend to construct the beams using serrated apertures with an optimised shape. The performances of our system led after simulation to a 70% filling factor with less than 2% fluctuation on the laser pattern intensity map. The optimisation was also checked from a financial point of view. The usual serrated apertures are already giving good results, so we attached ourselves to seek for financial effciency.

Key words : filling factor, optimisation, serration, mask, aperture, intensity fluctuation, spatial frequencies, Fourier transform