Laser recording with truncated Gaussian beams.

Laser recording with a Gaussian beam and focusing lens of finite aperture is analyzed. It is shown that, for a given recorded spot size, optimal values exist for the lens f/number and filling factor, the ratio of Gaussian beam diameter to lens diameter, which minimize power. Sensitivity curves are presented for power vs f/number and vs filling factor. The on-axis focal plane intensity is maximized by deviating from the optimal filling factor at the expense of a slight power increase. Effects of power variations on recorded spot size are considered.