Use of induced spatial incoherence for uniform illumination on laser fusion targets. Memorandum report

We report a technique to achieve very uniform illumination of laser irradiated targets by inducing a controlled amount of transverse spatial incoherence in the output beam of a broadband laser. The spatial incoherence is created by imposing different optical delays upon different transverse sections of the beam, and choosing the delay increments to be larger than the laser coherence time tc = 1 delta. This technique may allow easy attainment of the pellet illumination uniformity required for laser fusion.