Generation of coherent wavefronts and images inside laser resonators
Résumé
We describe a new type of laser mode filtering using two complementary spatial filters located against the plane mirrors of a confocal lens resonator. With Nd/YAG as amplifying medium, we report the synthesis of two particular waves: a sinusoidally modulated wavefront, and a uniphase beam with a flat spatial profile and minimal divergence. The temporal evolution of the beam under construction is also recorded. The process is a new type of wavefront reconstruction, like holography, but without reference.