Diffraction Studies with Plane-Parallel Maser Interferometer

A helium-neon optical maser tube with high-quality fused quartz windows at the Brewster angle supports oscillations between external plane mirrors at 6328 Å, 1.15 μ, and 3.39 μ, producing over 40 mW at 1.15 μ and 28 mW at 3.39 μ in the dominant TEM00 mode. Calculations of Fox and Li are verified by means of apertures inside the resonator. Patterns made with various obstacles in the resonator bear a blurred resemblance to those made with the same obstacles in the 1-cm beam outside the resonator.