Beam homogenization model of frosted glass in laser interferometer systems

A ring source suppresses diffraction-induced annular coherent noise in interferometry, but a solid ring source can generate a central bright spot during propagation, degrading surface figure accuracy. This paper builds a frosted glass beam homogenization model to compute the minimum correlation length required to suppress the spot for different diffusers and proposes correlation length inversion and quantitative calibration using RMS roughness and angular scattering intensity. At 632.8 nm, simulations show that a 600 mesh double-sided frosted glass is effective. A prototype interferometer matches a Zygo interferometer within 2.34 nm PV and 0.83 nm RMS.