Simulating the beam steering accuracy and efficiency of a pixelated micromirror phase light modulator

Diffractive laser-based beam steering using pixelated phase spatial light modulators (SLMs) are an attractive alternative to mechanical monolithic-mirror systems because of their speed, programmability, and mechanical stability. Monolithic-mirror systems are limited in steering accuracy only by the mechanics with which the mirror is being steered. Diffractive steering devices, however, are limited in both steering accuracy and efficiency because of their pixelated structure as well as limited and discretized phase levels, which are sometimes unequally distributed. To quantify these limitations, we use Fourier analysis to simulate laser beam steering using a pixelated phase-based SLM. We use actual mirror response data to numerically evaluate the beam steering accuracy and efficiency of the 0.67 Texas Instruments Phase Light Modulator (TI-PLM) in both the visible and infrared. We find that both beam steering accuracy and efficiency are a function of steering angle if the beam is steered with integer-pixel gratings. Our analysis shows that the beam steering efficiency at the device’s design wavelength λ = 532nm is about 85% efficient and that the steering error is less than 0.5 µrad and varies at most within 1% of the diffraction limited spot size at that wavelength. We additionally find that if the device is used at λ = 1550nm the beam steering efficiency is about 10% and the steering error is less than 30 µrad and varies at most within 14% of the diffraction limited spot size at that wavelength.