Phase Quantization Study of Spatial Light Modulator for Extreme High contrast Imaging

TL;DR

This study investigates the phase quantization of spatial light modulators (SLMs) for high-contrast exoplanet imaging, analyzing how phase accuracy and actuator count influence wave-front control effectiveness.

Contribution

It provides a numerical simulation framework to determine SLM specifications needed for extreme high contrast imaging, comparing configurations and actuator impacts.

Findings

Higher actuator counts improve contrast performance.

Phase accuracy constraints are critical for effective wave-front control.

SLMs can match deformable mirrors in delivering high contrast.

Abstract

Direct imaging of exoplanets by reflected starlight is extremely challenging due to the large luminosity ratio to the primary star. Wave-front control is a critical technique to attenuate the speckle noise in order to achieve an extremely high contrast. We present a phase quantization study of a spatial light modulator for wave front control to meet the contrast requirement of detection of a terrestrial planet in the habitable zone of a solar-type star. We perform the numerical simulation by employing the SLM with different phase accuracy and actuator numbers, which are related to the achievable contrast. We use an optimization algorithm to solve the quantization problems that is matched to the controllable phase step of the SLM. Two optical configurations are discussed with the SLM located before and after the coronagraph focal plane mask. The simulation result has constrained the specification for SLM phase accuracy in the above two optical configurations. Finally, we have demonstrated that a SLM with more actuators can deliver a competitive contrast performance to that by using a deformable mirror.