Relative limitations of increasing the number of modulation levels in computer generated holography

TL;DR

This paper compares the effectiveness of increasing modulation levels in phase and amplitude spatial light modulators for holography, revealing that multi-level phase SLMs significantly improve quality, while amplitude SLMs show limited benefits.

Contribution

The study provides a comparative analysis of multi-level versus binary modulation in phase and amplitude SLMs, highlighting the limited advantages for amplitude devices.

Findings

Multi-level phase SLMs produce higher quality holograms than binary phase SLMs.

Multi-level amplitude SLMs offer only marginal improvements over binary amplitude SLMs.

Heuristic and numerical analyses support the limited benefits of increasing modulation levels in amplitude SLMs.

Abstract

Phase and amplitude spatial light modulators (SLMs) capable of both binary and multi-level modulation are widely available and offer a wide range of technologies to choose from for holographic applications. While the replay fields generated with multi-level phase-only SLMs are of a significantly higher quality than those generated by equivalent binary phase-only SLMs, evidence is presented in this letter that this improvement is not as marked for amplitude SLMs, where multi-level devices offer only a small benefit over their binary counterparts. Heuristic and numerical justifications for this are discussed and conclusions drawn.