Designing a new spatial light modulator for holographic photostimulation

TL;DR

This paper presents the design, construction, and testing of a high-speed, large-field-of-view liquid crystal spatial light modulator for holographic photostimulation, enabling faster and more extensive neural stimulation experiments.

Contribution

The authors developed a novel LCoS SLM with high resolution and speed, including custom hardware and FPGA algorithms, to significantly improve holographic photostimulation capabilities.

Findings

Achieved 500 Hz hologram update rate at 1064 nm wavelength.

Designed a custom FPGA system for high data throughput.

Demonstrated enhanced science applications with increased speed and field of view.

Abstract

Driven by the demands for speed and field of view in the holographic photostimulation community, we designed, built, and tested a liquid crystal on silicon (LCoS) spatial light modulator (SLM) with a 1536x1536 square pixel array and high-voltage LC drive. We discuss some of the engineering work that made the MacroSLM possible, including the custom FPGA board for handling huge data rates, the large pixel size for minimizing rolloff and crosstalk, and the temperature control to handle heating effects from the high-voltage controls and high-power laser illumination. We also designed an FPGA implementation of the overdrive method for increasing liquid crystal switching speed, allowing us to overcome the significant data bottlenecks that limit frame rates for large arrays. We demonstrate 500 Hz hologram-to-hologram speed at 1064 nm operating wavelength, and discuss the new science that these speeds and array sizes have enabled.