Kilohertz binary phase modulator for pulsed laser sources using a digital micromirror device

TL;DR

This paper presents a novel optical design that enables high-speed, dispersion-free binary phase modulation using a digital micromirror device, suitable for pulsed laser applications like nonlinear microscopy.

Contribution

The authors develop a DMD-based phase modulation method that overcomes inherent amplitude modulation and dispersion issues, enabling 20 kHz binary phase pattern switching.

Findings

Achieves dispersion-free binary phase modulation with DMD

Enables 20 kHz switching in two-photon fluorescence

Overcomes limitations of amplitude-only DMD modulation

Abstract

The controlled modulation of an optical wavefront is required for aberration correction, digital phase conjugation or patterned photostimulation. For most of these applications it is desirable to control the wavefront modulation at the highest rates possible. The digital micromirror device (DMD) presents a cost-effective solution to achieve high-speed modulation and often exceeds the speed of the more conventional liquid crystal spatial light modulator, but is inherently an amplitude modulator. Furthermore, spatial dispersion caused by DMD diffraction complicates its use with pulsed laser sources, such as those used in nonlinear microscopy. Here we introduce a DMD-based optical design that overcomes these limitations and achieves dispersion-free high-speed binary phase modulation. We show that this phase modulation can be used to switch through binary phase patterns at the rate of 20 kHz in two-photon excitation fluorescence applications.