Wavefront shaping in complex media with a 350 kHz modulator via a 1D-to-2D transform

Abstract

Controlling the propagation and interaction of light in complex media has sparked major interest in the last few years. Unfortunately, spatial light modulation devices suffer from limited speed that precludes real-time applications such as imaging in live tissue. To address this critical problem we introduce a phase-control technique to characterize complex media based on the use of fast 1D spatial light modulators and a 1D-to-2D transformation performed by the same medium being analyzed. We implement the concept using a micro-electro-mechanical grating light valve (GLV) with 1088 degrees of freedom modulated at 350 KHz, enabling unprecedented high-speed wavefront measurements. We continuously measure the transmission matrix, calculate the optimal wavefront and project a focus through various dynamic scattering samples in real-time, all within 2.4 ms per cycle. These results improve prior wavefront shaping modulation speed by more than an order of magnitude and open new opportunities for optical processing using 1D-to-2D transformations.

Fast optical wavefront engineering for controlling light propagation in dynamic turbid media

“…In 2018, by adopting the 1 D grating light valve (GLV) with a refresh rate as high as 350 kHz as the phase playing device, Tzang et al promoted the speed of their TM measurement system by four orders of magnitude compared to those based on LC-SLM. 82 For 256 input modes, the total time length of 768 measurements used for con¯rming TM was 2.15 ms. Adding the times for data transfer and computing, the total latency of this TM-based WFE was 2.4 ms, i.e., average mode time was 9.4 s.…”

Real-time frequency-encoded spatiotemporal focusing through scattering media using a programmable 2D ultrafine optical frequency comb

“…Wavefront compensation is usually performed using a standard component called a spatial light modulator (SLM), which provides a large number of tiny light controllers to generate an optimal wavefront. State-of-the-art SLMs, such as SLMs based on ferroelectric liquid crystals (9), micro-electro-mechanical systems (MEMSs) (10), digital micromirror devices (11,12), and grating light valves (GLVs) (13), can operate at tens to hundreds of kilohertz, resulting in a response time on the orders of microseconds. However, wavefront measurement, as an active process, lags the compensation process in terms of response time, typically ranging from seconds to minutes.…”

“…The former two approaches obtain the optimal wavefront through an iterative process that typically experiences thousands of measurements, which scales linearly with the number of control modes and results in a long system runtime that can easily take up to a few hours. MEMSbased SLMs associated with field-programmable gate array electronics and one-dimensional (1D) GLV phase modulators have recently been used to reduce system runtimes (10,13). However, the number of control modes (or degrees of freedom) is limited to a few tens when the response times are on a millisecond scale, which inhibit their usefulness for biomedical applications.…”

Imaging through highly scattering environments using ballistic and quasi-ballistic light in a common-path Sagnac interferometer

“…Next to the recovery of weak ballistic components, detection and imaging of objects using the scattered light itself is seeing seen rapidly increasing interest [9][10][11][12][13][14]. While significant progress is being made to speed up reconstruction of scattered information [15], in many dynamic scattering environments the decorrelation times are still too short for speckle-based reconstruction methods.…”