Designing a new spatial light modulator for holographic photostimulation

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-tohologram speed at 1064 nm operating wavelength, and discuss the new science that these speeds and array sizes have enabled.

Design framework for high-speed 3D scanning tools and development of an axial focusing micromirror-based array

“…Spot intensity drops as target depth increases in either direction because escalating defocus requires sharper radial phase gradients and, in discrete array systems such as ones with micromirrors, efficiency scales inversely with phase gradient under a 2 relationship. 25 We find that the dynamic dioptric power range of the array alone (excluding the contribution of the offset lens) is ±2.89 diopters, which is comparable the ranges of commercially available optofluidic lenses that also make use of offset lenses. 26 In addition, as shown in Figure 5(b), lateral spot dimensions do not deviate significantly from the diffraction-limited spot size set by the aperture, focal length and wavelength of the optical system.…”

Large-scale Ising emulation with four body interaction and all-to-all connections

“…The relaxation of the spin system to its ground state, on the other hand, is achieved through feedback control. To speed it up, field-programmable gate arrays (FPGAs) or fieldprogrammable photonic gate arrays (FPPGAs) can be employed in the future [60][61][62] .…”

“…Yet, the main limitation with our current setup comes from the slow response of the SLM's. To establish a practical advantage, we will need to replace the SLM's with fast digital micromirrors controlled by FPGA, use all-optical feedback, or design hybrid optical-FPPGA hardwares [60][61][62] . Meanwhile, although the present optical Ising machine only supports two and four-body interactions, other processes of nonlinear optics, such as sum frequency, four-wave mixing, and high-order harmonic generation, can be employed to realize even higher-order interactions, whose computational complexity and intensity could quickly grow beyond the capability of existing computing platforms.…”

Folded optical design for high fidelity atmospheric emulation with a spatial light modulator

“…This will enable us to use the ALF-G to perform code word error rate testing of a photon counting real-time receiver. Other future work will include the build and testing of a C-band ALF-G capable of real time emulation of Greenwood frequencies in the hundreds of hertz using SLM's newly on the market in the last few years 21,22 . These new systems may allow the SLM method to overcome its main drawback when compared to rotating phase plates.…”