Optimization of a spatial light modulator driven by digital video interface graphics to generate holographic optical traps

Transmission matrix-based phase correction for optical systems

The demands in fields such as biology and communications are driving the development of structured light. However, the optical modulation devices which play an important role in generating structured light, often introduce phase distortion. Additional phase correction is required to obtain more precise modulation capabilities. In this Letter, we propose a transmission matrix (TM)-based phase correction method. With the measured TM, which establishes a link between the spatial light modulator (SLM) panel and the far-field distribution of the output, we can obtain the phase modulation achieving the ideal focus. The spatial distribution of the phase distortion can be extracted from the conjugate of this phase distribution. In our experiment, the sharpness metric of the focus dropped to about half. We further verified the availability of this method by correcting the phase distortion of Laguerre-Gaussian (LG) fields. We believe our method provides a simple way to achieve precise phase correction, which will be of interest in aspects of wavefront shaping and optical tweezers.

Recent progress in digital holography with dynamic diffractive phase apertures [Invited]

Digital holography with diffractive phase apertures is a hologram recording technique in which at least one of the interfering waves is modulated by a phase mask. In this review, we survey several main milestones on digital holography with dynamic diffractive phase apertures. We begin with Fresnel incoherent correlation holography (FINCH), a hologram recorder with an aperture of a diffractive lens. FINCH has been used for many applications such as 3D imaging, fluorescence microscopy, superresolution, image processing, and imaging with sectioning ability. FINCH has played an important role by inspiring other digital holography systems based on diffractive phase aperture, such as Fourier incoherent single-channel holography and coded aperture correlation holography, which also are described in this review.

Phase response optimization of a liquid crystal spatial light modulator with partially coherent light

This paper demonstrates a method to determine and calibrate the modulation characteristics of a liquid crystal spatial light modulator (SLM) for on-axis phase response with partially coherent light. A polarimetric approach has been implemented to obtain the phase characterization curve of the SLM. The corrections for phase response errors exhibited by SLM have been incorporated through encoded grayscale patterns to ensure a spatially uniform phase response and a linear relationship between addressed phase and phase delay by SLM. In this approach, corrections can be applied at selective pixels of the SLM's display without altering its gamma curve. Experimental results are presented that verify the feasibility of the proposed approach.

Calibration of a phase-only spatial light modulator for both phase and retardance modulation

Liquid crystal spatial light modulators (SLMs) are usually configured and calibrated for phase modulation. However, as they are variable retarders, they also have application as polarization modulators. We show that conventional phase-only calibrations are insufficient for this purpose, and a separate retardance calibration is needed. To overcome this shortcoming we report a simple Twyman-Green interferometer-based setup to realize SLM phase and retardance calibration. For phase calibration, we identify the non-linear, spatially variant response to the drive voltage of the SLM using fringe analysis and both horizontally and vertically polarized incident light. For retardance calibration, we use incident light polarized at 45° and assess the intensity variation. The methods presented are compatible with in situ calibration of SLMs.