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A TUTORIAL ON WAVEFRONT SHAPING WITH SPATIAL LIGHT MODULATORS:
THE NEXT GENERATION OF POSSIBILITIES
Monika Ritsch-Marte
Division for Biomedical Physics, Medical University of Innsbruck, Austria E-mail: [email protected]
KEY WORDS: spatial light modulators, wavefront shaping, Fourier filtering in microscopy, aberration correction, phase contrast, quantitative phase imaging, artifact reduction in phase microscopy, optical tweezers.
This tutorial exemplifies the state-of-the-art in applications of liquid-crystal based spatial light modulators (SLMs) in optical microscopy. After a brief introduction on SLMs in general, it will be explained how an SLM can act as a programmable Fourier filter, to emulate various contrast mechanisms such as bright field, dark field, (spiral) phase contrast, or differential in-terference contrast (DIC) [1]. Some examples demonstrating the great flexibility the SLM-based “synthetic holography” approach offers will be given, e.g. holographic multiplexing in order to target multiple focal planes or to combine images of different parameter settings in one exposure.
Recently demonstrated possibilities brought about by SLMs that are able to phase-shift the wave by several multiples of 2π will be emphasized. It will be discussed how this feature can be utilized, for instance, to speed up the effective time required for updating the pattern, or to imprint several dedicated holograms to be read out by different wavelengths, e.g. one for im-aging in the visible and one for trapping in the near-infrared, by one and the same pattern, cf. Fig.1. The tutorial concludes with summarizing the overall advantages and limitations for in-corporating an SLM panel into an optical microscope set-up.
Figure 1: Multi-color wavefront shaping with a LC-SLM.
[1] C. Maurer, A. Jesacher, S. Bernet, and M. Ritsch-Marte: „SLM-Microscopy: What spatial light modulators can do for microscopy“, Lasers and Photonics Reviews, 5, 81-101 (2011)
