Spatial light modulator

About: Spatial light modulator is a research topic. Over the lifetime, 9043 publications have been published within this topic receiving 130143 citations.

Complex amplitude reflectance of the liquid crystal light valve.

Abstract: The complex amplitude reflectance of the liquid crystal light valve (LCLV) is determined as a function of the writing intensity and applied voltage using an approximate model. The input and output polarizers are assumed to have arbitrary directions. The theoretical results based on this model match our experimental measurements. This theory allows us to optimize the operation of the LCLV as an intensity or phase-only spatial light modulator. When the polarizers are orthogonal and the input polarizer is at -34 degrees with the front liquid crystal director, the intensity reflectance reaches 100% (compared to 81% for the conventional configuration). Phase-only modulation is realizable by use of appropriate applied voltage bias and configuration of polarizers.

Optical Sectioning Fluorescence Spectroscopy in a Programmable Array Microscope

Abstract: We report the use of a programmable array microscope (PAM) for the acquisition of spectrally resolved and high-throughput optical sections. The microscope is based on the use of a spatial light modulator for defining patterns of excitation and/or detection of fluorescence. For obtaining optically sectioned spectral images, the entrance slit of an imaging spectrograph and a line illumination pattern defined with a spatial light modulator are placed in conjugate optical positions. Compared to wide-field illumination, optical sectioning led to greater than 3 X improvement in the rejection of outof-focus fluorescence emission and nearly 6 X greater peak-to-background ratios in biological specimens, yielding better contrast and spectral characterization. These effects resulted from a reduction in the artifacts arising from spectral contributions of structures outside the region of interest. We used the programmable illumination capability of the spectroscopic system to explore a variety of excitation/detection patterns for increasing the throughput of optical sectioning microscopes. A Sylvester-type Hadamard construction was particularly efficient, performing optical sectioning while maintaining a 50% optical throughput. These results demonstrate the feasibility of full-field highly multiplexed confocal spectral imaging.

Coherent inverse scattering via transmission matrices: Efficient phase retrieval algorithms and a public dataset

Abstract: A transmission matrix describes the input-output relationship of a complex wavefront as it passes through/reflects off a multiple-scattering medium, such as frosted glass or a painted wall. Knowing a medium's transmission matrix enables one to image through the medium, send signals through the medium, or even use the medium as a lens. The double phase retrieval method is a recently proposed technique to learn a medium's transmission matrix that avoids difficult-to-capture interferometric measurements. Unfortunately, to perform high resolution imaging, existing double phase retrieval methods require (1) a large number of measurements and (2) an unreasonable amount of computation. In this work we focus on the latter of these two problems and reduce computation times with two distinct methods: First, we develop a new phase retrieval algorithm that is significantly faster than existing methods, especially when used with an amplitude-only spatial light modulator (SLM). Second, we calibrate the system using a phase-only SLM, rather than an amplitude-only SLM which was used in previous double phase retrieval experiments. This seemingly trivial change enables us to use a far faster class of phase retrieval algorithms. As a result of these advances, we achieve a 100x reduction in computation times, thereby allowing us to image through scattering media at state-of-the-art resolutions. In addition to these advances, we also release the first publicly available transmission matrix dataset. This contribution will enable phase retrieval researchers to apply their algorithms to real data. Of particular interest to this community, our measurement vectors are naturally i.i.d. subgaussian, i.e., no coded diffraction pattern is required.

Methods involving direct write optical lithography

Abstract: An improved optical photolithography system and method provides predetemined light patterns generated by a direct write system without the use of photomasks. The Direct Write System provides predetermined light patterns projected on the surface of a substrate (e.g., a wafer) by using a computer controlled component for dynamically generating the predetermined light pattern, e.g., a spatial light modulator. Image patterns are store in computer and through electronic control of the spatial light modulator directly illuminate the wafer to define a portion of the polymer array, rather than being defined by a pattern on a photomask. Thus, in the Direct Write System each pixel is illuminated with an optical beam of suitable intensity and the imaging (printing) of an individual feature is determined by computer control of the spatial light modulator at each photolithographic step without the use of a photomask. The Direct Write System including a spatial light modulator is particularly useful in the synthesis of DNA arrays and provides an efficient element for polymer array synthesis by using spatial light modulators to generate a predetermined light pattern that defines the image patterns of a polymer array to be deprotected.

Application of dynamic diffractive optics for enhanced femtosecond laser based cell transfection

Abstract: We demonstrate the advantages of a dynamic diffractive optical element, namely a spatial light modulator (SLM) for the controlled and enhanced optoinjection and phototransfection of mammalian cells with a femtosecond light source. The SLM provides full control over the lateral and axial positioning of the beam with sub-micron precision. Fast beam translation enables time-sequenced irradiation, which is shown to enhance the optoinjection efficiency and alleviate the problem of exact beam positioning on the cell membrane. We show that irradiation in three axial positions doubles the number of viably optoinjected cells when compared with a single dose. The presented system also enables untargeted raster scan irradiation which provides a higher throughput transfection of adherent cells at the rate of 1 cell per second. Additionally, fluorescent imaging is used to demonstrate cell selective two-step gene therapy. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)