Complex modulation characterization of liquid crystal devices by interferometric data correlation

Martı́n-Badosa, Estela; Carnicer, Artur; Juvells, Ignasi; Vallmitjana, Santiago

doi:10.1088/0957-0233/8/7/011

Cited by 37 publications

(29 citation statements)

References 12 publications

(14 reference statements)

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“…The wavefront aberration was then measured, and a conjugated correction phase (modulo 2π) was displayed on the SLM, taking into account its modulation curve [32,33]. This relates phase modulation with the gray level displayed; as images on the sensor have only 22 × 24 pixels, gray level values of the remaining pixels of the SLM were computed by interpolation.…”

Section: Experimental Setup and Proceduresmentioning

confidence: 99%

“…We used an LCoS reflective SLM (Holoeye LC-R 2500), which has an active area of 19:5 mm × 14:6 mm and supports digital video interface (DVI) signals with a resolution of 1024 × 768 pixels (pixel pitch 19 μm, fill factor 93%) [28]. The SLM was tilted 45°with respect to the optical axis [31] and sandwiched between two linear polarizers (P1 and P2) with proper orientations to provide phase-mostly modulation [32,33]. A beam splitter divides the beam in two: one half enters a commercial microscope to trap microscopic particles; the other is redirected to a SH wavefront sensor.…”

Section: Introductionmentioning

confidence: 99%

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Correction of aberration in holographic optical tweezers using a Shack-Hartmann sensor

2009

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Optical aberration due to the nonflatness of spatial light modulators used in holographic optical tweezers significantly deteriorates the quality of the trap and may easily prevent stable trapping of particles. We use a Shack-Hartmann sensor to measure the distorted wavefront at the modulator plane; the conjugate of this wavefront is then added to the holograms written into the display to counteract its own curvature and thus compensate the optical aberration of the system. For a Holoeye LC-R 2500 reflective device, flatness is improved from 0:8λ to λ=16 (λ ¼ 532 nm), leading to a diffraction-limited spot at the focal plane of the microscope objective, which makes stable trapping possible. This process could be fully automated in a closed-loop configuration and would eventually allow other sources of aberration in the optical setup to be corrected for.

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Section: Experimental Setup and Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Correction of aberration in holographic optical tweezers using a Shack-Hartmann sensor

2009

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“…When a constant reference grey level is displayed on one half of the modulator and the remaining values are sequentially displayed on the other half, shifted interference fringes can be seen on the CCD image. The relative phase shift φ can be accurately measured with the fringe analysis method described in [30], as:…”

Section: Characterization: Phase-only Configurationmentioning

confidence: 99%

Design strategies for optimizing holographic optical tweezers set-ups

Martı́n-Badosa¹,

Montes-Usategui²,

Carnicer³

et al. 2007

J. Opt. A: Pure Appl. Opt.

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Abstract. We provide a detailed account of the construction of a system of holographic optical tweezers. While a lot of information is available on the design, alignment and calibration of other optical trapping configurations, those based on holography are relatively poorly described. Inclusion of a spatial light modulator in the setup gives rise to particular design trade-offs and constraints, and the system benefits from specific optimization strategies, which we discuss.

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“…Figure 2(a) is a polar diagram of the set of complex values accessible by modulators SLM 1 (blue dots) and SLM 2 (red dots). Both curves have been determined using the method presented in [20], which is appropriate for transmissive twisted-nematic modulators. nm and M (2) nm are required to encode each complex value, C nm .…”

Section: Codification Proceduresmentioning

confidence: 99%

Reconfigurable beams with arbitrary polarization and shape distributions at a given plane

Maluenda¹,

Juvells²,

Martı́nez-Herrero³

et al. 2013

Opt. Express

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Methods for generating beams with arbitrary polarization based on the use of liquid crystal displays have recently attracted interest from a wide range of sources. In this paper we present a technique for generating beams with arbitrary polarization and shape distributions at a given plane using a Mach-Zehnder setup. The transverse components of the incident beam are processed independently by means of spatial light modulators placed in each path of the interferometer. The modulators display computer generated holograms designed to dynamically encode any amplitude value and polarization state for each point of the wavefront in a given plane. The steps required to design such beams are described in detail. Several beams performing different polarization and intensity landscapes have been experimentally implemented. The results obtained demonstrate the capability of the proposed technique to tailor the amplitude and polarization of the beam simultaneously.

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Complex modulation characterization of liquid crystal devices by interferometric data correlation

Cited by 37 publications

References 12 publications

Correction of aberration in holographic optical tweezers using a Shack-Hartmann sensor

Correction of aberration in holographic optical tweezers using a Shack-Hartmann sensor

Design strategies for optimizing holographic optical tweezers set-ups

Reconfigurable beams with arbitrary polarization and shape distributions at a given plane

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