Multipoint phase calibration for improved compensation of inherent wavefront distortion in parallel aligned liquid crystal on silicon displays

Otón, Joaquı́n; Ambs, Pierre; Millán, Marı́a S.; Pérez‐Cabré, Elisabet

doi:10.1364/ao.46.005667

Cited by 94 publications

(58 citation statements)

References 37 publications

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“…Strictly speaking, a lateral derivative of this error is added to the observed pattern. Taking into account that the typical errors due to the curvature are of the order of λ over the area of a typical SLM [9][10][11][12], and also that a typical aperture can contain approximately 1000 elementary cells in one direction, the magnitude of this error over one elementary cell can be evaluated as being of order of λ/1000. As an important practical consideration, the observation should be performed in the first Fresnel plane, where the shear value is the smallest and thereby this residual phase error is also minimum.…”

Section: Resultsmentioning

confidence: 99%

“…In all cases, it is critical to perform an experimental determination of the spatial phase distribution of the SLM as a function of the parameter that controls the signal applied to the device (typically, the gray-level of the image displayed by commercial LC devices). A lack of spatial uniformity in the phase response of a SLM can appear due to addressing errors or to factors that are voltage-independent, as, for example, the curvature of the surface device, which causes variations in the LC thickness [8][9][10]. In the case of widespread used liquid crystal on silicon (LCoS) displays, the reflected wavefronts can be distorted by the curvature of the silicon backplane [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…A lack of spatial uniformity in the phase response of a SLM can appear due to addressing errors or to factors that are voltage-independent, as, for example, the curvature of the surface device, which causes variations in the LC thickness [8][9][10]. In the case of widespread used liquid crystal on silicon (LCoS) displays, the reflected wavefronts can be distorted by the curvature of the silicon backplane [9][10][11]. Typical magnitudes of this kind of phase errors are of the order of λ over the aperture of the device.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Phase calibration of spatial light modulators by means of Fresnel images

Martínez-León¹,

Jaroszewicz²,

Kołodziejczyk³

et al. 2009

J. Opt. A: Pure Appl. Opt.

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Reliable application of spatial light modulators (SLMs) as programmable diffractive optical elements requires a thorough calibration. In this paper, we propose a method for calibrating SLMs based on the evaluation of Fresnel images. Fresnel images generated by a binary phase diffraction grating consist of binary irradiance distributions whose visibility depends on the phase modulation. By displaying on our device a diffraction grating with a binary phase step along one direction and a linearly increasing phase along the orthogonal direction, we perform a complete phase calibration. In this way, the phase modulation for every pixel and for every value of the entrance signal can be determined experimentally.Additionally, data acquisition can be significantly simplified with this scheme.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Phase calibration of spatial light modulators by means of Fresnel images

Martínez-León¹,

Jaroszewicz²,

Kołodziejczyk³

et al. 2009

J. Opt. A: Pure Appl. Opt.

View full text Add to dashboard Cite

show abstract

“…The reconstructed images were recorded and processed with the use of a SP620-USB CCD-camera of Spiricon Inc. with a high dynamic range. As known (Oton et al, 2007), the spatial calibration of reflective LCoS SLM is essential for the correct use of the modulator in applications with high requirements of the wavefront control. We determined the additional phase 2D-distribution compensating the distortions of a wave front which appear due to the imperfection of SLM (backplane curvature, thickness variations of the liquid crystal layer across the aperture of the SLM, and so on) and elements of the optical system, by using the interference-based method proposed by Oton et al (2007).…”

Section: Optical-digital Systemmentioning

confidence: 99%

Weighting Iterative Fourier Transform Algorithm for Kinoform Implemented with Liquid-Crystal SLM

Kuzmenko¹,

Iezhov²,

Kim³

2011

Fourier Transforms - Approach to Scientific Principles

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“…The SLM curvature was measured using a Michelson interferometer, and was corrected for in the experiment. 10 During the recording stage, a focused US transducer (Olympus NDT, V324-SU) emitted 800-ns US pulses repeatedly every 30 ls into the sample. The focal length of the US transducer was 14 mm.…”

mentioning

confidence: 99%

Frequency-swept time-reversed ultrasonically encoded optical focusing

Suzuki

Wang

2014

Applied Physics Letters

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A technique to rapidly scan an optical focus inside a turbid medium is attractive for various biomedical applications. Time-reversed ultrasonically encoded (TRUE) optical focusing has previously demonstrated light focusing into a turbid medium, using both analog and digital devices. Although the digital implementation can generate a focus with high energy, it has been time consuming to scan the TRUE focus inside a sample. Here, by sweeping the frequencies of both ultrasound and light, we demonstrate a multiplex recording of ultrasonically encoded wavefronts, accelerating the generation of multiple TRUE foci. Using this technique, we obtained a 2-D image of a fluorescent target centered inside a turbid sample having a thickness of 2.4 transport mean free paths. Fluorescence imaging is widely used to obtain biological images by scanning an optical focus. 1 However, due to scattering, optical focusing using an ordinary lens is limited to shallow depths of one transport mean free path, or 1 l t 0 ($1 mm in human skin), 2 beyond which scattering both reduces the amount of light arriving at the target and blurs the resulting image.One way to overcome this limitation is to use timereversed ultrasonically encoded (TRUE) focusing. 3,4 In TRUE focusing, a focused ultrasonic (US) pulse, applied inside a turbid sample, frequency modulates (or encodes) light within the acoustic volume. A phase-conjugated version of the encoded wavefront is then generated, using either analog or digital phase conjugate mirrors (PCMs). 3-6 Digital PCMs, consisting of a camera and a spatial light modulator (SLM), are attractive for higher energy focusing. [4][5][6] To record the encoded wavefront, a reference beam interferes with the encoded light on the camera, causing the intensity of the interferogram to beat at their difference frequency. 6 The encoded wavefront is extracted from the beat, and then its phase-conjugated version is reproduced using the SLM. Upon back-propagation to the sample, the phase-conjugated beam forms an optical focus at the original location of the ultrasound volume.It has been previously shown that TRUE focusing improves the resolution, thereby allowing deep fluorescence imaging beyond 1 l t 0 inside a scattering medium. 4-6 However, one of the challenges of applying digital TRUE focusing for imaging was the long time (several seconds) taken to generate a single optical focus. 5,6 The low signal-to-noise ratio (SNR) of the encoded-light detection typically mandates that multiple frames of interferograms be recorded and averaged to obtain a single encoded wavefront.Here, we propose a method called frequency-swept TRUE focusing, which takes advantage of the multiple recorded frames used for encoded-light detection to accelerate TRUE focal scanning. By sweeping the frequency of both the ultrasound and the light at the same time, we achieve simultaneous recording of multiple wavefronts, corresponding to different positions along the acoustic axis, without sacrificing SNR and using the same number of camera frames. A simi...

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Multipoint phase calibration for improved compensation of inherent wavefront distortion in parallel aligned liquid crystal on silicon displays

Cited by 94 publications

References 37 publications

Phase calibration of spatial light modulators by means of Fresnel images

Phase calibration of spatial light modulators by means of Fresnel images

Weighting Iterative Fourier Transform Algorithm for Kinoform Implemented with Liquid-Crystal SLM

Frequency-swept time-reversed ultrasonically encoded optical focusing

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