Parallel phase-shifting digital holography with adaptive function using phase-mode spatial light modulator

May, 2012

Author(s): Miao Lin, Kouichi Nitta, Osamu Matoba, and Yasuhiro Awatsuji

Abstract:

“Parallel phase-shifting digital holography using a phase-mode spatial light modulator (SLM) is proposed. The phase-mode SLM implements spatial distribution of phase retardation required in the parallel phase-shifting digital holography. This SLM can also compensate dynamically the phase distortion caused by optical elements such as beam splitters, lenses, and air fluctuation. Experimental demonstration using a static object is presented.”

Link to Publications Page

Publication: Applied Optics, (subscription required)

Issue/Year/DOI: Applied Optics, Vol. 51, Issue 14, pp. 2633-2637 (2012)
doi:10.1364/AO.51.002633


Determination of wavefront structure for a Hartmann Wavefront Sensor using a phase-retrieval method

March, 2012

Author(s): A. Polo, V. Kutchoukov, F. Bociort, S.F. Pereira, and H.P. Urbach

Abstract:

“We apply a phase retrieval algorithm to the intensity pattern of a Hartmann wavefront sensor to measure with enhanced accuracy the phase structure of a Hartmann hole array. It is shown that the rms wavefront error achieved by phase reconstruction is one order of magnitude smaller than the one obtained from a typical centroid algorithm. Experimental results are consistent with a phase measurement performed independently using a Shack-Hartmann wavefront sensor.”

Link to Publications Page

Publication: Optics Express, (free download)

Issue/Year/DOI: Optics Express, Vol. 20, Issue 7, pp. 7822-7832 (2012)
doi:10.1364/OE.20.007822


Pure two-dimensional polarization patterns for holographic recording

January, 2012

Author(s): Ulises Ruiz, Clementina Provenzano, Pasquale Pagliusi, and Gabriella Cipparrone

Abstract:

“Two-dimensional (2D) polarization patterns are achieved by the interference of two pairs of beams with perpendicular planes of incidence and orthogonal polarizations (i.e. linear or circular). In both cases, imposing a phase shift of π/2 between consecutive beams contains the amplitude modulation of the optical field in the superposition region and, thus, pure 2D polarization patterns are created. The recording of these interference fields in a polarization-sensitive material, namely an amorphous azopolymer, creates reconfigurable 2D periodic microstructures with peculiar diffraction properties.”

Link to Publications Page

Publication: Optics Letters, (subscription required)

Issue/Year/DOI: Optics Letters, Vol. 37, Issue 3, pp. 311-313 (2012)
doi:10.1364/OL.37.000311


Binocular adaptive optics vision analyzer with full control over the complex pupil functions

December, 2011

Author(s): Christina Schwarz, Pedro M. Prieto, Enrique J. Fernández, and Pablo Artal

Abstract:

“We present a binocular adaptive optics vision analyzer fully capable of controlling both amplitude and phase of the two complex pupil functions in each eye of the subject. A special feature of the instrument is its comparatively simple setup. A single reflective liquid crystal on silicon spatial light modulator working in pure phase modulation generates the phase profiles for both pupils simultaneously. In addition, another liquid crystal spatial light modulator working in transmission operates in pure intensity modulation to produce a large variety of pupil masks for each eye. Subjects perform visual tasks through any predefined variations of the complex pupil function for both eyes. As an example of the system efficiency, we recorded images of the stimuli through the system as they were projected at the subject’s retina. This instrument proves to be extremely versatile for designing and testing novel ophthalmic elements and simulating visual outcomes, as well as for further research of binocular vision.”

Link to Publications Page

Publication: Optics Letters, (subscription required)

Issue/Year/DOI: Optics Letters, Vol. 36, Issue 24, pp. 4779-4781 (2011)
doi:10.1364/OL.36.004779


Fabrication of microscale medical devices by two-photon polymerization with multiple foci via a spatial light modulator

October, 2011

Author(s): Shaun D. Gittard, Alexander Nguyen, Kotaro Obata, Anastasia Koroleva, Roger J. Narayan, and Boris N. Chichkov.

Abstract:

“Two-photon polymerization is an appealing technique for producing microscale devices due to its flexibility in producing structures with a wide range of geometries as well as its compatibility with materials suitable for biomedical applications. The greatest limiting factor in widespread use of two-photon polymerization is the slow fabrication times associated with line-by-line, high-resolution structuring. In this study, a recently developed technology was used to produce microstructures by two-photon polymerization with multiple foci, which significantly reduces the production time. Computer generated hologram pattern technology was used to generate multiple laser beams in controlled positions from a single laser. These multiple beams were then used to simultaneously produce multiple microstructures by two-photon polymerization. Arrays of micro-Venus structures, tissue engineering scaffolds, and microneedle arrays were produced by multifocus two-photon polymerization. To our knowledge, this work is the first demonstration of multifocus two-photon polymerization technology for production of a functional medical device. Multibeam fabrication has the potential to greatly improve the efficiency of two-photon polymerization production of microscale devices such as tissue engineering scaffolds and microneedle arrays.”

Link to Publications Page

Publication: Biomedical Optics Express, (free download)

Issue/Year/DOI: Biomedical Optics Express, Vol. 2, Issue 11, pp. 3167-3178 (2011)
doi:10.1364/BOE.2.003167


Coaxial holographic encoding based on pure phase modulation

September, 2011

Author(s): Wei Jia, Zhongyu Chen, Fung Jacky Wen, Changhe Zhou, Yuk Tak Chow, and Po Sheun Chung

Abstract:

“We describe a simple technique for coaxial holographic image recording and reconstruction, employing a spatial light modulator (SLM) modified in pure phase mode. In the image encoding system, both the reference beam in the outside part and the signal beam in the inside part are displayed by an SLM based on the twisted nematic LCD. For a binary image, the part with amplitude of “1” is modulated with random phase, while the part with amplitude of “0” is modulated with constant phase. After blocking the dc component of the spatial frequencies, a Fourier transform (FT) hologram is recorded with a uniform intensity distribution. The amplitude image is reconstructed by illuminating the reference beam onto the hologram, which is much simpler than existing phase modulated FT holography techniques. The technique of coaxial holographic image encoding and recovering with pure phase modulation is demonstrated theoretically and experimentally in this paper. As the holograms are recorded without the high-intensity dc component, the storage density with volume medium may be increased with the increase of dynamic range. Such a simple modulation method will have potential applications in areas such as holographic encryption and high-density disk storage systems.”

Link to Publications Page

Publication: Applied Optics, (subscription required)

Issue/Year/DOI: Applied Optics, Vol. 50, Issue 34, pp. H10-H15 (2011)
doi:10.1364/AO.50.000H10


Closed-loop adaptive optics with a single element for wavefront sensing and correction

September, 2011

Author(s): Raúl Martínez-Cuenca, Vicente Durán, Justo Arines, Jorge Ares, Zbigniew Jaroszewicz, Salvador Bará, Lluís Martínez-León, and Jesús Lancis

Abstract:

“We propose a closed-loop adaptive optical arrangement based on a single spatial light modulator that simultaneously works as a correction unit and as the key element of a wavefront sensor. This is possible by using a liquid crystal on silicon display whose active area is divided into two halves that are respectively programmed for sensing and correction. We analyze the performance of this architecture to implement an adaptive optical system. Results showing a closed-loop operation are reported, as well as a proof of concept for dealing with aberrations comparable to those typically found in human eyes.”

Link to Publications Page

Publication: Optics Letters, (subscription required)

Issue/Year/DOI: Optics Letters, Vol. 36, Issue 18, pp. 3702-3704 (2011)
doi:10.1364/OL.36.003702


Controlling ghost traps in holographic optical tweezers

September, 2011

Author(s): Christina Hesseling, Mike Woerdemann, Andreas Hermerschmidt, Cornelia Denz.

Abstract:

“Computer-generated holograms displayed by phase-modulating spatial light modulators have become a well- established tool for beam shaping purposes in holographic optical tweezers. Still, the generation of light intensity patterns with high spatial symmetry and simultaneously without interfering ghost traps is a challenge. We have implemented an iterative Fourier transform algorithm that is capable of controlling these ghost traps and demonstrate the benefit of this approach in the experiment.”

Link to Publications Page

Publication: Optics Letters, (subscription required)

Issue/Year/DOI: Optics Letters, Vol. 36, Issue 18, pp. 3657-3659 (2011)
doi:10.1364/OL.36.003657


Wavefield imaging via iterative retrieval based on phase modulation diversity

September, 2011

Author(s): José A. Rodrigo, Tatiana Alieva, Gabriel Cristóbal, and María L. Calvo

Abstract:

“We present a fast and robust non-interferomentric wavefield retrieval approach suitable for imaging of both amplitude and phase distributions of scalar coherent beams. It is based on the diversity of the intensity measurements obtained under controlled astigmatism and it can be easily implemented in standard imaging systems. Its application for imaging in microscopy is experimentally studied. Relevant examples illustrate the approach capabilities for image super-resolution, numerical refocusing, quantitative imaging and phase mapping.”

Link to Publications Page

Publication: Optics Express, (free download)

Issue/Year/DOI: Optics Express, Vol. 19, Issue 19, pp. 18621-18635 (2011)
doi:10.1364/OE.19.018621


Implementation of phase-shift patterns using a holographic projection system with phase-only diffractive optical elements

July, 2011

Author(s): Wei-Feng Hsu, Yu-Wen Chen, and Yuan-Hong Su

Abstract:

“We proposed a method to implement spatial phase-shift patterns with subdiffraction limited features through a holographic projection system. The input device of the system displayed phase-only diffractive optical elements that were calculated using the iterative Fourier-transform algorithm with the dummy-area method. By carefully designing the target patterns to the algorithm, the diffractive optical elements generated the Fourier-transformed images containing the phase-shift patterns in which the widths of dark lines were smaller than the diffraction limit. With these demonstrations, we have successfully shown that the near-field phase-shift lithographic technique can be realized through an inexpensive maskless lithographic system and can still achieve subdiffraction limited images.”

Link to Publications Page

Publication: Applied Optics, (subscription required)

Issue/Year/DOI: Applied Optics, Vol. 50, Issue 20, pp. 3646-3652 (2011)
doi:10.1364/AO.50.003646