Encoding the Intensity and Phase Gradient of Light Beams with Arbitrary Shapes

Author(s):

Serrano-Trujillo, Alejandra; Ruiz-Cortés, Victor

Abstract:

“We present an approach for engineering the intensity trajectory and phase gradient of light beams with arbitrary shapes by estimating their parametric equations using Freeman chain code and by applying the fast Fourier transform. The analysis of the electric field distribution expected for a given curve allows the phase extraction over each local coordinate, generating a phase pattern to be displayed over a spatial light modulator. The intensity and phase gradient of eight different shapes is encoded during our experiments. The far field intensity profiles are captured and compared in shape to those designed, while the encoded phase is demonstrated by implementing a common path interference setup with a pair of beams from the spatial light modulator. The designed beams, initially drawn either by hand or generated with software, exhibit both the intensity and phase profiles encoded onto them.”

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Publication: Applied Sciences
Issue/Year: Applied Sciences, Volume 13; Number 5; Pages 3192; 2023
DOI: 10.3390/app13053192

Tailoring arbitrary hybrid Poincaré beams through a single hologram

Author(s):

Shiyao Fu and Yanwang Zhai and Tonglu Wang and Ci Yin and Chunqing Gao

Abstract:

“Hybrid Poincaré beams (HPBs) are a kind of structure field with anisotropic polarizations. Here, we demonstrate an approach to tailor HPBs with arbitrary states, through encoding a single hologram on a liquid-crystal display device along with a stable optical system. The state of the obtained HPB is determined only by the encoded holograms with special design, which means it is not necessary to adjust any optical elements or hardware when generating various HPB states. Moreover, perfect HPBs can also be generated through the proposed scheme. In the experiment, the obtained HPBs are analyzed through a polarizer and a special parameter S3/S0, showing good agreement with prediction. This work opens an insight in encoding single holograms for tailoring arbitrary HPBs and inspires various applications.”

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Publication: Applied Physics Letters
Issue/Year: Applied Physics Letters Volume 111, Issue 21
DOI: 10.1063/1.5008954

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

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.”

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

Nonimaging speckle interferometry for high-speed nanometer-scale position detection

Author(s): E. G. van Putten, A. Lagendijk, and A. P. Mosk

Abstract:

“We experimentally demonstrate a nonimaging approach to displacement measurement for complex scattering materials. By spatially controlling the wavefront of the light that incidents on the material, we concentrate the scattered light in a focus on a designated position. This wavefront acts as a unique optical fingerprint that enables precise position detection of the illuminated material by simply measuring the intensity in the focus. By combining two fingerprints we demonstrate position detection along one in-plane dimension with a displacement resolution of 2.1 nm. As our approach does not require an image of the scattered field, it is possible to employ fast nonimaging detectors to enable high-speed position detection of scattering materials.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 37, Issue 6, pp. 1070-1072 (2012)
DOI: 10.1364/OL.37.001070

Fabrication of three-dimensional electrospun microstructures using phase modulated femtosecond laser pulses

Author(s): Nathan J. Jenness, Yiquan Wu, Robert L. Clark.

Abstract:

“Electrospun polycaprolactone nanofibers were selectively ablated to form microstructures via the phase modulation of femtosecond laser beams. Ablation width (1–15 μm) and depth (15–110 μm) resolution were dependent upon the selection of pulse energy and microscope objective. Because phase modulation shapes light in a maskless fashion, desired templates were digitally created and physically transferred to electrospun mats within a matter of minutes. Several microarchitectures were formed in parallel by dividing pulse energy between multiple foci, substantially increasing throughput. The data presented herein demonstrates that phase-based laser ablation can be used to rapidly shape and tailor electrospun mats in three dimensions.”

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Publication: Materials Letters
Issue/Year: Materials Letters, Volume 66, Issue 1, 1 January 2012, Pages 360–363
DOI: 10.1016/j.matlet.2011.09.015

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

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.”

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Publication: Biomedical Optics Express
Issue/Year: 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

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.”

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

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

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.”

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

Recursive wavefront aberration correction method for LCoS spatial light modulators

Author(s): J. García-Márquez, J.E.A. Landgrave, N. Alcalá-Ochoa, C. Pérez-Santos

Abstract:

“We present two accurate and relatively simple interferometric methods for the correction of wavefront aberrations of about 3 wavelengths (3λ) in spatial light modulators (SLMs) of the liquid crystal on silicon (LCoS) type. The first is based on a recursive use of a wavefront fitting algorithm in a Wyko™ interferometer, in which Zernike polynomials are employed as the basis functions. We show here that the successive use of only three measurements is required to obtain a peak-to-valley (PV) error as low as λ/10, with an uncertainty of λ/30, in the compensated wavefront. The second method makes use of the actual optical path difference (OPD) computed by the interferometer at each pixel of the image of the interferogram of the LCoS modulator (LCoS-M). From numerical interpolation of these OPD values we were able to assign the required OPD compensation at each pixel of the LCoS-M. With this method, PV errors of the compensated wavefront as low as λ/16, with an uncertainty of λ/30, were obtained for the entire LCoS-M, or of λ/33 for the disk that we used as the domain of the Zernike polynomials in the first method.”

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Publication: Optics and Lasers in Engineering
Issue/Year: Optics and Lasers in Engineering, Volume 49, Issue 6, Pages 743-748, (2011)
DOI: 10.1016/j.optlaseng.2011.01.024

Aberration compensation using a spatial light modulator LCD

Author(s): R. Amézquita, O. Rincón and Y. M. Torres

Abstract:

“The dynamic correction of aberrations introduced in optical systems have been a widely discussed topic in the past 10 years. Adaptive optics is the most important developed field where the Shack-Hartmann sensors and deformable mirrors are used for the measurement and correction of wavefronts. In this paper, an interferometric set-up which uses a Spatial Light Modulator (SLM) as an active element is proposed. Using this SLM a procedure for the compensation of all phase aberrations present in the experimental setup is shown.”

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Publication: Journal of Physics: Conference Series
Issue/Year: J. Phys.: Conf. Ser. 274 012111 (2011)
DOI: 10.1088/1742-6596/274/1/012111
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