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.”

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Publication: Optics Letters, (subscription required)

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


Estimation and Compensation of aberrations in Spatial Light Modulators

February, 2011

Author(s): Augusto Arias and Roman Castaneda

Abstract:

“The spatial light modulator (SLM) Holoeye LC-R720 is based on LCoS (Liquid Crystal on Silicon) technology. Due to the induced curvatures on the silicon plate by the production process, there are static aberrations in the wave-fronts modified by the SLM. In order to calculate the aberrated wave-front we used phase-shifting interferometry, an optimization algorithm for far field propagation, and the geometric characterization of the focal spot along the caustic. Zernike polynomials were used for expanding and comparing the wave-fronts. The aberration compensation was carried out by displaying the conjugated transmittance on the SLM. The complexity of the experimental setup and the requirements of the digital processing of each estimation method were comparatively analyzed.”

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Publication: Journal of Physics: Conference Series, (free download)

Issue/Year/DOI: J. Phys.: Conf. Ser., Volume 274, 012060, (2011)
doi:10.1088/1742-6596/274/1/012060


Aberration compensation using a spatial light modulator LCD

February, 2011

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, (free download)

Issue/Year/DOI: J. Phys.: Conf. Ser. 274 012111 (2011)
doi:10.1088/1742-6596/274/1/012111


Rapid calculation algorithm of Fresnel computer-generated-hologram using look-up table and wavefront-recording plane methods for three-dimensional display

August, 2010

Author(s): Tomoyoshi Shimobaba, Hirotaka Nakayama, Nobuyuki Masuda, and Tomoyoshi Ito

Abstract:

“A rapid calculation method of Fresnel computer-generatedhologram (CGH) using look-up table and wavefront-recording plane (WRP) methods toward three-dimensional (3D) display is presented. The method consists of two steps: the first step is the calculation of a WRP that is placed between a 3D object and a CGH. In the second step, we obtain an amplitude-type or phase-type CGH to execute diffraction calculation from the WRP to the CGH. The first step of the previous WRP method was difficult to calculate in real-time due to the calculation cost. In this paper, in order to obtain greater acceleration, we apply a look-up table method to the first step. In addition, we use a graphics processing unit in the second step. The total computational complexity is dramatically reduced in comparison with conventional CGH calculations. We show optical reconstructions from a 2,048×2,048 phase-type CGH generated by about 3×104 object points over 10 frames per second.”

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Publication: Optics Express, (free download)

Issue/Year/DOI: Optics Express, Vol. 18, Issue 19, pp. 19504-19509 (2010)
doi:10.1364/OE.18.019504


Optical reconstruction of digital holograms recorded at 10.6 μm: route for 3D imaging at long infrared

June, 2010

Author(s): Melania Paturzo, Anna Pelagotti, Andrea Finizio, Lisa Miccio, Massimiliano Locatelli, Andrea Gertrude, Pasquale Poggi, Riccardo Meucci, Pietro Ferraro

Abstract:

“We demonstrate the optical reconstruction in the visible range (0.532μm) of digital holograms recorded at long IR wavelengths (10.6μm) by means of a spatial light modulator. By using an integrated recording-reconstruction system, it is, in fact, feasible to achieve direct imaging of holograms acquired outside the visible range, i.e., in the IR spectrum. By choosing a Fourier recording configuration, the reconstructed image, obtained at about a 20 times shorter wavelength than the acquisition image, exhibits minor aberrations, which do not significantly affect the optical reconstruction. The high NA achievable at a long IR wavelength allows us to image large objects at reasonable distances.”

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Publication: Optics Letters (subscription required)

Issue/Year/DOI: Optics Letters, Vol. 35, Issue 12, pp. 2112-2114 (2010)
doi:10.1364/OL.35.002112


Implementation of a digital optical phase conjugation system and its application to study the robustness of turbidity suppression by phase conjugation

February, 2010

Author(s): Meng Cui, Changhuei Yang

Abstract:

“In this work, we report a novel high capacity (number of degrees of freedom) open loop adaptive optics method, termed digital optical phase conjugation (DOPC), which provides a robust optoelectronic optical phase conjugation (OPC) solution. We showed that our prototype can phase conjugate light fields with ~3.9 x 10−3 degree accuracy over a range of ~3 degrees and can phase conjugate an input field through a relatively thick turbid medium (μsl ~13). Furthermore, we employed this system to show that the reversing of random scattering in turbid media by phase conjugation is surprisingly robust and accommodating of phase errors. An OPC wavefront with significant spatial phase errors (error uniformly distributed from – π/2 to π/2) can nevertheless allow OPC reconstruction through a scattering medium with ~40% of the efficiency achieved with phase error free OPC.”

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Publication: Optics Express, (free download)

Issue/Year/DOI: Optics Express, Vol. 18, Issue 4, pp. 3444-3455 (2010)
doi:10.1364/OE.18.003444


Refining common path interferometry with a spiral phase Fourier filter

August, 2009

Author(s): Christian Maurer , Stefan Bernet, Monika Ritsch-Marte

Abstract:

“Recently, spiral phase filtering for isotropic edge enhancement and for optical thickness measurements of phase samples has been implemented in microscopy, using gray value images on a spatial light modulator (SLM) placed in a Fourier plane of the sample. In a common path interferometer, the light going through the central part of the helical phase hologram is overlapped with the light passing through the periphery of the phase filter. Replacing the center by a disk of uniform phase leads to pseudo-relief images, with the apparent illumination direction depending on the gray level of the central area. If one uses such images to reconstruct the optical thickness of phase objects, the reference wave through the central part ideally should have a plane wavefront. This is normally not the case, especially when the imaging setup requires a relatively large central area around the DC Fourier component. This paper shows how a direct measurement of the amplitude of the reference beam, which can be done in the given setup by simply changing the image on the SLM, can increase the accuracy of phase measurement, allowing one to determine the refractive index with a relative error below 0.6%.”

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Publication: Journal of Optics A, (subscription required)

Issue/Year/DOI: J. Opt. A: Pure Appl. Opt. (2009) 11 094023
doi: 10.1088/1464-4258/11/9/094023


A novel three-dimensional holographic display system based on LC-R2500 spatial light modulatora

March, 2009

Author(s): Huadong Zheng, Yingjie Yu, Cuixia Dai

Abstract:

“A novel holographic display system is proposed in this paper. The system takes LC-R2500, a kind of reflective liquid crystal spatial light modulator, (LC-SLM) as the core display unit, which can meet the requirement of real-time reconstruction of three-dimensional (3D) objects from holograms in free space. The relationship between hologram recording and image reconstruction is discussed, and the parameters associated with the magnification of reconstructed image over original object are determined. Experimental results of holographic display using the system are also given in the end.”

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Publication: Optik – International Journal for Light and Electron Optics – via ScienceDirect.com, (subscription required)

Issue/Year/DOI: Optik – International Journal for Light and Electron Optics, Volume 120, Issue 9, May 2009, Pages 431-436
doi:10.1016/j.ijleo.2007.11.002


Color holographic reconstruction using multiple SLMs and LED illumination

January, 2009

Author(s): Fahri Yaras and Levent Onural

Abstract:

“A color holographic reconstruction technique by using three light emitting diodes (LEDs) is described. Reflective type phase-only spatial light modulators (SLMs) are used since they are suitable for in-line phase holograms. Gerchberg-Saxton iterative algorithm is used for computing phase holograms. Three phase holograms are calculated separately for red, green and blue colors, for a color reconstruction, and separately loaded to corresponding SLMs. Three LEDs are used for illuminating those phase holograms and reconstructions are combined and captured. Experimental results are satisfactory. ”

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Publication: SPIE Proceedings, (subscription required)

Issue/Year/DOI: Proc. SPIE, Vol. 7237, 72370O (2009);
doi:10.1117/12.806875


Applications of LCoS-based adaptive optical elements in microscopy

August, 2008

Author(s): Andreas Hermerschmidt, Jan Haffner, Tobias Haist, Wolfgang Osten

Abstract:

“Liquid crystal on silicon (LCoS)-based spatial light modulators (SLMs) are versatile adaptive optical elements. In microscopy, among their applications are aberration sensing and correction in wide-field microscopy and also the implementation of holographic optical tweezers. For aberration correction, the required scene-based wavefront sensing can be implemented as a modified correlation-based Shack-Hartmann approach where a high-resolution SLM first senses and then corrects the aberrations. For the implementation of holographic optical tweezers, the SLM serves as a variable optical beam-splitter which is addressed with holograms computed by fast algorithms implemented on the graphics processing unit (GPU) of a common PC almost in real-time.”

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Publication: Proceedings IEEE/LEOS Internationall Conference on Optical MEMs and Nanophotonics, 2008 – via IEEE Xplore (subscription required)

Issue/Year/DOI: Proceedings IEEE/LEOS Internationall Conference on Optical MEMs and Nanophotonics, 2008,
DOI: 10.1109/OMEMS.2008.4607842