Rapid phase calibration of a spatial light modulator using novel phase masks and optimization of its efficiency using an iterative algorithm

Author(s):

Amar Deo Chandra and Ayan Banerjee

Abstract:

“We develop an improved phase calibration method of a reflective SLM using interferometry by employing novel phase masks. In the process, we definitively determine the actual maximum phase throw of our SLM which provides a recipe for users to verify supplier specifications. We generate optimised phase masks by using Iterative Fourier Transform Algorithm (IFTA) and compare their performance with global linear corrections in the look-up table (LUT) and find that the former perform with around 20% better efficiency. Besides obtaining an array of 1D/2D spots having high uniformity (90%) using IFTA, our result exemplifies the use of iterative algorithms for improving efficiency of phase limited SLMs. Finally, our improved phase calibration method enables threefold faster phase measurements, and to the best of our knowledge, is the first endeavour directed towards enabling rapid phase characterisation of an SLM using interferometric measurements. We believe that it can have very useful applications in settings which may require fast phase calibrations as well as for real-time, multi-wavelength spectroscopic applications.”

Link to Publications Page

Publication: Journal of Modern Optics
Issue/Year: Volume 67- Issue 7
DOI: 10.1080/09500340.2020.1760954

Compact design for optical-see-through holographic displays employing holographic optical elements

Author(s):

Pengcheng Zhou and Yan Li and Shuxin Liu and Yikai Su

Abstract:

“Holographic AR display is a promising technology for head-mounted display devices. However, it usually has a complicated optical system and a large form factor, preventing it from widespread applications. In this work, we propose a flat-panel design to produce a compact holographic AR display, where traditional optical elements are replaced by two holographic optical elements (HOEs). Here, these two thin HOEs together perform the optical functions of a beam expander, an ocular lens, and an optical combiner. Without any bulky traditional optics, our design could achieve a compact form factor that is similar to a pair of glasses. We also implemented a proof-of-concept prototype to verify its feasibility. Being compact, lightweight and free from accommodation-convergence discrepancy, our design is promising for fatigue-free AR displays.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express Volume 26, Issue 18
DOI: 10.1364/OE.26.022866

Accelerated generation of holographic videos of 3-D objects in rotational motion using a curved hologram-based rotational-motion compensation method

Author(s):

Hong-Kun Cao and Shu-Feng Lin and Eun-Soo KimAbstract:

“Abstract: A new curved hologram-based rotational-motion compensation (CH-RMC) method is proposed for accelerated generation of holographic videos of 3-D objects moving on the random path with many locally different arcs. All of those rotational motions of the object made on each arc can be compensated, just by rotating their local curved holograms along the curving surfaces matched with the object’s moving trajectory without any additional calculation process, which results in great enhancements of the computational speed of the conventional hologram-generation algorithms. Experiments with a test video scenario reveal that average numbers of calculated object points (ANCOPs) and average calculation times for one frame (ACTs) of the CH-RMC-based ray-tracing, wavefront-recording-plane and novel- look-up-table methods have been found to be reduced by 73.10%, 73.84%, 73.34%, and 68.75%, 50.82%, 66.59%, respectively, in comparison with those of their original methods. In addition, successful reconstructions of 3-D scenes from those holographic videos confirm the feasibility of the proposed system. ”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express Volume 26, Issue 16 pp. 21279-21300 (2018)
DOI: 10.1364/oe.26.021279

Lensless Stokes holography with the Hanbury Brown-Twiss approach

Author(s):

Darshika Singh and Rakesh Kumar Singh

Abstract:

“The recording and reconstruction of the Stokes parameter is of paramount importance for the description of the vectorial interference of light. Polarization holography provides a complete vectorial wavefront, however, direct recording and reconstruction of the hologram is not possible in a situation where the object is located behind the random scattering layer. The Stokes holography plays an important role in such situations and makes use of the Fourier transform relation between the Stokes parameters (SPs) at the scattering plane and the generalized Stokes parameters (GSPs) of the random field. In this paper, we propose and experimentally demonstrate the Stokes holography with the Hanbury Brown-Twiss (HBT) interferometer. We also propose and implement a lensless Fourier configuration for the Stokes holography. This permits us to reconstruct the wavefront from the GSPs at any arbitrary distance from the scattering plane. The application of the proposed technique is experimentally demonstrated for the 3D imaging of two different objects lying behind the random scattering medium. Depth information of the 3D objects is obtained by digitally propagating the generalized Stokes parameters to a different longitudinal distance. The quality of the reconstruction is assessed by measuring the overall visibility, efficiency, and PSNR of the reconstruction parameters.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 26, Issue 8, pp. 10801-10812 (2018)
DOI: 10.1364/OE.26.010801

Demonstration of a vectorial optical field generator with adaptive close loop control

Author(s):

Jian Chen and Lingjiang Kong and Qiwen Zhan

Abstract:

“We experimentally demonstrate a vectorial optical field generator (VOF-Gen) with an adaptive close loop control. The close loop control capability is illustrated with the calibration of polarization modulation of the system. To calibrate the polarization ratio modulation, we generate 45° linearly polarized beam and make it propagate through a linear analyzer whose transmission axis is orthogonal to the incident beam. For the retardation calibration, circularly polarized beam is employed and a circular polarization analyzer with the opposite chirality is placed in front of the CCD as the detector. In both cases, the close loop control automatically changes the value of the corresponding calibration parameters in the pre-set ranges to generate the phase patterns applied to the spatial light modulators and records the intensity distribution of the output beam by the CCD camera. The optimized calibration parameters are determined corresponding to the minimum total intensity in each case. Several typical kinds of vectorial optical beams are created with and without the obtained calibration parameters, and the full Stokes parameter measurements are carried out to quantitatively analyze the polarization distribution of the generated beams. The comparisons among these results clearly show that the obtained calibration parameters could remarkably improve the accuracy of the polarization modulation of the VOF-Gen, especially for generating elliptically polarized beam with large ellipticity, indicating the significance of the presented close loop in enhancing the performance of the VOF-Gen.”

Link to Publications Page

Publication: Review of Scientific Instruments
Issue/Year: Review of SCientific Instruments 88, 125111 (2017)
DOI: 10.1063/1.4999656

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.”

Link to Publications Page

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

Tightly focused optical field with controllable photonic spin orientation

Author(s):

Jian Chen and Chenhao Wan and Ling Jiang Kong and Qiwen Zhan

Abstract:

“The spin angular momentum of photons offers a robust, scalable and highbandwidth toolbox for many promising applications based upon spin-controlled manipulations of light. In this work, we develop a method to achieve controllable photonic spin orientation within a diffraction limited optical focal spot produced by a high numerical aperture objective lens. The required pupil field is found analytically through reversing the radiation patterns from two electric dipoles located at the focal point of the lens with orthogonal oscillation directions and quadrature phase. The calculated pupil fields are experimentally generated with a vectorial optical field generator. The produced photonic spin orientations are quantitatively evaluated by their spin densities according to the tightly focused electric fields calculated by Richard-Wolf vectorial diffraction theory to demonstrate the validity and capability of the proposed technique.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Volume 25, Number 16 pp. 19517-19528 (2017)
DOI: 10.1364/OE.25.019517

Precise spatio-temporal control of rapid optogenetic cell ablation with mem-KillerRed in Zebrafish.

Author(s):

Buckley, C. and Carvalho, M. T. and Young, L. K. and Rider, S. A. and McFadden, C. and Berlage, C. and Verdon, R. F. and Taylor, J. M. and Girkin, J. M. and Mullins, J. J.

Abstract:

“The ability to kill individual or groups of cells in vivo is important for studying cellular processes and their physiological function. Cell-specific genetically encoded photosensitizing proteins, such as KillerRed, permit spatiotemporal optogenetic ablation with low-power laser light. We report dramatically improved resolution and speed of cell targeting in the zebrafish kidney through the use of a selective plane illumination microscope (SPIM). Furthermore, through the novel incorporation of a Bessel beam into the SPIM imaging arm, we were able to improve on targeting speed and precision. The low diffraction of the Bessel beam coupled with the ability to tightly focus it through a high NA lens allowed precise, rapid targeting of subsets of cells at anatomical depth in live, developing zebrafish kidneys. We demonstrate that these specific targeting strategies significantly increase the speed of optoablation as well as fish survival.”

Link to Publications Page

Publication: Scientific Reports
Issue/Year: Scientific Reports, volume 7, Article number: 5096 (2017)
DOI: 10.1038/s41598-017-05028-2

An active coronagraph using a liquid crystal array for exoplanet imaging: principle and testing

Author(s): Xi Zhang, De-Qing Ren, Yong-Tian Zhu and Jiang-Pei Dou.

Abstract:

“High-contrast imaging coronagraphs, used for the detection of exoplanets, have always adopted passive coronagraph optical components. It is therefore impossible to actively optimize the coronagraphs to achieve their best performance. To solve this problem, we propose a novel high-contrast imaging coronagraph which combines a liquid crystal array (LCA) for active pupil apodization and a deformable mirror (DM) for phase correction. The LCA we use is an amplitude-only spatial light modulator. The LCA is well calibrated and compensates for its amplitude non-uniformity and nonlinear intensity responsivity. We measured the imaging contrasts of the coronagraph system with the LCA only and without the DM deployed. Imaging contrasts of 10-4 and 10-5 can be reached at an inner working angular distance of 2.5 and 5λ/D, respectively. A simulation shows that the phase errors on the coronagraph pupil limit the contrast performance. The contrast could be further improved if a DM is deployed to correct the phase errors induced by the LCA and coronagraph optics.”

Link to Publications Page

Publication: Research in Astronomy and Astrophysics, (subscription required)
Issue/Year: Res. Astron. Astrophys., Vol. 12, Issue 5,(2012)
DOI: 10.1088/1674-4527/12/5/011

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.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 20, Issue 7, pp. 7822-7832 (2012)
DOI: 10.1364/OE.20.007822
1 2 3 … 18