Time multiplexing technique of holographic view and Maxwellian view using a liquid lens in the optical see-through head mounted display

Author(s):

Jin Su Lee and Yoo Kwang Kim and Yong Hyub Won

Abstract:

“We report a liquid lens based optical see-through head mounted display that can simultaneously display both a maxwellian view and a hologram. Holograms are reconstructed by an angular spectrum layer based synthesis method. A hologram and Maxwellian view are simultaneously displayed by focusing the liquid lens from 0 D to 20 D with 60 Hz. The hologram is reconstructed at a position 1.5 m from the eye, and it is confirmed that the Maxwellian view is clear, even if the focus of the eye changes from 50 cm to 1.7 m. In the proposed system, the liquid lens acts as a low-pass filter. Since the PSNR is about 23 dB in the currently used 10 mm diameter liquid lens, the image quality is not adequate. However, we successfully verify the feasibility of our proposed system. In addition, if a large diameter liquid lens of 30 mm or more is applied, excellent image quality of 30 dB or more can be realized.”

Link to Publications Page

Publication: Opt. Express

Issue/Year/DOI: Opt. Express, Vol. 26, Issue 2, pp. 2149-2159 (2018)
DOI: 10.1364/OE.26.002149

Near-eye light field holographic rendering with spherical waves for wide field of view interactive 3D computer graphics

Author(s):

Liang Shi and Fu-Chung Huang and Ward Lopes and Wojciech Matusik and David Luebke

Abstract:

“Holograms display a 3D image in high resolution and allow viewers to focus freely as if looking through a virtual window, yet computer generated holography (CGH) hasn’t delivered the same visual quality under plane wave illumination and due to heavy computational cost. Light field displays have been popular due to their capability to provide continuous focus cues. However, light field displays must trade off between spatial and angular resolution, and do not model diffraction.

We present a light field-based CGH rendering pipeline allowing for reproduction of high-definition 3D scenes with continuous depth and support of intra-pupil view-dependent occlusion. Our rendering accurately accounts for diffraction and supports various types of reference illuminations for hologram. We avoid under- and over-sampling and geometric clipping effects seen in previous work. We also demonstrate an implementation of light field rendering plus the Fresnel diffraction integral based CGH calculation which is orders of magnitude faster than the state of the art [Zhang et al. 2015], achieving interactive volumetric 3D graphics.

To verify our computational results, we build a see-through, near-eye, color CGH display prototype which enables co-modulation of both amplitude and phase. We show that our rendering accurately models the spherical illumination introduced by the eye piece and produces the desired 3D imagery at the designated depth. We also analyze aliasing, theoretical resolution limits, depth of field, and other design trade-offs for near-eye CGH.”

Link to Publications Page

Publication: {ACM} Transactions on Graphics

Issue/Year/DOI: ACM Transactions on Graphics, Vol. 36, No. 6, Article 236. (November 2017)
DOI: 10.1145/3130800.3130832

Holographic near-eye displays for virtual and augmented reality

Author(s):

Maimone, Andrew and Georgiou, Andreas and Kollin, Joel S

Abstract:
“We present novel designs for virtual and augmented reality near-eye displays based on phase-only holographic projection. Our approach is built on the principles of Fresnel holography and double phase amplitude encoding with additional hardware, phase correction factors, and spatial light modulator encodings to achieve full color, high contrast and low noise holograms with high resolution and true per-pixel focal control. We provide a GPU-accelerated implementation of all holographic computation that integrates with the standard graphics pipeline and enables real-time (≥90 Hz) calculation directly or through eye tracked approximations. A unified focus, aberration correction, and vision correction model, along with a user calibration process, accounts for any optical defects between the light source and retina. We use this optical correction ability not only to x minor aberrations but to enable truly compact, eyeglasses-like displays with wide elds of view (80◦) that would be inaccessible through conventional means. All functionality is evaluated across a series of hardware prototypes; we discuss remaining challenges to incorporate all features into a single device.”

Link to Publications Page

Publication: ACM Transactions on Graphics (TOG)

Issue/Year/DOI: ACM Transactions on Graphics, Vol. 36, No. 4, Article 85. (July 2017)
DOI: 10.1145/3072959.3073624

Chromatic aberration control with liquid crystal spatial phase modulators

Author(s):

Jose L. Martinez and Enrique J. Fernandez and Pedro M. Prieto and Pablo Artal

Abstract:

“The chromatic behavior of diffractive optical elements, exhibiting 2π-wrapped phase profiles, implemented into liquid crystal spatial light modulators (LC-SLM) is described. A wrapped phase map is only equivalent to the original continuous profile for the design wavelength while at other wavelengths there are unwanted phase jumps and the profile does not correspond to a pure defocus. For those conditions the wrapped profile behaves as a multiple order lens (multi-focal lens). The optical power dispersion for each order is linearly proportional to the wavelength, while the energy of each order depends on the design wavelength and the material dispersion. For practical purposes, for most of the visible range only first order (main defocus) is relevant but two other orders may also be considered depending on the actual PSF of the system. As an application, we demonstrate that the longitudinal chromatic aberration of the eye can be compensated by the diffractive lens dispersion when the appropriate defocus is programmed into the SLM.”

Link to Publications Page

Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 25, Issue 9, pp. 9793-9801 (2018)
DOI: 10.1364/OE.25.009793

 

Speckle reduced lensless holographic projection from phase-only computer-generated hologram

Author(s):

Chenliang Chang and Yijun Qi and Jun Wu and Jun Xia and Shouping Nie

Abstract:

“This paper presents a method for the implementation of speckle reduced lensless holographic projection based on phase-only computer-generated hologram (CGH). The CGH is calculated from the image by double-step Fresnel diffraction. A virtual convergence light is imposed to the image to ensure the focusing of its wavefront to the virtual plane, which is established between the image and the hologram plane. The speckle noise is reduced due to the reconstruction of the complex amplitude of the image via a lensless optical filtering system. Both simulation and optical experiments are carried out to confirm the feasibility of the proposed method. Furthermore, the size of the projected image can reach to the maximum diffraction bandwidth of the spatial light modulator (SLM) at a given distance. The method is effective for improving the image quality as well as the image size at the same time in compact lensless holographic projection system.”

Link to Publications Page
Publication: Optics Express

Issue/Year/DOI: Optics Express, Vol. 25, Issue 6, pp. 6568- 6580 (2018)
DOI: 10.1364/OE.25.006568

Full parallax three-dimensional computer generated hologram with occlusion effect using ray casting technique

Author(s):

Hao Zhang, Qiaofeng Tan and Guofan Jin

Abstract:

“Holographic display is capable of reconstructing the whole optical wave field of a three-dimensional (3D) scene. It is the only one among all the 3D display techniques that can produce all the depth cues. With the development of computing technology and spatial light modulators, computer generated holograms (CGHs) can now be used to produce dynamic 3D images of synthetic objects. Computation holography becomes highly complicated and demanding when it is employed to produce real 3D images. Here we present a novel algorithm for generating a full parallax 3D CGH with occlusion effect, which is an important property of 3D perception, but has often been neglected in fully computed hologram synthesis. The ray casting technique, which is widely used in computer graphics, is introduced to handle the occlusion issue of CGH computation. Horizontally and vertically distributed rays are projected from each hologram sample to the 3D objects to obtain the complex amplitude distribution. The occlusion issue is handled by performing ray casting calculations to all the hologram samples. The proposed algorithm has no restriction on or approximation to the 3D objects, and hence it can produce reconstructed images with correct shading effect and no visible artifacts. Programmable graphics processing unit (GPU) is used to perform parallel calculation. This is made possible because each hologram sample belongs to an independent operation. To demonstrate the performance of our proposed algorithm, an optical experiment is performed to reconstruct the 3D scene by using a phase-only spatial light modulator. We can easily perceive the accommodation cue by focusing our eyes on different depths of the scene and the motion parallax cue with occlusion effect by moving our eyes around. The experiment result confirms that the CGHs produced by our algorithm can successfully reconstruct 3D images with all the depth cues.”

Link to Publications Page

Publication: Journal of Physics: Conference Series

Issue/Year/DOI: Volume: 415
DOI: 10.1088/1742-6596/415/1/012048

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.”

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

The Applications and Technology of Phase-Only Liquid Crystal on Silicon Devices

Author(s): Collings, N.; Davey, T.; Christmas, J.; Chu, D.; Crossland, B.

Abstract:

“An introduction to the technology of liquid crystal on silicon (LCOS) devices leads on to a discussion of the application areas which have been and are being opened up by the development of phase-only devices.”

Link to Publications Page

Publication: Journal of Display Technology, (subscription required)

Issue/Year/DOI: Journal of Display Technology, Vol. 7, Issue 3, pp. 112-119 (2010)
doi:10.1109/JDT.2010.2049337

Speed-up of hologram generation using ClearSpeed Accelerator board

Author(s): Noriyuki Tanabe, Yasuyuki Ichihashi, Hirotaka Nakayama, Nobuyuki Masuda and Tomoyoshi Ito

Abstract:

“We have sped up the calculation of a computer-generated hologram by parallel computing using ClearSpeed Advance Dual CSX600 PCI-X Accelerator Board by ClearSpeed Technology plc. By using two boards in parallel, our system was able to perform the calculation 50 times as fast as a personal computer.”

Link to Publications Page

Publication: Computer Physics Communications – via ScienceDirect.com (subscription required)

Issue/Year/DOI: Computer Physics Communications, Volume 180, Issue 10, October 2009, Pages 1870-1873
doi:10.1016/j.cpc.2009.06.001

Superhydrophobic surface structures in thermoplastic polymers by interference lithography and thermal imprinting

Author(s): Christian W.J. Berendsen, Marek Škereň, David Najdek and František Cerný

Abstract:

“We present a method to produce superhydrophobic surfaces in thermoplastic polymer substrates. The method involves the creation of a nickel stamp using a customized laser interference lithography technique and electroplating processes. This stamp is used to emboss sub-micrometer periodic structures into the thermoplastic. The modified surface is coated with a hydrophobic plasma-polymerized hexafluoropropene layer. Surfaces with different periodicity and relief depth were created. On the surface with the highest aspect ratio, advancing water contact angles of 167° were measured with a water contact angle hysteresis of below 5°.”

Link to Publications Page

Publication: Applied Surface Science – ScienceDirect.com (subscription required)

Issue/Year/DOI: Applied Surface Science, Volume 255, Issue 23, 15 September 2009, Pages 9305-9310
doi:10.1016/j.apsusc.2009.07.001