Browsing by Author "Hassanfiroozi, Amir"

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Dual layer electrode liquid crystal lens for 2D/3D tunable endoscopy imaging system
(2016-04-18)
Hassanfiroozi, Amir
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Huang, Yi-Pai
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Javidi, Bahram
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Shieh, Han-Ping D.
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光電工程學系
In this paper, we demonstrate a multi-functional liquid-crystal lens (MFLC-lens) based on dual-layer electrode design. Compared with the previous 3D endoscopes, which use double fixed lens capturing, the proposed LC lens is not only switchable between 2D and 3D modes, but also is able to adjust focus in both modes. The diameter of the MFLC-lens is only 1.42mm, which is much smaller than the available 3D endoscopes with double fixed lenses. To achieve the MFLC-lens, a high-resistance layer needs to be coated on the electrode to generate an ideal gradient electric-field distribution, which can induce a lens-like form of LC molecules. The parameters of high-resistive layer are investigated and discussed with an aim to optimize the performance of the MFLC-lens. (C) 2016 Optical Society of America
Hexagonal liquid crystal lens array for 3D endoscopy
(2015-01-26)
Hassanfiroozi, Amir
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Huang, Yi-Pai
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Javidi, Bahram
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Shieh, Han-Ping D.
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光電工程學系
A liquid crystal lens array with a hexagonal arrangement is investigated experimentally. The uniqueness of this study exists in the fact that using convex-ring electrode provides a smooth and controllable applied potential profile across the aperture to manage the phase profile. We observed considerable differences between flat electrode and convex-ring electrode; in particular the lens focal length is variable in a wider range from 2.5cm to infinity. This study presents several noteworthy characteristics such as low driving voltage; 30 mu m cell gap and the lens is electrically switchable between 2D/3D modes. We demonstrate a hexagonal LC-lens array for capturing 3D images by using single sensor using integral imaging. (C) 2015 Optical Society of America
LC-lens array with light field algorithm for 3D bio-medical applications
(2016-01-01)
Huang, Yi-Pai
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Hsieh, Po-Yuan
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Hassanfiroozi, Amir
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Martinez, Manuel
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Javidi, Bahram
In this paper, liquid crystal lens (LC-lens) array was utilized in 3D bio-medical applications including 3D endoscope and light field microscope. Comparing with conventional plastic lens array, which was usually placed in 3D endoscope or light field microscope system to record image disparity, our LC-lens array has higher flexibility of electrically changing its focal length. By using LC-lens array, the working distance and image quality of 3D endoscope and microscope could be enhanced. Furthermore, the 2D/3D switching ability could be achieved if we turn off/on the electrical power on LC-lens array. In 3D endoscope case, a hexagonal micro LC-lens array with 350um diameter was placed at the front end of a 1mm diameter endoscope. With applying electric field on LC-lens array, the 3D specimen would be recorded as from seven micro-cameras with different disparity. We could calculate 3D construction of specimen with those micro images. In the other hand, if we turn off the electric field on LC-lens array, the conventional high resolution 2D endoscope image would be recorded. In light field microscope case, the LC-lens array was placed in front of the CMOS sensor. The main purpose of LC-lens array is to extend the refocusing distance of light field microscope, which is usually very narrow in focused light field microscope system, by montaging many light field images sequentially focusing on different depth. With adjusting focal length of LC-lens array from 2.4mm to 2.9mm, the refocusing distance was extended from 1mm to 11.3mm. Moreover, we could use a LC wedge to electrically shift the optics axis and increase the resolution of light field.
Liquid Crystal Lens Array for 3D Endoscope Application
(2014-01-01)
Hassanfiroozi, Amir
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Jen, Tai-Hsiang
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Huang, Yi-Pai
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Shieh, Han-Ping D.
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光電工程學系
A plano-convex electrode is presented for a liquid crystal lens array with a hexagonal arrangement, small inactive region, 30 mu m cell gap and low applying voltage. It uses circular curved electrodes to provide a smooth, controllable applied potential profile across the aperture to manage the phase profile.
Liquid crystal lens array for 3D microscopy and endoscope application
(2016-01-01)
Huang, Yi-Pai
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Hsieh, Po-Yuan
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Hassanfiroozi, Amir
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Chu, Chao-Yu
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Hsuan, Yun
In this paper, we demonstrate two liquid crystal (LC) lens array devices for 3D microscope and 3D endoscope applications respectively. Compared with the previous 3D biomedical system, the proposed LC lens arrays are not only switchable between 2D and 3D modes, but also are able to adjust focus in both modes. The multi-function liquid crystal lens (MFLC-lens) array with dual layer electrode has diameter 1.42 mm, which is much smaller than the conventional 3D endoscope with double fixed lenses. The hexagonal liquid crystal micro-lens array (HLC-MLA) instead of fixed micro-lens array in 3D light field microscope can extend the effective depth of field from 60 um to 780 um. To achieve the LC lens arrays, a high-resistance layer needs to be coated on the electrodes to generate an ideal gradient electric-field distribution, which can induce a lens-like form of LC molecules. The parameters and characteristics of high-resistance layer are investigated and discussed with an aim to optimize the performance of liquid crystal lens arrays.
Security authentication using phase-encoded nanoparticle structures and polarized light
(2015-01-15)
Carnicer, Artur
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Hassanfiroozi, Amir
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Latorre-Carmona, Pedro
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Huang, Yi-Pai
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Javidi, Bahram
Phase-encoded nanostructures such as quick response (QR) codes made of metallic nanoparticles are suggested to be used in security and authentication applications. We present a polarimetric optical method able to authenticate random phase-encoded QR codes. The system is illuminated using polarized light, and the QR code is encoded using a phase-only random mask. Using classification algorithms, it is possible to validate the QR code from the examination of the polarimetric signature of the speckle pattern. We used Kolmogorov-Smirnov statistical test and Support Vector Machine algorithms to authenticate the phase-encoded QR codes using polarimetric signatures. (C) 2015 Optical Society of America