Browsing by Author "Chen, Po-Ju"

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An electrically tunable imaging system with separable focus and zoom functions using composite liquid crystal lenses
(2014-05-19)
Chen, Ming-Syuan
;
Chen, Po-Ju
;
Chen, Michael
;
Lin, Yi-Hsin
;
光電工程學系
We demonstrated an electrically tunable optical image system with separable focus function and zoom function based on three tunable focusing composite liquid crystal (LC) lenses. One LC lens in charge of the focus function helps to maintain the formed image at the same position and the other two LC lenses in charge of zoom function assist to continuously form an image at image sensor with tunable magnification of image size. The detail optical mechanism is investigated and the concept is demonstrated experimentally. The magnifications of the images can be switched continuously for the target in a range between 10 cm and 100 cm. The optical zoom ratio of this system maintains a constant similar to 6.5:1 independent of the object distance. This study provides not only a guideline to design the image system with an electrically optical zoom, but also provide an experimental process to show how to operate the tunable focusing lenses in such an image system. (C) 2014 Optical Society of America
An electrically tunable optical zoom system with separated focusing and zooming functions
(2013-01-01)
Chen, Ming-Syuan
;
Chen, Po-Ju
;
Lin, Yi-Hsin
;
光電工程學系
;
Department of Photonics
In this paper, we demonstrated an electrically tunable optical zoom system with separated focusing and zooming functions. The optical mechanism is discussed. The focusing distance and magnification of the image can be controlled separately by focusing lenses and zooming lenses. As a result, the zoom ratio is independent of objective distance and only depends on the tunable range of the lens power of the active-optical elements. This study helps designing many applications with an optical zoom function, such as cell phones, holographic projectors, pico projectors and endoscopes.
An electrically tunable optical zoom system with separated focusing and zooming functions
(2013-01-01)
Chen, Ming-Syuan
;
Chen, Po-Ju
;
Lin, Yi-Hsin
;
光電工程學系
;
Department of Photonics
In this paper, we demonstrated an electrically tunable optical zoom system with separated focusing and zooming functions. The optical mechanism is discussed. The focusing distance and magnification of the image can be controlled separately by focusing lenses and zooming lenses. As a result, the zoom ratio is independent of objective distance and only depends on the tunable range of the lens power of the active-optical elements. This study helps designing many applications with an optical zoom function, such as cell phones, holographic projectors, pico projectors and endoscopes.
Augmented reality with image registration, vision correction and sunlight readability via liquid crystal devices
(2017-03-27)
Wang, Yu-Jen
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Chen, Po-Ju
;
Liang, Xiao
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Lin, Yi-Hsin
;
光電工程學系
Augmented reality (AR), which use computer-aided projected information to augment our sense, has important impact on human life, especially for the elder people. However, there are three major challenges regarding the optical system in the AR system, which are registration, vision correction, and readability under strong ambient light. Here, we solve three challenges simultaneously for the first time using two liquid crystal (LC) lenses and polarizer-free attenuator integrated in optical-see-through AR system. One of the LC lens is used to electrically adjust the position of the projected virtual image which is so-called registration. The other LC lens with larger aperture and polarization independent characteristic is in charge of vision correction, such as myopia and presbyopia. The linearity of lens powers of two LC lenses is also discussed. The readability of virtual images under strong ambient light is solved by electrically switchable transmittance of the LC attenuator originating from light scattering and light absorption. The concept demonstrated in this paper could be further extended to other electro-optical devices as long as the devices exhibit the capability of phase modulations and amplitude modulations.
Electrically adjustable location of a projected image in augmented reality via a liquid-crystal lens
(2015-11-02)
Chen, Hung-Shan
;
Wang, Yu-Jen
;
Chen, Po-Ju
;
Lin, Yi-Hsin
;
光電工程學系
An augmented reality (AR) system involving the electrically tunable location of a projected image is implemented using a liquid-crystal (LC) lens. The projected image is either real or virtual. By effectively doubling the LC lens power following light reflection, the position of a projected virtual image can be made to vary from 42 to 360 cm, while the tunable range for a projected real image is from 27 to 52 cm on the opposite side. The optical principle of the AR system is introduced and could be further developed for other tunable focusing lenses, even those with a lower lens power. The benefits of this study could be extended to head-mounted display systems for vision correction or vision compensation. We believe that tunable focusing LC optical elements are promising developments in the thriving field of AR applications. (C) 2015 Optical Society of America
Electrically tunable microlens arrays based on polarization-independent optical phase of nano liquid crystal droplets dispersed in polymer matrix
(2015-06-29)
Yu, Ji Hoon
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Chen, Hung-Shan
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Chen, Po-Ju
;
Song, Ki Hoon
;
Noh, Seong Cheol
Electrically tunable focusing microlens arrays based on polarization independent optical phase of nano liquid crystal droplets dispersed in polymer matrix are demonstrated. Such an optical medium is optically isotropic which is so-called an optically isotropic liquid crystals (OILC). We not only discuss the optical theory of OILC, but also demonstrate polarization independent optical phase modulation based on the OILC. The experimental results and analytical discussion show that the optical phase of OILC microlens arrays results from mainly orientational birefringence which is much larger than the electric-field-induced birefringence (or Kerr effect). The response time of OILC microlens arrays is fast similar to 5.3ms and the tunable focal length ranges from 3.4 mm to 3.8 mm. The potential applications are light field imaging systems, 3D integrating imaging systems and devices for augment reality. (C) 2015 Optical Society of America
Influence of alignment layers on crystal growth of polymer-stabilized blue phase liquid crystals
(2016-04-01)
Chen, Po-Ju
;
Chen, Michael
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Ni, Shih-Ya
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Chen, Hung-Shan
;
Lin, Yi-Hsin
The feature that devices based on blue phase liquid crystals (BPLCs) is free of alignment layers. However, the alignment layers could affect the morphologies of BPLC-devices as well as the electro-optical properties. In this paper, we investigate the influence of alignment layers to crystal growth of polymer-stabilized blue phase liquid crystals (PS-BPLCs). Without alignment layer, PS-BPLCs experiences both homogeneous nucleation and heterogeneous nucleation, and the morphology appears in random crystal orientations. On the contrary, when the surfaces coated with alignment layers, a heterogeneous nucleation dominates during the crystal growth process. We further proposed a possible mechanism for crystal growth under different surface condition. This study provides an alternative method to control crystal growth of PS-BPLCs, which is for facilitating many PS-BPLCs based photonic devices. (C) 2016 Optical Society of America
PHOSPHORS AND LIGHTING APPARATUS USING THE SAME
(2009-06-25)
CHEN, Teng-Ming
;
Chen, Po-Ju
A phosphor has a chemical formula of: (X1-mEum)4Y(BO3)3, wherein X is at least one of the group consisting of Ca, Sr and Ba, and Y is at least one of the group consisting of Li, Na and K, while 0