On liquid crystal diffractive optical elements utilizing inhomogeneous alignment

Valyukh, Sergiy; Chigrinov, Vladimir G.; Kwok, Hoi Sing; Arwin, Hans

doi:10.1364/oe.20.015209

Cited by 16 publications

(13 citation statements)

References 38 publications

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“…In order to see both the microdisplay located immediate vicinity of the eye and objects from ambient, it is necessary to have a switchselectable lens. Liquid crystal (LC) lenses are most suitable for such purposes [19][20][21][22]. Although they cannot compete with refractive lenses in low F-number, LC lenses, nevertheless, are suited for a microlens array for a contact lens [10,11].…”

Section: Resultsmentioning

confidence: 99%

“…In summary, although we have mostly considered the customary refractive lens, the many results obtained in this work can be applied for other types of lens, e.g. gradient index (GRIN) lenses [18,[20][21][22]. GRIN lenses based on liquid crystals are tuneable and can be driven by low voltage (up to 1V) [20][21][22].…”

Section: Resultsmentioning

confidence: 99%

“…gradient index (GRIN) lenses [18,[20][21][22]. GRIN lenses based on liquid crystals are tuneable and can be driven by low voltage (up to 1V) [20][21][22]. By using this feature, it is possible to increase essentially functionality of NED.…”

Section: Resultsmentioning

confidence: 99%

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Assessment of minimum permissible geometrical parameters of a near-to-eye display

Valyukh

Slobodyanyuk

2015

Appl. Opt.

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Light weight and small dimensions are some of the most important characteristics of near-to-eye displays (NEDs). These displays consist of two basic parts: a microdisplay for generating an image and supplementary optics in order to see the image. Nowadays, the pixel size of microdisplays may be less than 4 mu m, which makes the supplementary optics the major factor in defining restrictions on a NED dimensions or at least on the distance between the microdisplay and the eye. The goal of the present work is to find answers to the following two questions: how small this distance can be in principle and what is the microdisplay maximum resolution that stays effective to see through the supplementary optics placed in immediate vicinity of the eye. To explore the first question, we consider an aberration-free magnifier, which is the initial stage in elaboration of a real optical system. In this case, the paraxial approximation and the transfer matrix method are ideal tools for simulation of light propagation from the microdisplay through the magnifier and the human eyes optical system to the retina. The human eye is considered according to the Gullstrand model. Parameters of the magnifier, its location with respect to the eye and the microdisplay, and the depth of field, which can be interpreted as the tolerance of the microdisplay position, are determined and discussed. The second question related to the microdisplay maximum resolution is investigated by using the principles of wave optics. (C) 2015 Optical Society of Americ

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Assessment of minimum permissible geometrical parameters of a near-to-eye display

Valyukh

Slobodyanyuk

2015

Appl. Opt.

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“…Several types of liquid crystal beam steerers can be dis− tinguished, for instance the tunable gratings which employ diffraction of light and the devices in which refraction is used [4][5][6][7][8]. The refractive beam steerers operate like electri− cally controlled liquid crystal wedges or prisms.…”

Section: Introductionmentioning

confidence: 99%

Simulation of electrically controlled nematic liquid crystal Rochon prism

Buczkowska

Derfel

2016

Opto-Electronics Review

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“…The orientation of an optic axis can be controlled by means of an external electric field which offers beam steering and other electro-optic applications. Several types of liquid crystal beam steerers can be distinguished, for instance the tunable gratings which employ diffraction of light or the devices in which refraction is used [3][4][5][6][7][8]. In this paper, we propose several beam steering devices in which the crucial role is played by a typical twisted nematic cell.…”

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Application of twisted nematic cell in beam steering devices

Derfel¹,

Buczkowska²

2015

Photon. Lett. Poland

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Abstract-Several simple beam steering devices composed of twisted nematic cells and typical optical elements are proposed. Principles of operation are described, based on elementary optical phenomena as total internal reflection or polarisation by reflection. The deflection angles are calculated for exemplary parameters. The possibility of modifications of the proposed devices is discussed.Beam steering optical devices find applications wherever the light beam direction needs to be rapidly changed. The devices based on electro-optical effects in liquid crystalline systems are of particular interest because they offer several advantages over mechanical modulators, in particular no need to apply mechanical force to move optical elements, low driving voltage and low cost [1][2]. Nematic liquid crystals are often employed for beam steerers. They are birefringent uniaxial media with positive optical anisotropy, n = n e  n o > 0. The orientation of an optic axis can be controlled by means of an external electric field which offers beam steering and other electro-optic applications. Several types of liquid crystal beam steerers can be distinguished, for instance the tunable gratings which employ diffraction of light or the devices in which refraction is used [3][4][5][6][7][8]. In this paper, we propose several beam steering devices in which the crucial role is played by a typical twisted nematic cell.The twisted nematic cell (TN) is the most popular liquid crystal device used both in the simplest displays as well as in technologically advanced devices, e.g. in multicolour screens [2]. The nematic layer is confined between two transparent plates with transparent electrodes. When it is not subjected to an external electric field, the optic axis remains parallel to the plates but changes continuously its orientation through 90° from the first plate to the second plate. If the thickness of the layer is suitably chosen, the plane of polarisation of linearly polarised light, incident normally on one surface of the layer, rotates effectively through 90°. Under the action of voltage significantly exceeding the threshold value U T , the twisted structure unwinds. The optic axis becomes perpendicular to the plates and the polarisation of the incident light is not affected. The principle of operation of the devices proposed in the following is based on the * E-mail: gderfel@p.lodz.pl possibility of switching between two orientations of the polarisation plane of light emerging the twisted nematic cell. Figure 1 shows the device composed of a TN cell and a Wollaston prism. The Wollaston prism is a kind of polarising beam splitter made of calcite, which is uniaxial birefringent crystal with negative optical anisotropy n = n e  n o < 0, where n e = 1.4552 and n o = 1.6557 (for  = 632.8 nm). The prism is composed of two parts. The optic axis in the first part is perpendicular to the optic axis in the second part. The prism deflects the beam with respect to its initial direction depending on the polarisation of the beam [9]. The ...

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On liquid crystal diffractive optical elements utilizing inhomogeneous alignment

Cited by 16 publications

References 38 publications

Assessment of minimum permissible geometrical parameters of a near-to-eye display

Assessment of minimum permissible geometrical parameters of a near-to-eye display

Simulation of electrically controlled nematic liquid crystal Rochon prism

Application of twisted nematic cell in beam steering devices

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