KEYWORDS: Light scattering, 3D displays, Camera shutters, Scattering, 3D modeling, 3D image processing, Visualization, Switching, 3D volumetric displays
3D display with a volumetric screen is developed because it composes the most realistic 3D image of 3D object or scene.
The display experimental model using a stack of light-scattering shutters based on the ferroelectric LC layer was created
for the first time. Physical mechanisms of FLC layer scattering were studied. The bistable scattering regime which is
most appropriate for practical applications was found, and the total time of scattering switching on and switching off was
less than 250μs at ± 80 V. The experiments showed that the possible number of FLC shutters in a volumetric screen of
the real time 3D display can be as high as 30-100.
The electric field initiates the director reorientation in the whole volume of FLC layer and eventually results in the motion of domain walls. Dynamics of the domain wall motion in helix free FLC cell is considered. The domain wall motion velocity depends on the frequency of electric field change and on the polar coefficient of anchoring energy Wp. Increasing the frequency or the polar part ofthe anchoring energy (when the frequency is constant) gives rise to decrease of electrooptic response time 1/τ0.1-0.9 by a factor 2-3 times. Due to this the electrooptical response time can be as small as 100 μs when the electric field is about 4V/μm. These parameters are most suitable to be used in an active matrix
display (or micro-display) with the high resolution.
Advances and key display applications are discussed. Computer, compact mobile, TV and collective large screen displays are mentioned. Flat panel displays step on CRT devices to leave them behind in 2007. Materials, active matricies and applications of bright radiative field emission and organic LED displays are developing successively and pressing other technologies to be used in photo-cameras, cellular phones, auto-cars and avionics. Progress in flexible screens can substantially extend the display design and application soon. 3D display systems are under intensive development, and laser is an important unit in some vaiants of holographic and volumetric 3D displays. Value forecast of different display markets is presented.
Requirements to the volumetric displays and their features in comparison with 2-D screen based 3-D displays are considered. The main difference of a volumetric display is a possibility to look around displayed 3-D object by many observers from other sides simultaneously, and no points of view are calculated for this. Optical, optical-mechanical and optical-electrical methods of addressing the voxels in a volumetric media are discussed. Basic features, advantages and disadvantages of concrete volumetric display developments on the base of the two-photon absorption, rotating helix or disc, light scattering in liquid crystal shutters are presented. Problems and prospects of volumetric displays are discussed.
Modulation characteristics of the light passing through a polarizer-free electrooptical cell based on a double uniaxially oriented film of polymer dispersed ferroelectric liquid crystals (PDFLC) have been studied. Theoretical analysis is presented of the dependence of the maximum light transmission, modulation depth and contrast ratio on the angle between the orientation of PDFLC films, on their optical anisotropy and the molecular tilt angle (Theta) . Parameters under study have been measured, and the experimental results are in good agreement with the theoretical estimations.
Advances in the field of studying the electrooptics of ferroelectric liquid crystal and possibilities of their practical use are considered. Liquid crystal compositions are developed with steady bistable and multistable properties and high multiplex ability for composing and displaying blocks of both the binary and analog information in fast spatial light modulators and high resolution information displays. Liquid crystal cells are created with electrooptical response time of a few microseconds.
A new principle of continuous gray scale for passively addressed FLC displays and SLM matrices is proposed. It is based on the multistability effect in C*FLC. Conditions of its exhibition are defined. Experimental results for FLC cells and the laser beam intensity attenuator are given.
The optical pattern recognition is performed traditionally on the base of the Fourier transform of images and their following matched filtration. However this recognition is not invariant to the orientation and scale changes of images. This problem can be solved due to the Fresnel transform perhaps.
The extended sphere of the laser successful use at large vagueness of the gear of radiation interaction with biological and biosimilar objects is a main modern paradox in the application of low-intensity coherent radiation in biology and medicine. There are rather regularly, for example, the reasons of immateriality of such parameters as laser radiation coherency degree for biostimulation, but the replacement of semi-conductor lasers by the light diodes isn't observed in medical practice until now. there are also no convincing results on comparative analysis of biostimulated effect under coherent and noncoherent radiation. Action of coherent electromagnetic radiation of the visible and infrared spectral range causes, as appear, the same type structure-optical changes in various objects biological liquids, cells suspensions, model biomolecular solutions, cells of plan, insects and animals. The medicobiologic consequences of laser effect are extremely variable because of the complexity of biological object and sophistication of research techniques and analyses. The energy doze of radiation acting onto a bio-object, as a rule, is extremely small, and hence like the case of extremely high frequency radiation one can to name this action by the 'informative' one, i.e., initiating only biosystem reactions is produced due to its own energy. In connection with the relatively slow biosystem response to the laser radiation action, the nonlocality of this reaction at the local action and large variety of biochemical reactions caused with laser radiation one can assume the existence of uniform physical mechanism realizing the biostimulation effect of laser radiation for various biosystems.
The steady bistable regime in FLC layers was found using FLC compositions with its own (volume) bistability. The grayscale in such a FLC possessing high spontaneous polarization value is demonstrated and explained. The row addressing time 50 mks and multiplexivity 1200 (at optical contrast more than 20:1) are reached in FLC passive addressed matrix. Monostable FLC with 2.5 mks response time (at optical contrast not less than 50:1) can be used in fast optical light valves and active addressed matrices for SLM- spatial filters.
We call the bistabifity of ferroelectric liquid crystal (FLC) cells as the surface bistability (SB), if the dispersion part of anchoring energy is responsible for this type of bistabiity. SB was predicted theoretically [1] and investigated experimentally [2-4] .It was shown, that SB there exists in SSFLC cells possessing the bookshelf structure of smectic C layers [2] and SB there exists only in limited region of multidimensional space of cell and driving voltage parameters [3]. Anchoring energy of FLC with solid surface for SB structures is [4]: 102 iO erg / cm2 On the other hand there exists the volume bistability (VB), which have been observed by us recently in thick (15 mkm and more) layers of new FLC compositions [5].VB is a special phenomenon caused only with stereo chemical nature of the FLC composition and quite independent upon surfaces. In this work we would try: to found the physical principle for experimental measurement of an average free energy density of ferroelectrics, -to describe manifestations for both SB and VB, - to compare SB and VB from point of view their free energy parameters.
A hybrid device which consists of a liquid crystal spatial light modulator (LC SLM) connected through fiber optics to a TV screen, being interfaced to a desk-top computer, is used for generating binary phase-only spatial filters (BPOFs) in a real-time TV/optical correlator. An adaptive optical/digital correlator with a BPOF and nonlinear feedback is described. The LC SLM phase-error correction is implemented using an iterative algorithm. The BPOFs with improved discrimination ability and circular harmonic BPOFs with spatial carrier are generated with the system.
A method is described for the scanning of a 3D scene, in which the scene cross sections are oriented along, rather than normally, to the line of sight of the observer.
The hybrid device which consists of a liquid crystal spatial light modulator connected through fiber optics to a TV screen, being interfaced to a desk-top computer, is used for generating binary phase-only spatial filters (BPOFs) in a real-time TV/optical correlator. An adaptive optical/digital correlator with a BPOF and nonlinear feedback is described.
The developed principles of optimization of the molecular structure and the mixture composition of smectic C* ferroelectric liquid crystal (FLC) are discussed, which significantly allow us to increase the speed of the electro-optic response in planar alignment of FLS. The achieved results reveal opportunity of construction of fast spatial light modulators with multiplexing owing to bistability with the time of electrical addressing about 1 microsecond(s) .
A holographic associative memory in a feedforward network is implemented using photosensitive liquid crystal light valve (LCLV) as a phase conjugate mirror (PCM). In the case of three simple binary images stored in the Fourier hologram the completely reconstructed single output image (rectangle) is observed with only a quarter of the image present as an input. Because of non-zero cross correlation and high gain the restoration remains even if the input image is rotated by 25 degree(s) about the optical axis and is either tilted or swung horizontally by up to 45 degree(s). Parallel analog and digital optical computing operations are demonstrated by using an interferometric arrangement with a LCLV-based PCM. Image subtraction, coherent and incoherent image addition, OR, XOR, and NOT optical gates are achieved by controlling the phase difference between two spatially multiplexed signal-bearing waves.
An IR-spatial filter is proposed for usage in a focal plane. This filter screens the IR-array locally, where the IR signal is followed by a signal in the visible region (only noisy signals or jamming interferences are assumed to be followed by visible light). The filter discussed here is based on a photosensitive spatial light (IR) modulator, abruptly diminishing its transmittance in IR, when (and where) visible light intensity is over the settled threshold. The experiments were performed when the attenuation of interference was about one order.
The suggested algorithm and propose construction of an electro-optical system provide an abrupt drop in information flow in a situation like global visioning of the earth's surface. An estimation of the efficiency of this algorithm gives the data flow compression in the vision system by a factor of 103 - 105. Initial experiments confirm the basic principles of this proposal.
There are several research centers in Russia which deal with optical information processing (OIP). They are primarily located in Moscow: the P. N. Lebedev Physics Institute and the Institute of Information Transmission Problems, belonging to the Russian Academy of Sciences, the Institute of Optical and Physical Measurements of the Russian Committee of Standards, Moscow State University and Moscow Physical Engineering Institute. Some of the advances of these centers in OIP will be mentioned, as well as those of the Institute of Automation and Electrometry of Sibirean branch of the Russian Academy of Sciences (Novosibirsk-city).
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