We propose a novel flat panel-based head-up display (HUD) to realize a large viewing angle automotive display. The proposed flat-panel geometry is straightforward to integrate into the dashboard. We also provide a flat-panel compatible solution to eliminate the ghost image and stray-light in large field of view using space-variant polarization sheets and optimized directional filtering, respectively. The proposed system provides an image area that is about 14 times larger compared to commercial HUD, and the P-polarized virtual image is also viewable with polarized sunglasses. The virtual image distance in our experimental system is closer than in commercial HUD.
KEYWORDS: Crystals, Sensors, Optical engineering, Single mode fibers, Optical filters, Photon polarization, Mirrors, Laser crystals, Transmittance, Signal to noise ratio
A small, portable, high-flux correlated photon-pair source has been designed and constructed from simple opto-mechanical parts. Unique to this device is its straightforward alignment process, together with the direct coupling of signal and idler photons into polarization-maintaining single-mode optical fibers. Spontaneous parametric down-conversion is used to produce photon pairs in β-barium borate (BBO) at a center wavelength of 810 nm. Owing to the applied type-I phase-matching, coincident photons have identical polarization. The estimated fiber-coupling efficiency is 51%, the measured photon and coincidence flux are 636 and 130 kHz/mW, respectively, normalized to pump power (44 mW). The source has an extremely wide wavelength spectrum of 202-nm FWHM, measured at the fiber output, which limits the actual heralding ratio to 20%.
We examine the chromatic properties of ghost images appearing in expanded viewing angle polarization-type head-up display systems. We propose an achromatic polarization correction method to suppress ghost images in the whole visible spectral range. The method is based on the use of two half-wave plates of orthogonal optical axis–one being laminated on the combiner, the other attached to the head-up display (HUD) projector. We show that in this configuration the dispersion of the two waveplates cancel each other. Based on the results, a ghost image free colour HUD is demonstrated with 13 ° × 40 ° FOV. We present our modeling and experimental results and our demonstration HUD system.
We present an optical set up that significantly reduces the ghost images appearing due to multiple reflections on both surfaces of the combiner (typically the windshield) of head-up display (HUD) systems. The method is based on an optimized polarization correcting optics attached to the HUD projector. For the quantitative investigation of the ghost images, we calculate the ghost image suppression ratio as a function of viewing direction using a custom algorithm based on ray tracing and Jones-vector formalism. We also present experimental results on the proposed configurations exhibiting very good agreement with calculation results. As a result, the ghost image free viewing area of polarization-type HUDs can be increased more than fourfold.
The application of phase-only input data pages has several advantages with respect to conventional amplitude
modulated holographic storage: It avoids the saturation of the storage material by providing a smooth Fourier
plane, improves the response in associative read-out, increases the light efficiency of the recording object wave
and provides the opportunity of data encryption. However, if the information is carried by the phase of object
wave front recovery of the data from the reconstructed beam is problematic with simple intensity sensitive
devices as a CCD camera. To solve this problem we propose a compact phase to amplitude data page conversion
method and apply it to the output of a Fourier holographic data storage system. The phase to amplitude
conversion uses a birefringent crystal to generate two equal intensity copies of the reconstructed data page that
are geometrically shifted by an integer number of pixels with respect to each other each other. The interference
of these two phase modulated images is projected on the detector field of the camera. The interference pattern
contains low and high intensity pixels if the phases of the interfering pixels are opposite and identical
respectively. Using proper data coding, the original data matrix recovered from the intensity pattern of the CCD.
Fourier plane homogeneity, bit error rate and positioning tolerances of the proposed holographic storage method
are investigated by computer modeling and a comparison is provided with amplitude modulated data pages.
We propose a simple and robust method for the recovery of phase data pages. We provide experimental proof of the
concept and investigate its applicability to optical encryption and encrypted holographic storage. Finally we discuss a
possible compact optical implementation of the method.
We present non-volatile readout of thin film polarization Fourier holograms using different wavelengths. We demonstrate application of imaged reference phase coding in portable holographic demonstrator. Experimental results approve applicability of preliminary computer simulations.
High density polarization holographic demonstrator system has been developed using ~2 µm thick azobenzene polyesters on reflective card form media. One possible development of the system is the introduction of phase encoding into the reference arm that provides enhanced security applications. Simulations were carried out with a custom computer program based on mathematical model of the system to generate code sets optimal in terms of code number and security level. The model is suitable also for the prediction of expected tolerances necessary before the definition of a working system. Performed experiments proved applicability of the model for possible system considerations. We also present our concept of extending thin-film holographic principle to multilayered holographic storage of increased capacity.
Performances of high quality imaging systems are often affected by surface or glass defects, like scratches, bubbles or other localized disturbances. The goal of the present investigation is the modeling of air inclusions in the lens material and analyzing the resulting changes in the wavefront distortion and in the diffraction spot quality. CD and DVD focusing objectives are especially sensitive to this type of defect, since the size of the diffraction spot and the power-density distribution determines the quality of both the written pits and received signal. We used OSLO and ZEMAX optical design software to model these errors. This model includes the DVD objective lens and the disc. The objective lens is a plano-convex lens made of glass with an aspheric layer on its convex side. Bubbles are incorporated as ball-shaped air inclusions. The computations are based on ray tracing and physical optics propagation methods. From these computations we can calculate the intensity distribution in the focal spot and the encircled energy in the Airy disk. These calculations help us determine the tolerances of DVD objective lenses to air inclusions in function of the bubble size, shape and position. The practical application of the model will allow us to redefine the quality criteria for the used DVD lenses.
We present our results on polarization holographic data storage in thin azobenzene side chain polymers. Two different systems have been demonstrated: a read only system with red diode laser and a read&write system with green frequency doubled solid state lasers. Error free operation have been proved at 2.77 bit/µm2 data density. We have also demonstrated enhanced security holographic storage by applying phase coded reference waves imaged onto the hololographic storage material. We also present the concept of extending the principle to multilayer holographic storage.
The goal of our project is to develop a rewritable holographic memory card system based on thin film polymer media. The data is stored in form of polarization Fourier holograms that present high efficiency even for thin material. The present communication deals with the modeling and the optimization of the system operation. We have developed a computer model based on fast Fourier transformations, taking the parameters of the optical processes into account. The model was used to assess the effect of various parameter sets, optical arrangements and elements on the performance of the system. The results are tested experimentally. Here we present the system model, the main optimization possibilities and other opportunities to utilize the model.
Phase-mostly modulation mode of a Sony LCX016AL-6 liquid crystal display has been found for appropriate elliptical polarization states of the input and output light with calculation using Jones matrices. Phase delay measurement with an accuracy of 2° were performed using a simple diffractive technique at different gray levels. Our measured results agree well with the theoretical calculation with Jones matrices. Both gave about 10% intensity variation and more than 200° phase modulation in the whole range.
Polarization holographic read/write and read only demonstrator systems have been developed using ~2 µm thick azobenzene polyester on a card form media. The thin-film holographic system has practical advantages, e.g. high diffraction efficiency, no cross talk between the holograms, reading in reflection mode, no hardware servo, different wavelengths for writing and reading (non-volatile storage), data encryption possibility, no problem with material shrinkage, etc. The candidate azobenzene polyester has good thermal, room temperature and ambient light stability and good optical properties for the purpose of thin film application. Using thin-film holography the possibilities of multiplexing are limited, however, raw data density as high as 2.77 bit/µm2 has been achieved in an optimized Fourier holographic system using high numerical aperture (NA³ 0.74) objective in a 8f arrangement with sparse code modulation and Fourier-filtering at 532 nm. High density polarization holographic demonstrator systems have been developed using ~2μm thick azobenzene polyesters on reflective card form media. FFT computer simulation of the system including saturation model of the material allows optimization of system components including data density and capacity. A raw density as high as 2.77 bit/μm2 has been achieved without multiplexing in a compact, portable read/write sytem at 532 nm allowing more than 1000 readout without data loss. A separate read only system working at 635 nm realizes non-volatile readout and allows card exchange at a data density of 1.3 bit/μm2. Security level of the presents holographic optical card systems can be further increased by using phase encoded reference beam. Advantageous applications of the proposed encrypted holographic card system are also outlined.
We present the improved demonstrator of our rewritable holographic memory card system. High density optical storage is realized in a non-commercial optical set-up. Fourier transformed recording is used in a polarization holographic arrangement realizing reading and writing from the same side of the data carrier which is a modified plastic card. Holograms containing binary information of 300 x 220 bits are as small as 0.0484 square mm. The storage layer is amorphous polyester providing repeated writing and erasure cycles and thousandfold readouts without loss of information. Alternate read only system providing non-volatile storage can be realized using 635 nm laser diode.
KEYWORDS: Holograms, Polarization, Multiplexing, Data storage, Signal to noise ratio, Holography, Spatial light modulators, Fourier transforms, 3D image reconstruction, Convolution
We introduce a new physical model for description of thin polarization holograms recorded and reconstructed with complex reference beams. Next we apply this model for two fundamentally different arrangements supposed to be used in a data storage system based on phase coded thin polarization holograms. On the basis of the model, we construct some computer programs for simulation of the storage system and optimization of the phase codes. We investigate the feasibility of multiplexed and security encrypted data storage in the form of thin polarization holograms based on the phase encoding method.
We are developing a holographic memory card drive using thin polymer storage layer on credit card sized plastic carriers. The main features of the card are high storage density, re- writability and resistance to harsh environment (e.g. electromagnetic noise, mechanical intolerance, high temperature and humidity). The optical system of this device uses Fourier holograms to record information. The present communication deals with the optimization of the storage density by computer modeling of the system. The model is based on fast Fourier transformations, taking the parameters of the optical processes into account. The model was used to assess the performance of various parameter sets. The results are tested experimentally. The work suggests that storage density higher than 1 bit/micrometers 2 may be achieved in the thin holograms of this memory card at raw bit error rate values below 103.
Our goal is to develop a re-writable holographic memory card system based on thin film polymer media on credit card size plastic carriers. Data is stored in our system in form of polarization holograms that present high efficiency and excellent suppression of higher orders even for thin material. Data is written on the card in a parallel way using spatial light modulators to encode the object beam that is Fourier transformed by a custom objective lens and interferes with the reference beam (of orthogonal polarization) on the card. We use reflective carrier in order to read out the data from the same side of the card. This allows us to have a compact system and standard ID 1 type carrier card. The optical system and the data organization are optimized to have a data density higher than 1bit/micrometers 2. We expect to pass the limit of 10 bit/micrometers 2 with the introduction of phase coded multiplexing that would provide more than 2Gbyte capacity if using half the card area as active surface.
We developed a standard credit card-shaped general-purpose data carrier, a reflective Holographic Memory Card (HMC), and the appropriate equipment for its handling. Data recording and retrieval are accomplished by polarisation Fourier holography using a thin layer of photo-anisotropic polymer as the storage material. The data density is about 1 bit/micrometers 2, the maximum storage capacity of the card is around 10 Mbytes assuming a 10 x 10 mm storage area. Data is stored in the form of microholograms, from which 40x40 pieces are recorded on the HMC. The optical system involved performs data writing/reading/erasing and also locates the position of the microholograms. Main components of the optical system are an SLM and CCD for opto-electronic conversion, a frequency-doubled solid-state laser source, a beam shaping system that provides homogeneous illumination of the SLM, an interferometer for hologram construction, special Fourier transforming objectives and a random-phase mask for optimised hologram recording. Our results include conceptual planning, design, fabrication and assembling of the optical system. In the present paper we describe principle of operation including layout of the elements, and explain the operation of the equipment in detail.
We present a novel solution for high-density optical storage of data in thin media. The holographic memory card of Optilink provides sixty-fold data density enhancement compared to present commercial LaserCard devices. The 1 - 2 micrometers thin amorphous polyester storage film is capable of rewritable storage using a single laser source for writing and erasing. The polarization holographic principle used in reflection mode requires demanding optical solutions. Successful data evaluations prove applicability of the new system. Density enhancement up to 16 bit/micrometers 2 with the use of 20 - 30 micrometers thick layer is also outlined.
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