An optical design of digital light processing projector accommodating three pieces of micro digital mirror array display panels is presented. The system is configured by the combination of a color separation unit and a color re-combination prism, which combines light signals from individual display panels and then directs the synthesized full color images projected onto the screen. The color separation unit comprises two dichroic filters set at 40 degrees with respect to the optical axis of the system and two reflecting mirrors with relay lens for guiding light. The color re-combination unit is contructed in the form of a modified x-prism for better achievement of image contrast, color saturation, and light efficiency. The present system out-performs systems based on the configuration of Philips prism in less occurrence of degraded image quality associated with teh thermal influence of the optical engine, short optical path in prism and back focal length of the projection lens, and the physical size and weight of the unit. Comparisons in overall optical characteristics of the proposed system and those designed by means of various modules of single prism, which operates color separation and color combination processes along same optical path through the prism block will also be presented.
A novel compound prism device consisting of a cubic polarizing beam splitter (PBS) and a non-polarizing dichroic prism is configured as the core component of the illumination unit of a full color projection display system of three pieces of reflective type liquid crystal imaging panels. When the in-coming light beam impinging on the PBS at 45 deg. of incidence, the beam component polarized perpendicularly to the plane of incidence is reflected and directed toward a LCD panel of red-image signal addressed after transmitted through a red-passing dichroic filter. The beam component polarized in parallel with the plane of incidence of the PBS is transmitted and passing through a red-cut dichroic filter. The rest portion of the light beam is then got the blue and green color bands separated by the dichroic filter at 30 deg. of incidence and directed to a blue and green signal addressed LCD panel respectively.
All the dichroic filters are designed polarization independent and the PBS has a high contrast ratio of 1000 for the on/off states of teh addressed pixels of the image panels. The color separation and re-combination prism unit will provide a screen uniformity of d(u',v') <0.01 when it is accomodated in the projector with a projection lens assembly of F/#2.4.
A new compact front UXGA projector is introduced with three one inch reflective LCD panels; It delivers 1000 lumens with the advantages of the compactness and high resolution. Three PBS cubes and one recombination cube are employed for separation and recombination of the three primary colors. A newly developed PBS cube is used not only as a polarization selector but also as a dichroic mirror, and a parallelogram prism array is plugged in front of the polarization converter to make the green light and the blue light orthogonally polarized each others. Compared to the old design, this new one gets the advantage of the space savings. The telecentric projection F/2.5 lens is characterized as a zoom range from 45 mm to 55 mm. Lateral colors are eliminated to be under 0.8 pixels. MTF is estimated as 60% on axis and 40% at 0.7 field. Distortion is around -1.7%.
A thin film color selective beam splitter is designed and the method of fabrication is described through a single deposition process of a coating system onto the two lateral faces of a triangular prism with base angles of 60 deg. and 45 deg. respectively. Properly prepared contact prisms are then cemented onto the two coated surfaces to make all the incoming and outgoing light beams normal to the prism block. The tri-chromatic prism provides the primary colors R, G, B according to the sequence that the red color is first reflected when the modulated white beam is incident at 30 deg. onto the dichroic filter deposited on the lateral face with the base of 60 deg., and then the rest part of the spectrum is incident at the other dichroic filter of the system at 45 deg. to get the blue and green beams separated. Color performances of the system from the thin film filters constructed with TiO2 and Al2O3 as the high and low index layers respectively are analyzed. The advantages to use the tri-color prism block in a projection device with reflective liquid crystal light valves are discussed.
A compact 60-inch LCD rear projection television optimized with depth less than 60 cm has been developed by using three 1.3' poly-Si TFT-LCDs of 1024 X 768 pixels resolution. Three primary colors of the projection system are separated and synthesized by dichroic mirrors and X-prism respectively. Polarization converter is used to increase the optical throughput and an aspherical hybrid projection lens with f equals 19.97 mm and f/# equals 2.4 is designed to effectively shorten the projection distance. A Fresnel lens and a fine lenticular lens screen can create a morie' pattern free picture. Under a 120 W UHP lamp, the brightness of the rear projection TV can achieve 460 nits luminance.
Optical thin film color splitting and combining components for 3 panel projection display were designed using TiO2 and SiO2 as high and low refractive index materials, respectively, and fabricated by reactive electron-beam deposition at a substrate temperature of 300 degrees C. The resulting coating performances on the brightness and color performance were analyzed by chroma meter. The correlations between these results and their spectral curves measured by spectrophotometer were discussed.
The technique of mid-frequency plasma polymerization was employed to deposit scratch-resistant and anti-fogging films on transparent polycarbonate substrates. The input monomer used for depositing scratch-resistant coatings was tetramethyldisiloxane (TMDSO). Variation of oxygen-to-TMDSO ratio study indicated that the hardest film was formed using equal amount of oxygen and TMDSO. The typical deposition rate was about 3 micrometers /hr. Typical operation pressure, TMDSO flow and oxygen flow were 2 X 10-2 Torr, 30 sccm and 30 sccm, respectively. The deposited polysiloxane layer was characterized as a hard, highly transparent and durable against scratching and abrasion film. Further depositing a thin hydrophilic film on top of the polysiloxane layer significantly improved the surface wettability and therefore dramatically increased the anti-fogging capability. The monomer used for polymerization deposition of the anti- fogging film was vinyl acetate, and the typical flow for vinyl acetate monomer and oxygen were 15 sccm and 10 sccm, respectively.
Head-up display is gaining increasing access in automotive vehicles for indication and position/navigation purposes. An optical combiner, which allows the driver to receive image information from outside and inside of the automobile, is the essential part of this display device. Two multilayer thin film combiner coating systems with distinctive polarization selectivity and broad band spectral neutrality are discussed. One of the coating systems was designed to be located at the lower portion of the windshield. The coating reduced the exterior glare by approximately 45% and provided about 70% average see-through transmittance in addition to the interior information display. The other coating system was designed to be integrated with the sunshield located at the upper portion of the windshield. The coating reflected the interior information display while reducing direct sunlight penetration to 25%. Color fidelity for both interior and exterior images were maintained in both systems. This facilitated the display of full-color maps. Both coating systems were absorptionless and environmentally durable. Designs, fabrication, and performance of these coating systems are addressed.
TiO2-SiO2 composite films are sandwiched between indium tin oxide (ITO) layer and soda lime glass as a buffer layer. The TiO2-SiO2 composite and ITO layers are sequentially deposited on glass substrates by ion-assisted electron-beam evaporation in the same coating chamber. Influences of the TiO2-SiO2 composite film with various compositions on the structural, optical, and electrical properties of ITO layer before and after annealing in air at 300 degree(s)C and 500 degree(s)C for 1h are systematically investigated using a x-ray diffractometer, spectrophotometer, and four point probe. Surface roughness of as-deposited and post-annealed samples are measured by talysurface and scanning electron microscopy. Correlations between the electrical properties and the surface roughnesses and structures of ITO coatings are also discussed.
The influence of the deposition rate on the microstructure and hardness of TiO2-SiO2 and TiO2-MgF2 composites and their single component films prepared by reactive ion-assisted coevaporation in the deposition rate range 0.14 to 2 nm/s are investigated using an x-ray diffractometer, a transmission electron microscope, and a microhardness tester. It is found that the hardness of the composite films and their single components increase with a decreasing deposition rate. However, the hardnesses of TiO2-SiO2 and TiO2-MgF2 composite films were generally lower than that of pure SiO2 and MgF2, respectively, at the same component deposition rate. This indicates that the addition of TiO2 reduces the hardness of Si02 and MgF2 films. The ultrahigh hardness of pure MgF2 films deposited by ion assistance at the deposition rate of 0.14 nm/s probably results from the high packing density, low lattice defects, and the small grain size (<20 nm) with the preferred orientation of [110]. Furthermore, the homogeneous dispersion of these hard nanoscale MgF2 grains within the amorphous TiO2 matrix causes the hardening of the composite film.
Ion-assisted deposition (IAD) processes configured with a well-controlled plasma source at the center base of a vacuum chamber, which accommodates two independent e-gun sources, is used to deposition TiO2MgF2 and TiO2-SiO2 composite films of selected component ratios. Films prepared by this technology are found durable, uniform, and nonabsorbing in visible and near-IR regions. Single- and multilayer antireflection coatings with refractive index from 1.38 to 2.36 at (lambda) equals 550 nm are presented. Methods of enhancement in optical performance of these coatings are studied. The advantages of AR coatings formed by TiO2-MgF2 composite films over those similar systems consisting of TiO2-SiO2 composite films in both visible and near-IR regions are also presented.
Hardness of TiO2-MgF2 and TiO2-SiO2 composite films prepared by reactive ion-assisted coevaporation were strongly dependent on the microstructures and evaporation rates of each component. The softening of the composite films at low TiO2 composition is caused by the dispersion of amorphous TiO2 particles in the sort amorphous SiO2 or soft crystalline MgF2 matrix, which is obtained at the high evaporation rate of SiO2 or MgF2. In contrast, the hardening of the composite films at high TiO2 composition is produced by the dispersion of hard amorphous SiO2particles or hard crystalline MgF2 grains with the size <20 nm within the amorphous TiO2matrix, which is obtained at the low evaporation rate of SiO2 or MgF2. In these cased, the evaporation rate of TiO2 is always maintained at 0.2 nm/s.
Composite TiO2-MgF2 films are fabricated by reactive ion-assisted coevaporation. The optical, structural, mechanical, and chemical properties of these films are systematically studied. From the analysis of x-ray diffraction and spectrophotometer data the crystallographic phase compositions and the optical properties of the composite films are found to be controlled by the relative deposition rate of two evaporation sources. The refractive index and the microhardness of the composite films behave nonlinearly with respect to the composition of the films. When the molar fraction of TiO2 is higher than 40%, the hardness of the composite films exceeds that of pure TiO2 and glass substrate. The surface morphologies of all composite films are featureless and very smooth. It has been shown that composite TiO2-MgF2 films prepared by reactive ion-assisted coevaporation are very suitable for the design and fabrication of single-layer and multilayer antireflection coatings.
The optical and structural properties of TiO2-MgF2 mixed films prepared by coevaporation with ion-assisted deposition have been investigated. The composition of coevaporated TiO2-MgF2 mixed films can be tuned by controlling the relative deposition rates of the two sources. Most of the films with thicknesses less than 500 nm are found to be homogeneous in optical properties. The optical and structural properties of the mixed films change from MgF2-dominant to TiO2-dominant as the TiO2 content in the mixed film increases. The dependence of the refractive index with composition can be fitted by Bottcher's formula at low TiO2 content and by Lorentz-Lorentz formula at high TiO2 content in the mixed films. An application of TiO2-MgF2 mixed films for the design and fabrication of antireflection coatings in the near infrared region has also been discussed.
Optical and physical properties of MgF2, ZnSe, and composite ZnSe-MgF2 films deposited by co-evaporation of ZnSe and MgF2 on glass substrates at elevated temperatures are studied. MgF2 films deposited on glass substrates at temperature of 200 degree(s)C were found durable, resistant to wet environment, high in film packing density, and having a very reproducible refractive index of 1.38 to 0.75 micrometers . ZnSe films formed under same substrate conditions were also found dense and reproducible. The refractive indices of these films were determined to be 2.50 +/- 0.01 at 0.75 micrometers . The adhesion of the films to the substrate declined drastically in hot and wet environment. Composite films deposited on glass substrate at 200 degree(s)C by co-evaporation of ZnSe and MgF2 with selected individual evaporation rates were observed to be uniform, durable, and enhanced in protection against hazardous environments.
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