Study On Ultra-thin Laser Projection Display Technology

After the invention of lasers, progress made in laser-based display technology hasbeen very promising. Laser-based displayhas entered the projection area and has the ambition to infiltrate from low(picoprojection) towards high light output systems(digital cinema),who is marked as a " fourth-generation display technology ".One of the benefits of lasers is their narrow spectral bandwidth. As a consequence, the display can have a very large colour gamut, if the lasers are carefully selected. Another benefit is the very low intrinsic étendue of the source. One can imagine using less complex, more efficient, smaller but more powerful optical systems. This not only for scanning projectors, but also for 2D light valve based projectors(LCOS, LCD, DLP). Laser light source combined with ultra short focal projection lens, in the realization of large color gamut, large screen, high brightness display at the same time, can greatly reduce the volume of the system and save user's space, with a broad commercial prospects. Laser diode is used to pump laser crystal Nd: YVO4, by LBO frequency doubling technology, 455 nm, 532 nm and 640 nmareselectedas primaries. Laser emitted by a semiconductor laser and solid state lasers using 56 fibers who is coupled into a single fiber formed 32 W white light(color temperature 6500k),the power of primaries are 32 W, 12 W, and 18 W respectively.According to the chromaticity theory, color reproduction transformation matrix between the laser gamut and the common NTSC color gamut color gamut is deduced, and proposed the gamut expansion algorithm, the hardware adopts the FPGA and ASIC combination to achieve a real-time image color space conversion and extension.Based on the analysis of the speckle mechanism, methods of speckle reduction are compared. Using engineering diffuser with antireflection coating(transmission rate of 95%) driven by step stepper motor,the speckle contrast is lowered to 3% and ensures the system has a high optical efficiency.Using a 0.65 inch digital micromirror device(DMD) chip produced by TI Inc. as spatial light modulator, the efficiency of the whole projection system and the coupling relationship between the illumination system and the imaging system are analyzed based on the theory of nonimaging optics. We discuss three kinds of structure respectively in the aspect of design principle, difficulty of processing and testing prospects. A 65 inch telecentric projection lens is designed adopting catadioptric structure with a projection distance of, whose indicators meet the requirements of the project. In order to explore the projection lens potential, we design a 100 inch projection lens with a projection distance of. In addition to the illumination uniformity of, the indicators meet the requirements of the projection display.Finally, the catadioptric 65 inch ultra short focal projector lens prototype is completed. Using the testing device, the image distortion, contrast, brightness uniformity, which are the main indicators were tested,test results meet the requirements.