Tetsuro Mizushima

Second Harmonic Generation with High Conversion Efficiency and Wide Temperature Tolerance by Multi-Pass Scheme

We proposed a multi-pass second harmonic generation scheme in which condensed fundamental light passed through a nonlinear crystal many times. The multi-pass scheme was realized by using a wide periodically-poled MgO:LiNbO3, concave mirrors and condensing optics. The total wavelength conversion efficiency of the multi-pass scheme was increased because non-converted fundamental light which had passed through the nonlinear crystal was re-injected and condensed into the nonlinear crystal and converted. Moreover the total temperature tolerance of the multi passes was widened because the fundamental beam passes had different phase-matching temperature and compensated for miss conversions of other passes. In this work, continuous-wave 5 W green light (532 nm) with 66% conversion efficiency and wide temperature tolerance were obtained.

20.3: A Bright and Efficient Mobile Projector Using a Compact Green Laser

We have developed an ideal W-class compact green laser for mobile projectors. The wall-plug efficiency of the laser was higher than 15% over wide temperature range. By using RGB lasers and small LCOS projection optics, a mobile projector with high brightness (100 lm) and excellent efficiency (20 lm/W) was demonstrated.

L‐9: Late‐News Paper: Laser Projection Display with Low Electric Consumption and Wide Color Gamut by Using Efficient Green SHG Laser and New Illumination Optics

air-cooled RGB lasers including a compact and efficient green SHG laser and new illumination optics for speckle noise reduction, we developed advanced laser projection engine. A prototype of laser rear projection display with low electric consumption (about 50W) for light sources and wide color gamut (137%NTSC) was realized. 1. Introduction the last decade, several different micro-display technologies (LCD, DMD and LCOS) have been developed and projection displays captured the large screen market for business and home theater. Most projection displays are now using lamps as light sources, such as high-pressure mercury lamps and metal halide lamps. Laser light sources are attractive for projection displays. Projection displays based on RGB lasers can provide extremely wide color expression with the narrow spectrum of lasers. Due to small etendue, laser lights are projected with high efficiency. Lasers have longer life time and faster response time than lamps. As high brightness and high power efficiency of lasers contribute to downsizing systems and improving electric efficiency, laser projection displays will find wide applications (1-3). However, for realizing laser displays there are two problems. The one is a suitable green laser with high efficiency, high power and compact size. As there are no green diode lasers and conventional green lasers for high output power need big mechanisms such as water-cooling devices, it is difficult to downsize and to decrease electric consumption. The other problem is an interference phenomenon called speckle. As lasers have high coherency, speckle noises are superposed on projected images (4). We overcome these problems and demonstrate a laser rear projection display with low electric consumption.

P‐206L: Late‐News Poster: Low Electric Consumption 3.6W Green SHG Laser Light Source Applicable to Laser Projection Systems

Highly-efficient fully air-cooled green laser light source with frequency doubling module is reported. As a result, 3.6 watts green laser light generation with about 9% wall-plug efficiency is achieved. By using fully air-cooled RGB lasers including the green SHG (Second Harmonic Generation) laser and illumination optics for speckle noise reduction, a laser projection engine is prototyped. A laser rear-projection system with this laser projection engine shows several merits; wide color gamut (133%NTSC), 61inch large screen size, and low electric power consumption (less than 100W, at 650cd/m2).