RGB lasers for laser projection displays

JENOPTIK Laser, Optik, Systeme GmbH has developed the first industrial all-solid-state Red-Green-Blue laser system for large image projection systems. Compact in design (0.75 m(3) 180 kg, 3 kW power consumption), the system consists of a modelocked oscillator amplifrer subsystem with 7 ps pulse duration and 85 MHz pulse repetition frequency, an optical parametric oscillator (OPO), and several non-linear stages to generate radiation at 628 nm, 532 nm and 446 nm with an average output power above 18 W. Each of the three colors is modulated with the video signal in a contrast ratio of 1000:1 and coupled into a common low order multi mode fiber. The system architecture relies on efficiently manufacturable components. With the help of FEM analysis, new engineering design principles and subsequent climatic and mechanical tests, a length stability below 50 mu m and an angle stability below 10 mu rad have been achieved. The design includes efficient laser diodes with integrated thermo-electric cooler and a life time above 10000 hours. The stability of the output power is better than +/- 2% in a temperature range from 5 degrees C to 40 degrees C. The system operates reliably for more than 10000 hours under field conditions. The design is based (among others) on work by Laser-Display-Technologie KG and the University of Kaiserslautern.