The Heat Effect Problem Of Blue Laser And It's Temperature Control

Presently in the laser research field, blue laser have gained great attention, because of its strongpoint of high efficiency,compactness,high stability,long lifetime and in addition its wildly use in many other fields. But the technology of blue laser which output power reaches watt-level is still immature. So it has great important meaning to do the research of this field.This paper is a part of a solid state blue laser research program. One of the main factors that effects the performance of solid state blue laser is the temperature of its working crystals. This thesis discusses the heat effect problem of working crystal and introduces the design of a temperature control equipment of this solid state blue laser. At first the thesis introduce the theory of generating 473nm blue light. The output of LD 808nm laser acts as pump laser for Nd:YAG crystal. The Nd:YAG crystal output 946nm laser light through quasi-three-level transition from 4F3/2 to 4I9/2.The 946nm laser light then change to 473nm when it pass the SHG(Second Harmonic Generation) crystal LBO, and therefore output blue laser.And then mainly discusses the effect of temperature for these two crystals. The Nd:YAG crystal need to work in low temperature to reverse the number of its particle which is a condition of quasi-three-level transition. And what more, because the Nd:YAG crystal will certainly absorb heart when working, the temperature of the crystal is different between in the center and around ,thus generate heat effect. For cavity design, the crystal may see as lens. LBO is a kind of nonlinearity optical crystal, when light goes through it, it will also absorb heat. The marching angle of LBO crystal is the function of its temperature, therefore the temperature effects the double frequency efficiency of LBO.And then introduce the temperature control system for these two crystals. The control system includes hardware and software. The hardware part includes these parts: the MCU controller,the temperature senor,the power driver module for TEC(Thermoelectric Coolers),the EEPROM for saving parameters,the LED drive chips and the output voltage monitor. The software part use PID arithmetic to control...