Power stabilization of diode pumped solid state lasers by means of adaptive control of drive current

Şentürk, Tayfun
Lasers provide precision and sensitivity for various applications. However, some fundamental properties make lasers very susceptible to external changes. When stability of laser parameters is required the traditional approach is to stabilize the working environment, such as strict temperature and climate control, mechanical isolation as well as damping of any vibration. This traditional approach is very difficult to implement in harsh industrial environments and almost impossible for many military applications. One frequently used state-of-the-art laser type in industrial and military applications is diode pumped solid state lasers. Fundamentally, temperature of various components, small deviations in optical properties and opto-mechanical alignments over time as well as aging cause output power of such lasers to drift away from the desired level. Tracking of all these critical stimuli is impractical and even when achieved, it would result in a complex multi-input control algorithm design. To overcome this difficulty, firstly, a reliable internal laser output energy measurement system is designed, implemented and tested under various operating conditions. The output from this sensor provides the feedback signal for the control algorithm. A closed-loop control system is expected to be designed and optimized for regulation of output energy of a SISO type laser device by setting the drive current adaptive to the environmental conditions. The algorithm and implemented system is experimentally tested.