Abstract

We describe a means of stabilizing a laser beam along a particular line in space with a modest investment in components. Such a device has immediate use in laser research and in educational aspects of laser technology, e.g., routing ultrashort optical pulses to multiple sites for both educational and research purposes. We illustrate the technology by an example involving the directing of a laser beam from one vibration-isolated optical table to another similar table. The goal is to maintain the beam on the second table at a fixed location and fixed orientation relative to the surface of the second table. The laser beam alignment system consists of a laser source, two mirrors on motorized gimbal mounts, two fixed dual-axis lateral-effect photodetectors, and a computer-based controller. A simple proportional-integral-derivative control algorithm is implemented. Model identification with sinusoidal signals is first performed. The control law design is then computed using multivariable control toolboxes developed at Rensselaer. The gain coefficients are then down loaded to a C-program that functions as a controller.

© 1991 Optical Society of America