Evaluation of an attenuation system for an infrared free-electron laser

This study concerns the attenuation of the incident power from a free-elect ron laser (FEL) in steps of up to two orders of magnitude, while maintainin g optical beam geometry. We have developed and evaluated the properties of a FEL attenuation filter system, which can be attached and detached, with t he position of the focusing lens and the target sample fixed. As a result, we have established that our FEL attenuation filter system enables two orde rs of magnitude of power control for infrared wavelengths between 5.5 and 6 .5 mum. We conclude that the attenuation system is extremely useful for var ious FEL applications. (C) 2001 American Institute of Physics.