Fully automated beam-alignment and single stroke guided manual alignment of counter-propagating multi-beam based...

In a previous paper [J. S. Dam et al, Opt. Express 15, 1923 (2007)] we demonstrated computerized "drag-and-drop" optical alignment of a counter-propagating multi-beam based micromanipulation system. By inclusion of image analysis, we report here on the extension of this work to accommodate a completely automated beam-alignment process. Additionally, to maintain a cost-effective and technically less demanding system architecture, we also report on a computer-guided manual alignment procedure. In the manual version, the computer analyzes the initial misalignment and the required compensations for each mirror in the system are calculated. Subsequently, the user is guided in adjusting the mirrors exactly by the requisite amount. This way, all mirrors only need to be moved once. The image analysis utilized in both calibration schemes employs a fitting algorithm to determine the position of beam-center with sub-pixel accuracy, thereby providing "better than human" alignment.