Tips and tricks for aligning an image derotator

摘要

One possible key reference element in optical alignment is represented by the rotational stage, a mechanical bearing, orany similar suitable device having enough accuracy and precision so that optical tolerances are reasonably relaxed wrtimperfections in the rotational movement. This allows a safe, reliable, easy to reproduce, determination of both raysparallel to the axis or to their centering within almost any plane. An image derotator, that in its simplest form is made upby three flat mirrors arranged in a so called K-mirror layout, moving together on a precision rotating stage, seems to bethe most safe, strong, and self built-in alignment tool. Moreover you can use the mechanical part as well as the opticalone. Care has to be given when internally and externally aligning has to be accomplished within a certain degree ofprecision. To further make the situation more complex, the technical overall requirements can be tight enough that thedistribution of the error budget among the various components (imperfect mechanical rotation, imperfect internalalignment, flexures during rotations) is not due to a single item. In this case, in fact, a number of tips and tricks can beuseful to find out which is the best approach to follow. The specific case of the two K-mirrors on board LINCNIRVANAis here illustrated in a few lessons.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.