Modeling and control of optical fiber micropositioning in a thermal adhesive

An actuation and control concept for alignment of optical fibers in compact imaging systems, namely endoscopic microscopy probes, is presented. The system uses a thermal adhesive to allow repeated positioning of the optical fiber, allowing partial compensation for alignment errors arising from mechanical settling and adhesive drying behavior during manual instrument assembly. A lumped-parameter dynamic model for temperature-dependent adhesive behavior is proposed, together with a simple integral controller. Experimental testing with a larger mock-up is used to verify that the dynamic model can replicate system behavior and to evaluate controller performance. Positioning of a 100 mu m diameter fiber with 5 mu m accuracy after 3-4 iterations is achieved in the prototype system.