Curing-in-the-loop strategy for multidimensional-shrinkage compensation in active alignment FAC assembly

Tight tolerances for the final position and orientation of optical components are best controlled in automated and high volume production with statistical process control. Semi-automated and low-volume scenarios on the other hand are in need for a suitable approach, capable to react resiliently on remaining uncertainties of the bonding process. Active alignment has proven to lower the tolerances for finding the optimal position regarding the overall performance. We will present a novel shrinkage-compensation strategy, which extends the active control loop to integrate the curing process. We will discuss the adhesive properties necessary for the realization of our strategy and our measurement equipment used for the characterization of such properties. Besides a predicable shrinkage curve, the critical cross-linking level, until no further manipulation is possible, is a key factor. Furthermore, the machine concept, the curing capabilities and the active evaluation needs to follow special requirements. Since the shrinkage-behavior is highly sensitive to the amount of UV, the effective power on the adhesive needs to be controlled by optimizing the orientation of the light source. We integrated the UV-light in our micromanipulator in order to always ensure an optimal illumination In order to apply regression analysis for a multidimensional shrinkage model, misalignments in the selected degrees of freedom must be observable with sufficient precision. As validation of our strategy, we examine the collimation of a diode laser bar.