A force sensing system detecting adhesive thickness during microassembly processes

Typically, optical assembly components are bonded by adhesives with a refraction index adapted to the component material. To realise proper function of the microoptical system calculations of an optical design determine the limiting conditions to be fulfilled during assembly. Main sources of error in not reaching the requirements of the optical design are the positioning accuracy of the assembly system, tolerances of the assembly components itself and various bonding parameters like adhesive thickness. Adjusting the adhesive layer causes tolerances concerning thickness and angular errors of the layer which might reduce the functionality of the microoptical system. To avoid these aberrations and to adjust the adhesive layer with respect to the conditions given in the optical design, a force sensing system was developed, integrated into several geometrically adapted, self-adjusting vacuum grippers.