Flexture based alignment mechanisms

For high accuracy alignment of optical components in optical instruments TNO TPD has developed dedicated, monolithic, flexure-based alignment mechanisms, which provide accuracies below 0.1 ?m and 0.1 ?rad as well as stabilities down to picometers per minute. High resolution, high stability alignment mechanisms consist of an adjustment mechanism and a locking device. Complex monolithic flexure-based mechanisms are designed to align specific degrees of freedom. They are realized by means of spark erosion. The benefits of these mechanisms are no play, no hysteresis, high stiffness, a simplified thermal design and easy assemblation. The overall system can remain a passive system, which yields simplicity. An actuator is used for positioning. Locking after alignment is mandatory to guarantee sub-nanometer stability per minute. A proper design of the locking device is important to minimize drift during locking. The dedicated alignment mechanisms presented here are based on: (a) the results of an internal ongoing research program on alignment and locking and (b) experience with mechanisms developed at TNO TPD for high precision optical instruments, which are used in e.g. a white light interferometer breadboard (Nulling) and an interferometer with picometer resolution for ESA’s future cornerstone missions “DARWIN” and “GAIA”.