Design and assessment of monolithic high precision translation mechanisms

Crucial to the success of devices such as the scanning tunnelling microscope is the availability of translation mechanisms of very high precision. Elastic design is a natural approach to this problem and here one family of such devices, mechanisms cut from a monolith and using 'web hinges', is examined in detail. Simple design rules, derived in part from finite-element analysis, are given and manufacturing tolerances considered. It is demonstrated that the drive system can cause significant parasitic motion even in very stiff systems and so a non-contact force transducer utilising a solenoid and permanent magnet is investigated. Experimental investigation confirms that even with very routine, low-cost manufacturing methods the combination of these devices can produce 'slideways' with subnanometer out-of-plane inaccuracies.