Design and test of a novel cost-effective piezo driven actuator with a two-stage flexure amplifier for chopping mirrors

摘要

A fast chopping secondary mirror is the critical functioning assembly in an astronomical telescope for infraredobservation. Normally, a chopping mirror is driven by precision high-load and high-stiffness linear actuators which areexpected to be lightweight, compact and further cost-effective. The stroke of the actuator is typically required to up toseveral hundred microns with typical load capacity up to several hundred Newtons. We developed a novel piezo-basedprototype linear actuator with a two-stage rhombic flexure amplifier. In this paper, first we present the detail designscheme of the actuator by analytical calculations with comprehensive Finite Element Analysis (FEA) verification.Afterwards, we also present the procedures and results of tests of linearity, load capacity, eigenfrequency, stability andrepeatability. The selected piezoelectric drive unit is a block of 35x10x10 mmsup3/sup with output force up to 4000 N. Thetwo-stage displacement amplifier is simply integrated by two identical singular rhombic flexures orthogonally mountedtogether. Each stage, one rhombic flexure with a longer axis of 76 mm long, is designed with an ideal amplification ratioof 3, which leads to a final theoretical compound amplification ration of 9. In order to realize the basictriangular-amplification principle in a rhombic flexure, we introduced flexure joints at all the eight ends of its four edgebars. The singular rhombic flexures can be efficiently manufactured by electrical discharge wire-cutting process at a timein batch by being overlapped in layers. Afterwards we carried out related measurements to test its performance.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.