Design and Evaluation of a Prototype Instrument for Measuring Roundness Profiles of Micro Shafts

INTRODUCTION This paper describes the design and some initial evaluation of a prototype instrument for measuring roundness profiles of axially symmetric micro components with diameters below 500 μm. The instrument will measure form error in micro-scale cutting tools used for micro machining, small-hole metrology probes, and other high aspect ratio micro structures. The instrument will operate on the same physical principles as scanning probe microscopes, which measure surface topography using either fluctuations in tunneling of currents between probe and sample (scanning tunneling microscope or STM) or fluctuations in oscillations of a resonating cantilever beam (atomic force microscope or AFM). The instrument will measure roundness profiles using a fixed-sensitivedirection arrangement of the detector, similar to macro scale metrology instruments, as illustrated in Fig. 1. In this paper, we give an overview of the instrument and then concentrate on the design and evaluation of the instrument’s axis-ofrotation.