Abstract
This article reveals a non-contact measurement method for evaluating micro cutting tool diameter in precision of sub micrometer in atmosphere environment. Practically, optical methods are widely used in non-contact tool measurements. However, the generally-used geometrical optical measurement methods do fundamentally not have sub micrometer precision due to well-known light diffraction phenomenon, notably when measuring a micro tool. We have been proposing and developing a measurement method particularly for the micro tool applying laser diffraction. In this article, we subtracted a transparent light component from a laser light distribution diffracted by the micro tool to be measured to enhance diffraction pattern characteristics. Consequently, micro rods of 15, 20 and 30 micrometer in diameter could be precisely measured. Furthermore, in order to verify this measurement validity, a 2 helical flutes micro tool (20 micrometer in diameter) during rotation (4 min^<-1>) was also measured as 400 nm difference comparatively with an image from a scanning electron microscopy (SEM) image.
