Abstract
The purpose of this paper is to describe a simple non-contact displacement sensor by means of optical method. Scattered light from rough work surface is separated into two light spots by passing through two apertures. The spots are detected with two photo-electric devices shifted by its radius of detecting area to the aperture axis. Intensity ratio, ρ=(Ib- Ia) (Ib+Ia), is proportional to the displacement of work surface. The displacement sensor with this principle has been developed. The sensor is 70 mm in height and 54 mm in diameter. The sensor consists of two photodiodes, two quartz glass bars, one LED as a light sorce and one condensing lens. It is effective for many kinds of work materials having the surface roughness of more than 1 μm Rz, The sensor measures 8 mm of range and the resolution for 5 mm range is approximately 2 μm with ±2 μm repeatability. The sensor also measures the tilted work surface displacement up to 6 degree from the optical axis.
