A Displacement Measurement System using CD Optical Pickups and the Mouse Interface of a Personal Computer

Abstract

In the material testing, the displacement measurement system is indispensable. And usually such tests are done on a lot of test pieces and are continued for long time interval. Therefore, the simplified and automated displacement measurement system is required. In this paper, the authors propose a simple automatic displacement measurement system and give some experimental results. The proposed system utilizes a grating made by the photographic technology, a pair of optical pickups for CD, and the mouse interface for a personal computer. The movement of the grating that is detected by the CD optical pickups is processed by the mouse interface and is recorded as the mouse data with the personal computer. Simultaneously, the quantity of the displacement is automatically measured by the resolution of 1/4 of the grating interval by the mouse interface. Using the prototype equipment that utilizes a grating of which line interval is 100 µm, the 25 µm resolution has been obtained under the displacement speed of 0.5 mm/s. The maximum displacement speed of the system can be extended on the theory to 400 mm/s when using the grating of 100 µm line interval, but the investigation of the practical speed is left as a next problem. Because the mouse interface can detect the two-dimensional movement, the system is easily applied to measure the elongation between two points on the test piece. As the CD optical pickup and the mouse are very popular equipments, it is easy to obtain them. At the same time, as their structure and characteristics are well known, the applicability of these devices is excellent. Also, the proposed system is a very simple system. Therefore, this system will be able to be applied to various fields.