Study On Micro-displacement Detection Technique Based On DVD Laser Head

In precision measurement, because of the accuracy of measurement required to micro measurement level even than nano measurement level, so the contact detection method is easy to produce elastic deformation and affect the measurement precision, and the component surface to be measured or even cause wear and tear,therefore, the precision of non-contact measurement is better.Non-contact detection methods have many advantages,such as fast speed, high measuring accuracy, therefore, more and more widely used in precision measurement. Now there are many the non-contact measuring instruments in the market,for example, capacitance sensor,inductance sensor, laser interferometer, etc., but the cost is higher, and not easy to handle and carry, complex operation, so its application scope is limited.In this paper, on study of the principle of automatic focusing by the Digital Versatile Disc( DVD) laser head, on the basis of the displacement of voice coil motor with its driving voltage is linear in a certain range,compensate the DVD laser focus error signal to get servo focus error signal, as the voice coil motor driving voltage, then the micro displacement is obtained. In this paper,the micro displacement measurement system was designed and tested,analyzes the test results and error factors. The method based on DVD laser micrometer displacement detection with high precision,low cost and its measurement range can reach to 200 um, the measuring accuracy is200 nm, it can be widely used in various kinds of complex precision detection.