Research On Optical & Noncontact Thickness-Displacement Meter

Optical & noncontact thickness-displacement meter is a high-tech measuring instrument. It is a synthesis combined with optical, mechanical and electrical knowledge. Under the control of computer this meter not only can realize many noncontact measurements in high definition and efficiency without destroying object surface, but also can be easy to fulfill some automatic demands like dynamic sampling, real time processing, on-line measuring. So it will be well used in the modern industry measurement and has a wide prospect in the future.The meter is based on the triangular measuring principle of laser. In this research scheme, semiconductor laser is used as the light resources, PSD(Position Sensitive Detector)as the sensor, and computer as a system of high speed sampling & processing data. The main idea of this research can be summed up as following words, reflecting light or scattering light upon the surface of measured object formats an image on the photo surface of PSD by a optical system, because of the good relationship between the offset of image point in PSD and the offset of object thickness, a mathematical model can be founded according to this relationship .It can measure the shift of object thickness through these analyses of movement of image point position in PSD, and this device can be tested its reliability with many practical specimens.This article formulized emphasis on the measuring principle of meter, analyzed the work process of the meter, discussed the factor that affected the measuring definition, designed software & hardware of the apparatus and fashioned a prototype model. In practical measuring, we drew a satisfied conclusion, and reached the designed requirements.The resolving power of this meter is 0.2 micron and range of measurement is 1000 micron.