Design Of A Pocket Laser Measuring Device Based On The PSD

With the rapid development of science and technology, more and more advanced measurement means are requested. The photoelectric method has been paid much attention for its advantages of non-contact, well precise, pocket-size and real-time characters. On many assembly lines, such as the paper's thickness and flatness detection in the papermaking industry, the banknote's thickness real-time monitoring and control in banknote manufacturing company, copper cover control on the circuit board in circuit board manufacturing factory and the film thickness control in film production progress, a measurement device located on a certain place is needed to on-line detect the specific parameters or working status so as either to real-time track and record needed information or to give a fast feedback to regulate production process according to the measured information, by which not only the product's quality can be guaranteed, but also the assembly line can operate in a optimized condition.. In order to satisfy these application demands, a laser position detecting device used position sensitive detector (PSD) was designed based on the laser triangulation principle. The correlative techniques to improve the precision of the device have been thoroughly studied.The main tasks are as follows:1. Laser triangulation principle is introduced systematically. The laser detecting device matching Scheimpflug's condition has been designed. The related designed parameters are optimized.2. According the theory of PSD, the positioning accuracy of PSD caused by different size of the laser spot is discussed and simulated to conclude that compacting spot size of laser beam may improve the precision without doubt. A quality evaluation function of the Laser beam used in the device has been established. Two laser spot size compacted optical assembles with two-lenses or three-lenses have been designed., the detail optimal data are given.3. The hardware circuits of the device have been designed. The means of collecting and processing faint electric current is proposed. The intelligent control system based on MCS-51 microcomputer has been designed. In addition, the essential measuring software is programmed. 4. System calibration is completed using high precision metrological grating. The testing data is processed, and the system's error is analyzed.5. Finally, the main content of this dissertation is summarized and the developed trend for this research have been forecasted and discussed.