A Displacement Measuring System Design Based On Linear CCD With White-light Interferometry Technology

White-light interferometry is a new technology developed from the1970s. Taking thewidth of white-light interference as its unit of measurement, this technology is of highaccuracy and high sensitivity. Thus, it can be applied to measure extremely smalldeformation, and has been widely used in optical-fiber products, materials research,biomedical engineering, etc.Through CCD (Charge-coupled Device), the optical signals can be transformed intoelectronic signals. Due to its high integration, low power consumption as well as its highaccuracy, CCD also has an extensive application in image sensoring. However, up till now,measuring systems which apply white-light interferometry technology are commercializedonly in a few foreign countries. At home, there is still a large space for exploration.In this thesis, a measuring system based on linear CCD white-light interferometrytechnology is designed. Through the acquisition, storage, transmit and algorithmic analysisof white-light interfering fringe signals, positioning of central zero-order fringe is achieved.When white light is interfered, its signals, accorded with Gaussian distribution, are collectedby high-speed linear CCD and transformed into electronic signals. Then, a special ADoriented to CCD is employed to filter, denoise, and convert the electronic signals.Corresponding digital signals are acquired and stored in high-speed asynchronous FIFO ofFPGA. Finally, the interfered signals are transmitted to host computers through high-speedEthernet. This hardware system is based on Xilinx FPGA.In addition, this thesis investigates CCD pixel orientation, so as to improve the accuracyof this system. During the process of collecting signals, noises are introduced into CCD,which results in the fact that the central zero-order fringe cannot be positioned accurately. Tosolve this problem, the author makes a comparison of two pixel orientation algorithms, andputs forward an improved gravity center method. Meanwhile, the results of these two measurements are analyzed respectively, according to which, a conclusion is drawn, that is,and the improved gravity center method can obtain results of higher accuracy.It is proved that, the system designed in this thesis can be applied to position centralzero-order fringe, with high processing speed and high accuracy. What’s more, this system isof great practical value.