The Design Of Multi-dimensional Displacement Measurement In Non-contact Method

Measurement of small displacement is divided into contact and non-contact two types at present. The representatives of contact are ICP vortex displacement sensor, fiber grating displacement sensors Etc. Its characteristics are measured stable and reliable. However, the measurement process need to install a sensor on the tested objects. So it can only be used in the actual use of a relatively fixed occasions. The representative of non-contact type is laser Measurement. Its biggest advantage is non-contact measurement and high precision measurement. But it also have lots shortcomings. Just as the measuring need a large probe, it need a long time from boot to measure stably, the reliable work time of laser devices is limited, the structure of multi-dimensional measurement is too complex Etc.In this paper, the purpose of the study is based on analysis of the various methods of measurement and find out the advantages of the existing non-contact measurements, but also to achieve multi-dimensional measurement of measurement.The basic idea for the study is: For the displacement of more than 1 um measurement, Use of video microscopy way to enlarge the target and acquisit the image, and use the image processing technology to de-noising, binary and extract image feature. When a real-time displacement happen, use the same image processing way to extract the image feature and matching feature points with original image feature points to achieving multi-dimensional micro-contact displacement measurement. For 100 nm-1um the sub-micron-level displacement, as light diffraction happen when microscopic zooming. It lead to Image feature points position have a greate error. So the paper use improved Lloyd lens device, make use of the small changes of interference fringes to measuring the displacement indirectly. The greatest significance of the study is that this method can be used in real-time instant film thickness measurement Etc. and other measurement ways can't.The characteristic of using image processing as a measurement calculation is large volume of data processing, and consuming a vary time. For the realization of the real-time digital image processing, look up the relevant papers in the design processing. It achieves a plan based on FPGA by comparing the different methods based on digesting papers. It uses hardware description language to realize hardware module. And it solves the speed problem of the video image processing by functional hardware module. Therefore, this paper mainly completes the derivation of design module, the collection, processing and export of the image data, and experiment results. The study involved different chips program download or configuration, so development a multi-purpose programming cable(Utility model patents:200420094721.5) .It can be used to program different chips with switch mode on PC management software, and it is fully compatible with the official download software. This ensures the convenience of the design programming. Presently, the cable can used to program chips from Altera, xilinx, Lattice and various SCM.