Research On Precise 2-D Plane Grating Measurement System And Key Technology

Measurement technique is closely connected with the development of science and industrial technology. On the demand of the requirements of the more and more measurement accuracy in modem science and technology especially in information technology, MEMS technology, aerospace technology, many new theories, methods are developed to improve the accuracy and efficiency of the measurement, and promote the modern technologies' advance. In precise mechanics, electronics and MEMS' industries, the manufacture technique require precise measurement and location, especially in coordinate measuring machine (CMM) and computer numerical control (CNC) etc. 2-D measurement and location is crucial in those measurement system. In 2-D measurement system, generally 2 sets of one dimension measurement systems are employed to measure X and Y direction separately, the one dimension systems' location error especially Abbe error will reduce the measurement result's accuracy, and this measurement method also occupies larger space, in some miniature measurement system, this method isn't convenient or suitable. In micro-displacement measurement, the grating measurement system is widely used for its merits of high accuracy, large range, stability, not so strict measurement environment. The cross plane grating technique can realize 2-D micro-displacement measurement with the one dimension grating system's merits, and can realize compact system configuration, so it is a good solution to 2-D micro-displacement measurement, and that is the research work's motivation.This research is based on the project sponsored by the Henan Preeminent Youth Foundation (No. 02120001500) project: the key technique of laser-holographic grating minipore transducer. The dissertation researched the measurement principle of 2-D grating with single light source and the system's configuration and key technique, on the principle analysis, the experimental research was carried out. The 2-D grating measurement system is a compact system, can be easily mounted and location, and not sensitive to the measurement environment change. It's output of the square wave and pulse wave can be used to subdivision and control XY stage position simultaneously.This dissertation mainly researched 2-D plane grating measurement system and key technology, and developed the 2-D grating experimental system. The main contents and work are as follows:(1)The 2-D plane grating measurement principle was analyzed, the diffraction field's distribution of the 2-D plane grating was analyzed, and deduced the formulation of the 2-Ddiffraction;based on the physical optics, Doppler principle and Fourier optics, the principle of plane micro-displacement by single 2-D diffraction grating and single light source was deduced;the optical lens fringe signal affected by the optical lens was analyzed.(2)On the basic of plane micro-displacement employing single 2-D grating, the measurement system especially the light configuration and the signal detection circuit was researched. In order to acquire the higher quality measurement signal and reduce the sensibility of the grating movement, the system's light configuration and detection circuit was analyzed on the system experiment.(3)Based on the properties of the plane 2-D grating's micro-displacement signal, BP neural network was employed to subdivide the system's square wave to improve the system resolution, this subdivision method can reduce the detected electrical signal's deflection, and can acquired the high accuracy with about 6 or more training samples in each subdivision field. This method combining the hardware with software, reduce the hardware's sophistication and improve the measurement system's flexibility.(4)On the 2-D grating measurement principle and the BP signal subdivision method, the experimental 2-D grating system was development.(5)The 2-D grating measurement system's error source was analyzed in detail. The grating reference, laser source, and measurement environment are the main part that reduce the system's accuracy, the grating is the major systematic error source, the measurand (the grating's movement)is the main random error source.