| With the rapid development of micro-electromechanical system(MEMS)technology,a variety of micro and nano-level micro components have come out one after another,micro and nano-coordinate measuring machine is more and more important for the high precision measurement of micro-size devices.The probe system is the core part of coordinate measuring machine,which restricts the development of micro and nano coordinate measuring machine.An optical non-contact 3D nano-probe based on the optical reader of Blu-ray DVD is developed in this laboratory,which solves the problem of measuring the key dimensions on the surface of micro devices at the micro/nano scale.The probe includes an improved measurement module designed for height and edge measurement based on optical reader and an observation module based on CCD camera with co-focal light path to realize the alignment and focusing of the measurement spot and sample and the real-time observation measurement process.The main work of this thesis is as follows:1.Experimental system construction: The peripheral circuit is designed based on MC9S12 series MCU to initialize configuration and start Blu-ray DVD reader.Combined with the 3D high-precision nano-positioning platform,a high-precision measuring system for the size of small workpieces is built to realize the measurement of the key dimensions of the micro devices.2.System hardware circuit design: The peripheral circuit is designed based on MC9S12 series MCU to initialize configuration and start Blu-ray DVD reader.According to the measurement requirements,the post-stage signal processing circuit is designed to perform the sum operation,debiasing,normalization and filtering on the four-channel output signals of the reading head.3.System measurement and control software development: based on MC9S12 series microcontroller programming,initialize parameter configuration of optical reader and start blue light mode by means of serial communication.Based on MFC,the display software of signal acquisition and processing,the motion control software of macro and micro displacement positioning platform and the transverse and longitudinal trigger measurement software of the experimental system were written,which realized the function of automatic trigger measurement for the key dimensions of the micro workpiece surface.4.Probe Performance Verification: Based on the experimentally built system,the measurement performance of optical non-contact three-dimensional nano-probe was tested for resolution and repeatability.The measurement principle is to make use of the astigmatic principle of the astigmatic lens inside the reading head to set the linear interval of the probe output focusing error signal(FES)as the trigger threshold interval,and perform a linear fitting to the data within the interval to obtain the coordinate position of the preset trigger point(FES=0,namely the focus position),so as to improve the accuracy of the trigger point.Coordinate with 3D high precision nanometer positioning platform for height trigger measurement;Based on the principle of reflected light intensity and energy,a reasonable threshold was set for edge detection by using the output light intensity and signal(SS).The experimental results show that the longitudinal measurement resolution of the probe is better than 1 nm,and the standard difference is up to 21 nm.The resolution of transverse measurement is better than 3 nm,and the standard difference can reach 74 nm.The resolution and good repeatability of optical non-contact measurement are achieved. |
