Development of Precision Testing System for Angular Measurement of Astigmatic Pick-up Head
Date Issued
2010
Date
2010
Author(s)
Wang, Wei-Min
Abstract
Through the high resolution measurement function and the compact precision structure of the DVD pick-up head, the astigmatic atomic force microscopy (Astigmatic AFM) has substantially simplified its adjustment operation and significantly improved its measurement performance. Besides, the generally available DVD pick-up head makes the whole AFM system more economical. According to our optical analytical and experimental results, the DVD pick-up head possesses not only the translational measurement function but also the angular measurement function, which can be used to detect the angular displacement of a measured surface. The combination of the translational and angular measurement functions can increase profile measurement capability of DVD pick-up head and also enhance development of new AFM technology. The research aim of this thesis is to develop a precision testing system for validating the angular measurement performance of the astigmatic pick-up heads.
The precision testing system is mainly comprised of a precision tilting mechanism, which can precisely drive a high-reflective Si-wafer made mirror to produce accurate and high resolution angular displacement. And the high-reflective mirror is supported by two spike bearings or two knife bearings to realize frictionless rolling bearing contacts. Furthermore its created tilting angle must be calibrated by precision length standard. In order to repeatedly verify the angular measurement performance, the precision testing system is equipped with precision step motor and piezoelectric actuator to create coarse and fine tilting movements. Simultaneously the signal acquisition of the DVD pick-up head is implemented, and a processing platform built in the computer carries out thus testing process, signal processing, and data presentation functions.
Besides the common DVD pick-up head, an ITIR pick-up head is especially developed by improving the optical path in order to achieve symmetrical laser spot. The ITIR pick-up head is realized to solve the coupling problem between the focus error signal and the angular signal measured by the DVD pickup head. For validating the angular measurement performances of the DVD and ITIR pick-up heads, optical analysis, error analysis and diverse experimental testings are accomplished.
Subjects
Astigmatic atomic force microscopy
DVD pick-up head
Angular measurement performance
Precision tilting mechanism
Tilting bearing
Type
thesis
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