Optical diagnosis of surface features in holographic optical element

• Main Author: 莊富傑
• Other Authors: 郭文娟
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/t3w38s

碩士 === 國立臺灣師範大學 === 光電科技研究所 === 96 === In this thesis, a homemade differential confocal microscopy (DCM) in upright configuration was constructed successfully. The setup of the system, specification of the elements, optical beam path configurations are described in this thesis. Using light wavelength of 632.8nm, objective lens of 0.8 numerical aperture, axial and lateral resolution can reached to 4.2nm and 422 nm respectively, and dynamic range reached to 500 nm. The axial resolution of DCM is mainly limited by system noises, including mechanical vibration, optical background and electric noises. After noise was well excluded, the measured signal to noise ratio (SNR) reached to 75.7dB. Using the nanometer depth sensitivity of DCM, we measured the surface profile of several devices (e.g. microlens, polymer membrane, one-dimensional phase grating and two-dimensional photonic crystal) in non-invasive, non-contact, and non-destroy method. The lateral resolution of the topographic images is further enhanced by maximum-likelihood estimation (MLE) algorithm.