全像光學元件之表面特徵診斷

Abstract

本論文以正立式的架構搭建一套差動共焦顯微鏡，此系統的架構、元件和儀器的規格，及架構的設計文中也有詳細描述。系統以波長為632.8nm之光源、數值孔徑為0.8之物鏡為主，其縱向與橫向解析度分別可至4.2nm及422nm，並且動態範圍為500nm。由於差動共焦顯微術的軸向解析率限制主要來自系統的雜訊，經排除機械震動、光學雜訊與電性擾動等因素，可得到75.7dB的差動共焦訊雜比。 利用差動共焦顯微術對奈米級表面起伏的敏感性、及非侵入性、非破壞性、非接觸性等優勢，量測出幾種樣品的表面輪廓(例如：微透鏡、高分子膜、一維光柵和二維光子晶體)。並藉由最大可能估計法(maximum-likelihood estimation algorithm，MLE)來提升影像的橫向解晰度。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.