白光消色差相移干涉術量測三維表面輪廓

Abstract

本論文主要是研究白光相移干涉術進行三維表面量測的能力。架設Linnik式干涉顯微鏡，並使用旋轉波片的消色差相移法。 使用的白光光源是石英鹵素鎢絲燈，涵蓋可見光範圍(400~700 nm)的光源。理論上光源被要求是高斯功率光譜分佈，然而實際上石英鹵素鎢絲燈不是很好的高斯光譜分佈。因此分別加入兩個不同中心波長(589.5nm與629.5nm)的窄帶濾波片，來得到較佳的高斯分佈。最後將量測結果與使用Zygo儀器(NewView5000)所量測的結果進行比較。 論文中將相移架構分別放在輸入端與輸出端進行比較。比較結果可知輸入端在量測精度、對比度和重複性上都比輸出端優良，同時輸入端可避免在相移架構中波片旋轉所造成干涉條紋成像飄移的問題。使用相移法通常可達非常精密的縱向解析，但還是有著縱向深度量測範圍的限制。如能考慮白光同調長度短的特性，再結合最大強度位置掃描，將可大大提升縱向深度量測範圍。

This work focuses on the abilities of white-light phase-shifting interferometry (WLPSI) in 3-D surface profile measurement. We set up a Linnik type interferometric microscope in which an achromatic phase-shifting method with rotating waveplate is used. A quartz tungsten-halogen(QTH) lamp, covering the visible spectral range 400~700 nm, is used as the white-light source. In this theory the light source is required to have a Gaussian spectral power distribution. However, the QTH lamp does not have a good Gaussian spectral distribution. Two narrowband band-pass filters with central wavelength at 589.5nm and 629.5nm are used in order to get better Gaussian distribution. The measured results are compared with those measured by a Zygo instrument(Newview5000). In this work, the phase-shifting module is placed at input and output ends for comparison. The comparison shows that the input end case has better performance than the output end case in the measurement accuracy, contrast and repeatability. In the input end case the shift of interference pattern at the image plane can be avoided when the waveplate rotates in the phase-shifting module. Although phase-shifting method usually gives very good vertical resolution, it still suffers from a limited measurement range in the vertical direction. If we consider the characteristics of the short coherence length of white-light, this method combined with a vertical scanning of maximum intensity position can increase the vertical depth measurement range greatly.