- 學位論文
創新式雙狹縫彩色差動共焦高速形貌量測術之研發
Development of novel high-speed surface profilometry using double-slit chromatic differential confocal microscopy
摘要
本研究主要為發展創新型彩色差動共焦之三維形貌量測技術與系統，一般現行的差動共焦技術，乃將兩個感測器元件放置在焦點前後之光學架構進行差動共焦量測，由於CCD的偏位擺設位置方式使得兩組CCD的量測範圍產生差異，易於造成系統的水平量測範圍與水平解析同時降低，使得差動共焦量測在線上即時量測的應用性降低，一般而言，僅適用於單點式雷射共焦量測，對於線型掃描或寬頻光共焦量測方式，此方式應無法正常量測。因此本研究提出一種創新式差動共焦量測方法，以線型連續多波長光源並結合軸向色散物鏡、兩組不同寬度的線光源與兩組彩色線型光感測裝置之共焦量測架構，發展一種即時線型掃描彩色差動共焦量測技術。提出量測之系統為達差動共焦效果，光源部份以一組光源經由光纖一分為二，並在兩個光纖出口的前方放置大小不同的線型狹縫；兩道光源透過軸向色散物鏡聚焦至物體表面並反射，再透過兩組彩色線型光感測器來量測大小不同的狹縫的反射光。此兩反射光的訊號具有不同全寬半高值的RGB三顏色的強度反應曲線，將此光強度反應曲線經由正規化差動共焦運算，以分別求得RGB三色光的強度比值與量測深度的關係曲線，以此曲線為依據來進行型貌量測深度資訊之重建。所提出之差動共焦運算可將物體表面反射率的參數影響消除，量測重建時可有效抑制物體表面不均勻的反射率的影響。研究在一個量測系統的實例上，使用綠色光之軸向色散物鏡搭配雙狹縫架構，其深度量測範圍可達到45um，量測速度可比一般彩色共焦量測速度高數十倍以上。
並列摘要
This study presents a broadband differential confocal surface profilometer using novel double-slit chromatic confocal measurement for in-situ high-speed microscopic surface inspection. In-situ automatic optical inspection (AOI) on microstructures has become extremely important to ensure manufacturing quality. The conventional laser differential confocal techniques employ two line detectors to be placed in the front and rear of the image focusing plane for producing differential confocal phenomenon. For broadband chromatic confocal measurement, the above optical layout could bring misalignment errors and reduce measuring field of view (FOV). Therefore, a multi-wavelength differential confocal surface profilometer is developed by employment of a novel concept of using double slits for generating the differential gradient in confocal measurement. In the optical configuration, two different sizes of slits with individual opening sizes are placed in front of their corresponding imaging unit and designed to conjugate with the tested object surface. A chromatic microscopic objective based on various glass refractivity and shape curvatures is designed to disperse the two incident lights having an orthogonal polarization relationship into a vertical measuring range. The differential gradient is generated by correlating two depth response curves (DRC) which are measured by the two imaging units with their corresponding slits. A depth-focus response curve can be further established by a system calibration using standard step-height targets. The developed system can be used to measure the profiles of microstructures by one shot inspection without any vertical scanning required by conventional confocal measurement. The vertical measurement range can be designed for a range of a few hundreds of micrometers while its vertical resolution is capable of reaching down to 0.1 micrometers. The repeatability of the developed method can reach to 0.1 ?m within one standard deviation. Especially, the differential confocal principle developed is capable of measuring various surfaces having highly different surface reflectivity. The measuring speed can significantly break the limit of the traditional chromatic confocal methods and reach to the maximum speed of a line imaging unit.