線上雙狹縫彩色差動共焦量測系統與校正技術之精進研究

本研究主要目的在於提升既有線上雙狹縫彩色差動共焦量測系統之量測能力，彩色共焦量測技術為線上即時量測之關鍵量測方式，此技術運用軸向色散原理取代傳統共焦量測技術的垂直掃描過程，有效提升量測速度，但由於以光譜解析聚焦原理一般使得量測速度受到相當限制。因此，差動共焦量測術之發展則在於提升量測之量測維度，差動架構及其演算原理不無須垂直掃描，使用反射率正規化演算法可避免待測物反射率對深度量測結果之影響，惟其缺點在於光效率較差，以及即時深度量測範圍太小，使得目前其量測之應用性受限。因此，雙狹縫彩色差動共焦量測系統因應而生，採取結合彩色共焦技術與差動共焦技術之優點，惟先前實驗室所發展之量測探頭仍有數個缺點存在，主要在於其可量測景觀範圍(field of view)過小、探頭體積過大以及量測校正不易等問題，而影響其實際運用之可行性。因此，本研究開發一新型雙狹縫彩色差動共焦量測探頭，重新設計光路架構與探頭機構件，以提升整體之系統量測能力。本研究經研發後，目前所完成量測探頭之即時深度量測範圍可達150 μm，穩定量測線長為5 mm。經由實驗結果之驗證，量測鏡面之待測物時單條取像時間可小於1 ms。惟標準階高塊量測結果之一個標準差仍高達 2.32 μm，達可量測總深度(150 μm)將近2%，其主要原因來自於光偵測器之按電流過大所致，此仍是未來需要繼續精進之主要課題之一。總結來說，研發之雙狹縫彩色差動共焦量測技術已完成模組化並改善依些既有問題，使其擁有較大之量測範圍、光源使用效率等，已增進其在工業量測上的運用價值與可行性。

關鍵字

自動化光學檢測(AOI) ；共焦量測技術；彩色共焦量測技術；差動共焦量測技術；三維形貌量測

並列摘要

The main purpose of study is to enhance the measuring performance of the existing double-slit chromatic confocal system previously developed at NTU. Chromatic confocal measurement technology has become critical to advanced manufacturing processes in ensuring quality control on critical dimension. The technique employs the principle of axial light dispersion to replace traditional vertical scanning to increase the measurement efficiency. Furthermore, the development of the differential chromatic confocal method to achieve higher measuring efficiency by increasing the sensing dimension in conjugate point detection. A probe to combine chromatic and differential principle has been developed previously at NTU. However, it suffers from some measuring disadvantages, such as insufficient measuring FOV due to optical vignatting, probe size being too excessive to be integrated for in-situ inspection and poor measuring accuracy and repeatability. Therefore, the research is to develop a new type of the double slit confocal color differential measurement probe by addressing these key issues. The probe has been redesigned by re-considering light efficiency, compact probe size and measuring accuracy improvement. With the development, the depth measurement range has been improved to 150 μm with a stable line-scan length of 5 mm and reasonable speed of 1 ms per scan. From measuring some pre-calibrated targets, it was verified that in its repeatability test, one standard deviation of step height measurement was still up to 2.32 μm which is over 2% of the overall measurable depth range. The main source of the measuring error has been identified from the sensor dark current. Apparently, the precision level of the development is still not desirable, which will be improved continuously.