多頻率相移法絕對形貌量測術之不確定度分析與優化研究

Research on Measurement Uncertainty Analysis and Optimization on Digital Fringe Projection for Absolute Surface Profilometry

邱亮學(Liang-Hsueh Chiu)

指導教授 ： 陳亮嘉

國立臺灣大學/工學院/機械工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202003708

摘要

多頻率相移法絕對形貌量測術是將結構光影像投影至待測物表面後擷取其相位資訊，再透過相位與高度之間的轉換關係，推得物體的三維形貌輪廓。但此法在低訊噪比的量測環境可能得出錯誤的相位資訊，導致無法正確地重建待測物表面形貌，使量測不確定度增加。因此須分析並克服結構光相移量測法量測不確定度的關鍵誤差來源，使結構光相移量測法擁有高量測精度、低量測不確定度。
本研究旨在多頻率相移法絕對形貌量測術量測不確定度的分析與優化。針對系統量測不確定度進行分析，探討如何在光機設計時透過系統參數的設定降低高度對於相位的靈敏度(phase-height sensitivity)與相位不確定度，進而降低多頻率相移法絕對形貌量測術之高度量測不確定度。並提出系統量測不確定度優化的方法與流程，包含光機各項系統參數的設定，以及如何同時考量相機與投影機的解析度、量測範圍與相位不確定度，選出系統的最適條紋組合，搭配相機校正修正鏡頭畸變所導致的相位誤差以及相位與高度的非線性校正的最小平方法擬合，降低量測不確定度。
最後針對分析結果與優化方法進行實驗驗證，量化每個系統參數對量測不確定度的影響，包含光強振幅對封裝相位不確定度的影響、條紋大小對封裝相位不確定度的影響、條紋大小對高度對於相位靈敏度的影響以及條紋大小對條紋數不確定度的影響。透過本研究的量測不確定度分析與優化，優化後的量測不確定度降低了80.8%，選擇適當的條紋組合、系統參數與系統校正方法，可以使結構光相移量測法優化，擁有較佳的量測精度。

關鍵字

三維形貌量測 ； 多頻率相移法絕對形貌量測術 ； 量測不確定度 ； 多頻率相位還原法

並列摘要

Digital fringe projection profilometry (DFPP) is a 3-D measurement technique to get 3-D information of the objects by projecting the fringes onto the objects, calculating the phase values and doing the phase to height conversion. This technique remains several challenges such as high measurement uncertainty in low signal-to-noise ratio (SNR) regions. In order to make the measurement results have high precision and low measurement uncertainty, it is necessary to figure out and resolve the critical source of the measurement uncertainty. Therefore, this study aims to analyze the relationship between the system parameters and measurement uncertainty, and propose a method to minimize the phase-height sensitivity and phase uncertainty. Finally, optimize the measurement uncertainty of DFPP.
This study quantifies the influence of system parameters on measurement uncertainty, including the influence of the intensity and the fringe pitch on phase uncertainty and the influence of the fringe pitch on phase-height sensitivity and fringe order uncertainty. Ultimately, the measurement uncertainty decreased by 80.8% after optimization.

並列關鍵字

3-D measurement ； Digital fringe projection profilometry ； Measurement uncertainty ； Multi-frequency phase unwrapping

參考文獻

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