可變焦透鏡應用於微曲面量測的分析與實作

Abstract

本篇研究主要討論提升可變焦光學式距離感測器，其測量效能的技術開發與驗證，探討系統量測之穩定性，以及解析度等等系統量測特性。本論文的第一部分對於此距離感測系統的特性進行分析，此架構有別於傳統共焦量測設備需要加裝或搭配移動測量軸向的移動載具才可達到對焦量測距離的功能，而使用可變焦透鏡取代，可變焦透鏡原理是藉由不同的驅動電流，改變其自身的曲度，因此可變焦透鏡會依照不同曲度，而使入射光呈現不同的焦距，而藉由不同焦距來進行對焦定位。待量測系統建立後，本研究將此距離感測器與二維移動平台整合為一個三維量測系統；分別進行標準階梯與球面鏡的形貌掃描，用以幾何形貌量測的驗證。此外，基於此架構的基礎下，本研究採用以曲線擬合理論為基礎的最佳焦距定位演算法，提升距離量測的速度，探討此演算法對於系統整體量測速度增加的可行性與效能評估；第二部分，本研究在測試評估後選用訊號擷取較快速的光感測器搭配DAQ系統，量測系統之效能明顯地提升，並進行快速變焦量測，在此架構的改善下，可有效將系統量測速度提升200倍以上；此外，更新後之架構能有效的提高系統之解析度，而在本論文最後則進行實際標準階塊量測進行驗證。

This paper focus on the studies and applications of varifocal lens on micro scale non-contact 3D coordinate measurement. First of all, the stability, resolution and another character of this system were investigated through several arranged experiments. In the proposed experimental system, the focal length of the optical device was afforded by changing the curvature of varifocal lens by specified driving current. In this way, this system can vary its focal length to determine focus position and achieve the data of distance under measured. According the characteristics analyzed in the first part of this study. This paper proposes a measurement method of fast scan based on the concept of curve fitting technology under this architecture. The performance of this method was then evaluated and demonstrated the beneficial effect that the scanning speed can be increased in many times. Since that, the 3D scan measuring processes was thus could be expected. The second part, the architecture of system was changed. The performance of new system was evaluated again. According to the experimental results, the speed of measurement under the new architecture is 200 times more than the original architecture. In addition, the resolution can be increased with the new optical fiber introduced. As demonstrating results, examples of fast scan of three dimensional surface profile in step-height sample and Spherical mirror are presented as a reference.