- 學位論文
多波長大量程三維顯微技術研究
Chromatic Wide-range Microscopy for Full-Field Micro Surface Measurement
摘要
量測技術是工業上尺寸驗證中不可或缺的一環，隨著東西微小化與精度的提升，顯微量測技術更是日趨重要，相較於接觸式量測，非接觸式量測有更大的量測彈性，所以光學顯微量測技術已經成為微小量測的發展趨勢。 本研究以共焦顯微鏡量測方式(Confocal microscopy)作為理論基礎，去除掉濾光針孔以面光源全域方式進行量測，並配合彩色共焦微術(Chromatic confocal microscopy)與雜訊消除技術，以本研究室所發展的RG-ratio演算法進行物體三維輪廓重建(3D profile reconstruction)；為改善量程的不足，於系統添加差動式共焦顯微術(Differential confocal microscopy)演算法，使用三原色混成之白光光源，針對單一像素找出其對應的深度反應曲線(Depth response curve)，以單色深度反應曲線之斜邊為線性方程，最後取得單張景深(Depth of focus)範圍內之影像，即可對影像上每一像素做比值對深度的運算，進而重建待測物表面輪廓，以此方式將量程由5μm增加為20μm。 本研究開發出一套多波長大量程3D顯微探頭(chromatic wide-range microscopic probe)之技術，除了針對微奈米三維結構進行量測，並搭配基本折射理論量測透明薄膜之厚度與折射率。此系統由探頭光機模組及訊號處理模組兩部份構成，探頭光機模組由鹵素光源及光纖模組、準直透鏡、分光鏡、顯微物鏡、三色CCD元件及本研究自製的聚焦模組所組成；訊號處理模組含輸入光強之自動功率控制電路及正規化訊號之處理電路。搭配大量程聚焦模組對待測件進行一次掃描校正後，即可以對同一材質工件以單張影像重建待測物之輪廓，尺寸計算及視覺影像由PC負責顯示。本系統機構掃描範圍可達3mm、解析度0.1 μm、重複性0.2 μm，針對階高型結構可達到解析度為0.1 μm，量測重複可達0.1 μm。
並列摘要
With improvement of fabrication precision and increasing miniaturization of structure, measuring technology has become an important part in industry. non-contact measurement technology is more flexible than contact one, so it has been a trend for developing micro optical measurement technology. The research was based on “confocal microscopy” theory. Unlike traditional confocal microscope, a pinhole of the microscopic system is replaced by the objective to filter non-axial beam and generate an area light for full-field measurement. By using innovative multi-wavelength light correlation and digital image processing, a 3D-profile can be reconstructed by taking one picture of the measured sample. However, the measuring range is only 5 μm. In order to increase the measuring range, the differential microscopy algorithm was developed in the research. After longitudinal scanning, the depth response curve of any pixel on an image can be acquired and a linear function can be obtained from a sloping side of the depth response curve. Then the 3-D profile can be reconstructed by the linear function. In addition, the microscopy can also be utilized to measure the thickness and refractive index of a transparent plate with the law of refraction. A compact chromatic wide-range full field 3-D profilometer was developed by a halogen light source and coaxial optical configuration with a 3-chip CCD camera for individual light sensing. A vertical scanning module was invented for auto-focusing and calibration. The scanning range and accuracy of the module are 3 mm and 0.2 μm. From analysis of the measurement results, the 3-D profilometer was confirmed that the accuracy on the height measurement was 0.2 μm.