| 摘要: | 本論文提出一套新型光學式自動聚焦顯微鏡，其架構乃是將三角測距、刀緣法、重心法、像散法和兩個不同放大倍率的成像光路作結合，並從離焦光斑隨待測物相對位置之變化情形，以此作為聚焦的判斷依據。
本論文系統架構茲說明如下：一準直鏡將雷射光源準直擴束後，才通過一遮蔽物(knife)與分光鏡(BS1)，並藉由反射鏡將光源送至物鏡並聚焦於待測物上。由待測物產生一反射光束會依原路徑折反回光路系統中，此時，經由分光鏡(BS1)將光源反射至分光鏡(BS2)後，便可將光束分為兩道(光路I和光路II)，兩道光束最後各自通過兩相互垂直的圓柱透鏡，才各別成像於感測器(CCD1和CCD2)上。其中光路I適合長距離、低定位精度的聚焦
光路II適合短距離、高定位精度的聚焦，透過此系統來結合兩個光路，可達到長距離、高定位精度的聚焦。藉由兩光路之性能互補並結合訊號演算法來完成一套自動聚焦顯微鏡。
根據模擬與實驗結果顯示，我們的系統相較傳統使用凸透鏡之舊架構有較高之聚焦精度。且在相同聚焦精度下，以雙行程感測光路做聚焦時，其對焦次數都少於單光路聚焦。
In this thesis, a novel optics-based autofocusing microscope was developed based on triangulation, knife-edge method, centroid method, astigmatic method and two optical paths. According to the different distance between the sample and the objective lens, the shape of the laser spot also varies and can be detected by a CCD sensor, i.e., the defocus distances can be found.
In this structure of the proposed autofocusing microscope, the light beam is expanded and collimated by means of an expander lens and is then bisected by a knife. The light beam is then passed through BS1, mirror, objective lens and is incident on the sample surface. The laser light reflected from the sample surface passes back through the objective lens, mirror, BS1 and is then incident on a BS2, where it is split into two separate optical paths(Optical Path I and II). Finally, the two separate optical paths are passed through two cylindrical lens, where they are perpendicular to one another and is then incident on CCD1 and CCD2, respectively. The Optical Path I can be used to implement an auto-focus with both a large range of auto-focus distances and low focus accuracy. The Optical Path II can be used to implement an
auto-focus with both a short range of auto-focus distances and high focus accuracy. The two optical paths are combined using a self-written autofocus-processing algorithm to realize an autofocusing microscope.
The simulation and experimental results show that compared to conventional optics-based autofocusing microscopes with biconvex lens, the proposed microscope system has a higher focusing accuracy. In addition, under the same focusing accuracy, the focusing times of the proposed microscope system using two optical paths are less than that of the proposed microscope system using a single optical path. |
