像散式讀取頭干涉現象探討與位移量測應用

Investigation of Interference Phenomenon of Astigmatic Pick-up Head and its Application in Displacement Measurement

陳彥宏(Yen-Hung Chen)

指導教授 ： 黃光裕

國立臺灣大學/工學院/機械工程學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.00360

摘要

像散式讀取頭本可擷取光碟片上奈米尺度的資料軌，使用其聚焦誤差訊號(Focus Error Signal)之線性區則更可量測到奈米位移量，但其行程被侷限於6 um內；而量測行程可藉由更換物鏡焦距延長其感測位移範圍，但解析度會隨著量測行程增加而降低。為了擴大像散式讀取頭之量測行程與高解析度，本研究目的在於研究像散式讀取頭的干涉現象，並利用其開發雷射干涉儀。去除讀取頭物鏡所得的平行雷射光束，再配合半反射鏡與光干涉原理，像散讀取頭也可以在其投射面上創造出來干涉條紋。兩個光電感測器用來擷取反射鏡位移所產生的干涉條紋的變化，藉由分析干涉光變化達成奈米級且長位移之量測系統。
研究內容包括像散式干涉儀系統和兩個雙軸磁預壓水平調整平台的開發，讓讀取頭、半反射鏡和待測反射鏡可以容易對正。除了干涉寬度和訊號之間的干涉儀分析外，由像散式讀取頭所開發的雷射干涉也透過實驗機台進行位移量測驗證。位移量測行程從6 um延長到100 mm，最大位移量測解析度可達5 nm。

關鍵字

像散讀取頭 ； 像散現象 ； 位移量測 ； 麥克森干涉儀 ； 雷射干涉儀

並列摘要

Astigmatic pickup head is developed for capturing nano-scale data from the DVD disc. It can also be applied to measure nano-scale displacement by using its linear region of the focus error signal (FES), but the linear measurement range is only about 6 um. In order to extend its measurement range, object lens with long focal length is chosen, but it also induces resolution reduction.
In order to derive large measurement range and high resolution, the goal of this thesis is to study the interference phenomenon of the astigmatic pickup head and apply it to develop a laser interferometer. Through realizing parallel laser beam by removing the object lens, the astigmatic pickup head can also generate interference fringes on its projection plane by using the interference principle and half mirror. Two photoelectric sensors are utilized to capture the fringe change, which is induced by the displacement of a reflective mirror. Its displacement measurement resolution depends on the laser wave length, and the parallel laser beam reaches a longer measurement range.
This research includes the development of the astigmatic interferometer system with two precision 2-axes adjustment stages, which make the complicated alignment easily among the pickup head, the half mirror and the measured reflective mirror. Besides the interferometric analysis between the interference fringe and the output signal, our developed laser interferometer from the astigmatic pickup head is also verified by displacement measurement experiments. Its displacement measurement range is extended from 6 um to 100 mm, and its maximum resolution achieves 5 nm.

並列關鍵字

Astigmatic pickup head ； Astigmatic phenomenon ； Displacement measurement ； Michelson interferometer ； Laser interferometer

參考文獻

[5]Su D.C. , Chiu M.H.,and Chen C.D. “A heterodyne interferometer using an electro-optic modulator for measuring small displacements” ,J. Opt, Vol. 27, pp.19-23,1996.

[6] Armstrong, T. R. and Fitzgerald, M. P., “An Autocollimator Based on the Laser Head of a Compact Disc Player”, Meas. Sci. Technol. 3, pp.1072-1076, 1992.

[7] Rowsell, T. D., “Remote Measurement of Small Displacements Using a CD Pickup Head”, Med. Eng. Phys. Vol. 17, pp.459-461, 1995.

[8] Ehrmann, K., Ho, Arthur., and Schindhelm K., “A 3D Optical Profilometer Using a Compact Disc Reading Head”, Meas. Sci. Technol. 9, pp.1259-1265, 1998.

[9] Fan, K. C., Lin, C. Y., and Shyu, L. H., “The Development of a Low-cost Focusing Probe for Profile Measurement”, Meas. Sci. Technol. 11, pp.N1-N7, 2000.