波長調制外差式光柵干涉儀之研究

Study of wavelength-modulated heterodyne grating interferometer

李貴宇(Kuei-yu Lee)

指導教授 ： 李朱育

國立中央大學/工學院/光機電工程研究所/碩士(2007年)

摘要

本論文提出一種新穎的光學量測技術—波長調制外差式光柵干涉儀，一種利用波長調制外差光源結合光柵干涉技術測量面內精密位移的量測方法。所謂的面內位移是指待測物運動方向與量測光束方向為垂直關係。本研究以鋸齒波電流調變雷射二極體之波長配合設定的光程差產生外差光源，並且採用高密度的全像光柵進行面內精密位移量測，配合訊號解調技術，達到高精密度、高解析度與高靈敏度之量測能力，以滿足奈米定位技術的要求。
待測物以5 μm、1 μm、500 nm、100 nm、50 nm及10 nm不同大小的行程分別作出三角、正弦或方波形式的運動，根據量測結果製作盒鬚圖進行統計分析。本系統量測精密度優於5 nm，系統電子解析度優於1 pm，靈敏度為1.728 °/nm，最大可量測位移速度為2.6 μm/s。
最後針對可能影響系統的誤差因素進行討論，分類為內稟性、幾何誤差與環境誤差著眼探討。分別提出對實驗可能產生的誤差量與架設實驗、選擇材料的注意事項。其中內稟性誤差之一的週期性誤差，本論文提出如何以訊號處理的方法有效降低誤差量。

關鍵字

位移量測 ； 光柵干涉儀 ； 外差干涉術 ； 波長調制 ； 光學量測

並列摘要

A wavelength-modulated heterodyne grating interferometer is proposed to measure the displacement. A wavelength-modulated light is divided into s and p polarized parts, and these two polarized beams propagate with difference optical path. After combining these two polarized beams, we have the heterodyne light source. Then the heterodyne light is sent to the grating interferometer (GI). The optical phase variation which is induced by the grating movement will be measured by the heterodyne detection. By means of the measured optical phase variation and grating pitch, the displacement of the grating is determined.
The experimental results demonstrate that the proposed system has measurement range up to 5 μm with 5 nm precision. The theoretical predication shows that the sensitivity is 1.728 °/nm and the maximum velocity measuring ability is 2.6 μm/s. The measurement errors, such as the environmental error, the geometric error and nonlinearity error, are also discussed

並列關鍵字

heterodyne interferometry ； grating interferometer ； displacement measurement ； wavelength-modulated ； optical metrology

參考文獻

[6].G. E. Sommargren, “Optical heterodyne profilometry”, Appl. Opt., 20, pp.610-618, 1981.

[7].D. Pantzer, J. Politch and L. Ek, “Heterodyne profiling instrument for the angstrom region”, Appl. Opt., 25, pp.4168-4172, 1986.

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

[9].J. Y. Lee et al., “Heterodyne interferometer for measurement of in-plane displacement with subnanometer resolution”, Proc. SPIE, Vol.6280, pp.62800J, 2006

[10].H, Kikuta et al., “Distance measurement by the wavelength shift of laser diode light”, Appl. Opt., 25, pp.2976-2980, 1986.