本論文提出一套創新的波長調制外差光柵干涉儀，用以進行六自由度位移及角位移量測。此套干涉儀系統具備外差干涉術、麥克森干涉術，以及光柵干涉術的優點。
我們藉由調整雷射二極體的輸入電流來調製其輸出波長，進而得到外差光源，當此外差光源正向入射至一半穿透式光柵時，會分別產生反射光及穿透光。藉由光路設計使反射光形成麥克森干涉儀架構，用以進行面外位移量測。穿透光經過光柵後產生正負一階繞射光，將此兩道正負一階繞射光疊合後形成光柵干涉儀架構，用以進行面內位移量測。藉由分光技術的運用，我們可以在共用一個光源的條件下建構三組獨立的偵測架構，每一組偵測架構都具備面外及面內位移量測的能力。透過比對每兩組偵測架構間的量測結果，即可獲得角位移訊息。
為了驗證本干涉儀的可行性，我們進行了各種不同的量測實驗。由實驗結果可知，本干涉儀之位移及角位移量測解析度可達50 nm及 2 rad，面內位移及面外位移量測靈敏度分別為0.36°/nm 及1.03°/nm。實驗結果證明本干涉儀具備六自由度位移及角位移量測能力，同時亦具備高穩定性。

In this study, a novel wavelength-modulated heterodyne grating interferometer is proposed for six-degree-of-freedom (6-DOF) displacement and angular displacement measurements. This proposed interferometer has the advantages of heterodyne interferometry, Michelson interferometry, and grating interferometry.
To obtain a heterodyne light source, we adjust the laser diode injection current to modulate the emitted wavelength. When the heterodyne light beam perpendicularly enters a semi-transmission type grating, part of the light beam will be reflected while the other part will pass through. The detection configuration of Michelson interferometer can be constructed by using the reflected beam for out-of-plane displacement measurement. The +1st and -1st order diffraction beams will be formed as the light passes through the grating. The grating interferometry is constructed to detect the in-plane displacement by combining the +1st and -1st order diffraction beams. Furthermore, three identical detection configurations sharing the same light source can be obtained by using the technique of dividing method. Each detection configuration has the ability to sense in-plane and out-of-plane displacement information. Angular displacement information can then be acquired by comparing the displacement measurement result between each two detection configurations.
In order to verify the feasibility of our proposed interferometer, different kinds of experiments have been performed. The experimental results show that the displacement and angular displacement resolutions of the proposed interferometer can achieve 50 nm and 2 rad respectively. The sensitivities of the in-plane and out-of-plane displacements are about 0.36°/nm and 1.03°/nm respectively. The experimental results demonstrate that the proposed interferometer has the ability to measure 6-DOF displacement and angular displacements while maintaining high system stability

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