- 學位論文
白光光源式真直度干涉儀
Straightness interferometer with white-light source
摘要
本論文提出一套白光光源式真直度干涉儀，主要元件包含白光光源、偏極片、非偏極分光鏡、伍拉斯頓晶體、V型反射鏡、CCD攝像機、PZT位移平台。 伍拉斯頓晶體為雙折射晶體，光源入射晶體後會出射兩道分別為水平及垂直偏極態的光束，兩光束於晶體端有夾角1.6°，當出射光束入射至V型反射鏡後會沿著原光路反射回伍拉斯頓晶體並合為一道光束，此時會產生干涉現象，干涉信號可從CCD攝像機觀察得到。 當光束入射至伍拉斯頓晶體正中心時，出射之水平及垂直偏極態的光束有相同的光程，反之則產生光程差，因此光源入射伍拉斯頓晶體正中心時可觀察到最大光強的干涉條紋。將伍拉斯頓晶體作為量測端，可定義於最大光強的干涉條紋產生時的位置為空間絕對零點；干涉條紋的光強會隨量測端與入射光源之間產生的位移而發生變化，因此藉由其光強變化可反推得到此位移量。 本實驗系統使用掃描法與即時補償法作絕對位移量之量測：前者利用找尋空間絕對零點之位置作為量測基準；後者為當量測端受到位移時，系統藉由光強變化反推位移量並且作即時補償的動作，使其回復至空間絕對零點之位置，並且可由補償值得知其位移量。由實驗得知掃描法與即時補償法量測1μm之位移的平均量測誤差分別為0.0114μm及0.0136μm與0.11μm、0.09μm的穩定度；即時補償法的量測速率與範圍分別為30次/秒、 μm。 本研究實際架構出該干涉儀，由理論計算得系統靈敏度為33.509deg./ μm，且經實驗驗證了系統之正確性以及其可應用於量測位移真直度。
並列摘要
This paper proposes a white light source straightness interferometer. It consists of a white-light source, polarizer, NPBS, Wollaston prism, V type reflector, CCD camera and PZT translation stage. The Wollaston prism is a birefringence prism. When the light source incidents to the prism, it will produce S and P polarized beams respectively. The angle of S and P polarized beams is 1.6°. When the exit beams incident V type reflector, these beams will return Wollaston prism along the original optical path. These beams will match each other to become a superimposed beam. At the moment, the phenomenon of interference will occur. The signal of interference will be probed by CCD camera. When the light source incidents to the center of Wollaston prism, it will not occur the optical path difference. On the contrary, the optical path difference will be occurred by the displacement. So we can observe the biggest intensity of interference stripe when the light source incidents to the center of Wollaston prism. We take Wollaston prism as the measured head. And we can define the position of the biggest intensity of interference stripe as the absolute zero point in space. If someone causes displacement between the measured head and the incident light, the intensity of interference stripe will be varied. We can infer the displacement from the variation of the intensity of interference stripe. This experimental system uses the scanning and real time compensation techniques to measure absolute displacement. The former is using the absolute zero point in space to be the measured standard. The latter is when the measured head is moved by someone, the system can compensate the displacement by the intensity of interference stripe and can push the measured head to the absolute zero point in space. We can observe the actual displacement of the measured head by the compensation. We get the average measured error of 1μm measured displacement and the stability of the scanning and real time compensation techniques are 0.0114μm、0.0136μm and 0.11μm、0.09μm from experimental result. The measured rate of real time compensation techniques is 30 times per second. The range of compensation is ±3 μm. This study builds the interferometer in reality. We get the sensitivity of the system is 33.509deg./ μm. We can prove the accuracy of this experimental system by experiment. And the system can measure the straightness error of the measured sample in actuality.