- 學位論文
高精度DVD探頭位移回饋系統之研究
High Precision Displacement Feedback Control on DVD Optical Probe System
摘要
本研究主要是針對DVD探頭上的音圈馬達運動發展出一套新的檢測方法，以避免因為利用電壓值換算的過程，導致磁滯現象的誤差來源。藉由與DVD探頭並聯一個和DVD探頭上完全相同的音圈馬達，本文稱之為第二組音圈馬達，並使用組裝完成的邁克生干涉儀，利用干涉的條紋數，進而換算出第二組音圈馬達所行走的距離。同時，套用光碟機聚焦控制的原理，當待測物反射面不在讀取頭物鏡的聚焦面時，經由感測器所得到的失焦訊號，帶動物鏡重回聚焦平面而完成自動聚焦控制，進而帶動並聯的第二組音圈馬達，使兩組音圈馬達產生近似相同的位移量。最後再由邁克生干涉儀推算出待測物體的表面輪廓，完成高精度的DVD探頭系統表面輪廓量測儀。
並列摘要
A novel DVD-pickup-head-measurement system is presented. In order to avoid any kind of error caused by hysteresis in the voice coil motor ( VCM ) located at DVD-pickup head, we develop an advanced system with an additional VCM observed by a Michelson inferometer. And the secondary VCM will be parallel with traditional VCM on DVD pickup head. According to Ohm’s law, these two VCMs are driven with equivalent current. As a result, both VCMs move in accord. The displacement of the secondary VCM can be obtained by counting the fringes. In addition, this system takes into account the auto-focusing control principle; therefore, when the distance between objective lens and workpiece is not exactly at focal distance, the focus error signal ( FES ) detected by the photodetector will actuate both the voice coil motor located on DVD pickup head and also the secondary VCM to keep the focal distance. Thus, by means of feedback signal of the FES, the auto-focus control can be completed. Furthermore, we are able to obtain surface profile of the workpiece and achieve a higher resolution.