傳統的讀取頭效率不高，主因為雷射光源的垂直發散角與水平發散角不同，垂直方向的發散角比水平方向大的多，為了擷取圓形的雷射光束來利用，準直鏡以水平方向光線強度 的發散角來設計，因此在垂直方向有許多的雷射能量平白地浪費掉。有鑑於此，本論文分別利用水平方向共焦的柱面鏡組，與水平方向傾斜的菱鏡組來進行水平方向擴束，將水平方向光線強度 的雷射光束放大到與垂直方向光線強度 的雷射光束相同，再利用垂直方向的發散角來設計高效率的準直鏡。 本論文首先設計傳統型的藍光碟片讀取頭，涵蓋讀取頭的物鏡設計、準直鏡設計、讀取頭系統的公差分析與聚焦誤差訊號擷取，再模擬雷射光在讀取頭系統中的實際效率。為了提昇效率，導入水平擴束的概念，分別推導設計水平柱面擴束系統與菱鏡擴束系統，同樣涵蓋高效率藍光碟片讀取頭的準直鏡設計、系統公差分析、聚焦誤差訊號擷取與模擬實際效率。最後比較本論文所提出之設計的各項優缺點。 The low efficiency of traditional pickup head is limited by the difference of vertical divergent angle and horizontal divergent angle. The vertical divergent angle is much larger than the horizontal one. To get the circular laser beam, the collimating lens is designed with the divergent angle which intensity is in the horizontal direction. Therefore there is a lot of energy wasted. This thesis uses the cylindrical afocal system and the prismatic system to expand the beam separately in the horizontal direction. The expander makes the beam size which intensity is in the horizontal direction as large as the beam size which intensity is in the vertical direction. Then the highly efficient collimating lens is designed with the divergent angle in the vertical direction. First, this thesis designs traditional Blu-ray Disc pickup head. It covers the design of its objective lens, the design of its collimating lens, tolerance analysis and the focusing error signal, and then simulates the total efficiency. This thesis introduces the concept of beam expanded in the horizontal direction to improve the total efficiency. This thesis designs the cylindrical expander and prismatic expander. It also covers the design of the collimating lens, tolerance analysis and the focusing error signal, and then simulates the total efficiency. At last summarize all of the new designs which are proposed by the thesis.