高記錄密度碟片伺服訊號的量測

Abstract

隨著多媒體時代的來臨, 聲音與影像的加入使得所需的資訊容量迅 速擴增, 在有限的光碟面積下, 最有效的方法乃是提高記錄密度, 如何在 高記錄密度碟片上仍能正確地存取資料, 有賴精確偵測伺服訊號與驅動器 的配合. 本文的目的在量測高記錄密度碟片的伺服訊號, 並 探討碟片結構與傾斜角的影響. 我們架設了一簡單光碟讀取系統來量測窄 軌距碟片在不同傾斜角, 軌距寬度時定焦誤 訊號(FES)及定軌誤差訊號( TES)的變化. 伺服方法在定焦部分探討了刀緣法及像散法, 定軌部分則採 推挽法. 從實驗結果發現聚焦部分較不受碟片結構的影響, TES會隨軌距 縮減而變小且與溝槽深度有關, 碟片的傾斜會改變刀緣法的S-curve線性 區範圍, 像散法則較不受影響. Demand on storage capacity increases drastically due to the addition of sound and image for multimedia application. One of the effective ways to increase storage density is to increase recording density. How to load and save data correctly on high recording density optical disks depends on theprecise detection of servo signal and coordination of actuator. The objective of this thesis is to measure the servo signal on high recording density optical disks. We set up an optical read-out system to measure the focus error signal(FES) and tracking error signal(TES) of narrow track pitch disks with different tilt angle and track pitch. We use knife-edge method and astigmatic method for focus servo, push-pull methos for tracking servo, respectively. From experimental results, it is found that focusing is not affected by disks structure. The TES depends on groove depth and decreases as track pitch is reduced. Tilt of disks changes the range of S-curve linear region for knife-edge method, but is less affected for astigmatic method.