Development of a precision inspection machine for assuring the dynamic quality of the pick-ups used in optical disc drives

Chi Wei Chiu*, Chang-Po Chao

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


This study is dedicated to develop a novel precision on-line inspection machine that is used to weed out the optical pickups that fail to meet the required dynamic specifications. For a typical pickup used in optical disc drives, the optical and dynamic performances are two important attributes to its overall quality. The desired optical performance can often be achieved via manufacturing the optical components to the precisions required, while the dynamic performance is attributed to the actuation capability of the pickup, which integrally affected by the electrical and mechanical subsystems. In order to evaluate the quality of dynamic performance of pick-up, an inspection machine is designed and manufactured. The repeatability and linear relationship of the machine are examined to ensure inspection quality. A set of 12 pickups provided by the industry are used to test the reliability of the machine with the performance indices of each pickup being measured 12 times. Based on the measurements, the repeatability for all indices is shown well within their respective six-sigma ranges defined by the industry. On the other hand, the accuracy is assured since the correlation between the measurements by the designed inspection machine and those by an expensive laser Doppler vibrometer in a much higher precision are well above 90%. With satisfied reliability, accuracy and low cost, the designed machine is shown capable of serving as a satisfactory online inspection means to achieve required high manufacturing quality for optical pickups.

Original languageEnglish
Pages (from-to)581-586
Number of pages6
JournalJournal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Engineers, Series C/Chung-Kuo Chi Hsueh Kung Ch'eng Hsuebo Pao
Issue number5
StatePublished - 1 Oct 2006


  • Dynamic quality
  • Inspection machine
  • Optical pick-up
  • Six-sigma

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