An optical disk having both recording surfaces on which are formed pits trains. A recognizable display pattern is formed by a group of dummy pits formed on one of the recording surfaces. An apparatus for manufacturing the optical disk in which a light beam is modulated in accordance with a dummy...http://www.google.com.tw/patents/US5748607?utm_source=gb-gplus-share專利 US5748607 - Optical disc having large display patterns and its manufacturing apparatus 
