DVD와 호환 가능한 홀로그래픽 롬 시스템

We describe holographic ROM system to read bit-type data. It has optical system similar to general optical data storage system such as DVD. But because holographic data storage systems have to adopt imaging optical system, in our system bit-type data can be read out by different servos with DVD. We devised 3-hole method similar to 3- beam method for the tracking servo and used astigmatic optical system for the focusing servo. Also we developed the reference beam servo to measure movement of reference beam because especially holographic data storage systems need reference beam. The system was operated by these three servos and objective lens of NA 0.6. We obtained eye pattern from random data of 3T-2um track pitch. We also obtained another eye pattern from DVD disk by only using focusing servo PDIC in our system to verify the compatibility with DVD.