| 摘要 |
PROBLEM TO BE SOLVED: To provide an information device capable of variably controlling electrically, flexibly the beam shape and intensity distribution of a laser beam. SOLUTION: A laser beam emitted from a laser radiation source 1 is formed in a beam shape by means of a liquid crystal element 16 of the optical path, made incident on a condensing lens 11, and converged on the signal face of an optical disk (e.g. a recording layer face of a glass original disk 12). The converged laser beam is reflected by the optical disk, moved reversely on the optical path and reproduced as various signals. The liquid crystal element 16 is capable of magnifying the shape of a spot converged on the information recording layer face of the optical disk by converging small the transmitting shape of the irradiating laser beam. Therefore, it is possible to properly change the shape of a converged light spot so as to make it suit the size of a pit recorded on various different optical disks, and also to read in the optimum condition the information recorded on an optical disk. |
