| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical head device which is capable of changing the light quantity on an optical recording medium without changing the output of the exit light from a light source and is excellent in the characteristics of recording and reproducing of the optical recording medium. SOLUTION: In this optical head device, a liquid crystal element 3 in which transparent electrodes are formed on the opposed surfaces of two sheets of transparent substrates, a liquid crystal layer is interposed and held between the transparent electrodes and the direction of the liquid crystal molecules is twisted in a spiral form around the thickness direction of the liquid crystal layer, is arranged between a light source 1 and an objective lens 5 and a polarizer 4 for changing the quantity of the light emitting toward the optical recording medium in emission of the incident light by the polarization direction of the incident light is arranged between the liquid crystal element 3 and the optical recording medium 7, and a voltage controller 11 is connected to the transparent electrodes so that an arbitrary voltage can be impressed to the liquid crystal layer. |
