| 摘要 |
PROBLEM TO BE SOLVED: To provide an information recording card medium, in which the features of a hologram recording are effectively utilized while maintaining a prescribed positional precision and the cost is made lower, and to provide a reading device and a lighting head positioning method. SOLUTION: A recording device α is provided with a reading head C, an optical system D, and an actuator controlling circuit B. The head C has a lighting head C1 and a lighting head up-down positioning actuator C3. The system D is made by successively arranging a lens D1, which converges lighting beams L, a light guide D2, which guides the beams to the head C1, a beam splitter D3 and a light source D4 on an optical path. The circuit E is provided with a reflection returning light beam detecting element E1, which detects reflection returning light beams Lb via a beam splitter D2, a frequency comparator E2, which separates/compares the frequency components in the photoelectric converted signals of the beams Lb detected by the element E1, and a counter E3 which counts the number of up and down fluctuations in the signals of the beams Lb across a prescribed threshold. |
