| 摘要 |
PROBLEM TO BE SOLVED: To correctly detect the rotational extent of the mirror of a galvanomirror. SOLUTION: This is an optical information recording and reproducing head which makes the luminous flux emitted from a laser beam source parallel luminous fluxes and, thereafter, converges them on an optical disk by making them incident on an objective optical system through a deflection means 126. In this case, this head is constituted so that the rotational extent of an incident plane 127 is detected by putting the vicinity of a deflection surface of a deflection means 126 and the position of the principal plane of an objective optical system in roughly conjugate relation while arranging a relay lens group 29 and an imaging lens group 30 between the deflection means 126 and the objective optical system, by constituting the deflection member of the deflection means with first and second regions whose front surfaces are flat and the rear surface 128 of it with a deformed prism whose surface is a spherical surface or a columnar surface, by applying a transmission coating for transmitting one part of the parallel luminous fluxes to the first region of the incident plane 127 and a reflection coating for reflecting the transmitted luminous fluxes to the rear surface and an reflection preventing coating for emitting reflected luminous fluxes from the second region to the second region and by detecting the laser luminous fluxes emitted from the second region with a photodetector 40. |
