| 摘要 |
PROBLEM TO BE SOLVED: To enable information recording and reproduction with respect to plural storage media which differ from each other in thickness by forming an aperture variable film having such characteristics as to vary its transmittance at an incident angle, in accordance with the wavelength of incident light on or near the surface of a lens. SOLUTION: An aperture variable film 2, having such characteristics as to vary its transmittance at an incident angle in accordance with the wavelength of incident light, is formed on or near the surface of a lens body 1 in a single body to obtain the objective object lens 3. The incident angle to the aperture variable film 2 is prescribed by the surface inclination of the lens body 1, and the transmission characteristics of the object lens 3 are determined. Since the aperture variable film 2 is formed continuous on the lens body 1 in a single body by coating or other methods. Consequently, holders are made unnecessary and the object lens 3 will not cause off centering with respect to the aperture, even if it shifts at tracking. |
