| 摘要 |
PURPOSE:To reduce the size and weight of a titled pickup and to enhance the accuracy thereof by using a wavelength non-sensitive type grating lens optical system combined with two pieces of grating lenses. CONSTITUTION:The grating lens system is constituted by disposing the 1st and 2nd in-line type grating lenses 11, 12 on the same optical axis (alternate long and short dash line). The spherical waves diverting from the point P on the optical axis are diffracted by the 1st grating lens 11 to the optical axis side and is once intersected with the optical axis; thereafter, the waves are focused by the 2nd grating lens 12 onto the prescribed point Q on the optical axis. The optical pickup which is light in weight and small in size, is not affected by the fluctuation in the wavelength and has the high accuracy and reliability is obtd. by utilizing the grating lens optical system in such a manner. |
