| 摘要 |
PURPOSE:To obtain a necessary signal for controlling a beam and of reproduction information on the photoelectric conversion face in the specified shape by combining a coherent light source, an optical system and the hologram element of a lens Fourier transformation type recording the specific diffraction waveface as the means for controlling a beam. CONSTITUTION:A circular columnar lens 10 is arranged in the optical path reducing by a condensing lens 51 the parallel beam 13 with a coherent wave length lambda1 and the linear convergent beams 101, 103 facing the vertical direction each other and a nearly circular beam 102 at the medium position thereof are obtd. The Fourier transformation waveface of the circular beam 102 is taken out to the rear side Fourier transformation face (xsi1-eta1 coordinate display) of the lens 50 via the Fourier transformation lens 50 (focus distance f1) and by overlapping it on another plane wave including no aberration a so-called holo gram element 12 of a lens Fourier transformation type is made. Now a reference wave is easily obtd. by the convergence of the parallel beam 14 through the lens 15, with said beam coherent with the parallel beam 13. The necessary reproduction image is thus obtainable on the condensing face. |
