| 摘要 |
PURPOSE:To set a Bragg angle in reproduction optionally, by using a basic hologram with low diffraction efficiency for forming a phase type hologram having high diffraction efficiency and a different Bragg angle on the hologram, and obtaining double-layer structure. CONSTITUTION:The basic hologram 1'' with low diffraction efficiency formed on a glass substrate 2 is coated with a specific amount of a photosensitive agent to form a photosensitive agent layer 7. Then, the substrate 2 is irradiated on the reverse side with light 30 to expose the layer 7, forming a longitudinal section of interference fringe along the intermediate line between the transmitted light 31 and diffracted light 32 of the hologram 1''. By a treatment after the exposure, the phase type hologram 7' having high diffraction efficiency and a different Bragg angle from that of the hologram 1'' is formed. In this double-layer constitution, the upper layer hologram has the high diffraction efficiency and the hologram of the lower layer is disregarded, thereby setting the Bragg angle in reproduction optionally. |
