Focal plate using phase type diffraction grating

Abstract

Abstract PURPOSE: To obtain the defocus image of a bright visual field, easy focusing and of a natural state to be obtained by leaving zero-order diffracted light within the range where the intensity ratios to total diffracted light become the specific ratios. CONSTITUTION: Unit patterns having two square shape crests are arrayed in multiplicity in square form on one surface of a focal plate 1. Now, when a signal color spot light source of, e.g., a wavelength λ=550 mm is used and the image of said light source by this focal plate 1 is observed, the bright and natural defocus image may be observed if the values of the area ratio γ h that the portions of the crests of the diffraction grating occupy in the entire part of the diffraction grating of the focal plate are taken at 0.66, 0.77 in the boundary region of the phase differences θ=π by the combinations indicated by the shaded part of the graph, e.g., the portions of the crests and troughs of light. The intensity ratios R 0 of this time are 12%, 33%. Namely, if the 0 order diffracted light is left within the range where the intensity ratios to the total diffracted light become 5% to 50%, the bright and natural defocus images may be obtained. COPYRIGHT: (C)1980,JPO&Japio

Inventors

• 👤 Toshihide Doi
• 👤 Toyohiko Kashiwagi

Bibliographic Details