Optical: systems and elements – Diffraction – From grating
Reexamination Certificate
2005-08-16
2005-08-16
Assaf, Fayez G. (Department: 2872)
Optical: systems and elements
Diffraction
From grating
C359S576000, C359S566000
Reexamination Certificate
active
06930833
ABSTRACT:
A layered diffractive optical element is disclosed, with which a high diffraction efficiency is attained over a broad region of used wavelengths, and with which diffraction light of unnecessary diffraction orders can be suppressed. A diffractive optical element of the present invention includes a plurality of diffraction gratings made of materials with different Abbe numbers, the plurality of diffraction gratings being layered with each other. Moreover, the partial dispersion ratio with respect to a g-line and a F-line of the material constituting at least one of the plurality of diffraction gratings satisfies the condition represented by a specified expression.
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European Search Report issued in counterpart application EP 03 25 3415, dated Jan. 11, 2005.
Assaf Fayez G.
Canon Kabushiki Kaisha
Morgan & Finnegan , LLP
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