Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
2007-02-27
2007-02-27
Harrington, Alicia M (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C359S768000
Reexamination Certificate
active
11331286
ABSTRACT:
An original reading lens includes a four-group, five-element lens configuration including three positive lenses and two negative lenses, wherein the positive lens is constructed by a glass material of low dispersion, and the negative lens is constructed by a glass material of high dispersion, a partial dispersion θ gd is defined by θ gd=(ng−nd)/(nF−nc) by a refractive index nd of d line (587.56 nm), a refractive index nc of c line (656.27 nm), a refractive index nF of F line (486.13 nm), and a refractive index ng of g line (435.83 nm), a straight line connecting a coordinate point of a reference glass material K7, K7(θ gd, ν d) and a coordinate point of a reference glass material F2, F2(θ gd, ν d) on a plane with a coordinate system including the partial dispersion θ gd and an Abbe number ν d as orthogonal two axes is adopted as a reference line, and a partial dispersion deviation δ θ gd which is the deviation from the reference line of the partial dispersion θ gd of the material is positive in one or more positive lens.
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patent: 2001-166359 (2001-06-01), None
Harrington Alicia M
Ricoh & Company, Ltd.
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