Title:
fθ LENS
Document Type and Number:
Japanese Patent JP3201394
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide an fθ lens for two-dimensionally scanning optical system for a printed board drilling work capable of realizing high fθ linearity over a wide two-dimensional scanning range, the telecentric characteristic, and the convergence.
SOLUTION: This fθ lens consists of a first group G1 consisting of a positive convex lens on the object side, a second group G2 consisting of a negative concave lens on the object side, and a third group G3 consisting of only one component of positive lens, or two components of positive lens and negative lens, or positive lens and positive lens successively arranged from the object side, and totally having the positive refracting power, successively arranged from the object side, and the conditions of (a) -2.2≤f2/f≤-0.3, (b) 0.4≤f3/f≤0.9, (c) 1.8≤d/f≤2.4 are satisfied when f2 is a local length of the second group, f3 is a local length of the third group, (f) is a focal length of the total system, and (d) is a focal length from a front focal point to a rear focal point of the total system. A material of each lens is zinc selenide(ZnSe) or germanium(Ge). The design can be simplified and the number of lenses can be reduced when an aspherical lens is used as at least one of the lenses.
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Inventors:
Keiji Fuse
Application Number:
JP22643099A
Publication Date:
August 20, 2001
Filing Date:
August 10, 1999
Export Citation:
Assignee:
Sumitomo Electric Industries, Ltd.
International Classes:
G02B9/00; B23K26/064; G02B13/00; G02B13/14; G02B13/22; (IPC1-7): G02B13/00; G02B13/14; G02B13/22
Domestic Patent References:
| JP1068876A | ||||
| JP54150144A | ||||
| JP493910A |
Attorney, Agent or Firm:
Shigeki Kawase