US5982544A
Expired / Lapsed
US
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Zoom lens system having a diffractive surface
Assignee: Olympus Corp
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Filing: 1998-07-02
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Granted: 1999-11-09
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Expires: 2018-07-02
Abstract
Abstract The invention provides a compact yet high-zoom-ratio zoom lens system for use with lens shutter cameras, which is well corrected for aberrations albeit being made up of a small number of lenses. The zoom lens comprises a first lens group G1 of positive refracting power, a second lens group G2 of positive refractive power and a third lens group G3 of negative refracting power. The lens groups move for zooming from the wide angle side to the telephoto side, with a separation between the first and second lens groups becoming wide and a separation between the second and third lens groups becoming narrow. At least one lens group has a diffractive surface therein, and satisfies 1.8< beta T/ beta W<4.0 where beta T and beta W are transverse magnifications of the lens group having a diffractive surface at the wide-angle end and the telephoto end of the lens system.
Inventors
- 👤 Yasuji Ogata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:12
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/42; G02B27/4205; G02B27/4211; G02B15/00; G02B15/14; G02B15/143; G02B15/1431; G02B15/143103
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
78 words
A zoom lens system having a diffractive surface, which comprises, in order from an object side thereof, a positive lens group, a positive lens group, and a negative lens group, said lens groups moving for zooming from a wide angle side to a telephoto side thereof, with a separation between first and second lens groups becoming wide and a separation between second and third lens groups becoming narrow, wherein: said negative lens group has said diffractive surface therein.
Claim 2
Dependent Claim
78 words
A zoom lens system having a diffractive surface, which comprises, in order from an object side thereof, a positive lens group, a positive lens group, and a negative lens group, said lens groups moving for zooming from a wide angle side to a telephoto side thereof, with a separation between first and second lens groups becoming wide and a separation between second and third lens groups becoming narrow, wherein: said negative lens group has said diffractive surface therein.
Claim 3
Dependent Claim
118 words
A zoom lens system having a diffractive surface, which comprises, in order from an object side thereof, a positive lens group, a positive lens group, and a negative lens group, said lens groups moving for zooming from a wide angle side to a telephoto side thereof, with a separation between first and second lens groups becoming wide and a separation between second and third lens groups becoming narrow, wherein: at least one lens group has said diffractive surface therein, and satisfies the following condition (1): 1.8<β.sub.T /β.sub.W <4.0 (1) where β T and β W are transverse magnifications of said lens group having said diffractive surface at a wide-angle end and a telephoto end of said lens system.
Claim 4
Dependent Claim
118 words
A zoom lens system having a diffractive surface, which comprises, in order from an object side thereof, a positive lens group, a positive lens group, and a negative lens group, said lens groups moving for zooming from a wide angle side to a telephoto side thereof, with a separation between first and second lens groups becoming wide and a separation between second and third lens groups becoming narrow, wherein: at least one lens group has said diffractive surface therein, and satisfies the following condition (1): 1.8<β.sub.T /β.sub.W <4.0 (1) where β T and β W are transverse magnifications of said lens group having said diffractive surface at a wide-angle end and a telephoto end of said lens system.
Claim 5
Dependent Claim
46 words
The zoom lens system according to claim 1 or 2, wherein said first lens group comprises at least two lenses, and satisfies the following condition (2): 15<ν.sub.1 -ν.sub.2 <25 (2) where ν 1 and ν 2 are Abbe's numbers of lenses forming said first lens group.
Claim 6
Dependent Claim
32 words
The zoom lens system according to claim 1 or 2, wherein said diffractive surface satisfies the following condition (3): -0.01<Φ.sub.DOE <0 (3) where Φ DOE is a power of said diffractive surface.
Claim 7
Dependent Claim
20 words
The zoom lens system according to claim 4, wherein said diffractive surface satisfies the following condition (4): -0.005<Φ.sub.DOE <0 (4)
Claim 8
Dependent Claim
41 words
The zoom lens system according to claim 1 or 2, which satisfies the following condition (5): 0.4<Σd/D<1.0 (5) where Σd is a length from a first surface to a final surface, and D is a diagonal length of a film surface.
Claim 9
Dependent Claim
15 words
The zoom lens system according to claim 6, which satifies the following (6): 0.4<Σd/D<0.8 (6)
Claim 10
Dependent Claim
19 words
The zoom lens system according to claim 1 or 2, wherein said third lens group comprises a single lens.
Claim 11
Dependent Claim
17 words
The zoom lens system according to claim 8, wherein said third lens group comprises a plastic lens.
Claim 12
Dependent Claim
50 words
The zoom lens system according to claim 8, wherein a lens in said third lens group satisfies the following conditions (7): n.sub.d <1.65, ν.sub.d <50 (7) where n d is a d-line refractive index of a lens substrate, and ν d is a d-line Abbe's number of the lens substrate.
References Cited (Backward Citations)
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