Imaging optical system and imaging device including imaging optical system
AssigneeNissei Technology Corporation
InventorTakuya OTSU
Life of this patent
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Abstract
A wide-angle imaging optical system obtains sufficient information in the image periphery, and achieves high-performance imaging across the entire field of view. The imaging optical system uses stereographic projection, and includes, in sequence from an object, a first lens with a negative refractive power having a convex surface facing the object, a second lens with a negative refractive power, a third lens with a negative refractive power, a fourth lens with a positive refractive power, an aperture stop, a fifth lens with a positive refractive power, a sixth lens with a negative refractive power, and a seventh lens with a positive refractive power.
Claims6
An imaging optical system using stereographic projection with a field of view exceeding 180 degrees, the system comprising, in sequence from an object:
- a first lens with a negative refractive power having a convex surface facing the object;
- a second lens with a negative refractive power;
- a third lens with a negative refractive power;
- a fourth lens with a positive refractive power;
- an aperture stop;
- a fifth lens with a positive refractive power;
- a sixth lens with a negative refractive power;
- and
- a seventh lens with a positive refractive power,
- wherein the imaging optical system satisfies the conditional expressions:
- −23<f1/f<−12 (1)
- −8<f2/f<−5 (2)
- 2.5<f5/f<4.5 (3)
- −3.0<f6/f<−1.9 (4)
- where f is a focal length of the entire imaging optical system,
- f1 is a focal length of the first lens,
- f2 is a focal length of the second lens,
- f5 is a focal length of the fifth lens, and
- f6 is a focal length of the sixth lens.
Dependencies are inferred from the claim text.