Fixed focus image capturing lens
AssigneeRays Optics Inc.
InventorChing-Sheng Chang
Life of this patent
Estimating the term…
Abstract
A fixed focus image capturing lens, including a first lens group, a second lens group, and an aperture, is provided. The first lens group includes a first lens, a second lens, a third lens, and a fourth lens in sequence from an object side of the fixed focus image capturing lens to an image side thereof. The refractive powers of the first lens, the second lens, and the third lens are all negative. The second lens group includes four lenses having refractive power. The four lenses include a cemented lens. The aperture is disposed between the first lens group and the second lens group.
Claims20
A fixed focus image capturing lens, comprising:
- a first lens group, comprising a first lens, a second lens, a third lens, and a fourth lens in sequence from an object side of the fixed focus image capturing lens to an image side of the fixed focus image capturing lens, wherein refractive powers of the first lens, the second lens, and the third lens are all negative;
- a second lens group, disposed between the first lens group and the image side of the fixed focus image capturing lens, and comprising four lenses having refractive power, wherein the four lenses comprise a cemented lens;
- and
- an aperture, disposed between the first lens group and the second lens group;
- and the fixed focus image capturing lens satisfying following conditions of:
- (1) enabling a distance difference between a 555 nm wavelength light focusing surface and an 850 nm wavelength light focusing surface to be less than 20 μm;
- and
- (2) 0.61<D1/LT<0.97, where D1 is a lens outer diameter of an outermost surface of the first lens, and LT is a distance between outermost lens surfaces on two sides of the fixed focus image capturing lens on an optical axis.
A fixed focus image capturing lens, comprising:
- a first lens group, disposed with a first lens having negative refractive power, a second lens having refractive power, and a third lens having a negative refractive power in sequence from a magnification side of the fixed focus image capturing lens to a reduction side of the fixed focus image capturing lens;
- a second lens group, disposed between the first lens group and the reduction side, and comprising at least one cemented lens;
- and
- an aperture, disposed between the first lens group and the second lens group;
- a lens surface closest to the reduction side of the second lens group being concave;
- and the fixed focus image capturing lens being substantially a day and night confocal lens and meeting a following condition of:
- 0.06<EFL/LT<0.08, where EFL is an optical effective focal length of the fixed focus image capturing lens, and LT is a distance between outermost lens surfaces on two sides of the first lens group and the second lens group on an optical axis.
Dependencies are inferred from the claim text.