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US 7,256,949 B2Granted
Optical system with wavelength selecting device
AssigneeNikon Corporation
InventorsKouichi Ohshita, Mami Muratani
Life of this patent
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Abstract
The object is to provide an optical system with a wavelength selecting device. According to one aspect of the present invention, an optical system with a wavelength selecting device includes, in order from an object along an optical axis, an objective optical system composed of optical elements having refractive power and an aperture stop, a no-power optical group composed of optical elements having no refractive power, and an imaging device. The no-power optical group includes the wavelength selecting device for making short wavelength light be selectively substantially non-transparent. The wavelength selecting device preferably satisfies the predetermined conditional expressions.
Claims18
An optical system comprising:
- a plurality of lens elements having respective lens surfaces;
- wherein an optical member having transmittance of 5% or less with respect to ultraviolet light over a wavelength range from 340 nm to 390 nm includes a first interference film formed on one of said lens surfaces,
- the following conditional expressions being satisfied:
- 0<|Φ/R|<0.8
- 0°≦|B|<13°
- where Φ denotes the effective diameter of the lens surface, R denotes the radius of curvature of the lens surface, and B denotes an angle of the principal ray passing through the lens surface relative to the optical axis at the lens surface in the air side;
- and
- wherein the optical system includes a negative lens group and a positive lens group adjacent to the negative lens group;
- the negative lens group includes three lens elements which are a first negative lens element, a second negative lens element, and a positive lens element;
- and
- the lens surface is an image side surface of the second negative lens element.
8 more elements
An optical system comprising:
- a plurality of lens elements having respective lens surfaces;
- wherein an optical member having transmittance of 5% or less with respect to ultraviolet light over a wavelength range from 340 nm to 390 nm includes a first interference film formed on one of said lens surfaces,
- the following conditional expressions being satisfied:
- 0<|Φ/R|<0.8
- 0°≦|B|<13°
- where Φ denotes the effective diameter of the lens surface, R denotes the radius of curvature of the lens surface, and B denotes an angle of the principal ray passing through the lens surface relative to the optical axis at the lens surface in the air side;
- and
- wherein the optical system includes a negative lens group and a positive lens group adjacent to the negative lens group;
- the positive lens group includes a positive lens element located most toward the object side of the positive lens group;
- and
- the lens surface is an image side surface of the positive lens element.
8 more elements
An optical system comprising:
- a plurality of lens elements having respective lens surfaces;
- wherein an optical member having transmittance of 5% or less with respect to ultraviolet light over a wavelength range from 340 nm to 390 nm includes a first interference film formed on one of said lens surfaces,
- the following conditional expressions being satisfied:
- 0<|Φ/R|<0.8
- 0°≦|B|<13°
- where Φ denotes the effective diameter of the lens surface, R denotes the radius of curvature of the lens surface, and B denotes an angle of the principal ray passing through the lens surface relative to the optical axis at the lens surface in the air side;
- and
- wherein the optical system includes a negative lens group, a first positive lens group adjacent to the negative lens group, and a second positive lens group located most toward the image side in the optical system;
- and
- the lens surface is a most image side surface of the second positive lens group.
7 more elements
A method for forming an image of an object, comprising:
- providing an optical system that includes a plurality of lens elements and an interference film provided on a lens surface of one of the lens elements, the interference film having transmittance of 5% or less with respect to ultraviolet light over a wavelength range from 340 nm to 390 nm;
- and
- wherein the following conditional expressions are satisfied:
- 0<|Φ/R|<0.8
- 0°≦|B|<13°
- where Φ denotes the effective diameter of the lens surface, R denotes the radius of curvature of the lens surface, and B denotes an angle of the principal ray passing through the lens surface relative to the optical axis at the lens surface in the air side;
- wherein the optical system includes a negative lens group and a positive lens group adjacent to the negative lens group, wherein the negative lens group includes a first negative lens element, a second negative lens element, and a positive lens element;
- and
- wherein the interference film is formed on an image side surface of the second negative lens element.
6 more elements
A method for forming an image of an object, comprising:
- providing an optical system that includes a plurality of lens elements and an interference film provided on a lens surface of one of the lens elements, the interference film having transmittance of 5% or less with respect to ultraviolet light over a wavelength range from 340 nm to 390 nm;
- and
- wherein the following conditional expressions are satisfied:
- 0<|Φ/R|<0.8
- 0°≦|B|<13°
- where Φ denotes the effective diameter of the lens surface, R denotes the radius of curvature of the lens surface, and B denotes an angle of the principal ray passing through the lens surface relative to the optical axis at the lens surface in the air side;
- wherein the optical system includes a negative lens group and a positive lens group adjacent to the negative lens group, wherein the positive lens group includes a positive lens element located most toward the object side of the positive lens group;
- and
- wherein the interference film is formed on an image side surface of the positive lens element.
6 more elements
A method for forming an image of an object, comprising:
- providing an optical system that includes a plurality of lens elements and an interference film provided on a lens surface of one of the lens elements, the interference film having transmittance of 5% or less with respect to ultraviolet light over a wavelength range from 340 nm to 390 nm;
- and
- wherein the following conditional expressions are satisfied:
- 0<|Φ/R|<0.8
- 0°<|B|<13°
- where Φ denotes the effective diameter of the lens surface, R denotes the radius of curvature of the lens surface, and B denotes an angle of the principal ray passing through the lens surface relative to the optical axis at the lens surface in the air side;
- wherein the optical system includes a negative lens group, a first positive lens group adjacent to the negative lens group, and a second positive lens group located most toward the image side in the optical system;
- and
- wherein the interference film is formed on a most image side surface of the second positive lens group.
6 more elements
Dependencies are inferred from the claim text.