Illumination optical system, illumination apparatus, and illumination optical element

Patent metadata

Field	Value
Publication number	US-10180234-B2
Application number	US-201514801063-A
Country	US
Kind code	B2
Filing date	Jul 16, 2015
Priority date	Jul 24, 2014
Publication date	Jan 15, 2019
Grant date	Jan 15, 2019

Abstract

An illumination optical system includes an illumination optical element that irradiates a predetermined area of an illumination target surface with light in a planar manner. The illumination optical element has an optical surface directed toward the illumination target surface. The optical surface has, in a perpendicular direction which is perpendicular to an optical axis, a plurality of refractive surfaces each of which refracts light toward the predetermined area and which are formed at a constant pitch determined by the predetermined area.

First claim

What is claimed is:

1. An illumination optical system comprising:
a light source;
a collimating lens that converts light emitted from the light source into a collimated beam and that emits the collimated beam; and
an illumination optical element that irradiates a predetermined area of an illumination target surface with light in a planar manner,
wherein:
the illumination optical element has a first optical surface directed toward the illumination target surface,
the first optical surface has, in a perpendicular direction which is perpendicular to an optical axis, a plurality of first refractive surfaces each of which refracts light from the collimating lens toward the predetermined area and which are formed at a constant pitch which matches a width of the predetermined area,
the plurality of first refractive surfaces have concentric circular shapes point-symmetric about the optical axis or concentric rectangular shapes line-symmetric with respect to the optical axis, and have, in a section view that includes the optical axis, shapes of straight lines that form different angles with the optical axis,
a straight line of one of the first refractive surfaces which is closer to the optical axis forms a larger angle with the optical axis in the section view that includes the optical axis, than a straight line of another one of the first refractive surfaces that is farther from the optical axis, such that the light from the collimating lens is divided for each of the plurality of first refractive surfaces and such that all divisions of the divided light overlap each other within the predetermined area of the illumination target surface while remaining in the form of a collimated beam having a beam diameter matching the constant pitch, and
in the section view that includes the optical axis, (i) the optical axis passes through one of the first refractive surfaces, the one of the first refractive surfaces through which the optical axis passes is perpendicular to the optical axis in the section view that includes the optical axis, and the first refractive surfaces that are directly adjacent to the one of the first refractive surfaces through which the optical axis passes are continuous with the one of the first refractive surfaces through which the optical axis passes with no rise portion therebetween, or (ii) the optical axis passes through a boundary between two adjacent ones of the first refractive surfaces, and the two adjacent ones of the first refractive surfaces are inclined with respect to a plane extending in the perpendicular direction which is perpendicular to the optical axis.

2. The illumination optical system according to claim 1 , wherein the first optical surface further has, in the perpendicular direction, a plurality of second refractive surfaces each of which refracts light toward a portion of the predetermined area, the plurality of second refractive surfaces being provided farther away from the optical axis than the plurality of first refractive surfaces.

3. The illumination optical system according to claim 1 , wherein:
the illumination optical element has a second optical surface opposite the first optical surface, and
the second optical surface is a Fresnel surface.

4. An illumination apparatus comprising the illumination optical system according to claim 1 .

5. The illumination optical system according to claim 2 , wherein:
the plurality of second refractive surfaces have, in the section view that includes the optical axis, shapes of straight lines that form different angles with the optical axis, and
one of the second refractive surfaces which is closer to the optical axis forms a larger angle with the optical axis in the section view that includes the optical axis, than another one of the second refractive surfaces that is farther from the optical axis.

6. The illumination optical system according to claim 2 , further comprising a variable aperture that varies a beam diameter of light that enters the illumination optical element.

7. The illumination optical system according to claim 5 , wherein the plurality of second refractive surfaces are formed in the perpendicular direction at a constant pitch that is shorter than the pitch at which the plurality of first refractive surfaces are formed.

8. An illumination optical element that irradiates a predetermined area of an illumination target surface with light in a planar manner, the illumination optical element having an optical surface directed toward the illumination target surface, wherein:
the optical surface has, in a perpendicular direction which is perpendicular to an optical axis, a plurality of refractive surfaces each of which refracts light toward the predetermined area and which are formed in the perpendicular direction at a constant pitch which matches a width of the predetermined area,
the plurality of refractive surfaces have concentric circular shapes point-symmetric about the optical axis or concentric rectangular shapes line-symmetric with respect to the optical axis, and have, in a section view that includes the optical axis, shapes of straight lines that form different angles with the optical axis,
one of the refractive surfaces which is closer to the optical axis forms a larger angle with the optical axis in the section view that includes the optical axis, than another one of the refractive surfaces that is farther from the optical axis, such that light that has entered the illumination optical element as a collimated beam is divided for each of the plurality of refractive surfaces and such that all divisions of the divided light overlap each other within the predetermined area of the illumination target surface while remaining in the form of a collimated beam having a beam diameter matching the constant pitch, and
in the section view that includes the optical axis, (i) the optical axis passes through a first one of the refractive surfaces, the first one of the refractive surfaces is perpendicular to the optical axis in the section view that includes the optical axis, and the refractive surfaces that are directly adjacent to the first one of the refractive surfaces are continuous with the first one of the refractive surfaces with no rise portion therebetween, or (ii) the optical axis passes through a boundary between two adjacent ones of the refractive surfaces, and the two adjacent ones of the refractive surfaces are inclined with respect to a plane extending in the perpendicular direction which is perpendicular to the optical axis.

9. An illumination optical system comprising:
a light source;
a collimating lens that converts light emitted from the light source into a collimated beam and that emits the collimated beam; and
an illumination optical element that includes a plurality of refractive surfaces, the plurality of refractive surfaces being formed in a perpendicular direction which is perpendicular to an optical axis at a constant pitch which matches a width of a predetermined area of an illumination target surface, and having, in a section view that includes the optical axis, shapes of straight lines that form different angles with the optical axis, such that, in the section view that includes the optical axis, the collimated beam that has entered the illumination optical element is divided for each of the plurality of refractive surfaces and emitted from the illumination optical element such that all divisions of the collimated beam overlap each other in a planar manner within the predetermined area of the illumination target surface, one of the plurality of refractive surfaces which is closer to the optical axis forming a larger angle with the optical axis in the section view that includes the optical axis than another one of the plurali

Assignees

• Olympus Corp

Inventors

• Yamazaki Kentaro

Classifications

• G02B27/0972

  Prisms (prisms per se G02B5/04) · CPC title

• G02B27/0905

  Dividing and/or superposing multiple light beams · CPC title

• F21V5/00

  Refractors for light sources (characterised by cooling arrangements F21V29/504) · CPC title

• G02B3/08

  with discontinuous faces, e.g. Fresnel lens {(diffractive Fresnel lenses G02B5/1876)} · CPC title

• G02B5/045

  Prism arrays · CPC title