Light illumination device

• US 4,497,015 A
• Filed: 02/22/1983
• Issued: 01/29/1985
• Est. Priority Date: 02/26/1982
• Status: Expired

• Current Assignee: Nikon Corporation
• Original Assignee: Nippon Kotsu Kabushiki Kaisha (Nikon Corporation)
• Inventors: Okada, Masashi, Konno, Kunio
• Primary Examiner(s): Walsh, Donald P.
• Application Number:
  US06/468,551
• Time in Patent Office: 707 Days
• Field of Search: 362/268, 355/67, 355/71, 350/167, 353/38, 353/97, 353/98
• US Class Current: 362/268
• CPC Class Codes: F21W 2131/402 for working places
• CPC Class Codes: G03F 7/70075 Homogenization of illumination intensity in the mask plane by using an integrator, e.g. fly's eye lens, facet mirror or glass rod, by using a diffusing optical element or by beam deflection

Abstract

A device for providing an illumination of an object includes first and second optical integrators disposed on an optical axis in spaced-apart relationship. Light rays emitted from a point light source formed by an elliptical reflector mirror having a light-emitting source are incident on the first optical integrator, which forms a plurality of secondary images of the point light source. The second optical integrator receives luminous fluxes emitted from the secondary light source images to form a multiplicity of secondary images of the secondary light source images formed by the first optical integrator. Luminous fluxes from the secondary images formed by the second optical integrator are superimposed by a condenser lens on the object for illuminating the latter with light beams of uniform intensity.

Claims

1. A device for uniformly illuminating an object comprising:

(a) means for providing a light source;

(b) first optical means disposed to intersect across light energy emitted from said light source, said first optical means including a first multiplicity of lens elements for forming a multiplicity of images of said light source on a first focal plane and a second multiplicity of lens elements disposed in the vicinity of said first focal plane and corresponding respectively to said first multiplicity of lens elements for forming an image of said first multiplicity of lens elements on a second focal plane;

(c) second optical means disposed to intersect across light energy emitted from said first optical means, said second optical means including a third multiplicity of lens elements disposed in the vicinity of said second focal plane for forming a multiplicity of images of said second multiplicity of lens elements on a third focal plane and a fourth multiplicity of lens elements disposed in the vicinity of said third focal plane and corresponding respectively to said third multiplicity of lens elements; and

(d) third optical means for superimposing light energy emitted from said second optical means on said object.

2. A device according to claim 1, wherein said first optical means includes collimator means disposed between said light source and said first multiplicity of lens elements for converting the light energy from said light source into collimated light energy.

3. A device according to claim 1, wherein said third optical means includes condenser lens means, said fourth multiplicity of lens elements cooperating with said condenser lens means to form an image of said third multiplicity of lens elements on said object.

4. A device for projecting a pattern on a photomask onto a base plate through a projecting optical system, comprising:

(a) means for providing a light source;

(b) first optical means disposed to intersect across light energy emitted from said light source, said first optical means including a first multiplicity of lens elements for forming a multiplicity of images of said light source on a first focal plane and a second multiplicity of lens elements disposed in the vicinity of said first focal plane and corresponding respectively to said first multiplicity of lens elements for forming an image of said first multiplicity of lens elements on a second focal plane;

(c) second optical means disposed to intersect across light energy emitted from said first optical means, said second optical means including a third multiplicity of lens elements disposed in the vicinity of said second focal plane for forming a multiplicity of images of said second multiplicity of lens elements on a third focal plane and a fourth multiplicity of lens elements disposed in the vicinity of said third focal plane and corresponding respectively to said third multiplicity of lens elements; and

(d) third optical means disposed to intersect across light energy emitted from said second optical means, said third optical means forming an image of said fourth multiplicity of lens elements on a pupil of said projecting optical system.

5. A device for uniformly illuminating an object, comprising:

(a) means for providing a light source;

(b) collimator means for converting the light energy from said light source into collimated light energy;

(c) first multiplicity of imaging lens elements and second multiplicity of imaging lens elements disposed in matrix form, respectively, adjacent to a first plane and a second plane which intersects perpendicular to said collimated light energy in order, said second multiplicity of imaging lens elements each corresponding to said first multiplicity of imaging lens elements;

(d) third multiplicity of imaging lens elements and fourth multiplicity of imaging lens elements disposed in matrix form, respectively, adjacent to a third plane and a fourth plane which intersect perpendicular to the light energy passing through said first and second planes in order, said fourth multiplicity of imaging lens elements each corresponding to said third multiplicity of imaging lens elements; and

(e) wherein said light source, said second plane, and said fourth plane and said object are in optically conjugate relation to one another and said first plane and said third plane are in optically conjugate relation to each other.

6. A device according to claim 5, wherein each of said lens elements of said second multiplicity of imaging lens elements has an image magnification β

₁ satisfying the relationship β

₁ =R₂ /d₁, and each of said lens elements of said third multiplicity of imaging lens elements has an image magnification β

₂ satisfying the relationship β

₂ =d₂ /R₁, where R₁ is the aperture of the first and second multiplicities of imaging lens elements, d₁ the aperture of each of said lens elements of said first and second multiplicities of imaging lens elements, R₂ the aperture of the third and fourth multiplicities of imaging lens elements, and d₂ the aperture of each of said lens elements of said third and fourth multiplicity of imaging lens elements.