Intermediate range intensity modification of gaussian beam using optical integration means

• US 4,787,013 A
• Filed: 11/30/1987
• Issued: 11/22/1988
• Est. Priority Date: 11/30/1987
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Santa Barbara Research Center
• Inventors: Sugino, Paul S., Gardner, Leland V.
• Primary Examiner(s): Lazarus, Ira S.
• Assistant Examiner(s): Hagarman, Sue
• Application Number:
  US07/126,434
• Time in Patent Office: 358 Days
• Field of Search: 362/32, 362/235, 362/268, 362/236, 362/244, 362/246, 362/339, 362/26, 362/27, 362/326, 362/259, 350/96.15, 350/96.18, 350/96.28
• US Class Current: 362/552
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0057 in the form of a laser diode array, e.g. laser diode bar semiconductor laser arrays with beam combining arrangement H01S5/4012
• CPC Class Codes: G02B 27/09 Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for adapting the beam shape of a laser diode G02B19/0052; adapting the beam shape of an LED G02B19/0061; coupling into light guides using intermediate optical elements G02B6/4204; beam shaping specially adapted for lasers H01S3/005
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat

Abstract

An optical projection apparatus is disclosed for generating a planar light beam of substantially uniform intensity from a nonplanar multi-element light source 10 projecting a beam having a generally Gaussian intensity distribution. Light from the source 10 passes through an optical integrator rod 52 having a faceted entrance face 54 and a spherical exit face 50. The spherical exit face 50 is designed to move the image 42 of the rod entrance face that would otherwise be created between the objective lens 14 and output plane 40 to a position 48 between the lens 14 and the exit face 50. In such manner, localized hot spots which may be created by the image 42 of the entrance face are substantially eliminated thereby ensuring that the entire length of the beam between the lens 14 and output plane 40 has a substantially uniform intensity distribution.

Claims

1. Optical projection apparatus comprising:

a multi-element source projecting a beam having a generally Gaussian intensity distribution along an optical axis towards an output plane;

a rod of optically transmitting material disposed coaxially with the optical axis, the rod having an entrance face and an exit face;

an objective lens disposed between the rod exit face and the output plane, said objective lens having a given focal length; and

optical means for moving the image of the rod entrance face that would otherwise be created between the lens and the output plane to a position between the rod exit face and the lens;

whereby the intensity of the beam projected along the optical axis from the exit face to the output plane has a generally uniform intensity throughout the length of the projected beam.

2. The apparatus of claim 1 wherein said optical means comprises a spherical surface on the exit face.

3. The apparatus of claim 2 wherein the spherical exit face surface is adapted to image the rod entrance face at substantially the front focal length of the lens.

4. The apparatus of claim 3 wherein the entrance face of the rod is faceted.

5. The apparatus of claim 4 wherein the entrance face is defined by four triangular-shaped surfaces meeting at an apex disposed substantially coaxially with the optical axis.

6. Optical projection apparatus for projecting a light beam of substantially uniform intensity along an optical axis towards an output plane, said apparatus comprising:

a multi-element, nonplanar source of light projecting a beam along the optical axis towards the output plane;

a rod of optically transmitting material having its length disposed coaxially with the beam projected from the source, said rod having a substantially rectangular cross section throughout its length between an entrance face and an exit face, said entrance and exit faces having different geometric configurations adapted to effectively invert the intensity of the beam entering the entrance face thereby producing a beam at the exit face in the form of a plane source of forwardly directed light;

an objective lens disposed between the rod exit face and the output plane; and

optical means formed in the rod for moving an image of the entrance face that otherwise would be created between the lens and the output plane to a position between the rod exit face and the lens;

whereby the beam projected between the rod to the output plane has a substantially uniform intensity throughout its entire length.

7. The apparatus of claim 6 wherein the entrance face has faceted surfaces.

8. The apparatus of claim 6 wherein the optical means is a spherical surface integrally formed on the exit face of the rod.

9. The apparatus of claim 8 wherein the spherical surface is adapted to focus the image of the entrance face at substantially the front focal plane of the lens

10. The apparatus of claim 6 wherein said rod is constructed of a single piece of quartz material.

11. Optical projection apparatus comprising:

a nonplanar laser diode array projecting a beam along an optical axis to an output plane;

a quartz rod having a generally rectangular cross sectional area, a faceted entrance face and a spherical exit face;

an objective lens disposed between the rod exit face and the output plane, said lens having a given focal length; and

said rod exit face having a sufficient radius to image the rod entrance face at a location substantially coinciding with the front focal length of the objective lens;

whereby the beam projected from the exit face of the rod to the output plane has a substantially uniform intensity distribution throughout its length.