Binary diffraction optical element for controlling scanning beam intensity in a raster output scanning (ROS) optical system

• US 5,422,753 A
• Filed: 12/23/1993
• Issued: 06/06/1995
• Est. Priority Date: 12/23/1993
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Harris, Ellis D.
• Primary Examiner(s): Ben, Loha
• Assistant Examiner(s): Kong, Steve
• Application Number:
  US08/172,319
• Time in Patent Office: 530 Days
• Field of Search: 359/216-219, 359/17-18, 359/566-569, 359/565
• US Class Current: 359/216.1
• CPC Class Codes: G02B 26/106 having diffraction gratings as scanning elements, e.g. holographic scanners holographic optical elements G02B5/32, holography G03H
• CPC Class Codes: G02B 5/1876 Diffractive Fresnel lenses; Zone plates; Kinoforms G02B5/1842, G02B5/1847 take precedence; optical systems having diffractive correction means G02B27/0037; Fresnel lenses operating by refraction G02B3/08

Abstract

A binary diffractive optical element provides uniform intensity for the scanning beam of a raster output scanning (ROS) optical system by diffracting the excess intensity of the beam.

Claims

1. In a raster output scanning (ROS) optical system of a light source for emitting a light beam, optical means for focusing said light beam upon facets of a rotating polygon mirror, said facets scanning said light beam through focusing optical means along a scan line of a photosensitive medium, the improvement comprising

a binary diffractive optical element between said focusing optical means and said photosensitive medium, said binary diffractive optical element having a surface relief phase grating structure upon an optical substrate for diffracting a portion of the intensity of said scanning light beam to produce a uniform intensity for said scanning light beam over its region of scan.

2. In a raster output scanning (ROS) optical system of claim 1 wherein said uniform intensity is the lowest intensity to said scanning light beam over its region of scan.

3. A binary diffractive optical element for producing a uniform intensity to a scanning beam in a raster output scanning (ROS) optical system comprising

a surface relief phase grating structure upon an optical substrate, said surface relief phase grating structure diffracting a portion of the intensity of an incident scanning light beam wherein the remaining non-diffracted portion of said scanning light beam has a uniform intensity over its scan.

4. The binary diffractive optical element for producing a uniform intensity to a scanning beam in a raster output scanning (ROS) optical system of claim 3 wherein said uniform intensity is the lowest intensity to said incident scanning light beam over its region of scan.