Beam homogenizer

• US 6,278,550 B1
• Filed: 01/18/2000
• Issued: 08/21/2001
• Est. Priority Date: 02/28/1994
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Digital Optics Corp. (Adeia Inc.)
• Inventors: Feldman, Michael R., Kathman, Alan D
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): Juba, Jr., John
• Application Number:
  US09/484,050
• Time in Patent Office: 581 Days
• Field of Search: 359/9, 359/15, 359/599, 359/53, 359/67, 359/71
• US Class Current: 359/599
• CPC Class Codes: B23K 26/06 Shaping the laser beam, e.g. by masks or multi-focusing
• CPC Class Codes: B23K 26/064 by means of optical elements, e.g. lenses, mirrors or prisms
• CPC Class Codes: B23K 26/0643 comprising mirrors
• CPC Class Codes: B23K 26/0648 comprising lenses
• CPC Class Codes: B23K 26/066 by using masks
• CPC Class Codes: B23K 26/0665 by beam condensation on the workpiece, e.g. for focusing
• CPC Class Codes: G02B 19/0014 at least one surface having optical power
• 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 19/0095 for use with ultraviolet radiation
• 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
• CPC Class Codes: G02B 27/0944 Diffractive optical elements, e.g. gratings, holograms gratings per se G02B5/18; holograms used as optical elements per se G02B5/32
• CPC Class Codes: G02B 5/0252 using holographic or diffractive means
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 5/1819 Plural gratings positioned on the same surface, e.g. array of gratings plural diffractive elements positioned sequentially along the optical path G02B27/4272
• CPC Class Codes: G02B 5/1857 using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• CPC Class Codes: G03H 1/0236 Form or shape of the hologram when not registered to the substrate, e.g. trimming the hologram to alphanumerical shape substrates bearing a hologram G03H1/0272
• CPC Class Codes: G03H 1/2286 Particular reconstruction light G03H1/24 takes precedence; Beam properties
• CPC Class Codes: G03H 2001/085 : Kinoform, i.e. phase only encoding wherein the computed field is processed into a distribution of phase differences
• CPC Class Codes: G03H 2001/303 : Interleaved sub-holograms, e.g. three RGB sub-holograms having interleaved pixels for reconstructing coloured holobject
• CPC Class Codes: G03H 2222/35 : Transverse intensity distribution of the light beam
• CPC Class Codes: H04B 10/50 : Transmitters
• CPC Class Codes: Y10S 359/90 : Methods

Abstract

A beam homogenizer that minimizes undesired intensity variations at the output plane caused by sharp breaks between facets in previous embodiments. The homogenizer includes a hologram made up of irregularly patterned diffractive fringes. An input beam illuminates at least part of the hologram. The hologram transmits a portion of the input beam onto an output plane. In doing so, the energy of the input beam is spatially redistributed at the output plane into a homogenized output beam having a preselected spatial energy distribution at the output plane. Thus, the illuminated portion of the output plane has a shape predetermined by the designer of the homogenizer.

Claims

1. A diffusing element for use as a reticle in a lithographic system, the diffusing element comprising:

a substrate having a lithographically created structure on its surface, which structure converts an input beam illuminating at least part of said structure into an output beam having a preselected energy distribution in an output plane of the lithographic system, wherein substantially all of said output beam is non-orthogonally incident on the output plane, the energy distribution of the output beam being substantially independent of position and spatial energy distribution of the input beam, both diffusing and shaping of the output beam being provided by said structure.

2. The diffusing element of claim 1, wherein said structure substantially eliminates the output beam incident on a center of the output plane.

3. The diffusing element of claim 1, wherein said structure forms a ring in the output plane.

4. The diffusing element of claim 1, wherein the energy distribution over the angular distribution of the output beam is substantially uniform.

5. The diffusing element of claim 1, wherein the diffusing and shaping are provided by a single surface.