Diffractive homogenizer with compensation for spatial coherence
US6072631A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 9, 1998 |
| Grant date | Jun 6, 2000 |
| Priority date | — |
| Expiry date | Jul 9, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03H2001/085
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A diffractive homogenizer is provided for receiving a beam of laser energy and producing a desired illumination pattern in a target plane. The homogenizer is made up of a plurality of diffractive sub-elements, each of which contributes to all or a portion of the desired image. By combining the contributions of many sub-elements to form the final image, a homogenizing effect is realized. In preferred embodiments, the sub-elements are designed to compensate for the finite spatial coherence of the incident laser beam and to control the numerical aperture distribution of the transmitted light. Each sub-element is composed of a large number of discrete pixels, each of which alters the phase of radiation passing therethrough by a selected amount. The pixel arrangement is chosen, using computer modeling and optimization techniques, such that the interference pattern created by the collective pixels in a sub-element makes up the desired image (or a portion thereof). A technique is also provided for reducing the intensity of the image formed by a selected sub-element, which may be located in a laser "hot spot", by randomizing a selected percentage of the pixels located in that sub-element. …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.