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Browse Prior Art Database

Homogenizer for High Power Laser

IP.com Disclosure Number: IPCOM000122043D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 71K

Publishing Venue

IBM

Related People

Goodman, D: AUTHOR [+12]

Abstract

Because the output of excimer lasers is not uniform, some apparatus for producing a more uniform beam is often required. There are several traditional methods for homogenization, the most important being mirror tunnels and lens arrays. For high-power laser applications, there are several problems with the standard methods. Focusing a high-power beam in the air can result in ionization, producing a number of particles which collect on the optical surfaces and scatter light, reducing throughput. Focusing within or upon a material surface results in the destruction of the material.

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Homogenizer for High Power Laser

      Because the output of excimer lasers is not uniform, some
apparatus for producing a more uniform beam is often required.  There
are several traditional methods for homogenization, the most
important being mirror tunnels and lens arrays.  For high-power laser
applications, there are several problems with the standard methods.
Focusing a high-power beam in the air can result in ionization,
producing a number of particles which collect on the optical surfaces
and scatter light, reducing throughput.  Focusing within or upon a
material surface results in the destruction of the material.

      Described here is a homogenizer based on the traditional light
tunnel, with modifications for high-power lasers.  A cross-sectional
diagram is shown. The basic features are:
     (1) The tunnel is hollow, since absorption losses in solid
tunnels could be excessive and browning could occur.
     (2) The coatings are dielectric, especially designed for work at
grazing incidence, to reduce losses and prevent damage to the tunnel
substrates.
     (3) The tunnel is held within a cell which may be either
evacuated or filled with an inert gas.  This prevents ionization due
to the beam focused near the front end of the tunnel.  The cell also
provides a clean environment, preventing the accumulation of dust or
other air- borne contaminants.  The cell has planar windows on each
end, which are anti-reflection coated.  The distance fro...