Browse Prior Art Database

Eliminating Coherent Overshoots in Laser Treatment of Materials

IP.com Disclosure Number: IPCOM000116663D
Original Publication Date: 1995-Oct-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Wagner, D: AUTHOR

Abstract

Disclosed is a method to render the laser illumination more incoherent by introducing an aperture directly before the lens which significantly decreases the imaging aperture without reducing the laser intensity.

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Eliminating Coherent Overshoots in Laser Treatment of Materials

      Disclosed is a method to render the laser illumination more
incoherent by introducing an aperture directly before the lens which
significantly decreases the imaging aperture without reducing the
laser intensity.

      The coherent laser radiation may easily be focussed by lenses
and allows material treatment with light.  Normally, not the whole
laser beam is required and apertures or masks are used which cause
diffraction and overshoots at their edges.  Most applications in
material treatment or for measurement purposes however require a
homogeneous profile.

      The grade of coherence is defined to be the quotient of
illuminating aperture and imaging aperture.  Coherent illumination
has a coherence value of zero, whereas in the case of incoherent
illumination the value is &infinity..

      In microscopy with its extensive light sources of high
divergence it is possible and usual to enhance the grade of coherence
by increasing the illuminating aperture thus, rendering the radiation
more incoherent.

      When using laser light the illuminating aperture may be
increased with the help of ground-glass plates or a complex
illumination system consisting of several single lenses.  This
possibility is very complicated and drastically reduces the
intensity.

      Introducing an aperture directly before the lens significantly
decreases the imaging aperture and provides a homogeneo...