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Resonators with Variable Internal Lenses

  • Norman Hodgson
  • Horst Weber

Abstract

In solid state lasers the active medium exhibits the properties of a thermally induced lens when the material is pumped. The refractive power is brought about by a combination of heat generation due to absorption of pump and laser radiation and the flow of heat to the outer periphery due to cooling. For a laser rod this leads to a temperature distribution which is parabolic with respect to the radial position r if the thermal conductivity is constant and the medium is illuminated homogeneously by the excitation source (Fig 12.1). This results in a similar radial dependence of the index of refraction:
$$n(r) = {n_0}\;(1\; - \;\gamma {r^2})$$
(12.1)
where n 0 is the index of refraction at the center. A bundle of parallel rays incident on the laser rod is focused by the thermal lens for γ > 0 since the optical path length n(r)ℓ inside the medium is longer for rays being closer to the center of the rod.

Keywords

Pump Power Beam Quality Stable Zone Beam Quality Factor Refractive Power 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag London 1997

Authors and Affiliations

  • Norman Hodgson
    • 1
  • Horst Weber
    • 2
  1. 1.Humphrey InstrumentsCarl Zeiss Inc.San LeandroUSA
  2. 2.Optisches InstitutTechnische Universität BerlinBerlinGermany

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