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366. LASER CAVITY: A Program to Aid in the Design of a
Four-Mirror Laser Having a Tightly Focused Beam in Two
of Its Three Segments
by Donald A. Chernoff, Department of Chemistry and The
James Franck Institute, The University of Chicago,
Chicago, Illinois 60637
Tight focusing of the laser beam inside a laser cavity
is necessary for applications such as continuous
operation of dye lasers, acousto-optic cavity dumping,
and intracavity frequency doubling. Focusing may be
accomplished either with a lens or a mirror. Kogelnik,
Ippen, Dienes, and Shank1 have discussed the properties
of astigmatic resonators containing one off-axis
focusing mirror. A key feature is the fact that the
spacing between the mirrors at the tightly focused
segment of the cavity is very critical. In designing a
laser cavity to suit the requirements of the components
placed at the beam focus, it is convenient to express
performance criteria in terms of the confocal parameter
in the various regions of the cavity. The confocal
parameter, b, is determined by the construction
parameters: mirror curvatures, spacings and angles of
incidence. The radius of the beam at the focus is
wo = (lb/2p)1/2 ,
where l is the wavelength of the light.2,3
The evaluation of trial cavity configurations using the
formulas given by Kogelnik and co-workers is easy for a
cavity containing one tight focus, but is tedious for
the cases of two or more foci. The LASER CAVITY
program is arranged for the two foci case. Users
interested in more complicated situations would need to
add a few statements to the STABIL and MAIN routines.
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References:
1. H. W. Kogelnik, E. P. Ippen, A. Dienes, and C. V.
Shank, IEEE J. Qu. Elec., QE-8, 375(1972).
2. A. Yariv, Introduction to Optical Electronics (New
York: Holt, Rinehart and Winston, 1971).
3. S. E. Harris and R. W. Wallace, "Focusing and
Collimation of Gaussian Laser Beams," Application
Note No. 5, Chromatix Inc. (1975).
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FORTRAN IV (IBM)
Lines of Code: 264
Recommended Citation: D. A. Chernoff, QCPE 11, 366
(1978).
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