โ Scribed by Siegman, Anthony E.; Holmes, Dale A.
No coin nor oath required. For personal study only.
This paper gives brief descriptions of three recent developments not so much in laser resonators themselves as in the tools for analyzing and measuring the quality of laser beams and resonators. These tools include personal computer programs for analyzing laser beams and resonators; a new method for characterizing and measuring the "beam quality" of a laser output beam; and a new "ray-pulse" method of analysis for describing beams and resonators which involve any combination ofultrashort optical pulses, broadband optical signals, and dispersive optical elements.
The continuing evolution (if not revolution) in personal computer technology, combined with new and improved numerical algorithms, makes it possible at this point to do numerical beam propagation and resonator design calculations on desktop personal computers which used to require mainframe computers and sometimes overnight runs in batch mode. At the same time the graphics capabilities of modern personal computers permit one to display the results of these calculations with near-instantaneous response as on-screen graphs and plots, rather than wading through foot-thick piles of computer printout to view and understand these results.
My research group in particular has recently developed four interactive beam and resonator design programs which run on the Apple Macintosh series of personal computers and are very useful to designers of laser beams and resonators. These programs include:
. "ABCD," a program for doing interactive on-screen design and analysis of resonators and beam propagation systems using complex-valued ray matrices or ABCD matrices and complex gaussian beams.
. "FRESNEL," a program for doing Huygens-integral beam-propagation calculations through free space or through arbitrary paraxial systems in one transverse rectangular or cylindrical dimension using FFT or FliT techniques.
An iterative option also permits Fox-and-Li resonator mode calculations to be done on-screen.
. "VSOURCE," a program for calculating the lowest and higher-order eigenvalues and eigenmodes of strip or circular unstable optical resonators with almost any Fresnel number using the "virtual source" algorithm for unstable resonator modes.
S "VRM," a simple program for calculating the Hermite-gaussian or Laguerre-gaussian modes and eigenvalues of geometrically unstable variable-reflectivity-mirror (VRM) resonators. A brief description of each of these programs is given in the following sections.
In general these programs follow the notation and terminology used in the author's LASERS text.1 The "ABCD" program is compiled using Microsoft QuickBASIC and can be run on any Macintosh computer. The other three programs are written in Pascal and will operate best on a Macintosh II or higher-level model equipped with the 68881 numerical coprocessor. These programs will be available for public distribution at moderate cost through Stanford University's Software Distribution Center later in 1990. Readers interested in receiving further information should write to the author. Only Macintosh versions of the programs will be available; porting of this software to other models of personal computer is not presently planned.
The "ABCD" program initially displays an on-screen "palette" of paraxial optical elements such as thin or thick lenses, free-space regions, ducts, laser rods, Brewster windows, and gaussian apertures, each represented by a graphic icon, across the bottom of the Macintosh screen. Using the mouse, the user can select or "click on" individual paraxial elements and drag them to the upper part of the screen in order to build a cascaded ABCD system of arbitrary complexity. Dialog boxes allow numerical parameter values as well as a user-defined name or label to be supplied for each element. As the cascaded system is built, Macintosh-style mouse commands allow individual or multiple
๐ SIMILAR VOLUMES