%% 
%%  A DANTE-Edition example
%% 
%%  Example 33-03-19 on page 694.
%% 
%%  Copyright (C) 2011 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% 
%% ==== 
% Show page(s) 1
%% 
\documentclass[]{article}
\pagestyle{empty}
\setlength\textwidth{375.57637pt}
\setlength\parindent{0pt}

\usepackage{pst-optic}

\begin{document}
\psset{unit=0.75}
\begin{pspicture}(-8,-2)(8,5.75)
  \pnode(-8,1.5){A}\pnode(8,1.5){B}
  \uput[45](A){A}\uput[135](B){B}
  \pnode(0,0){START}
  \psframe[fillcolor=lightgray,fillstyle=solid,linecolor=blue](-8,-1.5)(B)
  \psset{linecolor=red,arrowsize=3pt,arrows=->}
  \multido{\n=20+5}{29}{%
    \refractionRay(START)(1;\n)(A)(B){1.5}{1}{END}
    \arrowLine(START)(END){2}\arrowLine(END)(END'){1}
    \psOutLine[length=3](END)(END'){Q}\arrowLine(END')(Q){3} }
\end{pspicture}
\end{document}