\documentclass[a4paper,12pt]{article}
\usepackage{epic, eepic}

\usepackage{amsmath, amssymb, hymcbk, xspace}
\usepackage{euscript,  array}
\usepackage[T1]{fontenc}
%\usepackage{tipa1}
%\usepackage{calc, wasysym, textcomp, ulsy}

\begin{document}
\pagestyle{empty}


\setlength{\unitlength}{1mm}
\begin{picture}(100,30)


\put(0,20){\vector(1,0){100}}\thicklines  
\put(25,20){\makebox(0,0)[c]{[}}\put(25,24){\makebox(0,0)[b]{$a$}}  
\put(84,20){\makebox(0,0)[c]{]}}\put(84,24){\makebox(0,0)[b]{$b$}}  
\allinethickness{.8mm}\put(25,20){\line(1,0){59}}\thinlines\put(0,10){\vector(1,0){100}}\thicklines  
\put(25,10){\makebox(0,0)[c]{[}}\put(25,14){\makebox(0,0)[b]{$a$}}  
\put(84,10){\makebox(0,0)[c]{]}}\put(84,14){\makebox(0,0)[b]{$b$}}  
\allinethickness{.2mm}\multiput(3,9)(2,0){11}{\NESO}\multiput(85,9)(2,0){7}{\NESO}  
\put(15,2){\makebox(0,0)[b]{\interfer{a}{b}}}\put(15,15){\makebox(0,0)[b]{or}}

\end{picture}
  

\end{document}

%%% Local Variables: 
%%% mode: latex
%%% TeX-master: t
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