\documentclass[a4paper]{article}
\usepackage{pstricks}
\usepackage[margin=2cm,noheadfoot]{geometry}

\parindent0pt
\pagestyle{empty}
\nofiles
\begin{document}
\centering
\newcount\WL

\def\WaveToPS#1%
 {\definecolor{tmp}{wave}{#1}%
  \extractcolorspec{tmp}\tmp
  \expandafter\convertcolorspec\tmp{rgb}\tmp
  \expandafter\WaveToPSi\tmp,}
\def\WaveToPSi#1,#2,#3,%
 {\pstVerb{/Red{#1}def /Green{#2}def /Blue{#3}def}}

\definecolor[ps]{lambda}{rgb}{Red Corr Green Corr Blue Corr}%
\pstVerb{/Corr{dup 0 gt {Gamma exp}if }def}

\def\DisplayBar#1#2%
 {\linethickness{1.25\unitlength}\WL=360
  \pstVerb{/Gamma{#1}def}%
  \multiput(360,#2)(1,0){456}%
   {\WaveToPS{\the\WL}%
    {\color{lambda}\line(0,1){50}}\global\advance\WL1}%
  \linethickness{0.25\unitlength}\WL=360
  \multiput(360,#2)(20,0){23}%
   {\picture(0,0)
    \line(0,-1){5}
    \multiput(5,0)(5,0){3}{\line(0,-1){2.5}}
    \put(0,-10){\makebox(0,0){\the\WL}}\global\advance\WL20
    \endpicture}%
  \put(350,#2){\makebox(0,50)[r]{\small$\gamma$\,=\,#1}}}

\unitlength.75pt
\begin{picture}(510,345)(310,-10)
\sffamily\tiny
\DisplayBar{0.4}{0}%
\DisplayBar{0.6}{70}%
\DisplayBar{0.8}{140}%
\DisplayBar{1.0}{210}%
\DisplayBar{1.2}{280}%
\end{picture}

\end{document}
