%% This LaTeX-file was created by <jl> Fri Mar  7 15:29:27 1997
%% LyX 0.10 (C) 1995 1996 by Matthias Ettrich and the LyX Team

%% Don't edit this file unless you are sure what you are doing.
\documentclass[12pt,letterpaper,oneside,onecolumn]{article}
\usepackage[]{fontenc}
\usepackage[dvips]{epsfig}

%%
%% BEGIN The lyx specific LaTeX commands.
%%

\makeatletter
\def\LyX{L\kern-.1667em\lower.25em\hbox{Y}\kern-.125emX\spacefactor1000}%
\newcommand{\lyxtitle}[1] {\thispagestyle{empty}
\global\@topnum\z@
\section*{\LARGE \centering \sffamily \bfseries \protect#1 }
}
\newcommand{\lyxline}[1]{
{#1 \vspace{1ex} \hrule width \columnwidth \vspace{1ex}}
}
\newenvironment{lyxbibliography}
{
\begin{thebibliography}{99}}
{\end{thebibliography}}
\def\lxq{"}
\newenvironment{lyxcode}
{\list{}{
\rightmargin\leftmargin
\raggedright
\itemsep 0pt
\parsep 0pt
\ttfamily
}%
\item[]
}
{\endlist}
\newcommand{\lyxlabel}[1]{#1 \hfill}
\newenvironment{lyxlist}[1]
{\begin{list}{}
{\settowidth{\labelwidth}{#1}
\setlength{\leftmargin}{\labelwidth}
\addtolength{\leftmargin}{\labelsep}
\renewcommand{\makelabel}{\lyxlabel}}}
{\end{list}}
\newcommand{\lyxletterstyle}{
\setlength\parskip{0.7em}
\setlength\parindent{0pt}
}
\newcommand{\lyxaddress}[1]{
\par {\raggedright #1 
\vspace{1.4em}
\noindent\par}
}
\newcommand{\lyxrightaddress}[1]{
\par {\raggedleft \begin{tabular}{l}\ignorespaces
#1
\end{tabular}
\vspace{1.4em}
\par}
}
\newcommand{\lyxformula}[1]{
\begin{eqnarray*}
#1
\end{eqnarray*}
}
\newcommand{\lyxnumberedformula}[1]{
\begin{eqnarray}
#1
\end{eqnarray}
}
\makeatother

%%
%% END The lyx specific LaTeX commands.
%%

\pagestyle{plain}
\setcounter{secnumdepth}{3}
\setcounter{tocdepth}{3}
\begin{document}

The elasto-optic effect:

\( n^{2}=1+\frac{4\pi Nq^{2}}{m(\omega ^{2}_{0}-\omega ^{2})} \). For most transparent materials, you get: \( 1+\frac{4\pi Nq^{2}}{m\omega _{0}^{2}} \)= plasma frequency/something
like plasma frequency. 

\( \triangle (\frac{1}{n^{2}})_{ij}=\Pi _{ijkl}\epsilon _{kl} \) where \( \epsilon _{kl} \) is the strain tensor. The \( \Pi  \) is of order1.

This is the stress induced birefringence of the material. 

phase difference is \( \triangle \theta \rightarrow \triangle n\frac{l}{\lambda }=\epsilon \frac{l}{\lambda } \)

Standard definition is \( phaseshift=\frac{C\sigma l}{\lambda } \) where C is a Brewster= \( 10^{-13}cm^{2}/dyne \)

\begin{itemize}

\item glass 3Br

\item polystyrene C=9

\item polyethylene C=2000

\item Gelatin C=5000

\end{itemize}



\end{document}