\documentclass[12pt]{article}
\setlength\parindent{0pt}
\newcommand{\boldsymbol}[1]{\mbox{\boldmath $#1$}}
\newcommand{\bigmath}[1]{\displaystyle{#1}}
\newlength{\myVSpace}
\setlength{\myVSpace}{1ex}
\newcommand\xstrut{\raisebox{-.5\myVSpace}{\rule{0pt}{\myVSpace}}}% \myVSpace is the height of the box

\begin{document}
\addtolength{\jot}{1cm}% only for eqnarray-environment

\begin{eqnarray}
\varphi\left(z_{1}\right) & = & P\frac{-i}{2\left(s_{1}-s_{2}\right)\left(1+is_{1}\right)}\left[1-\frac{z_{1}}{\sqrt{z_{1}^{2}-R^{2}\left(1+s_{1}^{2}\right)}}\right]\\
\psi\left(z_{2}\right) & = & P\frac{+i}{2\left(s_{1}-s_{2}\right)\left(1+is_{2}\right)}\left[1-\frac{z_{2}}{\sqrt{z_{2}^{2}-R^{2}\left(1+s_{2}^{2}\right)}}\right]
\label{equation array}
\end{eqnarray}


\begin{equation}
\left.\begin{array}{ccc}
\xstrut\varphi\left(z_{1}\right) & = & \bigmath{P\frac{-i}{2\left(s_{1}-s_{2}\right)\left(1+is_{1}\right)}\left[1-\frac{z_{1}}{\sqrt{z_{1}^{2}-R^{2}\left(1+s_{1}^{2}\right)}}\right]}\\
\xstrut\psi\left(z_{2}\right) & = & \bigmath{P\frac{+i}{2\left(s_{1}-s_{2}\right)\left(1+is_{2}\right)}\left[1-\frac{z_{2}}{\sqrt{z_{2}^{2}-R^{2}\left(1+s_{2}^{2}\right)}}\right]}\end{array}\right\}
\label{matrix}
\end{equation}


\addtolength{\myVSpace}{3cm}% see preamble for definition

\begin{equation}
\left.\begin{array}{ccc}
\xstrut\varphi\left(z_{1}\right) & = & \bigmath{P\frac{-i}{2\left(s_{1}-s_{2}\right)\left(1+is_{1}\right)}\left[1-\frac{z_{1}}{\sqrt{z_{1}^{2}-R^{2}\left(1+s_{1}^{2}\right)}}\right]}\\
\xstrut\psi\left(z_{2}\right) & = & \bigmath{P\frac{+i}{2\left(s_{1}-s_{2}\right)\left(1+is_{2}\right)}\left[1-\frac{z_{2}}{\sqrt{z_{2}^{2}-R^{2}\left(1+s_{2}^{2}\right)}}\right]}\end{array}\right\}
\label{matrix2}
\end{equation}

\end{document}