\begin{pspicture}[showgrid](0,-0.3)(3,3.3)
\pnode(0,2.5){A}
\pnode(2,2.5){B}
\pnode(2,1.5){C}
\mirror[labelangle=-45](A)(B)(C){M}
\optbox[position=start,labeloffset=0,labelref=relative](C)(B){Laser 1064 nm}
\drawbeam(A){1}{2}
\end{pspicture}