%% examples/optics-lens.tex
%%
%% Demonstrates the physicslens shape from tikzphysics.optics.

\documentclass[tikz, border=5mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{tikzphysics.optics}

\begin{document}

\begin{tikzpicture}
  \draw[->] (-3.5,0) -- (3.5,0)
    node[right] {\scriptsize principal axis};

  \node[physicslens,
        physics lens radius=5,
        physics lens thickness=0.25,
        physics lens aperture angle=30]
    (L) at (0,0) {};

  \fill (L.vertex) circle (1pt) node[below right] {\tiny vertex};
  \fill (L.front-25) circle (1pt) node[left] {\tiny front-25};
  \fill (L.front-75) circle (1pt) node[left] {\tiny front-75};
  \fill (L.back-mid) circle (1pt) node[right] {\tiny back-mid};
\end{tikzpicture}

\end{document}