Optics-lab library, made for RustFig (original work, MIT OR Apache-2.0).

Parts drawn the way physics papers draw optical setups, beyond xfig's own
Optics library: laser, red beams (solid, with arrow, dashed, expanded band,
diverging cone), convex, concave and cylindrical lens, flat mirrors (plain and
with hatched back, perpendicular and at 45 degrees), concave mirror, dichroic
mirror, beam splitter cube and plate, polarizing beam splitter, half- and
quarter-wave plate, polarizers, iris, coiled fibre and fibre coupler,
photodiode, detector, CCD camera, acousto- and electro-optic modulator,
optical isolator, prism, grating, cavity, vacuum chamber, cryostat, viewport,
flange pair, sample holder, and three examples (example_*.fig: Michelson and
Mach-Zehnder interferometer, fibre-coupled laser to detector).

Every part is one compound with the optical axis through its centre, on the
1/4-inch grid (axis at y = 3/4 inch in the figure); parts in the beam have
their beam ports 1 inch apart on the grid, so they line up at the same height.
Beams are xfig's red. Labels are LaTeX text with the TeX flag ($\lambda/2$).

The files are written by `cargo xtask libraries` (xtask/src/libraries/optics.rs);
change the generator, not the files.
