Lightweight hollow rooftop mirrors for stabilized interferometry

Hollow rooftop mirrors, also known as dihedral retroreflectors, can simultaneously preserve polarization, minimize chromatic dispersion, and allow beams to be stacked inside an interferometer. Two hollow rooftop mirrors were fabricated and characterized using a Fizeau interferometer and an inexpensive home-built jig instead of a master cube. The mass was 3.3 g for a clear aperture surface area of 110  mm 2 with maximum retroreflected beam deviation of 12 arc s. With a hollow rooftop mirror mounted on a piezoelectric transducer in one arm of a Mach-Zehnder interferometer, a displacement stability of ± 0.8  nm rms was achieved using active feedback. The rooftop mirrors’ suitability for Fourier transform spectroscopy was demonstrated.