Multi-pass optical delay configuration using a retroreflector pair for Fourier transform interferometers

Corner cube retroreflectors can be used in Fourier transform interferometers to create multi-pass optical delay configurations to increase the resolution of the interferometer. This paper will present a multi-pass optical delay design using two identical retroreflectors and it will prove that this design will be the theoretically most efficient design to achieve as many passes as possible using two identical retroreflectors. A formula will be derived to calculate the relation between beam diameter, retroreflector position and the number of passes. An experiment was conducted to demonstrate this design which achieves 24 passes and the resulting interferometer has a scanning range of about 7.2 m.