(a) Schematic of the broadband rotary joint. (b) and (c) Tolerance analysis on coupling efficiency of the broadband rotary joint; less than ±5% coupling efficiency fluctuation can be achieved within alignment tolerance of ±85 μm (lateral misalignment) or ±9 mdeg (angular misalignment) (b), while providing over 80% of one-way throughput at a maximum separation of 70 mm between the two lenses (c). (d) Photograph of the assembled broadband rotary joint. (e) Intensity throughput fluctuation of the broadband rotary joint at two representative rotation speeds. (f) Comparison of the input and output spectrum of the broadband rotary joint; maximum spectrum variation was less than 2% (see the inset). B, bearing; M, DC motor; P, pulley; KM, five-axis kinematic mount.