Fig. 2.

In joint aperture OCT (JA-OCT), the sample is illuminated by one active beam and additionally probed by passive beams. a) Rendering of a symmetric JA-OCT geometry with active center beam and three probe beams. b,c) Schematic sample arm configurations for JA-OCT. An intermediate focus may allow for more flexible beam alignment, since the lenses may have a larger distance between each other. d) If all beams have the same size, dense packing allows for a maximum of 6 probe beams surrounding the active beam. e) However, JA-OCT is neither restricted to a symmetric configuration nor to beams of the same size. a: active (illuminating) beam; p: passive (probe-only) beam.