Figure 4: An example of fluorescence imaging integrated with the OCT sample arm. The system uses the same objectives for OCT and fluorescence imaging for simultaneous OCT and fluorescence recordings. (a) The placement of fluorescence imaging path in the OCT sample arm. (b) The SOLIDWORKS design of the fluorescence imaging path. (c) The schematic of the optical design of the path. The fluorescence imaging path uses two semi-Plössl lenses to image the back-focal plane of the objective to the entrance pupil of an imaging lens. There is an adjustable iris in this path to adjust the aperture diameter of the imaging system. This is helpful to reduce the aberration in the optical path and improve the imaging resolution. Fluorescence camera (EXi Aqua, QImaging, BC, Canada), adjustable iris (SM1D12CZ, Thorlabs, NJ, USA), imaging lens (AC254-040-A, Thorlabs, NJ, USA), optical filter, semi-Plössl lens (AC254-100-A + AC254-250-A), visible light dichroic mirror (FF440-520-Di01, Semrock Inc., NY, USA), semi-Plössl lens (AC254-075-A + AC254-200-A), long-pass infrared dichroic mirror (FF875-Di01, Semrock Inc., NY, USA), and objective lens.