Fig. 1. Ultrathin 3D printed endoscope design.

a Schematic of the 3D printed OCT endoscope inside an artery. b Microscope image of the 3D printed off-axis freeform total internal reflection (TIR) mirror on the tip of the no-core fiber that is fusion spliced onto the light-guiding single-mode fiber. c Optical design of the system with light exiting the single-mode fiber, expanding in the no-core fiber, being reflected and phase-shaped at the freeform mirror, passing the catheter sheath and focusing into the artery tissue. d Photo of the 3D printed OCT endoscope, which rotates and is pulled back to accomplish full 3D OCT scanning