109 MHz optical tomography using temporal magnification.

Ultrafast optical tomographic imaging with a 109 MHz A-scan rate is achieved by using temporal magnification. Based on two four-wave mixing (FWM) time lenses with carefully designed group delay dispersion, we construct a temporal imaging system with a magnification factor of 48.3×. The two time-lens scheme not only relaxes the requirement for the pump source but also facilitates the application for tomographic imaging. As a proof-of-concept demonstration, our system achieves an axial resolution of 140 μm in air (∼105  μm in biosample) over a 28 mm depth range with sensitivity up to 55 dB. We then evaluate the imaging performance using a fish-eye lens at a 109 MHz A-scan rate. Utilizing better dispersion-engineered nonlinear media, resolution of less than 5 μm in the biosample with higher sensitivity may be achieved. We believe this scheme will provide a promising solution for video-rate 3D tomographic imaging.