Real-time en-face optical coherence tomography using a 9 GHz photodetected signal

A modality of down-conversion leader-follower optical coherence tomography (OCT) is evaluated for delivering an en-face OCT image when the photodetected signal pulsates at 4-9 GHz. En-face images are demonstrated from an object extending over 1.6 cm employing an I&Q demodulator and a digitizer of only 250 kS/s when using a VCSEL swept source at 100 kHz. The method presented responds to the need to provide guidance in adjusting the position and orientation of the sample to be investigated in front of the scanning head of a fast swept-source OCT system that, due to the combined effect of sweeping speed and large data, cannot provide images in real-time.