Buffer-averaging super-continuum source based spectral domain optical coherence tomography for high speed imaging.

In super-continuum (SC) source based spectral domain optical coherence tomography (SC-SDOCT), the stability of the power spectral density (PSD) has a significant impact on OCT system sensitivity and image signal to noise ratio (SNR). High speed imaging decreases the camera's exposure time, thus each A-scan contained fewer laser pulse excited SC wideband emissions, resulting in a decrease of SNR. In this manuscript, we present a buffer-averaging SC-SDOCT (BASC-SDOCT) to improve the system's performance without losing imaging speed, taking advantage of the excess output power from typical SC sources. In our proposed technique, the output light from SC was passed through a fiber based light buffering and averaging system to improve the PSD stability by averaging 8 SC emissions. The results showed that 6.96 µs of SC emission after buffering and averaging can achieve the same PSD stability equivalent to a longer exposure time of 55.68 µs, despite increasing the imaging speed from 16.8 kHz to 91.9 kHz. The system sensitivity was improved by 8.6 dB, reaching 100.6 dB, which in turn improved SNR of structural imaging, Doppler OCT velocity measurement, and speckle variance OCT (SVOCT) angiographic imaging as demonstrated by phantom and experiments.