Sub-second a-scan acquisition using marginal spectral-domain quantum optical coherence tomography

We report an optimized implementation of spectral-domain quantum optical coherence tomography (SD-QOCT) capable of acquiring axial scans (A-scans) of multilayer samples in the absence of mechanical scanning, at an unprecedented speed. Implementing a novel strategy, we demonstrate a proof-of-concept system that integrates a diffraction grating, a high-resolution intensified CCD camera and a high-flux photon-pair source operating in the VIS-NIR region (≈800 nm). This configuration enables the acquisition of an entire marginal SD-QOCT interferogram in a single camera exposure, yielding a transverse A-scan with a record acquisition time of 100 ms for a mirror sample, which extends to 10 s for a glass coverslip, and a penetration depth of ≈4 mm. The measured interferometric response shows excellent agreement with the theoretical model. These results represent a decisive step toward the practical deployment of SD-QOCT as a competitive imaging modality for biomedical applications.