High resolution line-field SD-OCT with 2.5 kHz frame rate for cellular resolution imaging of biological tissue

A line-field, spectral domain optical coherence tomography (LF-SD-OCT) system was developed for in-vivo, noncontact, cellular resolution imaging of biological tissue. The LF-SD-OCT system utilizes a broadband laser with a spectrum centered at ~790 nm and spectral bandwidth of ~140 nm to achieve 1.8 μm axial and ~5 μm isotropic lateral resolution in biological tissue. A high speed 2D camera was used to achieve frame rate of 2.5k B-scans/s. The system’s SNR was measured to be 92 dB at 100 μm away from the zero-delay line for 2.8 mW optical power incident on the imaged object, with 18 dB roll-off over a scanning range of 1 mm. The LF-SD-OCT system was used to image the cellular structure of cucumber and the cucumber seed where the high spatial resolution was sufficient to resolve cellular nuclei. Then the system was used to image in-vivo human skin (fingertip), where the spiral structures of the sweat glands, as well as a large number of capillaries were observed in the epidermal layer. Images of the healthy human cornea were also acquired from locations near the corneal apex and the periphery and showed the tissue cellular structure and vasculature. Currently, the corneal images were acquired ex-vivo, as we are waiting for ethics clearance to conduct in-vivo corneal imaging studies with the novel LF-SD-OCT system.