Ultrabroadband OCT for simultaneous visible and near-infrared light imaging of the mouse retina

Hyperspectral optical coherence tomographic imaging of the retina using the visible-near-infrared wavelength range improves the use of spectroscopic information for biomarkers of retinal diseases without compromising the achievable axial resolution. Previous efforts to develop an optical coherence tomograph that covers both visible and near-infrared wavelengths were hampered by the challenges in designing a broadband spectrometer with adequate performance. In this work, we describe an ultrabroadband OCT system we designed that advances the state-of-the art in two major aspects: the design and implementation of a broadband spectrometer employing a 4k-pixel line camera achieving a spectral range of greater than 450nm with a central wavelength of 680nm; and an achromatised imaging system that minimises aberrations in the visible-near-infrared wavelength range for imaging mouse retina. The system provides an axial imaging range greater than 0.67mm within the retina with a larger than 40 ∘ field angle. With this, we demonstrated ultrabroadband mouse retinal structural imaging in vivo and simultaneous visible and NIR waveband visualization of axon fiber bundle within the retinal nerve fiber layer for the first time. Our system opens new avenues for enhanced functional imaging of the mouse retina.