- X. Yao, Y. Gan, C. C. Marboe, and C. P. Hendon, "Myocardial imaging using ultrahigh-resolution spectral domain optical coherence tomography," Journal of biomedical optics 21, 061006-061006 (2016).
Configuration of the Ultrahigh-Resolution SD-OCT System
Figure 1 shows the schematic of the SD-OCT system. A lownoise supercontinuum laser (SuperK EXTREME, NKT Photonics) was employed to serve as a broadband light source. A set of dichroic and edge-pass filters (Thorlabs DMSP1000, FELH0650, FESH1000) was used to shape a light spectrum centered at 840 nm with an initial full width at half maximum (FWHM) bandwidth over 170 nm from the supercontinuum, which was then delivered to a free-space Michelson interferometer through a single-mode fiber (Thorlabs 780HP) and an achromatic coupler (Thorlabs AC080-010-B). The bandwidth of the source was expected to further shrink due to the cutoff wavelength of the single-mode fiber at around 730 nm.
In the OCT imaging system, the fiber-coupled light was first collimated by an achromatic collimator (AC1, f = 19 mm) and divided into sample and reference arms by a 50/50 nonpolarized beam cube (NPBC). In the sample arm, a low-NA broadband scan lens (Thorlabs LSM03-BB) was used as an imaging lens, and a pair of galvo scanners (Thorlabs GVS002) was used to transversely scan the focused beam over the sample. Dispersion mismatch was minimized by adding a block of glass (Thorlabs DCLSM03) in the reference arm. Backscattered signals from the two arms were recombined at the NPBC and back-coupled to a single-mode fiber (Thorlabs 780HP) by an achromatic collimator (AC2, f = 19 mm). The interference signal was then measured by the home-built spectrometer.
In the spectrometer, the collimated light beam (AC3, f = 50 mm) was dispersed by a transmission diffraction grating (Wasatch Photonics, 1200 lp∕mm) and focused onto a 2048pixel CCD line-scan camera (e2v, AVIIVA-II EM4 BA9, 12bit) by a customized focusing lenses system. The camera, with a maximum line rate of 70 kHz, was controlled by a CameraLink framegrabber (NI, PCIe-1433) and synchronized with a pair of galvo scanners through a data-acquisition (DAQ) device (NI, PCI-6221).
Image display, spectral data acquisition, and storage were all controlled by a home-built software platform written in lab view.