Optical coherence microscopy (OCM) has unique advantages of high-resolution volumetric imaging without relying on
exogenous labels or dyes. It combines the coherence-gated depth discrimination of optical coherence tomography (OCT)
with the high lateral resolution of confocal microscopy, offering an excellent balance between the resolutions and
imaging depth. However, as the lateral resolution becomes higher, the imaging depth of OCM decreases and its three-dimensional
imaging capability is greatly degraded. To overcome this limitation, we used amplitude apodization to
create quasi-Bessel beam illumination in order to extend the depth of focus. The lateral and axial resolutions of our
OCM system were measured to be 1.6 μm and 2.9 μm in tissue. The imaging depth was extended by ~3.0X (~100 μm)
beyond that of the standard Gaussian beam OCM. Using zebrafish embryos as a test system, we demonstrate extendedfocus
OCM for structural imaging studies, which revealed the detailed anatomy deep in embryos.
A phase variance optical coherence microscope (pvOCM) has been created to image blood flow in the microvasculature of zebrafish embryos, without the use of exogenous labels. The pvOCM imaging system has axial and lateral resolutions of 2.8 μm in tissue and imaging depth of more than 100 μm. Images of 2 to 5 days postfertilization zebrafish embryos identified the detailed anatomical structure based on OCM intensity contrast. Phase variance contrast offered visualization of blood flow in the arteries, veins, and capillaries. The pvOCM images of the vasculature were confirmed by direct comparisons with fluorescence microscopy images of transgenic embryos in which the vascular endothelium is labeled with green fluorescent protein. The ability of pvOCM to capture activities of regional blood flow permits it to reveal functional information that is of great utility for the study of vascular development.
A phase variance optical coherence microscope (pvOCM) has been created to visualize blood flow in the vasculature of zebrafish embryos, without using exogenous labels. The pvOCM imaging system has axial and lateral resolutions of 2 μm in tissue, and imaging depth of more than 100 μm. Imaging of 2–5 days post-fertilization zebrafish embryos identified the detailed structures of somites, spinal cord, gut and notochord based on intensity contrast. Visualization of the blood flow in the aorta, veins and intersegmental vessels was achieved with phase variance contrast. The pvOCM vasculature images were confirmed with corresponding fluorescence microscopy of a zebrafish transgene that labels the vasculature with green fluorescent protein. The pvOCM images also revealed functional information of the blood flow activities that is crucial for the study of vascular development.