Journey to the centre of the earth - Lin Yangchen
©Lin Yangchen


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One could mistake this for a satellite pass over the fractured karst landscape of the Yucatán Peninsula, with its ancient and mysterious sinkholes concealed in lush forest. The main image is one of 23 optical sections of a fluorescence-mode confocal laser scan of the chalky surface of the upper-left fascia pattern of a coconut definitive. The 3.60 μm-thick section was visualized by combining the fluorescence signals from simultaneous laser excitation wavelengths of 404.8 nm (1.7 mW), 486.2 nm (0.9 mW), 561.5 nm (0.9 mW) and 638.8 nm (1.6 mW). Laser power was measured at the tip of the optical fibre and totalled 5.1 mW before passing through the objective on its way to the stamp. The dwell time was 3.03 μs and there was no visible damage to the stamp. The fluorescence signals were amplified through gallium-arsenide-phosphide photomultiplier vacuum tubes. The chalky surface is both pitted and cracked. The deep orange spots in the image are particles of unknown composition fluorescing at approximately 595 nm. These are not discernible under normal illumination. The bars at the bottom and right side of the figure show the full z-profiles of the fluorescence along the x and y crosshairs. The resolution on the x-y plane is 0.78 μm, while the z-resolution is 10.26 μm.

Acknowledgements
I am grateful to David Beech, Benedict Sim, Ernest Cheah, Clement Khaw and Goh Wah Ing for discussions and technical assistance, and to the Nikon Imaging Centre at the Singapore Bioimaging Consortium for providing state-of-the-art microscopy facilities.

References


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