Figure 3: Experimental imaging of the guinea pig retina.

(a) Light from a halogen lamp is injected into an optical fibre, collimated onto the retina and imaged by a confocal microscope. (b) Light transmission through the retina is reconstructed in 3D (obtained by the microscope’s z axis stack). Distinct light tubes of high transmission—the red channel (588 nm wavelength), spanning 150 μm, from the retinal surface to just above the photoreceptor layer are observed. The yellow channel is the auto-fluorescence track, used to locate photoreceptors outer segments. For this purpose, the stack was obtained using a long working distance lens. (c) Above the level of photoreceptors, the transmitted light is imaged using the microscope’s spectral mode. The 417–695 nm range is covered by 27 distinct images at intervals of 10 nm. Four representative images (48 μm × 48 μm each) for different wavelengths (417 nm, 491 nm, 577 nm and 695 nm) are shown.