Figure 4
mDSLM enhances imaging contrast in comparison to mSPIM. (a) An image generated by mSPIM (NAx = 0.06, NAy = 0.18) in a non-fluorescent gel containing fluorescent glass spheres (diameter = 7 μm). A 1% volume concentration of sub-micron lipid droplets was mixed into the gel to simulate a small amount of tissue scattering. mSPIM uses widefield camera detection and is therefore unable to reject the out-of-focus scattering background. This is visible in the overlaid line profile at y = 350 μm, which shows an increasing scattering-induced background as a function of z. The corresponding mDSLM (NAx = 0.06, NAy = 0.18) image is shown in (b). By using a laterally scanned elliptical Gaussian pencil beam to generate a 2D light sheet, mDSLM is compatible with confocal line detection, which rejects much of the scattering background. An image of a stationary Gaussian pencil beam (at y = 0 μm) is shown in (c), in which the size of the confocal slit is displayed. An example of out-of-focus background light due to tissue scattering is highlighted by the inset arrow. Image contrast as a function of z is plotted in (d), at 20 μm intervals, for both mSPIM and mDSLM. At z = 1200 μm, the contrast for mSPIM is reduced to ~30%, whereas for mDSLM the contrast remains >90%.
