Variation of imaging contrast for various illumination mechanisms.

<p>A prepared slide from a Gossypium stem is used to illustrate how each illumination mechanism affects the illuminated field of view, visible contrast, homogeneity, and signal quality. Different mechanisms provide varying degrees of freedom, contrast, and usability, such as periscopic illumination, battery-driven LED, Toslink fiber-optic cable, Ikea USB lamp, and Neopixel LED matrix.</p> <p>(PDF)</p>