Light fingerprints

Lasers (qv) and other high intensity or alternative light sources are usefiil in crime laboratories to visualize latent fingerprints, seminal fluid stains, obhterated writings, and erasures, and to aid in specialized photographic work. Infrared and ultraviolet light sources are also used to view items of evidence. 

Figure 3 Root fingerprints of Pseudomimets sp. associated with barley seedlings showing the production of siderophore by actively growing bacteria located in the zone of elongation behind the root tips. Root.s were pressed on to an iron-deficient minimal medium selective for Pseudomonas. After growth of the colonies, the production of siderophore was visualized by exposure of the agar plate to ultraviolet light, which causes the siderophore to Huoresce.

Another technique widely used to measure the cholesteric pitch is based on the Bragg scattering of monochromatic light (obtained by a helium-neon laser) from fingerprint or planar textures of the cholesteric32 Its angular dependence is strictly related to the cholesteric pitch. 

Sadly, this does not mean the planet is like Earth the blue tint probably comes from other gases in the planet s atmosphere. But what if one day scientists find a planet whose reflected light contains the telltale fingerprint of oxygen, as does that of our own... 

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