Using plasma to print invisible characters onto pencil lead (IMAGE)

Shinshu University

Using plasma to print invisible characters onto pencil lead

Caption

Plasma irradiation removes graphite from the pencil lead, exposing a thin layer of clay. By controlling the exposure time, the thickness of this layer can be varied to modulate the infrared (IR) reflection of the pencil lead sample. Using this method, letters can be written on the pencil lead sample that can only be seen using an IR camera.

Credit

Hiroshi Moriwaki from Shinshu University

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