| Popis: |
In this report, we show both theoretically and experimentally how the IR signature of a semiconductor scene (with band gap energy Eg) can be monitored through contactless emissivity control even if this scene thermometric temperature is kept constant. More specifically, we show how a scene emissivity in the spectral band beyond the fundamental absorption range (ω2 20 kHz) monitored by a shorter wavelength photo excitation of non-equilibrium charge carriers (ω1 > Eg/h, "visible range"). Experimental tests performed on Si and Ge scenes (300 < T < 600 K), demonstrate optically generated cold and hot images and, what is more important, negligible temperature contrast between an object and a background (Stealth effect in IR). |
