When the asbestos is seen in light near that wavelength, the minerals look darker than those around them.

VOA: special.2009.11.17

Many minerals in the asbestos family can absorb light with a wavelength measuring two-point three micrometers.

VOA: special.2009.11.17

They repaired an existing infrared wavelength camera and spectrometer.

VOA: special.2009.09.30