Abstract
Although the sun has its peak emission of ElectroMagnetic (EM) radiation around 480 nm (perceived as visible green), it still produces a great deal of UltraViolet (UV) wavelengths (100 nm – 400 nm). However, the largest portion of this radiant energy is blocked by the ozone layer of the atmosphere, only allowing the Long Wave UV (also called Near-UV or UV-A and comprising the spectral band between 315 nm and 400 nm) to reach the earth’s surface. Additionally, sensors acquiring this part of the UV wavelengths must be operated from low altitudes to minimize the effects of strong Rayleigh scattering to which the UV radiation is subjected. Consequently, this waveband of the EM spectrum is rarely employed in remote sensing and its reflected portion is only imaged in very specific applications. Archaeological aerial UV imaging can thus truly be seen as an almost completely unexplored research field. Although it is far from certain that this technique could enhance, let alone reveal new archaeologically related anomalies, this paper wants to discuss the practicalities of digital UV imaging: from the modification of Digital Still Cameras (DSCs) and the choice of a suited lens over the extremely important UV interference filter to the exposure and focus compensation needed. The use of a previously built, entirely remotely controlled device will shown to be indispensable as the inevitable long shutter speed compels the use of such a very stable, unmanned aerial platform. By presenting the very first archaeologically related aerial UV imagery, the weaknesses and/or advantages over conventional visible imaging might start appearing – notwithstanding the infancy of this approach – while also aiming to discuss the (future) use of this non-visible archaeological imaging.