Oldal 57 [57]
CHA, BR 7
Grant Agreement n" 228330
examination location) should also be carefully controlled, as they can significantly interfere
with the interpretation of the luminescence.
Filter in front of the camera:
For UV-reflected images a filter is reguired which will block radiation in the visible and IR
regions (400 - 1100 nm). This would reguire a filter with properties similar to the Schott glass
DUGI1IIX filter (see Figure 2-8 for transmittance curve and recommendations for alternatives
above).
1e+0
BLB UV lamp
1e-1
Excitation
wavelength
10-2
300 — 385400 500 600 700 800 900 1000
wavelength (nm)
350 400 700 1100
Wavelength range of a typical camera CCD/CMOS sensor
Figure 2-7. Schematic representation of the spectral output distribution (SPD) of a BLB ultraviolet light
compared to the wavelength range of a CCD/CMOS sensor. Shading shows wavelengths to be
excluded (filtered) in the acquisition of UV-reflected images.
Note that although the sensitivity of camera sensors is typically 200 — 1100 nm, the range
will be attenuated to the quoted 350 — 1100nm (in the modified cameras described in this
work) because of the widespread use of glass lenses. This would yield “UV-reflected”
images in the range 350 — 400 nm, with the filters recommended above. In order to collect
images that can truly be referred to as UV-reflected, quartz lenses would need to be used,
which would make the range of acquisition of these images) approximately 225 — 400 nm
with the filters recommended above. However, it should be noted that the sensitivity of
camera sensors drops off significantly at the extremes of its wavelength range (see Figure
2-2).
Version No. 1.0 49 Date : 14/10/2013