Stranica 61 [61]
CHARISMA B 7
LED lamp
350 400 700 1100
Wavelength range of a typical camera CCD/CMOS sensor
Figure 2-12. Schematic representation of the spectral output distribution (SPD) of a wide spectrum
LED compared to the wavelength range of a CCD/CMOS sensor. Shading shows wavelengths to be
excluded (filtered) in the acquisition of visible-induced infrared luminescence images.
— Visible-induced visible luminescence (VIVL) Images
Radiation source:
Blue LEDs
Filter in front of radiation source:
None
Filter in front of camera:
For VIVL images a filter is required which will block blue light in the visible region as emitted
by the blue LED (e.g. 400-500 nm). The filter selected should allow visible light to be
collected between 500 and 700 nm, but the choice of the filter depends on the type of
investigation undertaken.
Commonly used ranges in the investigations carried out to date are approximately between
520-700 nm and 475-700 nm, which requires filters with properties similar to the Lee No. 21
and Lee No. 16 filters (see Figure 2-14 and Figure 2-15 for transmittance curves). Note that
an additional filter is required which will allow only light in the visible region (400-700 nm)
through and block any UV or IR radiation, e.g. IDAS_UIBAR.
Version No. 1.0 53 Date : 14/10/2013