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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
