Rofin Polilight Flare PLUS, Руководство пользователя

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Polilight Flare Plus 2 manual –
14
LIGHT APPLICATIONS
Blood Marks
Although blood has a broad absorption spectrum, it only exhibits a single absorption maximum of
around 415 nm and does not display any photoluminescence properties. This means that blood marks
can only be detected directly using either the absorption or reflection mode.
In cases where the background surface bearing the blood marks is itself fluorescent, the latent marks
will not fluoresce while the rest of the exhibit will fluoresce. In this case the latent will often show
excellent contrast, typically a black mark against a bright yellow–orange field. Initial scanning should
be conducted using the 450 nm band for illumination with the operator wearing amber goggles. All
marks identified in the initial scanning should be further inspected using the full range of Polilight
Flare+2 bands to maximize detail.
Common fluorescent materials are varnishes, printing inks and fluorescent brighteners placed in paper
or clothing during manufacture. The latter materials usually absorb at the upper end of the UV range (280
to 360 nm) and emit in the blue region. If material bearing marks is not fluorescent, or only very weakly
fluorescent, scanning with the 415 nm band, which is compatible with the 415 nm blood absorption
maximum, can be undertaken. Blood marks look dark against a lighter background.
In the example shown in fig.5, the view under daylight conditions is on the left and the view when
illuminated with Polilight using a 415 nm light is on the right.
Figure 5. Bloody Fingerprints
wARNING
Yellow goggles should be worn to protect the eyes.