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Figure 3.23.: A lens with 20 mm focal length was fixed in front of the LED in order
to concentrate the light beam on the optical axis. The focal length was
chosen as such a value that the light beams were as if from the focal
point of the lens, as shown on the left. A heat sink was stuck to the
LED on the backside to dissipate the heat more efficiently, as shown
on the right.
range of thermal radiation as shown in Figure 3.25. The back insulating glass
was displaced by a polystyrene plate, in order to provide a uniform temperature
background.
Figure 3.24.: Configuration of the side-view infrared imaging. The infrared optical
access was provided by the infrared glasses, and the background of a
uniform temperature was provided by a polystyrene plate.
The impact enclosure and the impact surface for the bottom-view of infrared
imaging are shown in Figure 3.26. The drop impact took place on a 12 µm thick
aluminium film, which was laid on top of an infrared glass. The aluminum provided
a uniform background and avoided direct contact of the infrared glass with
the freezing drop. The bottom side of the aluminium film had black body coat-
72 3. Experimental Setup