Abstract of
LASER LIGHT SHEET IMAGING
OF GAS FLOW WITH LASER DIODES
B. Nath, W. Löber, W. Baetz and W. Holzapfel
Technology and applications of a novel laser light sheet
unit to the imaging of gas flow patterns in gas flow measuring and controlling
devices are described. Instead of applying very expensive high-power gas lasers
or solid-state lasers, a simply constructed, modularly extendable, laser light
sheet unit made with monomode laser diodes is used. The lower output power of
the laser diodes is compensated for by using a highly sensitive video camera.
To further improve the digital images, the grey-scale values are spread out, the
interlaced video frames are separated into two consecutive fields in con-junction
with a special pixel generating process, and the dark-field images are subtracted.
Performance of this laser diode light sheet technique is demonstrated by actual
application examples taken directly from the field of gas flow measurement and
control. One example of this is the Karman vortex street in a model of a vortex
flow meter. Another example is the flow detachment in a Venturi nozzle operated
under critical conditions to ensure constant gas flow. This is the full paper
version of our oral presentation at the 8th
International Symposium on Flow Visualisation, Sorrento, Italy, Sept. 1-4 1998.
The abstract was included in the printed proceedings [5].
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Diagnostics in Engineering, Volume 3, Part 1 Contents