Laser beta lasermike LS8000-3 - Manual (Page 17)

LaserSpeed 8000-3 Instruction Handbook
Installing the System
Part No. 93463 / Drawing No. 0921-01561 Page 17 of 221 Revision A (Sep 2007)
Mounting Distance
When the material is within the depth of field, the gauge makes accurate
measurements. Since the best signal comes from the center of the depth of
field, the center is the source of the best measurements. This is because the
two laser beams totally overlap at the center of the beam crossings and all of
the laser power is used to form fringes.
At the edges of the depth of field, however, some beam-crossing areas
overlap and some do not. The areas that overlap form fringes and thus yield
useful Doppler signals; the areas that do not overlap do not form fringes;
rather, they produce only noise with no Doppler signals. Any measurements
made outside the depth of field may not be reliable.
Laser Safety
When mounting of the gauge, ensure that the laser beams are blocked by
machinery or beam blocks when material is not present in the measurement
area.
Environmental Conditions
Ambient Temperature
All LaserSpeed gauges have a built-in cooling system for applications in which
ambient temperatures exceed 45ºC.
Cooling fluids can be routed through the gauge using the 1/8-inch NPT fittings
(1/4" NPT on LS8000E and LS8000X) on the back of the gauge. Typical flow
rates of 1.5 litres/minute for water and 50 liters/minute for air are sufficient.
There is minimal pressure drop through the gauge, so supply pressure can be
very low.
Ensure that the water temperature is above the condensation temperature or
dew point, to prevent condensation from collecting on the front window of the
gauge. If water condenses on the optical window, the laser beams could be
blocked, resulting in reduced performance or loss of function.
Coolant
In applications with coolants on the material, an air jet may be required to
remove the coolant from the measurement area. Since the speed of the
coolant is generally different from that of the material, erroneous
measurements could result. When incorporating an air jet, be sure to blow the
coolant from the measurement volume at 90° from the material’s motion. If the