Chapter 3: System Details
© 2018 Cutting Edge Optronics, Inc.
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Patara I and II Laser User Manual
Operating the Chiller
WARNING.
Do not operate laser without cooling. Inadequate heat dissipation will
seriously damage the laser diodes and will void warranty. If water is noticed in the
immediate vicinity of the laser, shut the laser system down immediately. Check to see if
the water is coming from the laser head. If so, return the laser for repair. If not, repair the
source of the leak and allow the unit to dry thoroughly before resuming operation.
The laser system has a coolant loop to prevent thermal damage to the laser diodes.
The diodes should be kept at approximately 20 °C to 35 °C. See the final ATP
Test Report Data Summary included with the laser for optimum temperature and
flow rate settings.
Operating the laser diodes for even a short period of time (even a few seconds)
without coolant will cause permanent damage. To help prevent this, all Northrop
Grumman drive electronics are equipped with a coolant interlock. This interlock
interrupts drive current to the diodes when coolant flow rate drops below a set
point. When setting up the laser system for the first time, Northrop Grumman
recommends testing the flow interlock before firing. Turn the eDrive on without
current applied to the laser, and then turn the chiller off. A coolant interlock fault
should appear on the screen. By testing the interlock with no current to the laser,
there is no risk of damaging the laser.
WARNING.
Do not operate the coolant system below air condensation temperature (dew
point) at the laser head. Condensation on the diode arrays can seriously damage the
laser head and will void the warranty. Consult a Northrop Grumman field service
engineer with any questions.
Air Condensation Temperature
The air condensation temperature (or dew point) is the highest surface
temperature that allows water to form from the ambient water vapor. The dew
point is dependent on the surrounding air temperature and relative humidity. If a
surface (such as a laser diode) is cooled at or below the condensation temperature,
water may collect on that surface. A formula for calculating dew point is given
below, along with a calculated table. All temperatures are given in Celsius.
