Wavelength Electronics QCL500 LAB, User Manual

Page: 18 / 24

18
PROBLEM POTENTIAL CAUSES SOLUTIONS
Noise current is higher than expected.
There may be ground loops in the
system; some system components
may be higher noise than expected;
cabling and shielding may be
inadequate.
Refer to Wavelength Electronics Application
Note AN-LD08: Manage Grounding to
Minimize Noise with the QCL Drivers :
www.teamwavelength.com/download/
applicationtechnotes/an-ld08.pdf
Also reference AN-LD09: Troubleshooting
Low Noise Systems :
www.teamwavelength.com/download/
applicationtechnotes/an-ld09.pdf
The output switched off unexpectedly
The instrument detected an internal
error.
(See Error Messages on page 19 .)
Switch the back panel power button off and
then on again, and turn the front panel power
button on.
The internal temperature has
exceeded 70ºC.
Allow the instrument to cool down and then
press the front panel power button.
20 kHz noise is in the output current QCL driver is operating in current limit.
If safe for the quantum cascade laser,
increase the output current limit setting.
When actively operating in current limit, the
safety circuits add noise to the output.
If I run my QCL at about 5% of maximum
output current, the transfer function
becomes non-linear and I see distortion in
my output current waveform.
QCL driver resolution is too low.
Select a QCL driver with a much lower
maximum output current. For example,
to run 50 mA, request a QCL125 (125 mA
maximum output).
My instrument doesn’t show up in the list.
( Remote Only )
Your instrument may not be turned on.
Power up the instrument and click Refresh
on the Choose Instrument window.
Your instrument may not be plugged in
to the computer.
Check that either a USB or Ethernet cable is
tightly connected to the instrument and to the
computer.
Your instrument may be on a different
sub-net.
Add the sub-net to the Choose Instrument
window and then click
Refresh
.
Actual current does not match the setpoint.
The setpoint exceeds the limit current
setting.
If the limit current can be increased without
damage to the QCL, increase the limit
current setting.
The QCL is compliance voltage
limited.
Increase the Max Supply Voltage slightly to
see if actual current increases. Follow the
instructions on page 20 to optimally set
the Max Supply Voltage.