HNL020R(L), HNL050R(L) Red HeNe Laser System
Chapter 5: Troubleshooting
Rev B, February 27, 2012
Page 15
Chapter 5
Troubleshooting
5.1. Technical
Failures
Problem
Fix
No light is being emanating from
the laser.
Make sure that the aperture is open.
Check to make sure that
•
the Alden plug is firmly seated into the power supply (it may
take more force to push the plug in all the way the first few
times),
•
the interlock connector is plugged in and fully seated,
•
the power supply is plugged into a working outlet, and
•
the aperture is open.
Note: There is a built in CDRH safety delay of 4 - 5 seconds
before the laser starts to lase after turning the key switch
The laser does not work and
there is something rattling
around inside the laser head
tube.
The glass gas tube may have broken during shipping. Please contact
your local tech support office for help.
The power supply does not turn
on.
The power supply Laser On
Indicator does not light.
Make sure the power supply is plugged in.
The laser has low output power.
The laser requires 10 minutes to meet published specifications. Make
sure to let it warm up.
Make sure that the laser is mounted correctly. See page 12 for proper
mounting techniques.
5.2.
Application Trouble Shooting
Some sources of trouble of a HeNe laser do not come from the laser failing or being out of spec. In some cases,
these laser are not suited to the application. One common mis-application comes from a HeNe laser, especially a
low power laser (~0.5 mW), being used in a metrology application.
Environment is an important consideration as well. Dirty environments can cause the optics to become
contaminated and the power output to drop below expected levels. Unstable output beams can be caused by
noisy environments with large sources of vibrations. Proper mounting on an optical table can reduce the effects of
ambient vibrations. Temperature is also a factor. If the environment where the laser is being used fluctuates in
temperature, the output power can experience a large amplitude change. Even blowing on the laser tube can
cause the output power to fluctuate significantly.
Randomly polarized lasers are actually rapidly changing, single polarization lasers. When averaged over time, the
light emitted from these lasers appears randomly polarized. However, any polarization optics in the path
(intentional or unintentional) can cause large variations in the output power. Only polarized lasers should be used
in applications that involve polarization optics.
While HeNe lasers are less sensitive to variations caused by back reflections, they are not immune to them. Large
retro-reflections back into the laser can cause unpredictable power changes. A free-space isolator can be used to
reduce or eliminate these effects. If possible, only a small angular deviation is needed to eliminate the back
reflections.
These HeNe lasers are ill suited to any application or experiment where a single frequency or long coherence
length is required.
