Melles-Griot 05-LHR-088 Helium-Neon Laser

05-LHR-088-097 Tube
05-LHR-088-097 Tube

Here’s another Helium-Neon to add to the electric glassware collection, a 2mW Melles-Griot 05-LHR-088 which I pulled from the optical assembly from an ancient Spectra-Physics SP910 laser level. This tube is a standard Red 632.8nm with Random beam polarisation. The specifications are in the table below:

Minimum Optical Powere/2 Beam DiameterDivergencec/2L Mode SpacingSupply Opr/Start VoltsNominal CurrentDiameter/Length
2mW0.63mm1.4mR641MHz1.82/10kV4.5mA29/241mm
Tube Label
Tube Label

The label shows that this tube was manufactured back in 1987. 34 years at the time of writing! There is a slight amount of brown deposit in the main bore, indicating the tube has seen some use, however it’s nowhere near as bad as the Barcode scanner tube I have, which must have spent many years operating. I am assuming the “2.6” hand-written onto the label next to the serial number was the power measured at the factory.

Anode End
Anode End

This tube is old enough to have 3-screw locking/adjustment collars on the mirror mounts. This one is at the anode end of the tube, with a cap over the HR mirror for protection.

OC Mirror
OC Mirror

The OC (Cathode) end of the tube has the same locking collar.

Tube Mounts
Tube Mounts

The original tube mounts are reattached here, made from Aluminium with silicone rubber pads.

Tube Running
Tube Running

Here’s the tube running on a LaserDrive 4.5mA PSU. The camera doesn’t quite pick up the colour of the discharge, it’s more salmon-pink.

Bore Closeup
Bore Closeup

A closeup of the bore more accurately shows the colour of the glow discharge in the tube.

Beam

Finally, the output beam from the tube. This one actually measured at 3.04mW on a Coherent LaserCheck, a bit higher than the assumed factory measurement of 2.6mW!

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