HP/Agilent 5517/5501B/N1211A HeNe Laser Tube in Magnet/Frame Zeeman Experiments

Description

Most are partial HeNe laser tube assemblies from HP/Hewlett Packard/Agilent/Keysight 5517A/B/C/D, 5501B, or N1211A metrology lasers.
All but the very low or no power ones (<
75 µW)
that may not lase at all come with the mounting feet and front optics frame.
The only practical difference is the style of the shape of the goldish-colored feet and shorter frame for the N1211A. ;-)  The glass laser tubes are all similar.  Disassembled versions are also available.  The photos show both types.
There is also a complete tube assembly (similar to last photo) that will lock in a 5517 small-body laser with an output power of over >125
µW.  It has a newer "Short" tube with a split frequency of around 2.75 MHz (5517C spec, but can be reduced).  Your choice of beam 1-2 or 6 mm beam size.
These red (633 nm) HeNe laser tubes are unsuitable for use in an actual HP/Agilent laser for commercial applications for various reasons, so don't complain when the 0,000,000.00 wafer fab you picked up on eBay for .98+shipping crashes using one of them. ;-)  But most produce a beam with enough power for experiments in the finer points of Zeeman split HeNe laser physics.  Absolutely everyone needs to investigate such things! ;-)  And by using the internal heater - unique to these tubes - they can be stabilized and locked using your own electronics at the optimum mode location for a split frequency display or even for your own two-frequency laser interferometer displacement measuring system.  (Additional optics and electronics required, inquire for details.)
The beam starts at ~1 mm at the tube and expands at 10 mR (10 parts per 1,000).  For those with feet and optics frame, a lens (shown in last photo) to convert it to a fairly well collimated 1-1.5 mm diameter beam is available for additional.  Expanders to convert to a 6 or 9 mm beam are also available - ask.
Demonstrate the Zeeman split frequency and circular polarized modes of an HeNe laser tube in an axial magnetic field.  Impress your friends and physics teacher. :)
The tube requires a ballast resistor of around 100K ohms and power supply of 4-4.5 mA at 1,700 V, typical for a 2 mW red HeNe (not included but available).
For just looking at the modes, any of the tubes >75
µW
would be satisfactory.  For incorporation into an interferometer, higher power is better.  For serious applications, check out my other listings for working lasers, measurement displays, and complete systems.
150 µW is way more than enough to detect and display the split frequency on an oscilloscope or frequency counter using a polarizer and biased photodiode as a detector.
The <75
µW tubes come without the frame or feet (6th photo) and may not lase at all and their wires may be too short and difficult to attach to, but are gas intact.  For those, the cost is basically for the magnet and glass high tech sculpture.  If you ask nicely, I'll send one that at least lights up to provide a nice glow when removed from the magnet. :)
The magnet is 4 inches in length by 2 inches OD and around 1.5 inches ID.  It is magnetized axially with an interior field of between 200 and 400 Gauss.  The field can easily be reduced.  Increasing it requires a magnet charger that can be built for about or less.  The maximum possible field is slightly over 500 Gauss for most, but a few will not go above around 325 G, probably they are Alnico 3 rather than Alnico 5.  For an extra /tube), I will boost the field to the maximum but cannot guarantee its final value.  And at the maximum field, even the tubes that lase may not produce a beat frequency or even any output beam, so you would then have to reduce the field until it does.
It's usually not that difficult to remove the magnet/tube from the feet and optics frame undamaged.  And with
only
about 3-4 hours of absolutely tedious fiddly work ;-) the glass tube can be removed intact from the magnet.  (I've heard that with proper tools - a.k.a. instruments of torture - this can be reduced to around 1 hour, but I'll believe it when I see it.)  The glass tube would make a cool high-tech art piece or very unusual laser lamp. :-)  As can be seen, these are not like your typical modern HeNe laser tube.
The 7th graphic shows an actual tube along with a diagram and X-ray view.
Two other photos show the bare glass tube after cleanup and magnet.  Those that I sell ("Disassembled") will all light.  The price is high to partially compensate me for my labor costs in discombobulating them, and for the required
discounted
chants and incantations to the gods of dead lasers. ;-)  Note that the tube you receive will likely still require cleanup to remove rubbery potting compound residue, but this is involves just a single edge razor blade and some pointy tools, care, and patience.
Photos are typical.
Magnet, frame, feet, and glass tube ONLY with short wires - NO connectors, ballast resistors, beam expander, or waveplate assembly.
To at least 0.00263% of the World's population of Homo Sapiens, these are definitely more valuable than used dirt - and that can also be found on eBay as well!  Used direct sold separately. ;-)
Thanks for looking,
--- sam