Antique Helium Neon Laser Photos - By Flavio Spedalieri

Elliott Helium Neon Laser
Circa 1970s

The following photos of an old Elliot Laser. This is a hot cathode type laser.

Unfortunately, this laser does not work. All gas has depleted most likely through the soft-seals that bond the Brewster
windows to the plasma bore. By visual inspection, the glasswork is fully intact, which is great should one day the I decide to get the laser
functioning again. I have confirmed that the filament is still intact by connecting a low voltage of 3-6 volts from AA batteries.

I acquired the laser more as a collectors Item. This laser is actually very intriguing and has some nice little features.
The most interesting property of this laser is the simplicity of the actual tube and resonator design.

Please note, these photos were taken with a mobile phone digital camera, and therefore quality is not great. I will endeavour to replace
these with high-quality photos at a later date.

The laser features adjustable mirror mounts that allow for optical alignment.

Output end of the Laser. The Brewster windows are bonded to the plasma
tube using a soft-seal. The Anode connection is also visible.

Another view of output end with the output coupler in view.

View showing the warm Cathode. The yellow coil of wire around the plasma bore is actually a trigger wire to ionise the gas (similar to a Xenon flash lamp trigger electrode).

The laser mirrors are 25mm in diameter. The mirrors are mounted
into a carrier that has an external thread that then screws
into the adjustable mounts.

All photos by Flavio Spedalieri

Same end of laser. This laser features an intra-cavity aperture control (blade diaphram as found in camera lenses). This aperture allows
for the control of the beam property and divergence and the modes
that will oscillate (which are responsible for the
TEM characteristics of the beam).

This view is of the trigger coil and the ballast resistor (green)