NIST Iodine Stabilie Helium-Neon Laser (Gallery)
The NIST iodine stabilized laser is one such device. The Frazier
Iodine Stabilized HeNe Laser (ISHL)
described elsewhere in Sam's Laser FAQ
is based on a NIST design, but this one I've dubbed it the "NIST ISHL"
because the unit has a NIST label but no model designation. And the only
other place I've found the same laser is on a NIST Web page: See:
Stabilized Helium-Neon Laser. The sample below of the
laser head is either the same one, or more likely, one of a
small number of copies. It's not clear which box in the NIST photo
is the controller, but it may be the PC-ish looking one with the
large NIST label.
The ISHL head contains a two-Brewster HeNe plasma tube (Melles Griot
05-LHB-290), custom-built iodine cell with Brewster windows including
a heater and photo diode/preamp, HR and OC mirrors, PZTs behind each
mirror (one for dither and one to scan
the optical frequency), and a second photodiode/preamp to monitor the
output beam. The controller includes the HeNe laser power supply (nothing
special), and the analog and digital processing to locate and lock onto
a specific peak of the iodine absorption spectrum. Based on the computer
monitor in the NIST photo, their controller uses a Windows PC
(or is at least monitored by a Windows PC), circa early 1990s.
Windows 3.1 or something like that. ;-)
Much more information on iodine stabilized lasers (including this one)
can be found in the chapter:
Commercial Stabilized HeNe Lasers
of Sam's Laser FAQ.
View 01 - Left front view. The glow of the tube is not nearly as
dramatic as in the NIST photo, above, which suggests either (1) that the
cover on this laser is less transparent or more likely (2) that the photo was
doctored. :) The latter is suggested by that fact that the beams have
definitely been enhanced for visual impact as the output power from both
lasers in the photo are much much less than 1 mW. In addition, the
beam from the ISHL is narrow, not fat as in that photo. :-)
View 02 - Front closeup view with NIST label. The beam sampler,
photodiode, and preamp are behind the black cover
View 03 - Right back view.
View 04 - Back closeup view. The connections to the PZT are behind
the black cover.
View 05 - Left front interior view.
View 06 - Right back interior view.
View 07 - Left side interior view.
View 08 - Right side interior view.
View 09 - Closeup of iodine cell. This is virtually identical to
those found in the Frazier or later NIST ISHL except that it has tapped
holes on one side so it can be secured directly to the HeNe laser tube
View 10 - Closeup of one of four (4) micrometers for tube centering.
The large cylindrical bar - one of 3 - is actually what supports the
entire resonator, secured at 2 points to the base.
View 11 - Closeup of connections to HR PZT. The HR mirror is glued
to the PZT which is glued to the rear plate.
View 12 - Closeup of beam sampler, photodiode, and its preamp.
The OC mirror is glued to a PZT as well.
View 13 - Closeup of the connectors on the instrumentation cables -
one each for phodiode (4 pins), OC PZT (2 pins), HR PZT (2 pins), iodine
cell photodiode (4 pins), and iodine heater/temperature sensor (4 pins).