-
Zygo 7701 Helium-Neon Laser (Gallery)
Like HP (now Agilent), Zygo also manufactures what is called a
"Two-Frequency HeNe Laser" for use in their interferometry based measurement
and calibration systems. All except the 7705 use an HeNe laser tube of
conventional design with an AOM to generate the two frequencies exactly
20 MHz apart. (The 7705 uses Zeeman-split technology like the HP/Agilent
lasers.) There are several versions of the 7701, differeing mainly in
the case style, except for very early ones that had a circular connector
instead of the DB25. Since the split/REF frequency is 20 MHz - much higher
than any HP/Agilent laser - the Zygo 7701 is not at all compatible with
them electronically, but except for the higher frequency optical receiver,
interferometer optics of Zygo systems are very similar.
Much more information on these lasers can be found in the chapter:
Commercial Stabilized HeNe Lasers
of Sam's Laser FAQ.
-
View 01 - Left front view.
-
View 02 - Front closeup view. The shutter selects the full beam,
no beam, or a narrow alignment beam.
-
View 03 - Right back view.
-
View 04 - Back closeup view.
-
View 05 - Left front interior view.
-
View 06 - Left side interior view.
-
View 07 - Right back interior view.
-
View 08 - Right side interior view.
be shielded.
-
Zygo 7702 Helium-Neon Laser (Gallery)
The primary difference between the 7702 and 7701 is in the use of a
microcontroller-based control PCB with a built-in AOM driver. Internally,
everything else is pretty much the same and modern chassis include all
mounting holes to be used for either laser. However, the 7702 has an
RS232 interface for diagnostics and firmware updates, and a fiber-optic
connector for the REF signal (in addition to the ECL REF signal).
-
View 01 - Left front view.
-
View 02 - Front closeup view. The shutter selects the full beam,
no beam, or a narrow alignment beam.
-
View 03 - Right back view.
-
View 04 - Back closeup view.
-
View 05 - Left front interior view.
-
View 06 - Left side interior view.
-
View 07 - Right back interior view.
-
View 08 - Right side interior view.
-
Zygo 7705 Helium-Neon Laser (Gallery)
The 7705 is a Zeeman-split HeNe laser functionally similar to the HP/Agilent
5517D, but in a much smaller case - approximately 10x2.5x2.4 inches - even
smaller than it appears in these
photos. The actual laser tube, which is less than 4 inches in length, is
custom made by or for Zygo.
-
View 01 - Left front view.
-
View 02 - Front closeup view. The shutter had positions only for open
and closed, no alignment aperture.
-
View 03 - Front plate closeup view.
-
View 04 - Front interior closeup view.
-
View 05 - Right back view.
-
View 06 - Back closeup view. The DB9F is for power and LOCK status while
REF is via the fiber-optic connector.
-
View 07 - Back plate closeup plate view.
-
View 08 - Back interior closeup view.
-
View 09 - Laser assembly consisting of tube assembly and Heater Board.
-
View 10 - Tube assembly top view. (The beam exits to the right.)
Note all the locations for alignment
set-screws and Loctite. :) The wide slot likely provides access to the
waveplate adjustments.
-
View 11 - Tube assembly bottom view. The cables (from left to right)
are: photosensors, heater, temperature sensor thermistor, HeNe laser
power supply DC input.
-
View 12 - Closeup of back of laser tube. The hole in the potted
ballast resistor(s) is for the REF beam to exit to the fiber-optic connector.
-
View 13 - Closeup view of front of laser tube. The large
collimating lens is the only thing really visible, but behind that are
the expanding lens and waveplate(s).
-
View 14 - Another angle of front of laser tube.
-
View 15 - Heater Board left view.
-
View 16 - Heater Board Right view.
-
View 17 - Closeup of Heater Board. Note the unpopulated position for
U1, presumably some type of power device that isn't used. The only
adjustment on the PCB is the trimpot (R43), possibly for the temperature
set-point at which switchover from preheat to locking takes place.
-
Zygo 7712 Helium-Neon Laser (Gallery)
The 7712 is in a much higher quality sealed case and uses
water cooling to achieve a long term stability about 10 times that of
the 7701 or 7702. Its output power is also about double that of
the 7701 or 7702. And there is an additional 42 MHz AOM to offset
the output from the lasing frequency to miminize effects of
back-reflections on laser stability. The microprocessor-based
controller is packaged on two PCBs with an RS232 interface
similar to that of the 7702.
-
View 01 - Left front view.
-
View 02 - Front closeup view. The shutter selects the full beam,
no beam, or a narrow alignment beam.
-
View 03 - Right back view.
-
View 04 - Back closeup view.
-
View 05 - Left back (underside) tube enclosure view.
-
View 06 - Left (underside) tube enclosure view.
-
View 07 - Interior showing optics and control PCBs.
-
View 08 - NEOS AOM (or what's left of it).
-
View 09 - Interior closeup.
-
View 10 - Control PCBs sandwich closeup.
-
View 11 - Interior with main parts labeled. (The HeNe laser tube
is below.)
