Honeywell GG1342 HeNe Ring Laser Gyro (Gallery)
This is the complete core assembly of the Honeywell GG1342 ring laser gyro.
The exterior view is of a unit manufactured in 1985 but the skins don't
survive going inside. ;( :-) So, a different unit (which I acquired first
already partially disassembled) was used for the interior
views. Based on date codes found on several parts, it was manufactured
in the early 1990s. However, the internal construction of the two units
is virtually identical.
Also included are photos of the HeNe laser power supply PCB with individual
outputs for the three GG1342s in the inertial platform. And an acceleromater
because it would feel lonely if left out. ;-)
The GG1342 was the first RLG Honeywell produced
commercially, but is structurally and functionally similar to later models
like the still current GG1320 (below).
View 01 - GG1342 exterior view 1.
View 02 - GG1342 exterior view 2.
View 03 - GG1342 exterior view 3.
View 04 - GG1342 Closeup of labels.
View 05 - GG1342 interior view 1.
View 06 - GG1342 interior view 2.
View 07 - GG1342 interior view 3.
View 08 - Closeup of GG1342 mirror/PZT assembly 1 (left).
View 09 - Closeup of GG1342 detector assembly. The 3-pin
photodiode package is for the fringe signals. The other one
is for monitoring the discharge intensity.
View 10 - Closeup of GG1342 mirror/PZT assembly 2 (right). The two black
laser connectors are also visible.
View 11 - Closeup of area of GG1342 dither PZT motor. The silvery
getter is also visible inside the block. It is nearly pristine.
View 12 - Closeup of GG1342 power/signal connector. This would include
the PZT drive signals, detector power and readout, and possibly laser power.
View 13 - Closeup of GG1342 cathode-end of assembly. The pink object
encloses the cathode. The pink may be a warning since unlike most HeNe
lasers, the cathode here is at around -900 V.
View 14 - Closeup of GG1342 anode 1. This one is just a spherical cap.
View 15 - Closeup of GG1342 anode 2. This one has the vacuum tip-off.
View 16 - Closeup of high voltage connectors and back of high voltage
View 17 - Closeup of GG1342 front of potted high voltage module. This
appears to be associated with starting only. The serpentine thin-film
resistor appears to have a value of more than 20 Mohms.
View 18 - Closeup of GG1342 Laser Regulator PCB in place.
View 19 - Closeup of GG1342 Laser Regulator PCB removed.
View 20 - Closeup of GG1342 Detector PCB in place.
View 21 - Closeup of GG1342 Detector PCB removed.
View 22 - GG1342 powered view 1. It's hot-wired directly from the HeNe
laser power supply to the two anode ballast resistors.
View 23 - GG1342 powered view 2. A tiny red dot from scatter on the
output mirror can be seen near the top.
View 24 - GG1342 powered view 3.
View 25 - Closeup of GG1342 left bottom (area of mirror 1) powered.
View 26 - Closeup of GG1342 bottom section powered.
View 27 - Closeup of GG1342 right bottom (area of mirror 2) powered.
View 28 - GG1342 with major parts labeled.
View 29 - GG1342 triple HeNe laser power supply PCB with HV cables.
View 30 - GG1342 triple HeNe laser power supply PCB top closeup.
It is not known whether the input is DC or 400 Hz. The 2N5416s at
the lower right are HV transistors, believed to be the current
regulators for the three outputs.
View 31 - GG1342 inertial platform triple HeNe laser power supply PCB
bottom closeup. A close inspection will reveal that the center white wire at
the top of the photo is not attached and may have been the original reason
this was removed from service. ;-) This board is supposedly named
"Mode HV PS" according to info obtained with it, but the marking appears to
be invisible. ;)
View 32 - GG1342 inertial platform triple HeNe laser power supply cables
with HV connectors. Red is plus and green is minus.
View 33 - GG1342 inertial platform accelerometer top view.
View 34 - GG1342 inertial platform accelerometer bottom view.
Honeywell HG1700 IMU with Triple GG1308 HeNe Ring Laser Gyro (Gallery)
The Honeywell HG1700 IMG (Inertial Measurement Unit) is used in a variety of
applications like missiles, UAVs, UUVs, and and other drones where the
lower performance and life expectancy of the very small GG1308 RLGs (leg
length of 0.8 inches) is adequate.
The HG1700 consists of three GG1308 RLGs, three vibrating beam quartz
accelerometers, and the integrated power supplies and communications and
control PCB, all in a package under 4x4x4 inches overall weighing less
than 2 pounds.
The first few photos are similar to those of the HG1700 found on the Web; many
of the others are of various stages of disassembly and its guts, and are
not available elsewhere anywhere. :-)
Since I've yet to find specs on the external connector to be able to power
the entire HG1700, the photos of the RLGs lit in all their glory
were taken using an adjustable
output HeNe laser power supply with an external 3.3M ohm ballast resistor for
each of the three anodes and six cathodes. The power supply voltage is
around 1.5 kV for all the photos
which includes the voltage drop across the external ballasts,
internal ballasts and other circuitry which is
part of the potted VMI module, and the discharges themselves. The starting
voltage is between 1.5 and 2.0 kV. The operating current
is under 0.105 mA for each discharge with a discharge voltage of
around 0.5 kV.
The dropout current is under 0.067 mA at a total operating voltage less than
1 kV. Note that much of the total voltage is made up of the drops across
the external ballasts, which would not be present for actual operation,
though there is probably some amount of active current regulation for at least
half the discharge paths to fine tune lasing gain. So the high voltage
inside the HG1700 under normal conditions isn't that high. :)
If anyone has access to documentation, please contact me via the links at
the top or bottom of this page.
View 01 - HG1700 IMU side with resilient mount. The mount around
the equator also is what holds the top and bottom together via a lock
ring having 12 holes for a matching unobtanium spanner wrench. The
yellow portion is an elastomer so the HG1700 body is not rigidly
attached to the mount.
View 02 - HG1700 IMU top with resilient mount.
View 03 - HG1700 IMU top with resilient mount removed. The top and
bottom parts of the case are a snug fit sealed with an O-ring.
View 04 - HG1700 IMU top label closup. A Web search for the model
"HG1700AG59" shows that it is a version with mid-level precision, which
may just mean a manufacturing sort. The "59" also specifies the type
of communications protocol, among other things.
View 05 - HG1700 IMU control main connector. This looks like a naked
DB-style connector but the pin spacing is larger.
View 06 - HG1700 IMU bottom side.
View 07 - HG1700 IMU bottom straight on.
View 08 - HG1700 IMU bottom with resilient mount removed.
View 09 - HG1700 IMU top interior revealing control PCB. This is
believed to have the only active electronics in the HG1700. It is secured
with four screws.
View 10 - HG1700 IMU top interior straight in.
View 11 - HG1700 IMU top interior with control PCB removed. The only
other part is a breakout PCB for the main connector.
View 12 - HG1700 IMU breakout PCB closeup.
View 13 - HG1700 IMU bottom interior revealing the top of triple GG1308
RLG assembly. The RLG assembly is secured with six screws and
a peg for orientation.
View 14 - HG1700 IMU bottom interior with RLG assembly removed
revealing triple accelerometers secured with screws and attached
via a thick flex cable.
View 15 - HG1700 IMU bottom interior straight in.
View 16 - HG1700 IMU accelerometer closeup. These look like tall TO5
transistor cans with 6 pins. They are labeled ACCELERX P/N 976-0513-004.
The "CAGE CODE" refers to the manufacturer's Governemt contractor ID.
View 17 - HG1700 IMU triple GG1308 RLG assembly top. This shows the
potted VMI module, ribbon cables and connectors, an just a hint of the
GG1308 RLG blocks.
View 18 - HG1700 IMU VMI potted module closeup. It is not entirely
known what is inside.
manufacturer of, among other things, HeNe laser power supplies. But
it may only have only passive components. There are diode/resistor paths
through it from each cathode of the GG1308 to the connector at the
3-o'clock position in the photo. The resistance is between 200K and 300K
and provides most of the ballast for the laser "tube" cathodes.
View 19 - HG1700 IMU RLG anode/PZT/power sensor/fringe detector
connector closeup. The pin at the top of the triad goes directly to
the HeNe laser anode for its RLB laser block; the two below it are for
the cavity length tuning PZT. The others are for the power sensor and
View 20 - HG1700 IMU RLG cathode connector closeup. Six of
the ten pins go through the VMI module (via at least a resistor and diode
for each) to the six RLG block cathodes.
The function of the other pins is not known but they may be for the PZT
dither motor and/or control signals.
View 21 - HG1700 IMU triple GG1308 RLG assembly bottom 1. This shows
the three RLG blocks, just over one inch across. :) Each has an associated
connector for the laser anode, mirror PZT, power sensor, and detector, but
not the two cathodes, which go to the potted VMI module.
View 22 - HG1700 IMU triple GG1308 RLG assembly bottom 2.
View 23 - HG1700 IMU triple GG1308 RLG assembly bottom 3.
View 24 - HG1700 IMU triple GG1308 RLG assembly bottom closeup.
View 25 - HG1700 IMU GG1308 RLG block 3. The detector
assembly is at the lower right.
View 26 - HG1700 IMU GG1308 RLG block 2. The two hemispherical
(more or less) cathodes attach via the ribbon cables to the potted VMI
View 27 - HG1700 IMU GG1308 RLG block 1. The lasing cavity
legs inside the block are 0.8 inches in length, thus the "08" in GG1308.
These are made of common BK7 to reduce cost (compared exotic materials
like Cervit or Zerodur for high precision RLGs). The power detector
assembly is at the top. Only one of the pair of solder bumps tests like
a silicon diode.
View 28 - HG1700 IMU GG1308 RLG block closeup.
View 29 - HG1700 IMU control PCB top.
View 30 - HG1700 IMU control PCB bottom. The module with the white
label is the high voltage transformer for either the HeNe laser power
supplies, the dither motor PZT power supply, or both.
View 31 - HG1700 IMU control PCB top closeup showing large chip. ;-)
View 32 - HG1700 IMU control PCB bottom closeup showing large chip. ;-)
This has the ARM designation but also "ASIC" so probably custom.
View 33 - GG1308 ring laser gyro assembly glowing 1. These show the
good stuff. The appearance isn't quite as impressive in "person"
but is still very illuminating. ;-)
View 34 - GG1308 ring laser gyro assembly glowing 2.
View 35 - GG1308 ring laser gyro assembly glowing 3.
View 36 - GG1308 ring laser gyro assembly glowing 4.
View 37 - GG1308 laser block glowing 5.
View 38 - GG1308 laser block glowing 6.
View 39 - GG1308 laser block glowing 7.
View 40 - GG1308 laser block closeup glowing 8. It's possible
to make that interior etching of the block.
View 41 - GG1308 laser block glowing - PZT closeup.
View 42 - GG1308 laser block glowing - power sensor closeup.
View 43 - GG1308 laser block glowing - detector closeup.
View 44 - GG1308 laser block glowing - cathodes closeup.
View 45 - GG1308 laser block with major parts labeled.