Photos of Helium-Neon Ring Laser Gyros

These are photos of commercial helium-neon ring laser gyros, only the Honeywell GG1342, GG1320, and GG1308 at present. Even so, this is already believed to be the most comprehensive selection of detailed publically accessible RLG photos on the Web - or in the explored Universe. ;-)

Much more information on ring laser gyros and details on all of these may be found at Sam's Laser FAQ Chapter: Laser Intruments and Applications in the sections starting with "Ring Laser Gyros".

• 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 module.
  • 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 GG1320 HeNe Ring Laser Gyro (Gallery)

  The Honeywell GG1320 RLG is used in numerous inertial navigation systems and is still considered state-of-the-art with a version in production as of 2018. Honeywell calls it a "Digital Ring Laser Gyro" as all the control electronics are contained within the 3.45", 1 pound package. Input is +5 VDC and +15 VDC, a Reset pulse, and Sample Request pulses. The status and angle data are returned via RS422. This unit is from 2001. The electronics are a bit different than what's shown in the current Photo of GG1320 Ring Laser Gyro in Honeywell Brochure. But from tests, it appears to be functionally identical.

  • View 01 - GG1320 top view of complete RLG.
  • View 02 - GG1320 bottom view of complete RLG.
  • View 03 - GG1320 closeup of label. There must be a way to determine the manufacturing date but it isn't obvious.
  • View 04 - GG1320 main connector. This is a female 25 pin Micro-D. One possible mate is a Glenair MWDM2L-25P—4E7.
  • View 05 - GG1320 top with outer cover removed.
  • View 06 - GG1320 bottom with outer cover removed.

  • View 07 - GG1320 interior after separating case shows the black mid-level plate on which laser block is mounted underneath and the top of PCB 1 monted in top of case with ribbon to main connector. Connections to the laser block are via the two long white connectors. Separate Ground wires connect the black plate, PCB 1, and top cover.

  • View 08 - GG1320 closeup of mid-level plate secured by six screws around its perimeter with the laser block between it and the rear of the case clamped via the three screws in the center through the dither motor core.

  • View 09 - GG1320 PCB1 mounted in top of case.
  • View 10 - GG1320 PCBs shows PCB 1 (floating) with ribbon to main connector and PCB 2 still mounted inside top cover.
  • View 11 - GG1320 PCB2 mounted in top of case.

  • View 12 - Closeup of top of GG1320 PCB 1.
  • View 13 - Closeup of bottom of GG1320 PCB 1.
  • View 14 - Closeup of top of GG1320 PCB 2.
  • View 15 - Closeup of bottom of GG1320 PCB 2.
  • View 16 - GG1320 laser block revealed! It is not actually attached to the black plate except by the (floating) white connectors.
  • View 17 - GG1320 laser block top view 1.
  • View 18 - GG1320 laser block top view 2.

  • View 19 - GG1320 laser block bottom view. The black rubber webbing secures the various wires going to the white connectors. The dither motor (top and bottom) is the only point of rigid contact with the RLG structure.

  • View 20 - Closeup of GG1320 mirror/PZT assembly 1. Note the 3 wires soldered to the PZT. This could provide some fine alignment in addition to adjusting the cavity perimeter to optimize the lasing mode position.

  • View 21 - Closeup of GG1320 AD590 temperature sensor.

  • View 22 - Closeup of GG1320 mirror 2/detector assembly. The 3-pin part has dual sensors for the fringe signals. The 2-pin part (under the tan glob) is as single sensor for monitoring the discharge intensity. They test like silicon diodes. The mirror substrate is shaped like a wedge which may mean that no corner prism is required. Somewhere in the vicinity there is a blue LED that is probably used to aid the HeNe in starting.

  • View 23 - Closeup of GG1320 mirror/PZT assembly 3. Similar to PZT 1.
  • View 24 - Closeup of area of GG1320 dither PZT motor. The silvery getter is also visible inside the block. It is pristine.

  • View 25 - Closeup of GG1320 cathode-end of assembly. This cathode cup in this one is chrome, no hot pink, possibly because it really cannot be powered by itself. Or at least it's not supposed to be powered except when safely enclosed. Right....

  • View 26 - Closeup of GG1320 anode 1. This one is just a spherical cap.
  • View 27 - Closeup of GG1320 anode 2. This one has the vacuum tip-off and red cover.

  • View 28 - GG1320 powered view 1. It's hot-wired directly from the custom power supply box to the two anodes via 470K ohm ballast resistors. There is also a 47K ohm resistor in series with the cathode as a precaution.

  • View 29 - GG1320 powered view 2. And yes, there does appear to be a tiny red spot on the inside of the mirror at the top of the photo.
  • View 30 - GG1320 powered view 3.
  • View 31 - GG1320 powered view 4.
  • View 32 - GG1320 powered closeup area of mirror 1.
  • View 33 - GG1320 powered closeup area of cathode.
  • View 34 - GG1320 powered closeup area of mirror 3.
  • View 35 - GG1320 powered closeup of area of dither motor.
  • View 36 - GG1320 laser block with major parts labeled.

• 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 fringe detector.

  • 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 module.

  • 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.

Honeywell GG1342 HeNe Ring Laser Gyro

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Honeywell GG1320 HeNe Ring Laser Gyro

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Honeywell HG1700 IMU with Triple GG1308 HeNe Ring Laser Gyro

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