Sensing motion with light

Technology

Our patented technology uses the physics of light, the Sagnac effect, to measure rotation with no moving parts, in a package a fraction of the size and weight of the legacy fiber-optic gyros that share the same physics.

How it works: Measuring rotation with light

A photonic gyroscope has no spinning mass and nothing that vibrates. It measures rotation using a property of light itself.

Light is sent around a closed path in both directions at once. When the path is still, both beams take the same time to travel it. When the path rotates, one direction becomes effectively longer and the other effectively shorter, and the two beams arrive slightly out of step. That difference in phase is proportional to the rate of rotation. This is the Sagnac effect, and it is the same principle behind the ring-laser and fiber-optic gyros trusted in aircraft and ships for decades.

What changes in a photonic gyroscope is how the optical path is built. Instead of hundreds of metres of hand-wound fiber, the interferometer is built on a photonic integrated circuit, produced with semiconductor-style manufacturing. The physics is unchanged. The size, the power draw and the repeatability are not.

The Sagnac effect: How light measures rotation

1. Split

Light enters the loop in both directions at once.

2. Rotate

Rotation makes one direction’s path effectively longer.

3. Compare

The phase difference at the detector is the rotation rate.

Inside the sensor : From light to rotation rate

The four stages every measurement passes through, many times a second.

1. Light source

Launch. Light is launched into the sensor with a broad spectrum, which suppresses the coherent back-scatter and cross-coupling that would otherwise appear as drift.

2. Waveguide

Split and circulate. The beam is divided in two and sent around the same closed path in opposite directions. This is the Sagnac interferometer, built on a photonic integrated circuit.

3. Detection

Interfere. The two beams recombine. Rotation makes one direction’s path effectively longer, and the phase difference that results is proportional to the rotation rate.

4. Signal processing

Resolve and output. The phase difference is demodulated, compensated across temperature and applied against factory calibration, then output as a rotation rate over RS-422 or CAN-FD.

In the lab : Light moving through a photonic chip

One of our photonic integrated circuits on the test bench. The pink trace is light in the waveguides, following the same optical path the rotation measurement depends on.

Being able to see the light is how the platform gets characterised. Before a design becomes a product we measure how efficiently light couples in, how cleanly it splits, and how much is lost on the way round. Those numbers decide the drift figure that ends up on a datasheet.

This is development hardware, not a shipping part.

Performance: Stability you can characterize

The number that decides an inertial sensor is gyro bias stability: how far the zero point wanders while the unit is running, in degrees per hour. It sets how quickly position error grows once there is no GNSS to correct it, which is the whole reason to buy a better IMU.

Our shipping units publish 0.5 °/hr minimum in-run bias stability, typically under 1.0 °/hr at 25 °C, with angular random walk of 0.03 °/√hr on the MK2E2 optical axis. The MK2Z prototype reaches < 0.01 °/hr on its optical Z axis. Every figure we publish is the same figure printed in the user manual that ships with the unit, including the minimum and typical columns.

Stability is also something you should be able to reproduce rather than take on trust. Each unit ships with its own outgoing static test report. Units have been tested to DO-160-style profiles at 2, 4 and 8 g vibration and 20 g and 40 g shock, and have passed Class A emissions and ESD testing. Independent third-party validation of MK2M2 and MK2E2 performance is underway at a specialist inertial laboratory.

If you want to see the drift rather than read about it, the road test comparing our photonic gyro against a MEMS unit over 21 minutes of GNSS-denied driving is published in full.

Roadmap: What we are building next

The MK2 family ships today. Here is what follows it.

  1. Shipping Now: MK2 family — IMU

    Tactical-grade IMUs today; the MK2Z nav-grade prototype reaches < 0.01 °/hr on its optical Z axis.

  2. 2026: NavigationGate — INS

    A drop-in INS board that fuses inertial data with GNSS and aiding sensors.

  3. 2026/2027: MK2 — Z3

    Navigation-grade optical sensing, targeting under 0.01 °/hr operational on all three axes.

  4. 2027: MK2 — E3

    The tactical-grade E-Series extended to optical sensing on all three axes, targeting < 0.5 °/hr.

Roadmap dates are planning targets, not commitments, and do not form part of any quotation or contract.