Smaller Optical Gyroscopes Navigate into Broader Markets
The article "Smaller Optical Gyroscopes Navigate into Broader Markets," discusses how integrated photonics are shrinking optical gyroscopes and opening doors to the UAV middle market for smaller aerial platforms. Current trends are driving the need for unmanned aerial vehicles (UAVs) that are smaller, able to operate in environments with limited or no GPS guidance, and capable of delivering enhanced pointing accuracy for mapping applications.
This is fueling the drive to reduce the dimensions of ring-laser and fiber optic gyroscopes to a fraction of those currently on board the Global Hawk. In some cases, this means fabricating smaller components for RLGs or replacing parts of fiber optic gyroscopes (FOGs) with photonic chips or hollow-core fibers. The use of integrated photonics will expand opportunities in the UAV market, with potential applications in agriculture, package delivery services, and remote monitoring and inspection.
The Sagnec effect
The Sagnac effect is used in optical gyroscopes and ring laser gyroscopes (RLGs) to measure angular velocity and orientation. Optical gyroscopes use fiber optic coils while RLGs use lasers and mirrors.
Frank Weiss comments, “One of the critical requirements of UAVs is operation in GPS-deprived environments. This is most prevalent in military applications but can be useful in autonomous terrain mapping as well. In this application, it is critical to maximize the time of flight available under autonomous navigation. Working from a defined reference and high- accuracy starting point and handing off these precision coordinates to an autonomously guided platform, a high-stability, low-drift gyro will perform better and for longer periods of time. RLG is well suited for this.”
RLG sensors are more durable against shock, vibration, and temperature compared to FOG systems. However, RLG technology requires mechanical dithering that can generate noise and unwanted signatures. Miniaturization of RFG components is improving SWaP-C and making it competitive with FOG devices, but further reductions in size and power may depend on advancements in RLG substrates.
Adam Morrow explains, “The ruggedness of the optics within RLG devices is further aided by coatings designed to survive extreme environmental conditions, as well as by substrate materials with high mechanical stability. Size limits are a function of the overall optical system design of the RLG, but weight reductions can be made in the frame. In doing so, care must be taken to not impair the mechanical stability of the RLG. Outside of the precision optical components, cost, and power consumption reductions can be looked at for the laser source as well.
The full article, written by James Schlett, Contributing Editor, can be found in the April 2023 issue of Photonics Spectra magazine or you can read the full publication on the Photonics.com website.
Our ring laser gyroscopes (RLG) are deployed in commercial aircraft, missiles, satellites, and other military vehicles. Vertical integration enables us to supply the entire ring laser gyroscope components package: RLG frame and optical components.
Our integration of capabilities delivers superior performance and streamlines sourcing.
How G&H works in airborne and spaceborne navigation
We are a leading designer and manufacturer of precision optical components, pump lasers, and fiber-optic couplers for inertial navigation systems used in avionics and defense. Whether the application calls for a ring laser gyroscope (RLG) for airborne or maritime navigation or a fiber-optic gyroscope (FOG) to guide the flight of a missile or UAV, we offer proven expertise in the development of both legacy and emerging inertial platforms.
Our heritage in precision optics, materials and optical applications, as well as our integration capabilities, enables us to deliver products with superior performance and streamlined sourcing.
We develop and deliver complete RLG optical assemblies as well as subassemblies that are built to fit your system. Our vertical integration enables us to supply the entire RLG package, including the frame and its optical components, as well as dedicated metrology to ensure reliable and consistent operation.
Our dedication to fiber optic innovation over the years is observable in the quality and effectiveness of our fiber optic components, from laser sources to passive components. All of our components are designed for harsh environments and undergo rigorous qualification processes and optical testing to ensure high reliability operation.
Product and technology development offered by G&H
With over 40 years of experience of producing high-quality and consistent Zerodur® frames, our RLGs deliver maximal stability over a large range of operating environments (namely, temperature, humidity, and environmental composition).
Flat, wedged, and curved mirrors used in RLGs are superpolished with surface roughness better than 1 Å RMS, with high-reflectivity IBS coatings designed to survive extreme environmental conditions. Alongside our mirrors, we manufacture precision beam splitters and combiners, prisms, and wedges using our advanced facilities and expert engineers to complete the assembly.
Extensive metrology capabilities are critical to our ability to meet and exceed difficult specifications:
- Zygo® ZeMapper™ for surface roughness and structure <1 Å
- OGP® CMM for geometrical tolerances down to sub-micron features
- 18” Zygo® Interferometer measures flatness up to 1/50th wave
Our line of high power diodes feature ruggedized, epoxy-free designs that are built to operate for long periods of time over wide temperature ranges and high shock/vibration environments. With an emphasis on stability and low noise, our sources are ideal for FOGs.
Manufacturing of high reliability fused fiber optic components, such as splitters and couplers, is carried out on specially developed workstations. Advanced fiber management, in-process screening, and customer specific validation tests are implemented to further enhance component reliability. The ultra-low loss of our fused fiber components promotes low noise and high performing FOGs.
Optical subassemblies and multichannel integration
With our extensive experience with all of the components in a FOG, we are also able to offer the development and manufacture of optical subassemblies for FOGs, including multichannel integration. Contact us today to discuss your requirements.