Compact Fiber Optic Gyroscope Nested Transceiver Module
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Solution Overview
Problem
Current fiber optic gyroscopes face challenges in achieving a compact, highly integrated form factor with high accuracy and low noise, while maintaining a closed loop feedback path and allowing for adjustable parameters like fiber coil length to optimize performance.
Innovation Solution
A compact fiber optic gyroscope design featuring a transceiver module with a non-coherent light source, optical circulator, photodiodes, and a processor to determine the phase relationship between counter-propagating beams, integrated within a cylindrical housing, allowing for adjustable fiber coil length and operational range to achieve low noise and high accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fiber optic gyroscope uses a long optical fiber coil (5 km or more) to achieve high measurement precision, then the device size and complexity increase significantly
Solution Approach 1:
The patent implements a nested integration architecture where the transceiver module is housed within a first housing that contains the fiber optic coil, creating a compact nested structure. The transceiver module itself contains nested components including the light source, optical circulator, and photodiodes arranged in a compact configuration within its housing, allowing the entire gyroscope system to achieve high precision measurement in a reduced volume
Solution Approach 2:
The patent merges the transceiver functions (light source, modulation, detection) into a single integrated transceiver module that directly interfaces with the fiber optic coil. This consolidation of multiple functional components into one modular unit reduces overall device volume while maintaining the precision requirements for rotational rate measurement
2Device complexity
If a fiber optic gyroscope integrates multiple components (light source, modulator, detector, processor) into a single housing to reduce device complexity, then manufacturing precision and assembly difficulty increase
Solution Approach 1:
The patent segments the gyroscope system into two main modular housings: a first housing containing the fiber optic coil and a second housing containing the transceiver module. This segmentation allows each module to be manufactured and tested independently, then integrated together, reducing the overall manufacturing precision requirements compared to a fully integrated single-housing design while still achieving component consolidation
Solution Approach 2:
The transceiver module is designed as a universal interface that handles multiple functions (light generation, modulation, signal detection) within a single standardized housing configuration. This multi-functional design simplifies the integration process by providing a standardized interface between the coil assembly and the transceiver, reducing assembly complexity
3Measurement precision
If a fiber optic gyroscope uses a closed loop feedback path to maintain constant phase difference for high accuracy, then the device requires additional active components increasing power consumption and complexity
Solution Approach 1:
The patent implements a closed loop feedback path where the processor monitors the interference signal from the photodiode and adjusts the phase modulator to maintain a constant phase difference between counter-propagating beams. This feedback mechanism ensures high measurement precision by actively compensating for phase drift while consuming power only when correction is needed
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables a gyroscope with rotational rate drift of less than 1 degree per hour and noise of less than 0.02 degrees random walk per square root hour, capable of recording angular rate changes of over 500 degrees per second, with adjustable parameters for user-defined performance.
Implementation Method 1
an optical circulator disposed in the second housing and in the path of the first beam of light to produce polarized second and third beams respectively, with polarization orthogonal to each other
Implementation Method 2
a phase modulator disposed in the first housing and coupled to the third beam from the transceiver module to produce fourth and fifth beams coupled to the first and the second end respectively of the optical fiber loop
Implementation Method 3
Due to an optical phenomenon known as the Sagnac effect, the beam traveling against the rotation experiences a slightly shorter path than the other beam resulting in a relative phase shift
Implementation Method 4
first and second photodiodes disposed in the second housing and coupled to the optical circulator, wherein the first photodiode is a transmit monitor photodiode coupled to the second beam, and the second photodiode is a receiver photodiode
Data Source
AI summary
A compact fiber optic gyroscope including a first housing; a transceiver module disposed in the first housing, the transceiver module including a second housing; a non-coherent light source disposed in the second housing for producing a first beam of light; a single lens for focusing the first beam of light; an optical circulator disposed in the second housing and in the path of the first beam of light to produce polarized second and third beams respectively, with polarization orthogonal to each other; and first and second photodiodes disposed in the second housing and coupled to the optical circulator, wherein the first photodiode is a transmit monitor photodiode coupled to the second beam, and the second photodiode is a receiver photodiode. The first housing further includes a planar optical fiber loop having a first end and a second end; a phase modulator coupled to the third beam emitted from the transceiver module to produce fourth and fifth beams coupled to the first and the second end respectively of the optical fiber loop respectively, and for receiving the return sixth and seventh beams from the second and the first ends respectively of the optical fiber loop.