Shanghai Gengyun Industrial Co., Ltd
Standard High Precision Free-Standing Fiber Coil for Φ120mm FOG
Quadrupolar Winding Principles
Standard high precision free-standing fiber coils for Φ120mm FOGs use quadrupolar winding patterns. This pattern alternates fiber layers to cancel thermal effects. The winding sequence reverses direction at specific layer boundaries. Proper tension control maintains pattern accuracy throughout winding. Understanding quadrupolar winding is essential for high-performance gyroscopes.
- Pattern Geometry
Quadrupolar winding divides the coil into four quadrants or layers. Fiber winds in one direction for the first layer. The second layer winds in the opposite direction. This pattern repeats for all layers in the coil. Pattern symmetry cancels thermal gradients across the coil diameter.
- Thermal Gradient Cancellation
Temperature changes create refractive index gradients across the coil. Quadrupolar winding makes these gradients symmetric about the center. Symmetric gradients produce no net phase error in the gyroscope. Non-quadrupolar patterns cause thermal drift in rotation measurements. Thermal cancellation is the primary benefit of quadrupolar winding.
Winding Tension Control
Consistent fiber tension is critical for coil stability. Tension variations cause geometric asymmetry and drift.
- Tension Effects on Coil Geometry
High tension stretches the fiber and changes its optical properties. Low tension allows fiber movement within the coil. Tension variations create asymmetric stress distributions. Stress asymmetry causes thermal and vibration sensitivity. Tension uniformity must be maintained throughout winding.
- Tension Control Systems
Active tension feedback maintains constant fiber pull force. Tension sensors measure force before fiber contacts the mandrel. Motorized payoff systems adjust to maintain setpoint. Tension accuracy of ±0.1 grams is typical for precision coils. Control precision directly affects gyroscope performance.
Thermal Stress Management
Thermal stress remains after winding due to coefficient differences. Several strategies minimize stress effects.
- Coil Annealing Processes
Post-winding annealing reduces residual stress in the coil. Temperature cycles relax stress without degrading fiber properties. Annealing temperature must stay below fiber coating limits. Ramp rates control stress relaxation without causing movement. Annealing optimization balances stress relief against other coil properties.
- Adhesive Selection and Curing
Adhesive holds the wound fiber in its final position. Adhesive shrinkage creates additional stress during curing. Low-shrinkage adhesives minimize winding pattern distortion. Curing temperature cycles must be controlled carefully. Adhesive properties affect long-term coil stability significantly.
Performance Verification Methods
Completed coils must pass several tests before gyroscope assembly. These tests verify winding quality.
- Thermal Drift Measurement
The coil is mounted in a temperature-controlled chamber. Rotation rate output is measured during temperature cycles. Thermal drift in degrees per hour per degree Celsius is calculated. Acceptable drift depends on gyroscope accuracy requirements. Drift testing validates quadrupolar winding effectiveness.
- Vibration Sensitivity Testing
Coils are vibrated at specified frequencies and amplitudes. Output during vibration indicates stress asymmetry. High vibration sensitivity indicates winding tension problems. Vibration testing simulates deployment environment conditions. Dynamic testing verifies mechanical stability of the wound coil.
FAQs
1. What is the typical fiber length in a Φ120mm FOG coil?
Fiber lengths range from 500 to 2000 meters depending on sensitivity needs. Longer fiber increases sensitivity but also increases loss. The Φ120mm diameter coil holds approximately 500-1000 meters typically. Length is optimized for the specific gyroscope accuracy requirement. Shorter coils may be used for less demanding applications.
2. How does winding tension affect gyroscope bias stability?
Tension variations create stress-induced birefringence changes. These changes cause scale factor and bias errors. Better than 0.1 gram tension control achieves high bias stability. Poor tension control degrades bias stability to unacceptable levels. Tension uniformity is more important than absolute tension value.
3. Can a quadrupolar coil be rewound if defects are found?
Rewinding is generally not possible without fiber damage. The fiber takes a permanent set during initial winding. Removing the fiber for rewinding creates micro-bends. Coils with winding defects are typically scrapped. Quality control prevents defects through process monitoring.
Company Introduction: With over 20 years of deep industry expertise, we specialize in customizing and supplying solutions for optical fibers, cables, raw materials, and manufacturing equipment. We deliver reliable technical support and product services.
About the Author: With 20 years of hands-on experience in optical transmission media, cable assemblies, and core substrate materials, we offer practical, expert insights grounded in full-industry-chain expertise.