Quadrupole Winding Pattern and Mechanics
Optical fiber gyro coils are commonly wound in a quadrupole pattern to reduce errors associated with thermal gradients and vibration. A typical quadrupole pattern (see Figure 1) is accomplished by beginning at the center of a fiber length and winding alternately from two feed reels each containing half the length. Coil winding is functionally divided into four operations:
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- Wind the base layer on a smooth surface having no features that determine the position of individual fiber turns
- Wind the mid-layer portions of layers (after the base layer) in the larger portion of individual turns where fiber lies in a groove formed by two adjacent underlying turns
- Make crossovers once in each winding turn (see Figure 2), where fiber crosses from one groove into the next groove in line
- Make transitions from completed layer to next higher layer
Each of these regions is unique in terms of the challenges presented to the coil winding process. The winding machines and proprietary winding methods assure successful completion of the overall winding in a consistent, repeatable manner.
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| Figure 1 |
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| Figure 2 |
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Winding Machine Development
We design and build semi-automated winding machines optimized for producing optical fiber gyro coils. These machines:
- Allow access to the coil for observation and fiber position adjustment
- Provide machine functions required to produce a quadrupole pattern wound gyro coil
- Eliminate hand contact associated with transfer between the two feed reels
- Maintain a consistent low tension during all stages of the winding
- Automate the correlated motions of product spool rotation and product spool axial traverse for maintaining a constant fiber feed angle
The philosophy for development of a quadrupole pattern optical fiber coil winding machines was established from the baseline configuration concept shown in Figure 3. In this concept, one side of the assembly turns with the product spool while the other side feeds fiber with servo control feedback provided by a low tension dancer arm.
The degree of automation achieved in our winding machine allows a skilled operator to devote full attention to fiber placement. As a result of this combination of machine design and operator proficiency, total winding precision is achieved in the resulting coil.
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| Figure 3 |
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