Sensor Fiber Optic Stripping Principle

Fiber optic stripping for sensors can be performed using mechanical, thermal, chemical, laser, or solvent-based methods, each tailored to the fiber type and coating material.

Mechanical Stripping

Mechanical strippers use precision blades to remove the fiber coating without damaging the glass cladding. They are widely used for end stripping and mid-span “window” stripping, especially for acrylate-coated fibers. Adjustable mechanical strippers allow for different fiber diameters and coating thicknesses, providing high-strength fusion splices when properly used.

However, tool wear and operator skill can affect repeatability and may introduce nicks on the fiber surface, reducing tensile strength and splice quality.

Thermal and Thermo-

Mechanical Stripping

Thermal methods soften the coating using heat, sometimes combined with mechanical blades to remove it. Non-contact thermal techniques, such as 3SAE's Burst™ Technology, use superheated air or nitrogen to cleanly burst the coating away from the fiber. These methods are chemical-free and suitable for high-strength applications like fiber Bragg gratings or mode field adaptors.

Thermo-mechanical stripping is also used for end stripping of single and ribbon fibers but may risk uneven coating removal or heat damage to surrounding buffers.

Chemical Stripping

Chemical stripping involves solvents or acids to dissolve or soften the coating. For polyimide-coated fibers, a mixture of methanol and acetone (2: 1 ratio) can be used to soak the fiber for several hours, causing the coating to expand and separate from the glass. After soaking, standard mechanical strippers can remove the coating easily.

This method is inexpensive and avoids the need for specialized equipment, but requires careful handling to prevent fiber damage. Laser StrippingLaser-based stripping, such as UV laser systems, provides a non-contact, automated method for removing coatings from single or ribbon fibers. This approach maintains high tensile strength, repeatability, and cleanliness, making it suitable for high-volume sensor fiber production.

Laser stripping is particularly advantageous for mid-span stripping and complex fiber geometries where mechanical or chemical methods are less effective.

Specialized Sensor Fiber Methods

For distributed sensing fibers, the striping-inscribing-recoating (SIR) method is used to fabricate kilometer-long backscattering-enhanced fibers. This method combines continuous low-loss stripping with grating inscription and flexible recoating, enabling sensor deployment in harsh environments. It ensures precise control over the stripped regions and maintains fiber integrity over long lengths.

Summary

The choice of stripping method depends on the fiber coating type, application requirements, and desired precision. Acrylate coatings are often stripped mechanically or thermally, polyimide coatings benefit from solvent-based methods, and high-precision or automated sensor applications may use laser or SIR techniques. Proper selection ensures high fiber strength, clean surfaces, and reliable sensor performance.