Standard Dimensions of High-Temperature Temperature Measuring Optical Cables

High-temperature optical cables typically use fibers with diameters of 200 µm or more, coated with polyimide, metal, or sapphire, and assembled in protective sheaths designed for extreme environments.

Fiber Core and Coating

For high-temperature applications, the fiber core diameter is commonly 200 µm, although smaller or larger diameters can be customized depending on the sensing system and measurement accuracy requirements. The coating material is critical for temperature resistance: Polyimide coatings: Suitable for temperatures up to ~300°CMetal coatings (aluminum or copper): Extend temperature tolerance to ~400–500°CSapphire fibers: Can withstand temperatures up to 1000°C and are used in extreme environments Cable ConstructionHigh-temperature optical cables are often constructed with multiple layers to ensure mechanical protection and thermal stability: Inner fiber: Single or multi-mode fiber, typically 200 µmBuffering: Optional polymer or metal buffer to protect the fiberSheathing: Metal tubing, stainless steel armor, or high-temperature polymers like PTFE or PE for environmental protection Connector type: ST or customized ferrules for high-temperature feedthroughs Standard Dimensions and LengthsFiber diameter: 200 µm (standard for high-temperature measurement)Cable outer diameter: Varies depending on protective layers; typical ranges from 2 mm to 6 mm for metal-free or armored cables Minimum bending radius: Short-term ~120 mm, long-term ~100 mm to prevent fiber damage Standard lengths: 2 m up to 20 m, extendable to 30 m with additional protective sheathing Environmental and Mechanical ConsiderationsHigh-temperature optical cables are designed to withstand: Operating temperatures: From -40°C to +800°C (silica fiber) or up to +1000°C (sapphire fiber)Mechanical loads: Short-term up to 1200 N, long-term up to 1000 NProtection against chemicals and abrasion: Metal or high-temperature polymer sheaths prevent degradation of the fiber and maintain optical performance CustomizationMany manufacturers offer custom dimensions for high-temperature optical cables, including: Fiber diameter adjustmentsCable outer diameter and sheathing materialsConnector types and feedthroughs for integration into industrial systems In summary, the standard high-temperature optical cable uses a 200 µm fiber with polyimide or metal coating, an outer diameter of 2–6 mm, and lengths from 2 to 20 m, with construction tailored to withstand extreme temperatures and mechanical stress.