Fiber optic cables carry light between the key components of a spectroscopy system, from light sources and samples to probes and spectrometers. Their optical performance, however, can change through routine use or exposure to challenging conditions. Tight bends, mechanical strain, deep-UV radiation, temperature fluctuations, and contamination can all reduce transmission over time. Good cable protection combines careful routing and connector maintenance with suitable fiber materials and protective jacketing, helping spectroscopy systems retain stable optical performance in laboratory and industrial environments.
Environmental and Mechanical Hazards in Fiber Optic Cable Setups
Fiber optic cables lose optical performance when mechanical stress or environmental exposure changes the condition of the fiber, its protective components, or its terminations. Common hazards include:
- Bending and mechanical strain- Macro-bending occurs if a cable follows a curve tighter than its recommended bending radius, allowing guided light to escape from the core into the cladding. Smaller distortions, known as micro-bends, introduce additional attenuation. Repeated flexing or excessive strain may also produce micro-fractures in silica, especially near termination points where mechanical forces become concentrated.
- Deep-UV exposure and Solarization- At wavelengths below approximately 230 nm, high-energy photons can cause solarization in standard silica fiber by forming color centers within the glass. These defects absorb portions of the transmitted radiation around 214nm, progressively reducing optical throughput during prolonged UV measurements. Avoiding solarization is particularly relevant to semiconductor photolithography monitoring, UV curing analysis, plasma emission spectroscopy, and excimer-lamp characterisation due to their use of deep-UV wavelengths.
- Temperature extremes- Elevated temperatures can affect the silica fiber, protective jacket, connector hardware, and bonding materials differently as they undergo thermal expansion. Repeated temperature changes may therefore place additional stress on a fiber optic cable assembly, while unsuitable jacketing or bonding materials can deteriorate prematurely in high-temperature environments.
- Chemicals, moisture, and abrasion- Chemical vapors, liquids, moisture, and physical abrasion can damage exposed cable components in process environments. Fiber optic cables used for reactor monitoring, combustion analysis, or chemical processing thus require protection suited to both the optical measurement and surrounding operating conditions.
In addition to cable conditions, other factors can affect transmission through the spectroscopy system. Contamination or poorly maintained terminations can introduce coupling losses. Additionally, fiber geometry should correspond with spectrometer entrance optics. For example, arranging multiple fibers in a linear array or using a bigger core fiber can match a 1 mm high spectrometer slit more efficiently than presenting the same fibers in a round bundle, helping more collected light reach the detector.
Protecting each component of the setup from avoidable sources of optical loss helps preserve consistent transmission and measurement performance over time.
Best Practices for Maintaining and Protecting Fiber Optic Cable Setups
Careful routing reduces the mechanical strain on the fiber optic cable before it affects measurement performance. Fiber optic cables should follow stable paths with gradual curves, sufficient slack, and secure strain relief near connectors. Moreover, fixed routing is extremely useful around movable sampling equipment, production machinery, and optical benches, where accidental pulling can transfer force directly to fiber terminations. Minimum bend-radius specifications should guide installation and subsequent repositioning.
Connector cleanliness deserves similar attention because contaminants can interfere directly with optical coupling. Dust, fingerprints, oils, and residues on SMA-905 or FC/PC connector surfaces can increase insertion loss and damage the fiber end face. A consistent inspection and cleaning procedure helps maintain transmission between instruments. Technicians should inspect optical surfaces before connection, use suitable fiber-cleaning materials, and protect disconnected terminations with clean caps.
Fiber selection also influences how effectively the cable transmits light across the required spectral range. Common choices for fiber optic cables include:
- High-OH silica fiber for UV/VIS measurements, where strong ultraviolet transmission is important.
- Low-OH silica fiber for VIS/NIR spectroscopy, where reduced hydroxyl absorption supports near-infrared transmission.
- Solarization-resistant fiber for sustained deep-UV measurements below approximately 230 nm. (Presolarization of the fibers (exposing it to UV light for several hours) guarantees stable transmission from the outset.)
- Solarization-resistant broadband fiber, which combines all 3 qualities above, offering good transmittance in the UV/VIS/NIR, including sustained deep UV measurements below 230nm.
Choosing the correct fiber material reduces avoidable transmission losses and supports consistent spectral performance throughout the operating range.
Matching Sheathing and Hardware to the Environment
Standard laboratory spectroscopy works well with lightweight, flexible protection that allows fiber optic cables to move without exposing the silica to unnecessary strain. Kevlar-reinforced polyvinyl chloride (PVC) sleeving with internal polytetrafluoroethylene (PTFE) tubing provides practical protection against routine handling around spectrometers, light sources, and sampling accessories. Its flexibility suits research benches where equipment configurations may change regularly.
Industrial installations place greater mechanical demands on fiber optic cable assemblies. Stainless steel BX armor can offer robust protection in environments that carry the risk of crushing or heavy mechanical contact. Chrome-plated brass mono-coil and flexible hooked-profile ME jacketing act as alternative constructions for abrasive or demanding environments. Furthermore, silicone-coated stainless steel mono-coil, identified as MS jacketing, delivers another protective option when cable assemblies need additional mechanical resilience.
High-temperature measurements need all components of the fiber optic cable assembly, not just the external jacket, to withstand elevated temperatures. Specialised high-temperature epoxies, metal sleeving, and thermal-resistant components help fiber assemblies tolerate increased thermal conditions. Such configurations are relevant to combustion studies, heated reaction vessels, industrial furnaces, and process monitoring near hot manufacturing equipment, where conventional cable materials may deteriorate prematurely.
Robust Fiber Optic Cables From Avantes
Avantes offers fiber optic cables engineered for spectroscopy systems spanning UV, visible, and NIR measurements, including broadband 200-2500 nm fibers, solarization-resistant options for sub-240 nm work, and core diameters from 8 µm to 1,000 µm. Our fiber optic cables can be supplied with several protective jacketing options, including Kevlar-reinforced PVC, chrome-plate brass, stainless steel BX, silicone-coated stainless steel MS, and specialised configurations for high-temperature environments. Advanced round-to-linear bundles are also available to improve coupling to 1 mm high spectrometer slits. Contact Avantes now to specify which of our fiber optic cables would best fit your wavelength range, measurement geometry, and operating environment.