Signal stability and low noise in remote spectroscopy depend upon fiber optics with high transmission. The transmission must be affected very little by environmental influences such as temperature, vibration, and ambient light levels. From a patented fiber design to our emphasis on high-quality materials, Guided Wave spectroscopic grade fiber optic cable is designed for the highest performance in transmission efficiency and durability. For near-infrared fiber, a polyimide coating and a patented silicone based buffer protect the fiber from thermal stress.
The standard thermally stable NIR fiber optic cable receives a tough outer jacket made of Tefzel™ and inner Kevlar™ strands for strength. This rugged design prevents damage during installation.
Inexpensive 200 micron telecommunication/consumer grade fiber optic cables are not appropriate for spectroscopic applications, as they cannot bring enough light to the detector. Guided wave supplies 400, 500, and 600 micron fiber optic cables. The NIR-O and Clearview db are optically matched to 500 micron, as it provides the best compromise between flexibility for installation and light throughput.
Manufacturing High Performance Fiber
All Guided Wave NIR fiber optic cable is constructed as a core-and cladding composite. The core, the filament that guides the light, consists of a thin strand of high-transmissivity fused silica. The cladding is an outer layer of doped, lower refractive index fused silica. This two-layer design keeps the light tightly confined to the central core of the fiber thus delivering a maximum amount of light at the far end. The diameter is tightly controlled during the fiber drawing process. This produces a fiber that centers extremely well in connectors and has a very low loss rate per kilometer.
Unprotected silica fiber is quite fragile. To improve the fiber’s strength and flexibility, it is coated with a polyimide material during the drawing process. Then, another protective layer is added, a carbon-loaded buffer of silicone RTV (U.S. Patent #5,381,505). The buffer reduces stray light, both external ambient light that “leaks” through the jacket and internal stray light or “cladding” modes. Finally, we add an outer protective jacket. Our “process fiber” – fiber optic cable for harsh environment applications or applications requiring long cable runs – receives a multi-layer jacket made of Tefzel™ and Kevlar™.
Two Kinds of NIR Fiber Cable
Presently, Guided Wave offers two different kinds of optical fiber optimized for your spectral region of interest. Each type can be jacketed as outlined above and terminated in SMA or FC style connectors. Cables and bare fiber are available in a variety of core diameters from 200 μm to 600 μm (contact Guided Wave for alternatives). The type of cable you’ll choose depends on your application:
Thermally Stable Process Fiber provides the lowest possible amount of internal light attenuation. It is appropriate for visible or near infrared (VIS-NIR) spectroscopy. It is especially effective for applications that require increased sensitivity in the spectral region near 1385 nm or where very long cables are necessary (up to 300 m). This cable is effective over the spectral range from 400 nm to 2100 nm.
Lab Grade NIR Fiber, intended for short laboratory-bench runs, is typically sold with the lab NIR-O analyzer. This more flexible NIR fiber can be supplied in PVC-coated steel monocoil jacket, steel armored BX jacket, or PVC-zip tubing.
NIR Fiber Jacketing Options
- Process fiber cable: Tefzel™ Kevlar™
- Laboratory fiber cable: PVC-coated, steel monocoil jacket
- Armored fiber cable: Steel BX Armor with PVC Jacket (150 meter maximum length)
Available NIR Fiber Diameters
- 200 μm (15 meter maximum length)
- 400 μm
- 500 μm
- 600 μm
Fiber Termination Options
- SMA 905
- Custom (call)
- Bifurcated (call)
- SMA 905 and FC Bulkhead Unions
- SMA 905 to FC Adapter
- Fiber Termination Kit and accessories
- Calibrated torque wrench for SMA 905 connectors
|Product Name||Thermally Stable NIR
Process Spectroscopy Fiber
|Wavelength Spectral Range||400-2100 nm|
|Fiber Run Typical (Length)||5 to 250 m|
|Temperature Maximum - Bare or Armored (If High-Temp Epoxy is used for termination)||315 °C|
|Temperature Maximum - Tefzel Jacket (If High-Temp Epoxy is used for termination)||165 °C|
|Temperature Maximum - PVC (If High-Temp Epoxy is used for termination)||105 °C|
|Temperature Minimum (Contact Guided Wave for alternatives)||-20 °C|
|Baseline Attenuation (Unjacketed)||≤ 3 dB/km @ 1550 nm|
|Attenuation Difference (1385 nm – 1550 nm)||< 5 dB/km|