When using a UV-Vis-NIR spectrometer or spectroradiometer to detect and analyze light over a spectral range, ensuring that the light signal reaches your instrument’s detectors with minimum attenuation is paramount to obtaining high-quality spectral data. Typically, the delivery of a light signal to an instrument is achieved using a fiber optic cable. With a variety of options available, there are several key features to consider when choosing the best fiber optic cable for your research.
1 – Quality & Durability
A fiber optic cable consists of a bundle of ultra-fine optical fibers contained within a protective jacket. Light signal travels through the individual fibers to your instrument’s detectors. The quality and integrity of each optical fiber are crucial to delivering the maximum amount of light. Due to their thin geometry, optical fibers are prone to breaking, and each broken fiber contributes to loss of signal, affecting your data. Choosing a high-quality, rugged fiber optic cable will minimize fiber breakage and maintain the highest spectral transmission with every scan.
2 – Fiber connection
Many manufacturers use signal-quenching couplers to mate their fiber optic cable to another fiber optic cable inside the instrument. To maintain a full signal through both cables and the coupler, the fibers must align perfectly, which is impossible to achieve with a fiber coupler. If the alignment is off, there is the potential to block some of the fibers from receiving the full signal. A fiber that can be directly mated to the entrance slit of the spectrometer will ensure seamless signal transmission and provide a much better signal-to-noise ratio.
3 – Replaceability
A fiber optic cable is the most fragile part of a spectrometer system. For instruments utilizing a fixed fiber optic cable, breakage means returning your instrument to the factory for repair and losing precious months of field campaign work.
4 – Calibration
Radiometric calibration involves converting values in a remotely sensed image to known spectral radiance values. For direct energy measurements such as radiance and irradiance, calibration is vital to collecting accurate and traceable data.
Spectral Evolution spectroradiometers are the only portable instruments on the market today with field-replaceable fiber optic cables. Our custom-made fiber optic cables are in a rugged yet flexible stainless steel jacket and mated directly to the spectrometer slit utilizing an innovative termination designed to ensure the highest spectral transmission. Each optical fiber in Spectral Evolution cables route to a rectangular opening at the extremity.
The precise fit and alignment of the fiber optic cable against the spectrometer slit ensures that the fiber optic can be replaced in minutes right in the field without loss of calibration. This unique design also delivers a much higher signal level to the detectors resulting in a significantly better signal-to-noise ratio.
The opposite end of a Spectral Evolution fiber optic cable features an SMA connector that allows for quick connection with various fore optics and accessories:
- Lenses that can reduce the fiber’s field-of-view cone from 25° down to as small as 1°
- Diffusers providing a 180° field of view, perfect for global irradiance measurements
- Reflectance contact probes with internal light sources for direct contact measurements
- Leaf-clip for precise reflectance measurements of leaves and other thin samples
- Integration, reflectance, and transmittance spheres
- Pistol grip fiber holder to ensure stability and accurate positioning of the fiber in regard to the target area.
Spectral Evolution fiber optic cables are radiometrically calibrated with the instrument to NIST standards before delivery. We keep a variety of standard fiber optic cables in stock and offer customized fibers with specific lengths, number of optical fibers, or bundle geometries.
A fiber optic cable is essential to retrieving optimum spectral data with UV-Vis-NIR spectrometers. Don’t settle for mediocre data or lost time in the field due to a broken fiber. Try the Spectral Evolution difference!
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