Why Use NIR Spectroscopy

Theory of Operation

Traditionally, absorption spectroscopy has been used in laboratories to perform precise analyses. For production environments, a very robust portion of the electromagnetic spectrum—UV/Vis/NIR—emerged for process analytics.

Absorption spectroscopy is a proven analytical technique

Although NIR data was once considered a challenge to interpret because of broader, overlapping peaks than in the IR region, the NIR region is information-rich and has many practical advantages when applied in a process environment. One of these advantages is the reliable performance of online fiber-optic coupled analyzers. The analyzer can be located in a safe environment away from the sample interface (sampling point) which is located in the process stream … thus giving the process engineer or operator simultaneous real-time information for multiple parameters as it occurs within the process. In addition, software tools evolved to make NIR interpretation routine and are performed automatically to provide the actionable information the operator needs. Process analyzer professionals and reliability engineers are now well-experienced in NIR-based analyzer system deployment throughout their plants.

Online, fiber-optically coupled NIR Analyzer Systems provide simultaneous real-time compositional and physical parameter information for better process control when more efficient light sources and more sensitive detectors became available decades ago, use of NIR online analyzer systems proliferated because spectral peaks could be more accurately measured, which results in more usable data for spectral analysis. In practice, NIR optical paths are much larger than those used for IR techniques, which allows for easy probe cleaning and servicing, when needed.

NIR sample interfaces are robust for long-term performance but also practical in size for easy cleaning or servicing, if needed.

A key benefit of an NIR spectrometer analyzer system includes the ability to quickly and accurately measure samples while keeping the main analyzer away from any potentially dangerous processes. Fiber optic cables connecting the sample interface (insertion probe, flow cell, vapor cell, etc.) to the analyzer make this possible. Carrying light energy over distance through a light-conduit (optically efficient fiber optic cables) can potentially introduce error sources for light measurement because the light must travel from the spectrometer to the optical probe and then back to the spectrometer for analysis. To perform optimally, it is especially important that all the components within the total analyzer system be tuned to work efficiently with each other. At Guided Wave all fiber optic cables, spectrometers, photometers, and optical probes (sample interfaces) are all designed and tested to ensure optimal transmission and compatibility. The improved transmission causes the NIR data to be more accurate and thus more accurately analyzed.

Optically matched and optimized components to increase the performance and reliability of the total analyzer system.

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