Nearinfraredteknik

Nearinfraredteknik refers to techniques that employ near-infrared light to analyze or image materials. The near-infrared region spans roughly 780 to 2500 nanometers and lies between visible and mid-infrared radiation. In this region, many organic molecules exhibit overtone and combination vibrations, notably involving C-H, N-H and O-H bonds. The resulting spectra are broad and overlapping, requiring multivariate calibration and chemometric methods to extract quantitative or qualitative information.

Two main forms are used: near-infrared spectroscopy (NIRS), which measures spectra for bulk samples and can be performed as diffuse reflectance, reflectance, or transmittance; and near-infrared imaging, including hyperspectral imaging, which adds spatial information. FT-NIR instruments, dispersive spectrometers, and various detectors such as InGaAs are common, with light sources ranging from tungsten halogen to specialized LED or laser-based emitters.

Applications are broad: quality control and process monitoring in food and feed, agriculture (moisture, protein, sugar content), pharmaceuticals (content uniformity and moisture), polymer and wood industries, and increasingly medical and biomedical research. In remote sensing, NIR data contribute to vegetation indices and soil analysis. Data interpretation relies on chemometrics, with methods such as partial least squares (PLS) regression, principal components analysis (PCA), and machine learning. Calibration models require representative samples and ongoing transferability checks.

Limitations include strong scattering in solids, dependence on calibration to specific materials, and limited depth penetration in turbid samples. Nearinfraredteknik continues to evolve with portable devices, hyperspectral systems, and advanced data analytics, enabling rapid, non-destructive analysis across diverse sectors.