Spektroradiometers

Spektroradiometers are instruments designed to measure the spectral power distribution of electromagnetic radiation, typically in the visible and near‑infrared ranges. They are widely used in fields such as photometry, color science, agriculture, and environmental monitoring to quantify how energy is distributed across wavelengths. Unlike conventional photometers that provide a single light intensity value weighted by a human‑eye sensitivity function, spektroradiometers record a full spectrum, enabling detailed analysis of material reflectance, color balance, and energy efficiency.

The basic principle of a spektroradiometer is based on an optical system that disperses incoming light into its constituent wavelengths using a prism, diffraction grating, or filter wheel. The dispersed light is then detected by a linear array of sensors or a set of narrow‑band detectors. Modern devices often employ silicon or InGaAs photodiode arrays, digital signal processing, and calibration routines to convert raw sensor outputs into spectrally resolved radiance or irradiance values. Calibration is typically achieved with laboratory light sources of known spectral power distribution, such as calibrated lamps or blackbody standards.

Spektroradiometers are classified by several criteria. Spectral resolution, the smallest distinguishable wavelength interval, ranges from a few nanometers for high‑resolution colorimetry to tens of nanometers for broad spectral analysis. Measurement range can extend from deep ultraviolet to mid‑infrared. Portability is another factor; handheld, benchtop, or airborne instruments differ in form factor and data handling capabilities. Many modern spektroradiometers also integrate a reference detector for real‑time correction of ambient fluctuations.

Typical applications include the assessment of crop health through vegetation indices, monitoring of air quality and pollutant spectral signatures, verification of lighting products against standardized color rendering indices, and the measurement of solar and artificial light sources for energy‑efficiency certification. In research, spektroradiometers support studies of material reflectance, luminaire design, and imaging system calibration. Their ability to provide precise, wavelength‑specific information makes them indispensable tools in both applied and fundamental science.