Spectroscopic Measurements: Exploring Matter Through Its Light
Need to identify, control, or monitor a material? The answer is often spectroscopic. Spectroscopy makes it possible to analyze matter by studying the light it emits or absorbs. At the heart of optical, photonic, and quantum technologies, it reveals information invisible to the naked eye and has become an essential tool in science, industry, and space exploration. Spectroscopic measurements were developed in the 19th century by Robert Bunsen and Gustav Kirchhoff at the University of Heidelberg in Germany to solve a major scientific and chemical problem: reliably identifying the elements present in complex substances — a task beyond the capabilities of traditional methods of the time.
This article invites you to discover how spectroscopic measurements work and why they have become indispensable in many technological applications.
How can we analyze light beyond its simple appearance? At the intersection of physics and chemistry, spectroscopy decomposes the light emitted or absorbed by matter to reveal its composition and fundamental properties. Used in laboratories, astronomy, medicine, and industry, this discipline derived from photonic optics transforms a natural phenomenon into precise data essential for many advanced technological applications.
Spectroscopic measurements rely on the precise analysis of interactions between light and matter. By decomposing electromagnetic radiation into its different wavelengths, spectroscopy makes it possible to characterize the chemical composition, structure, and physicochemical properties of a sample. These measurements quantify quantities such as absorbance, transmittance, reflectance, emission, and scattering, each revealing specific information about the material under study.
To obtain these data, sophisticated instruments are used, consisting of an appropriate light source (lasers, light-emitting diodes, broadband lamps), an optical system for spectral separation (diffraction grating, monochromator, interferometer), and a sensitive detector (photodiode, CCD camera, bolometer) coupled with analysis software. These spectrometers generally operate as point sensors, collecting light from a small area via an optical fiber or collection system, then extracting a precise spectrum without forming an image. This approach differs from hyperspectral cameras, which produce spectral images.
Spectroscopy exploits various optical phenomena depending on the mode of interaction between light and matter: absorption to study characteristic absorption bands, emission to analyze spontaneous or stimulated light, reflection and transmission to characterize surface and internal structure, and scattering to study the angular distribution of light. Unlike mass spectrometry, which analyzes ions in the gaseous phase, spectroscopy is non-destructive and based on photonic interactions.
This technique finds extensive applications in astronomy, where it enables the identification of the chemical composition of stars and galaxies — nearly 75% of the James Webb Telescope’s data are spectral — but also in industry for quality control, contaminant detection, and material characterization. In biology and medicine, spectroscopy is used for the non-invasive analysis of tissues and fluids, notably through Raman or infrared spectroscopy. It is also used in precision agriculture, remote sensing, photonics, and analytical chemistry.
Its main advantages lie in its ability to provide rapid, precise, and non-destructive analysis, often without contact, with high chemical selectivity. It can be easily integrated into automated and embedded systems and now benefits from artificial intelligence techniques to detect subtle variations that the human eye cannot perceive, thereby enhancing its relevance and efficiency in complex environments.
In summary, photometric measurements play a crucial role in translating light into understandable and usable data, aligned with human perception. Through strict standards and specialized instruments, they ensure quality, safety, and visual comfort in many fields, from public lighting to advanced technologies. Mastering these measurements means mastering light itself — to better illuminate our daily lives and our innovations.
Optech supports companies in the implementation of precise spectroscopic measurements, whether for research, quality control, or the development of innovative products.
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