This article provides an overview of the concepts of spectroscopy, spectral sensing, and spectral sensors. It explains how spectral sensing works, what information it provides, and how it can be used in research and industry applications.

What is spectroscopy?

Spectroscopy, also called spectral sensing, studies how light interacts with materials. It provides detailed information about the objects’ or scenes’ reflectance or emission properties. It’s an excellent tool for studying and identifying materials and defining material properties. Spectroscopy recognizes materials based on their unique spectral signatures by examining how light behaves in the target.

Spectroscopy is used to identify, classify and quantify materials in various application fields.

There are many different types of spectroscopy, including absorption spectroscopy, emission spectroscopy, reflection spectroscopy, and fluorescence spectroscopy. Different types of spectroscopy are used for specific applications and can be performed in a laboratory or remotely in a field setting. The most common way to use hyperspectral imaging is to measure the reflection spectra.

What is a spectral signature?

A material’s spectrum defines how much light the target emits, reflects, or transmits per wavelength.

Every material and compound interact with light differently, meaning that every material has unique spectra. In other words, the material’s spectrum depends on the material chemical composition and physical characteristics.

Just like fingerprints can be used to identify a person, spectra can be used to identify different materials. These spectral signatures of different materials can be captured with spectral sensors.

What is a spectral signature

What are spectral sensors, and how do they work?

Spectral sensors, also called spectrometers are instruments that are used in spectroscopy to study light. Spectral sensors capture and measure the light reflected or emitted by an object or scene in the form of a reflectance spectrum.

Reflectance spectrum

In short, the spectrum tells how much the target emits, reflects, or transmits light and how much specific color this light contains. This information can be used to identify and map the chemical and physical properties of the objects.

Reflectance spectrum - Emitted, reflected, transmitted

The spectrum is divided into multiple narrow bands, each corresponding to a specific wavelength of the electromagnetic spectrum, typically in the visible and near-infrared regions. Spectrum describes the amount of light at different wavelengths. The usual way to present a spectrum is a graph on a scale of intensity and wavelength.

Reflectance spectrum - Intensity & Wavelength

Spectral sensors can be divided into two main categories: point spectrometers and imaging spectrometers. Point spectrometers measure the light spectrum from a single point and are commonly used for laboratory analysis or in-situ measurements.

Imaging spectrometers, also called hyperspectral cameras, collect and process data from a large area to create a hyperspectral image providing both spectral and spatial information about the object.

The spectral information allows the identification and quantification of materials and substances present in the object. Spatial information tells how the material is distributed in the object or scene.

How can spectroscopy be used in research and industry applications?

In industry and research, spectroscopy is widely used in chemistry, biology, materials science, environmental science, and physics to study the properties of materials and substances, including their chemical composition, molecular structure, and reactivity.

In recent years, spectral sensors have become widely used also in various industrial applications, including mineral exploration, waste and food sorting, quality control, and many others.

Different spectral sensors are designed to cover a specific wavelength range of the electromagnetic spectrum, such as visible, near-infrared, short-wave, mid-wave, and long-wave infrared regions.

Spectral sensors operating in different wavelength ranges are suitable for various applications because different wavelengths reveal other spectral characteristics.

Defining the proper wavelengths and selecting a camera with suitable spectral and spatial resolution must be considered when designing a spectral imaging system for a specific application.

Specim offers the broadest range of hyperspectral cameras covering wavelengths from VNIR, NIR, SWIR, MWIR, and LWIR, widely used in the industry, research, and airborne applications.

Our experienced team of application specialists can help you with testing the feasibility of hyperspectral imaging and selecting the right kind of camera for your application.