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One of the founding fathers of spectroscopy is Issac Newton, who observed the color series using a prism and sunlight1 - he called this color series 'spectrum' (Latin for 'appearance'). Many well-known researchers continued these observations over the decades ...

Optical spectroscopy' refers to vibrational spectroscopy and electron excitation spectroscopy. They can be performed using typical optical components such as mirrors, lenses, gratings and prisms. Optical spectroscopy includes the techniques of: Infrared spe...

Matter can reflect or absorb electromagnetic radiation or the radiation can pass through the matter with little or no interaction. In the latter case, this is referred to as transmission.  The three basic principles of the interaction of light and matter If ...

All methods of optical spectroscopy have in common that absorption and emission are based on the quantum physical nature of light, i.e. the spectra obtained show discrete energy levels of electronic excitation or vibrational excitation. All observed energy lev...

UV and VIS spectroscopy is based on the excitation of electrons in the outer electron shell (orbital) of an atom or molecule. The energy input of the excitation radiation transfers electrons from the highest occupied orbital - the ground state - to the lowest ...

The essential component to obtain the spectrum at all is the 'dispersive element' or the 'dispersive unit'.7  If the dispersive element is additionally coupled with a slit to select a single wavelength, it is also referred to as a monochromator.  Fundamental ...

The beam path of optical spectrometers is always based on the same principles. The radiation first passes through a monochromator, then the sample and is then recorded by the detector. Due to the scanning process of the monochromator through the spectral range...

UV-VIS Spectroscopy For UV-VIS spectroscopy, a wide range of possible combinations of excitation source, optics, measuring geometry and sample chamber as well as detectors are available, which can be specifically selected depending on requirements. If, for ex...

Process spectroscopy has been firmly established in the industrial environment for many decades. The resulting spectral data is subject to automated evaluation procedures/methods. These automated methods monitor the process, the medium or the product. They con...

Imaging spectroscopy is an umbrella term for all techniques and possibilities for recording spectra that produce an image of a sample or measurement surface. It is a powerful tool for visualizing the relationships between the observed process and the propertie...

The referencing of spectra is one of the most important steps in the pre-processing of spectra, as the aim is to measure precisely and correctly. Once spectra have been recorded in insufficient quality or incorrectly referenced, improvement is not possible eve...

The multivariate methods of chemometrics - often also referred to as data mining, machine learning or deep learning/AI - offer the possibility of making superimposed and hidden information visible in the spectra. When using machine learning or AI methods, prec...

The choice of an optical spectroscopy technique, the measurement setup and the recording of the spectra must be carefully considered, and the following overviews are intended to provide an initial starting point.   Electron excitation Vibrat...

Modern industrial processes require ever-improving optical inspection for the in-process evaluation and assessment of products. Over the past two decades, optical non-contact technologies have been developed which, under the collective term 'machine vision', h...

In order to obtain a spectral dispersion, different spectrometer concepts are used for spectral imaging. Multispectral imaging: Multi-sensor: beam splitter and use of filters for several sensors; usually <10 spectral channels Multi-channel: spectral dis...

The optics/lenses of most HSI systems are variable, e.g. via the industry standard C-mount. This results in a wide range of configuration options, as illustrated in Fig. 3. The minimum working width of the HSI system is determined by the focal plane of the len...

As with other spectral methods, hyperspectral imaging involves an interaction (absorption, reflection) of the light with the sample. For this reason, broadband sources are preferred for illumination. For the spectral ranges mentioned, these are, for example, h...

One of the most important tasks in preparation for data acquisition is to focus the object under investigation. The wavelength at which the detector has the highest sensitivity or quantum efficiency should initially be selected as the focal point. With known s...

If a contextualization into a larger sample (or spectra) population is required or if correlations are to be examined that are not visible at first glance in individual samples, a machine learning approach respectively a mathematical-statistical evaluation of ...

In contrast to the machine learning methods of the 'soft modeling' approach, there is also the 'hard modeling' approach for evaluating the spectra. This refers to the physically exact description of the data. The simplest case is Lambert-Beer's law for describ...