Raman Spectroscopy
Durable filter coatings for reliable material analysis
Raman spectroscopy enables the analysis of gases, liquids and solids. In this process, scattered light is used that is produced by irradiating a substance with monochromatic light, called Raman scattering. The aim of Raman spectroscopy is the determination of vibrational and rotational states of molecules and their characterization in groups for the determination of structure and compound of a material. In order to obtain the useful information, the Raman scattering must be filtered out of the beam path.
Origin of the Raman Effect
Figure 1: Functional principle of a laser blocking filter
The Raman effect results from intensive monochromatic laser irradiation of a sample and the associated excitation of molecules. The lines in the scattering spectrum of the molecules differ in their frequency from the lines of the incident light. This circumstance is based on the interaction between electromagnetic radiation and electron sheath, which results in molecular oscillations and rotations. A large part of the laser light shines through the sample. A very small part of the laser light is scattered in all directions of space, called elastic or Rayleigh scattering. The minimal residual scattering detected by the spectroscope is the inelastically scattered Raman scattering, which contains the necessary information to the fabric sample.
Optimization of Raman scattering through high-quality filters
For the detection of Raman scattering by a spectrometer, the blocking of simultaneously occurring scatterings - such as those of the more intense Rayleigh scattering - is necessary (see figure 1). Special filters allow unwanted scattering to be blocked and allow only the desired Raman scattering to pass through. For optimum filter results, efficient, high-quality filter coatings are required. asphericon’s durable dielectric-based filter layers guarantee stress-reduced transitions in the fitting and blocking area for optimum results.
In addition to precise filters for the wavelength separation of laser light, you can also choose from a wide range of high-quality optics. For example, a completely diffraction-limited optical system that convinces not only with its best image quality but also with its compressed design.
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