What is Raman Microscope?

When light is irraidated on molecules, the light is scattered by molecules. Most of scattered light have the same frequency with incident light but some fraction of light have different freqency due to interaction between oscillation of light and molecular vibration. The phenomenon that the light is scattered with frequency change is called Raman scattering. Because this frequency modulation is specific to molecular vibration and phonon in crystal, it is possible to analyze composition of material or crystal lattice information by anayzing spectrum of Raman scattered light. This analysis method is Raman spectroscopy. Furthermore to analyze in microsocpic area with Raman spectroscopy, Raman spectroscopy is combined with Microcope as Micro Raman Spectroscopy.

Recently it is becoming very popular that Raman spectrum are measured at every point in area and microscope image at certain spectrum band is reconstructed to see distribution of spectral information. Raman instrument that has an ablitiy to show Raman spectral image is called Raman microscope.

Becuase it is very long to measure Raman spectra at all points in area, some few Raman makers are adopting the fast imaging method. Among them, Nanophoton technology is the fastest method. RAMANtouch has multi-channel spectrocopy techonoly that measures multi spectra at the same time. Typically 400 spectra are measured simultaneously while other method is spectral measurement one by one.

Micro Raman Spectrocope

 

Raman image

An image consists of many pixel which has a value. Raman image data consists of many spectrum and Raman image consists of pixes of value which are calculated from the band selection in Raman spectrum.

Spectral image is obtained by Laser Raman Microscope.

 

This Raman image shows distribution of several materials. Different material is expressed with different color. It is observed that Potassium phosphate (blue) and glucose (green) are distributed in the image. These materials have specific spectrum shown in the figure.

Raman shift

 
 

Raman color image make us understand how materials are distributed very obiously and easily becuase each material is shown with each color even though optical microscope can not tell the material difference. The figure shows the mixture sample of two different particles.

Purple:Condensation of Benzoguanamine and formaldehyde
Green:Polystyrene particle

Optical microscope image and Raman microscope image