General diagram of a Micro Raman Spectrometer
The MicroRaman spectrometer is designed for Raman spectroscopy of microscopic areas or microscopic samples. It can be configured with different color lasers resulting in different information about the sample from the Raman scattering.
MicroRaman Spectrometer Components
The micro Raman spectrometer, also called a Raman microspectrometer, combines aspects of both the microscope and the Raman spectrometer. In actuality, the micro Raman spectrometer is a fully integrated, purpose built instrument that can do Raman spectroscopy and digital imaging of microscopic samples.
Individually, the microscope is an optical instrument that uses lenses and mirrors to produce magnified images of microscopic objects or microscopic areas of larger objects. The sample is illuminated, through the objective, with a laser of a very narrow wavelength range.
The objective of the microscope is then used to collect the Raman scattered light from the sample. The light is focused and forms an image on the entrance aperture of the Raman spectrometer.
The Raman spectrometer portion of the MicroRaman spectrometer is an optical instrument for measuring the intensity of light relative to its Stokes shift from the wavelength of the exciting laser light. This shift is given in wavenumbers. A beam of light, collected from the sample, enters the device and is separated into its Stokes shifted frequencies by a diffraction grating. The separated light is then focused onto a CCD array detector where the intensity of each frequency is then measured by an individual pixel on the array. The CCD is then read-off to a computer and the result is a spectrum which displays the intensity of the inelastically scattered light vs. wavenumbers relative to the wavelength of the exciting laser.
In a micro Raman spectrometer, such as those from CRAIC Technologies, the Raman spectrometer is integrated with a specially designed microscope. The Raman spectrometer is built into the microscope, along with a digital imaging system, so that the maximum amount of light can be collected from the smallest samples. As such, micro Raman spectrometers are very flexible instruments able to measure the Raman spectra of microscopic areas.