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Here we introduce a series of filters, which are used in Fluorescence and Raman spectroscopy.
Fluorescence analytical instrument:
Fluorescence analysis: It is an analytical method, which takes an advantage of the characteristic that fluorescent material emits light at one wavelength when excited by an incident beam of a different wavelength.Raman spectroscopy: Raman effects was discovered in 1928 by Dr. V. Raman who was Indian and was the first Nobel prize-winner in Asia.This is an analytical method, which is used in wide fields such as spot area analysis combined with a Laser, which was invented in 1960s and with optical microscope in late 1970s.These measurement instruments deal with very fine and weak signals and as a consequence the optical elements are require high performance.
Configuration of optical filers in Fluorescent and Raman analysis is shown in figure 1.
BPF (Band Pass Filter)
This BPF is for passing only the wavelength of the exciting beam and cutting the remainder. It may require blocking over a wide range of wavelength depending on the measuring equipment.
DM (Dichroic Mirror)
The DM is usually placed at 45 degrees to the incident light and is designed to reflect an exciting beam so that it impinges on the object and then passes the fluorescent or Raman scattered light for observation.
Edge Filter
An Edge filter is required to have a very steep cut on characteristic so as to pass only fluorescent or Raman scattered light while blocking any unnecessary light from the object such as the reflected exciting beam.
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