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RazorEdge Filter Layout

by IDEX Health & Science

In many Raman spectroscopy layouts, the only filters needed are a laser-transmitting filter to clean-up the laser spectral output and a laser-blocking filter to ensure that no Rayleigh-scattered laser light reaches the detection system (seeFilter Types for Raman Spectroscopy Applications). In many high-performance Raman systems with microscopic imaging capabilities or highly sensitive remote probes it is desirable for the excitation laser beam and the Raman-shifted signal light to share a common light path. The illustrations below describe the two layouts and the ideal filters for each system.

standard raman spectroscopy layout

In the standard Raman spectroscopy layout, the laser excites the sample directly, and a laser-blocking filter (such as the ultrasteep RazorEdge® LWP filter) is positioned between the sample and the spectrometer to block the scattered laser light and pass the Raman-shifted signal light.

raman spectroscopy layout where the incident beam and signal light share the same path

In focusing or imaging systems where the incident beam and collected signal light to share a common path, a RazorEdge 45° beamsplitter reflects the laser light through the optics to the sample while efficiently transmitting the returning Raman-shifted signal light. A laser-blocking filter at normal incidence is used ahead of the spectrometer to completely block the undesired laser light.