Edge Filters vs. Notch Filters for Raman Instrumentation

Should you use an edge filter or a notch filter to block the laser line in your Raman system?

Choosing between an edge filter and a notch filter for a Raman system is a critical consideration that can significantly impact the quality and accuracy of the obtained spectra. Edge filters offer a broad-range spectral cutoff, blocking wavelengths either below or above a specified threshold. Notch filters, on the other hand, are more selective, blocking only a narrow band of wavelengths. The optimal choice depends on the specific application and the spectral properties of the analyte of interest. Factors such as the excitation wavelength, Raman shift, fluorescence interference, and desired spectral resolution should be carefully evaluated to determine the most suitable filter type for a given Raman experiment.

The RazorEdge edge filters and the StopLine notch filter are both available with OD>6 blocking of the laser line.  The main benefit of the RazorEdge filter is the very narrow transition width, allowing users to measure even the smallest Raman shifts. Although the StopLine notch filters do not transition as close to the laser line, they are tunable from 0° to 14°, or 1% of the laser line to allow users to shift the bandwidth in response to variable laser lines. The RazorEdge filters are tunable as well, from 0° to 8°, or 0.3% of the laser wavelength.   In addition to the greater ability to angle tune, the notch filter's dual passband allows users to measure Stokes and Anti-Stokes shifts without changing filters.

Learn more about RazorEdge Filter Layout

Learn more about Raman Spectroscopy:

• Coherent anti-Stokes Raman Scattering
• Raman Spectroscopy
• Stimulated Raman Scattering
• Surface-enhanced Raman Scattering
• UV Raman Spectroscopy