Filters play a crucial role in enabling high-fidelity Raman spectroscopy measurements. In many simple laboratory 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 (see Filter Types for Raman Spectroscopy Applications). However, in many high-performance Raman systems – such as those with microscopic imaging capabilities or highly sensitive remote probes – expensive and/or complex focusing and collection optics are used to couple the system to the sample region. For these systems it is desirable for the excitation laser beam and the Raman-shifted signal light to share a common light path. The illustrations below show how this layout can be accomplished with an ultrasteep dichroic beamsplitter used in conjunction with a laser-blocking filter. Semrock's RazorEdge Dichroic™ beamsplitter filters are ideal for these applications.