Your Choice of Raman Filters: Notch or Edge Filters

At Avantier, we offer both notch and edge filters, providing flexibility to suit various Raman spectroscopy applications. Your choice between these filter types depends on the specific demands of your work. It’s important to note that individual filters are required for each laser wavelength employed.

Edge filters function as long-pass optical filters, efficiently blocking all wavelengths up to a specified cut-off point, while transmitting those above the cutoff. For instance, a 532 nm edge filter would absorb light up to 534 nm, effectively blocking the 532 nm laser line and permitting the detection of the Raman spectrum beyond 534 nm. These filters are known for their environmental stability and can have an indefinite lifespan with proper care.

Raman notch filters, on the other hand, create a sharp, well-defined band where light is blocked. This absorption band must align precisely with the laser wavelength in use, typically spanning only a few nanometers. For example, if you are working with a 532 nm laser, you would choose a notch filter with a central absorption at 532 nm. Notch filters allow the transmission of Raman spectrum above this wavelength, as well as any lower-wavelength light. Notably, they can be employed for both Stokes and anti-Stokes Raman scattering, offering greater versatility. However, it’s essential to be aware that they have a limited lifespan and may degrade over time.