Edge filter

FIG. 18-132 Sectional view of the Cuno Flo-Klean backwashing edge filter. Fluid pumped through the nozzle loosens solids from the filter surface and clears the filtering area. The pump draws filtered fluid from the filter discharge and returns it to the system through the nozzle. Thus, there is no loss of backwash fluid. (Cuno Division, AMF, Inc.)... 

G Harding, R Armstrong, S McDaid and M J Cooper (1995) A K edge filter technique for optimization of the coherent-to-Compton scatter ratio method. Med. Phys. 22, 2007-2014. 

Figure 9. Narrow band, steep-edged filters showing three fluors effectively separated within a spectral window of less than 300 nm.

Figure 6. Ionization efficiency spectrum, obtained jrom a neutrai gyrovibronic intermediate state by scanning with photon hvt, either jrom a second laser, monochromator or edge filter.

Highly efficient notch filters that eliminate the Rayleigh line and transmit both the Stokes- and anti-Stokes Raman bands, or edge filters that transmit only the Stokes Raman bands and block all shorter-wavelength radiation. 

Clarifying filters for liquids include the gravity-bed filters for water treatment mentioned earlier and a variety of small cartridge and edge filters of various designs. Some cake filters, especially tank filters and continuous precoat filters, are used extensively for clarification. In a batch unit, the filtration rate and solids removal efficiency are typically almost constant for a considerable period of operation, but eventually the solids content of the effluent rises to an unacceptable breakthrough value, and backwashing of the filter element becomes necessary. 

The most common detectors in Raman instruments are PDAs and CCDs but for FT-Raman, single channel detectors are used, e.g. InGaAs. An extra requirement for the FT-Raman instrument is a notch or edge filter it is included to reject scattered laser light at the strong Rayleigh line, which could otherwise obscure the FT-Raman spectrum. 

---