How a Filter is Specified（2）

(2)  Edge pass filter (long pass and short pass)

• passband transmittance wavelength range(s) and level(s)

• ripple spec (allowed transmittance variation) for the pass band range(s) if applicable

• reflection or blocking band range(s) and level(s)

• cut-off value and/or edge steepness.

• for the definitions of cut-off and edge steepness, please refer to Longchuang’s “Edge Filters for Raman Spectroscopy” application note.

(3)  Notch filter

• reflection or blocking band range(s) and level(s)

• passband transmittance wavelength range(s) and level(s)

• ripple spec (allowed transmittance variation) for the pass band range(s) if applicable

(4)  Dichroic filter (long pass dichroic and short pass dichroic)

• passband transmittance wavelength range(s) and level(s)

• ripple spec (allowed transmittance variation) for the pass band range(s) if applicable

• reflection or blocking band range(s) and level(s)

(5)  Gain Flattening Filters (GFF)

• target transmittance curve data along with desired Peak-to-Peak Error Function (PPEF)

(6)  Solid Etalons and Single Cavity Etalons

• the free spectral range (FSR), Finesse, and FSR temperature variation

• for Single Cavity etalons the -3dB bandwidth (FWHM) needs to be specified.

Angle of incidence:

Angle of Incidence, or AOI, is the angle subtended by the nominal beam and the normal to the surface which it is incident upon.

Cone half-angle, or CHA, is the angle subtended by the nominal beam and the maximum (or minimum; the beam should be nominally symmetric) angle from that beam.

Cone full-angle or cone angle, is the angle subtended by the maximum angle in the beam and the minimum angle in the beam.