A. Half-peak bandwidth 1 nm:  half-peak bandwidth tolerance ±0.2 nm;

                                                      central wavelength tolerance +0.2, -0 nm

     B. Half-peak bandwidth 3 nm:  half-peak bandwidth tolerance ±0.5 nm;

                                                      central wavelength tolerance + 0.5, -0 nm

     C. Half-peak bandwidth 10 nm:  half-peak bandwidth tolerance ±2.0 nm;

                                                        central wavelength tolerance + 3, - 0 nm

     D. Half-peak bandwidth 40 nm: half-peak bandwidth tolerance ±8.0 nm;

                                                       central wavelength tolerance +10, - 0 nm

   Bandpass light filter, cut-off light filter, spectroscopic light filter,

   neutral-density light filter, reflective light filter.

   Soft film light filter, hard film light filter; hard film light filter is not only

   related to film hardness, but also its laser damage threshold, so it is

   widely used in laser systems, while soft film light filter is mainly used

   in biochemical analyzer.

   The light in the selected band passes through and the light outside the

   bandpass is cut off. Its optical indicators are mainly central wavelength

   (CWL) and half bandwidth(FWHM). It is divided into narrow bandpass

   and broad bandpass.

  Classification by short wave bandpass

  (also called low wave bandpass)

   The light shorter than the selected wavelength passes through and the

   light longer than that wavelength is cut off. Such as IR cut-off light filter.

  Classification by long wave bandpass

  (also called high wave bandpass)

   The light longer than the selected wavelength passes through and the

   light shorter than that wavelength is cut off. Such as IR transmission

   light filter.