The transmission spectrum filter of long-pass filters are often better shaped than short-pass filters because long-pass filters are often specified for use in a very broad region from 200nm to 2200nm. On the other hand, short-pass filters are only specified for use within a narrower region of wavelengths near the cut-off wavelength.

Can I just use long-pass filters to replace short-pass filters by taking the reflected beam off a long-pass filter instead of the transmitted beam off a short-pass filter if I am looking to reject the longer wavelength components in a mixture of beams (e.g, I want a 500nm beam in a mixture of 750nm and 1500nm beam).

  • 4
    $\begingroup$ The only thing I would be concerned about is how much of the filtering is accomplished by reflection and how much is accomplished by absorption. The reflected light filter curve may not be simply an inverted version of the transmitted light filter curve if absorption is also significant. $\endgroup$ – Brionius Jul 26 '15 at 23:49

Yes, depending on the quality of the filter, and as long as you make sure it is reflective rather than absorptive (i'm sure you've already checked this...)

One thing I would recommend is to move the hard spectral edge of the filter a few nm away from the signal band as clipping will give you ringing/kramers-kronig dispersive effects. This is particularly important if you're using a pulsed laser.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.