An interference filter is to be constructed for isolation of the nitrobenzene absorption band at 1537 cm-1.
(a) If it is to be based on first-order interference, what should be the thickness of the dielectric layer (refractive index of 1.34)?
(b) What other wavelengths would be transmitted?
The answer to part a is 2.43 um but I'm not sure how to get there.