What is an Etalon?
for a more complete explanation. Note that in general, the plate may not be perfectly aligned with the resonator mirrors, but slightly off-axis so the internal path length results in constructive interference at each surface at the lasing wavelength. However, as with a normal HeNe laser, the total length of the resonator is not critical as the lasing modes will shift under the gain curve to compensate. Any change in lasing wavelength that results due to mode cycling will not significantly affect the behavior of the thin plate as an etalon.
for a more complete explanation. Note that in general, the plate may not be perfectly aligned with the resonator mirrors, but slightly off-axis so the internal path length results in constructive interference at each surface at the lasing wavelength. However, as with a normal HeNe laser, the total length of the resonator is not critical as the lasing modes will shift under the gain curve to compensate. Any change in lasing wavelength that results due to mode cycling will not significantly affect the behavior of the thin plate as an etalon.
