single wavelength V-coating will provide reflectance less
than 0.25% for 0กใ incidence or 0.5% for 45กใ incidence at the
chosen wavelength. Dual wavelength coatings will approach
the performance of V-coats for two selected wavelengths. They
are useful for optics which must transmit a visible alignment
laser as well as a near IR process beam or for transmission
of fundamental and first harmonic wavelengths.
wavelength AR coating allows two center wavelengths radiation
pass through the substrate with high transmission. This coating
is often used in frequency doubling systems or the other muti-laser
output systems, as the Nd: YVO4 laser (1064nm) and its second
harmonic generation (532nm) green laser.