Ha/Hb Multiplex Grating
Measured Efficiency for the 1200/1620 l/mm multiplex grating at grating angles of 17, 23, and 33 degrees.
A multiplex grating contains two gratings within one unit. The second grating operates near the minimum of the Bragg spectral bandwidth of the first grating.
In this case, the 1200 l/mm grating diffracts Ha light while the 1620 l/mm grating component diffracts Hb light to the same angle of diffraction.