an optical device that divides a beam of light into two beams.

Bragg diffraction

the diffractive principle which a layered stack of parallel reflecting surfaces of alternate higher and lower refractive index will reflect a beam of light, if and only when the reflected wavefronts are of an appropriate wavelength and orientation to produce...

Bragg hologram

any hologram in which the Bragg condition is preferential than the grating condition in forming the image; a volume hologram.