Neutron monochromator for the ECHIDNA powder diffractometer at OPAL in Australia. ECHIDNA is the name of the new neutron High Resolution Powder Diffractometer at Australia 's new research reactor OPAL, ANSTO. OPAL ( Open Pool Australian Lightwater reactor) is a 20 megawatt pool-type nuclear research reactor that was officially opened in April 2007 It is made by slabs of [113] oriented Germanium crystals which are inclined towards each other in order to focus down the Bragg reflected beam.

A crystal monochromator is a device in neutron and X-ray optics to select a defined wavelength of the radiation for further purpose on a dedicated instrument or beamline. A monochromator is an optical device that transmits a mechanically selectable narrow band of Wavelengths of Light or other Radiation chosen from The term "Neutron Scattering" encompasses all scientific techniques whereby the deflection of Neutron radiation is used as a scientific probe This article is mostly concerned with applications of Synchrotron radiation. In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. It operates through the diffraction process according to Bragg's law. Diffraction is normally taken to refer to various phenomena which occur when a wave encounters an obstacle In Physics, Bragg's law is the result of experiments into the Diffraction of X-rays or neutrons off Crystal surfaces at certain angles

Similar devices are called crystal analyzer for the examination of scattered radiation.