Abstract
Historically, two methods have been used to determine the wavelength of neutrons: (i) a timeof-flight method that separates the velocity of pulsed neutrons by the flight time; and (ii) a method utilizing Bragg reflection by a monochromator, such as a single crystal or multilayer mirror. The former cannot be applied to electromagnetic waves because the light velocity is constant and independent of the wavelength, whereas “polychromators” such as prisms and gratings, which separate wavelengths via chromatic dispersion, are typically used in the infrared to soft X-ray range. Although polychromators require collimated beams to separate wavelengths with sufficient resolution, this aspect does not affect laser and synchrotron light because they are naturally collimated. Herein, we propose a novel idea of a neutron polychromator utilizing an elliptical multilayered mirror that can be applied to a wide beam with a large beam divergence. In addition, examples of reflectometer and spectrometer applications are presented.