Monochromator with linear wavelength scale - has diffraction grating rotating through angle of 20 degrees at uniform speed and connected to sine wave generator

摘要

A grating monochromator has a rapidly rotating diffraction grating by means of which exactly reproducible spectra can be generated with a linear scale of wavelengths. The grating rotates through an angle of about 20 deg. with a uniform speed drive, and is connected to an electrical sine-wave generator which is used for the presentation of the linear scale spectrum. The sinusoidal generator may comprise a diaphragm system passing a light-beam over a photocell in such a ways as to generate a sinusoidal output current, or a mechanically driven sine potentiometer. The system avoids the errors inherent in a system in which the grating is given a sinusoidal drive, which may be subject to mechanical wear or inaccuracies, and have limitations in operating speeds.