Grating monochromator wavelength calibration using an echelle grating wavelength meter

Abstract

Monochromators are a common utility for the spectral calibration of spectrometers. To guarantee traceability of characterization measurements to SI-standards, monochromators used as secondary standards must be properly calibrated. Common calibration procedures are based on the measurement of spectral lines emitted by gas-discharge lamps or lasers. Due to the nature of these light sources, the sampling of calibration points cannot be freely chosen. In this paper we present an approach where an echelle grating wavelength meter (WM) is used to traceably calibrate the emitted center wavelength of a monochromator at almost any sampling interval. In addition, it is possible to calibrate the monochromator outside the sensitive spectral range of the WM used. It is demonstrated how a WM is calibrated and then how it is used to calibrate the monochromator of DLR’s Calibration Home Base (CHB) for imaging spectrometers at DLR Oberpfaffenhofen, Germany. The same approach is also used for the monochromator, which is intended for the laboratory calibration of the German hyperspectral satellite mission EnMAP.