Calibration of monochromator wavelength based on continuous spectrum light source and Fourier transform spectroradiometer

The monochromator has been widely used in the field of optical precision measurement. It can effectively separate the monochromatic light of the specific wavelength required for the experiment from a complex spectrum and a continuous spectrum light source. The wavelength accuracy of a monochromator is an important indicator of its performance1/4 and the research of wavelength accuracy calibration methods to improve measurement accuracy is a hot theme for researchers around the world.When the monochromator is utilized for calibrating the wavelength in the ultraviolet, visible, and near-infrared region, low-pressure discharged lamps, such as mercury lamps and neon lamps, are usually used to calibrate on the well-known limited atomic emission lines of lamp to obtain the wavelength deviation value at the wavelength points of these lines.For some high-precision requirements, for example, when measuring the spectral responsivity of a reference solar cell using a tunable laser as light source, it is difficult for these discrete and finite lines to fully satisfy the demand.To solve this problem, a new method based on combination of continuous spectrum light source and fourier transform spectroradiometer was used. A calibrated experimental optical path was successfully built, and the wavelength deviation values of 322 wavelength points from 400 nm to 2000 nm were obtained. The optimal measurement repeatability reached 0.3 pm, which met the need for high-precision measurement requirement. As a comparison, a low-pressure discharged lamp method was also used. Using a mercury lamp and a neon lamp, a wavelength calibration experiment was performed on the same monochromator in the same wavelength range, and only 20 wavelength deviation values were obtained at its atomic emission lines wavelength point. The number of wavelength deviation values is less than 6.5% of that of the new method.The new method proposed in this paper,which not only can significantly improve the quality of the monochromator calibration wavelength deviation values, but in which the obtained values are able to establish traceability to the international SI unit system, is an ideal wavelength accuracy calibration method.