Analysis of temperature-induced spectral drift in the solar spectrometer driven by leadscrew and bar mechanism

Abstract A solar spectrometer is designed and developed, which uses a leadscrew and bar mechanism as the wavelength scanning mechanism, to achieve the accurate measurement of the solar spectrum in 170 nm-350 nm range. When measuring the standard spectrum of mercury lamp under laboratory conditions, there is a spectral drift due to temperature-induced deformation of the wavelength scanning mechanism. By using the finite element analysis method, the temperature sensitivity of each component in mechanism is analyzed. And then the linear superposition relationship between temperature rise and deformation is determined. Combined with the working principle of wavelength scanning mechanism, the corresponding relationship between temperature change and spectral drift is deduced. Spectral scanning and temperature monitoring were carried out simultaneously in instrument test to acquire temperature data of the wavelength scanning mechanism as it driving the gratings. Spectral drift was estimated according to the temperature variation and the maximum deviation between the predicted wavelength drift and the measured wavelength drift is 0.0016 nm, which is 6% of the measured wavelength. The experiment data validate the theoretical analysis results. The relationship between temperature change and spectral drift provides a theoretical reference for the correction of the measurement results and the thermal control of the instrument.