Broad band and high resolution scanning spectrum calibration technology

In order to achieve rapid and high spectral resolution detection in the broad band from ultraviolet to near infrared with an atomic emission spectrometer, an ultra-precision rotation stage is used to drive grating rotation to realize spectral segment-scan with high speed and high precision functioning together with an imaging CCD. However, during the scan, the wavelength increment of detector pixel changes nonlinearly with the angle of the grating, and the wavelength increments of different pixels are different, which becomes an obstacle to accurate spectral calibration. To compensate for the nonlinearity of the grating dispersion, the corresponding relationship between the wavelengths of the pixels at both ends of the detector and the rotational angles of the grating is calculated based on the grating equation while the wavelengths of the other pixels are calculated by using the wavelengths of the pixels at both ends with the linear dispersion law. Thus, with this methodology, the calibration of the full band of wavelength is implemented. After calibration, according to the corresponding relationship between the angle and the detection wavelength band, the grating is driven to rotate successively to realize the spectral segment-scan with high resolution and high speed in broad band. The wavelength accuracy and repeatability with this method are tested by using a mercury lamp. The results show that the wavelength accuracy is better than 0.018 nm and the wavelength repeatability is better than 0.001 nm in the wave band from 200 nm to 800 nm.