Fig. 1. Schematic diagram of tunable liquid crystal birefringent filter

Fig. 2. Normalized intensity of solar spectrum and prefilter

Fig. 3. Comparison of measurement errors between two methods

Fig. 4. The influence of the center wavelength drift of the prefilter on the measuring error

Fig. 5. Influence of optical path error of calcite on measuring error

Fig. 6. Experimental setup

Fig. 7. Measurement data

Fig. 8. Measuring result