Fig. 1. Convolution of 532.419 nm absorption line of solar photosphere and Lyot filter profile

Fig. 2. Gaussian fitting of spectral profile

Fig. 3. Error statistics and its influence on fitting accuracy

Fig. 4. Setup of the experimental system

Fig. 5. Online measurement pipeline of full FOV wavelength drift

Fig. 6. Reduction of error by multi frame average

Fig. 7. Pipeline and result of spectral profile fitting

Fig. 8. Separation of wavelength drift and ripple

Fig. 9. Residual of spherical fitting

Fig. 10. Results of repeated measurement

Fig. 11. Difference in repeated measurement