Sunlight coherence comparison
= Sunlight coherence comparison
Broadband sunlight has a short longitudinal <coherence length>, controlled by spectral <bandwidth>, but a wider transverse coherence region because the solar disk has a small angular size. The scales are $\ell_c\sim c/\Delta\nu$ and $w_c\sim\lambda/\delta$ for angular diameter $\delta$. Filtering changes the comparison.