I am a bit confused by the history here.
We know that in early 1800's Thomas Young performed the double-slit experiment to demonstrate light interference. After wave theory of light became more accepted, presumably people would turn to explaining other phenomena like the single-slit diffraction pattern. This leads me to two questions:
- What was the earliest discovery of single-slit diffraction or anything similar like small aperture diffraction? I've heard that Newton was the earliest to discover and write about this, but it's hard to find a concrete source verifying this.
- What was the earliest application of wave theory to single-slit diffraction after Thomas Young's initial experiments? What was the earliest attempt to explain it with wave theory?
I know that by around the 1850's, Fresnel already devised the mathematics that can predict diffraction phenomena such as the famous Arago's spot, but no mention of light going through a single opening is ever mentioned. It seems as if there is a plot hole in the history here.