Yes, of course: the single-slit diffraction pattern.
See how well they agree?
Each of the two slits in the double-slit experiment produces a large-scale diffraction pattern. That pattern modifies the simple two-slit interference pattern we expect from theory, so that the actual two-slit experiment yields a combination of the patterns.
The wavelength of this laser was 660 nm.
The width of the single slit was 0.02 mm.
The width of each of the double slits was 0.02 mm.
Q: What was the separation between the slits
of the two-slit experiment?