Remove the razor blade edge and reinsert the slit into the optical path. With green light (it's the easiest to see), widen the test slit to about 1 mm, and locate it about halfway between the source and the microscope. Inspect the pattern with the microscope. Again, you may have to rotate the slit about the optical axis to get a clear pattern, but the adjustment to make the pattern distinct will be very obvious.
Compare what you see now to the diffraction pattern of the narrower slit that you observed in the experiment on Fraunhofer diffraction. As you narrow the slit width, watch the transformation from Fresnel to Fraunhofer diffraction. The independent patterns of two edges far from one another will merge to make a Fraunhofer single slit pattern.
How would you expect the wavelength to influence whether the pattern you see is Fraunhofer or Fresnel diffraction? At what slit width does the transition from Fraunhofer to Fresnel diffraction take place?