What is the relationship between diffraction and resolving power?

[Peter G.]

Hi,

Going through a Physics problem in class today my teacher stated that we could only resolve if: θ = λ/b. Why? Is it because when that does not follow, there is no "black spot", therefore that light source can merge with another one?

Thanks,
Peter

 

[PeterO]

Hi,

Going through a Physics problem in class today my teacher stated that we could only resolve if: θ = λ/b. Why? Is it because when that does not follow, there is no "black spot", therefore that light source can merge with another one?

Thanks,
Peter

If you were to stand in the surf, there would not be small 60cm region of calmness on the shore. If you build a 50m "break water" , you do create a calm section at the beach. The problem is that your size was much smaller than the wavelength so the seas just diffracts around you as if you are not there.
If the light diffracts around a very small object, there will be no later evidence that an object was there -you can't see it.