# I'm not sure what my teacher means by resolution limit?

1. Sep 18, 2013

### Astronomer1

Hi all, this is 1 of my homework questions.

The resolution of microscopes is approximately half the illumination wavelength.

a) Assuming a visible microscope has an average wavelength of 550 nm, what is the
resolution limit?

I'm not sure what my teacher means by resolution limit?

2. Sep 18, 2013

### cepheid

Staff Emeritus
Welcome to PF Astronomer1

In this context, "resolution" and "resolution limit" mean the same thing. Your resolution is a limit, because it describes the limit to your ability to see two closely spaced objects as being separate/distinct from each other. If the separation of these two objects is smaller than the limit, then you will see them as being one object. You will not be able to tell that there are two. We say that the separation between the two objects could not be "resolved." I hope this helps.

3. Sep 18, 2013

### SteamKing

Staff Emeritus
The resolution limit for a microscope determines the smallest features which can be seen with the eye aided by the microscope. Things smaller than the resolution limit can't be seen with the microscope.

4. Sep 18, 2013

### Staff: Mentor

In "hand wavy" terms, resolution limit is the size of the smallest feature that can be individually distinguished by the observer. In practical terms, it's the smallest separation between two point-like sources of light for which they can be distinguished as separate points rather than a single extended object. Various optical material practicalities and wave-mechanic realities come into play in any real-world implementation, but a good rule of thumb is that the resolution is limited by the wave mechanics to half the wavelength of the light used.