resolution power of an optical system

[jian]

For a given optical system, there always a term called resolution power. It is called limitaion caused by diffraction.

 

 

I have known the equation

sin(theta)=1.22lambda/ampture.

But not really understanding the meanings.

 

Can anyone give a comprehensive explanlation about the resolution power or diffraction limitaion?

[Klaynos]

Yes, the Rayleigh criterion. My explanation will probably not be as good as one written and edited, so I'd suggest reading:

 

http://hyperphysics.phy-astr.gsu.edu/Hbase/phyopt/Raylei.html

 

And then coming back and asking any questions you have

[swansont]

Very roughly speaking, a point source will get smeared out by diffraction when you image it. When two sources next to each other can't be resolved because of this, that's your limit.

[jian]

what is the angle theta refer to?

Can anyone give me a graphic representation for the angle theta?

Thanks in advance.

[Klaynos]

theta is the minimum angle between two point sources that can be resolved...

 

I can't find an image for it, but if you were to draw a ray from each source to the centre of the lens then it'd be angle between the two lines.