Learning Forum

[uzmayaqoob1960]

can you plz help to understand these statements

 the spot size depends on the wavelength and F/#W, but the resolution
depends on the wavelength and entrance pupil diameter
 So a big F/3 lens can resolve finer detail than a small f/3 lens, even though the spot sizes are the same, because the image plane is further away.

Spot size Diameter (D)2*(1.22*lambda/NA)=2.44*lambda/NA 

How for big lenses image plane is further away?

[Niki Papachristou]

Hi Uzma,

Thank you for reaching out to us. I believe what you are describing can be explained by taking into account the definition of F#:

The f-number is given by:

F#=f/D

where f is the focal length, and D is the diameter of the entrance pupil (effective aperture).

If you want to increase the entrance pupil diameter and keep the same F# then the focal length will lave to be increased, hence the image plane is further away.

Hope that was helpful.

Kind Regards,

Niki

[uzmayaqoob1960]

Dear Niki

Thank you for your response . can u plz let me know how further imaging plane ensures better resolution?

[Niki Papachristou]

Hi Uzma,

Thank you for coming back. Can I ask you how you ended it up to this conclusion and show me your example of your different lenses with better resolution (some screenshots would be helpful)? I think the reason is simply since you are out of focus furthering your image plane you get better focus and as a consiquence better resolution.

Kind Regards,

Niki

[uzmayaqoob1960]

Dear Niki i have read this concept in one of your paid courses of zeemax.Snapshot is attched herewith.