Optical Engineering

[Zito]

Hello everyone,

Does anyone know what makes for a good design of a collimator?
In ZEMAX the lens design which provides the smallest overall beam width at infinity (or let's just say in the far field) yields larger aberrations as shown by ray fan and opd plots. Furthermore, the image of each field point is more aberrated with the better design. Does this make sense?

Thanks,

Zito

 

[IRstuff]

Depends on what you are trying to accomplish.

To a certain degree, you are trading performance at the edges of the FOV for performance at the center. So, the question is whether on-center performance is the only requirement? or does the entire FOV need to meet a certain level of performance.

TTFN

 

[Zito]

Thanks for the response IRstuff.

In my application power coupling is of the highest importance so the entire FOV needs to meet a certain dimeter since at infinity. After refreshing my memory with some optics basics I understand now that I will have to sacrifice performance at the centre to do this. The higher f/# systems yield better collimation (lower angle of divergence) but at the same time will always yield a larger Airy disk, so their diffraction limit is higher (relatively speaking). This is also the optical invariant.

I guess I didn't think this was the case for me originally since I am dealing with a fixed finite conjugate source, but I forgot that the f/# of my system is what defines the minimum spot size at the image plane.

Thanks again for your help.

Zito

 

[IRstuff]

Still not clear what you are doing. As a general rule, if you need more photons, you need a faster system.

TTFN