Learning Forum

[uzmayaqoob1960]

I wanna ask about spectrometer resolution .One way to enhance spectrometer which is documented on Zeemax size is to enhance system Aperture Diameter,I am very much confused b/w sustem aperture and surfcae aperture dimaeter.Though i find in  Zeemax guide that System aperture diameter defines the system overall F# ,Entrance pupil dimaeter,Stopsize and Numerical aperture .But i am confused as i have read that by increasing the F# ,spot radius will also incresase along with the incresae in detector size so no improvement in resolution.

(its resultion Formula).

This Fotmula depicts if fractional BW is high then Resolution will improve .If i have a bandwidth of 300 nm for spectrometer operational for 400nm to 700 nm.Then what would be the fractional BW in this scenario.Kindly help me to understand this concept

[Niki Papachristou]

Hi Uzma, 

Thank you for reaching out to us! I believe you should be considering a different formula to understand the relation between the spectrometer's resolution vs the F#. More spcifically on the Knowledge base article: How to build a spectrometer - theory on section Diffraction limit it is mentioned: Diffraction is a limiting factor for the resolution. And, the size of the Airy disk is given by:

Which means that a smaller F# (or a larger aperture diameter) leads to a smaller airy disk; and therefore pushing the diffraction limit further down.

I hope that was helpful.

Kind Regards,

Niki

[uzmayaqoob1960]

Thank you sir in your link:

" https://support.zemax.com/hc/en-us/articles/1500005578862-How-to-build-a-spectrometer-implementation"

We will use 30 mm cage elements and 1’’ lenses by Thorlabs to implement the spectrometer..What is 30 mm  cage element?

can you plz explain it?

[Niki Papachristou]

Hi Uzma,

This a standard optical component from Thorlabs, you can check it on their website.

Kind Regards,

mrs. Niki