Undergrad How to calculate the focal length and focal point of collimator?

[Barbossa]

TL;DR

I wanted to calculate the focal length and focal point of the collimator. The collimator diameter is 3mm and I wanted to focus on the 100-micrometre active area of the detector.

I wanted to calculate the focal length and focal point of the collimator. The collimator diameter is 3mm, and I wanted to focus on the 100-micrometre active area of the detector.

 

[BvU]

Hello @Barbossa ,

!​

That is very interesting. Do you have any input for your calculation ?

Is this homework or a school lab ?
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[Barbossa]

Hi
Thanks!. Yeah! The detector active area is 180 µm and lens diameter is 3 mm.

 

[BvU]

Yes, you said that. Do you realize that isn't enough ? What about a sketch of the situation, and what it is that you want to do -- exactly.

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