I How to narrow a beam to 1 mm diameter?

[Quant]

TL;DR Summary

How to narrow d=10 mm beam to d=1 mm

I have a collimated beam from a laser diode d= 10 mm and want to narrow it down to 1 mm. I suppose to use a lense to focus it and then use a lense to collimate it with d=1mm but this lense must have focus distance of 1 mm?? Are there such lenses? Or I must do it in other way?

 

[Philip Koeck]

TL;DR Summary: How to narrow d=10 mm beam to d=1 mm

I have a collimated beam from a laser diode d= 10 mm and want to narrow it down to 1 mm. I suppose to use a lense to focus it and then use a lense to collimate it with d=1mm but this lense must have focus distance of 1 mm?? Are there such lenses? Or I must do it in other way?

You can do it with 2 lenses. The first has to have 10 times the focal length of the second, for example 100 mm and 10 mm.
Place them so they share a focal point.