Use of beam expanders

[ruud]

Dear laserexperts . I would like to know how to properly use a beam expander as far as concerned focussing the beam for long distances ( 5miles- plus) . Is it correct to widen the laserbeam at first for less divergence after long distance or should one keep the beam very tiny on short distance for the best non diverging result after its ( long) voyage? Thank you !

 

[steve001]

Dear laserexperts . I would like to know how to properly use a beam expander as far as concerned focussing the beam for long distances ( 5miles- plus) . Is it correct to widen the laserbeam at first for less divergence after long distance or should one keep the beam very tiny on short distance for the best non diverging result after its ( long) voyage? Thank you !

Expand the beam then collimate the beam for minimal divergence aka infinite conjugate.

 

[Cyparagon]

We can help you a lot better if you actually tell us what you're trying to do rather than give an ambiguous specification with no background.