Hi All,

I want to collimate and parallel and finally densely pack beams coming out of multiple (say 4) laser diode to be coupled to a fiber optic.

In the literature some people have used small plane mirrors in addition to some other components like a big concave mirror and a final focusing lens.

It is mentioned that the reason of using small mirrors are to densely pack and parallel the output beam coming out from laser diode.

As a person out of the field, things that are not clear to me would be first what is the role of mirrors in paralleling?i.e. why not arranging laser diodes in a packed parallel arrangement and right after collimating each one separately, focus the beams to fiber just using a big focusing lens? What would be the need to intermediate components and what is their role?

Also what is the metric for quantifying and analyzing this packaging?

Thank you very much. Any ideas or insight are appreciated.