Using multiple lenses?

[LazyBeam]

Sorry I don;t know about lenses but I tried searching for this and came up with nothing.
Not even Google - tough to search for.

Lets say I want to manipulate a Laser beam after collimation. A typical (assume a decent beam is 1-1.5mrad). SO the aixiz (or whatever) focusing/collimating lens is between the diode and my optic I'm going to use to manipulate the beam.

To improve divergence of a 1-1.5mrad beam from a laser pointer would I place my secondary optics at it's focal from the Diode or the first lens? Or somewehere else?

What if I just wanted to manipulate the beam to change it's divergence... ?
For example... take a crappy 2mrad cheapie laser pointer and cut it down to 1mrad (but not collimate it)? Or expand the beam to 5mrad (for more of a flood effect)?

To sum up...

For all these tasks... what focal length lens would I need? Why?
Where would it need placed in the beampath to effect desired changes?
Is it's distance measured from the diode or the previous lens in the beampath?

Sorry for the hailstorm of questions... I've just never learned about optics in depth and am having a hard time tracking down the info myself. If there are any equation ya'll are using to get these answers please share them.

Thanks in advance guys (for putting up with inane n00b questions).

 

[Coherent Light]

Hey LB:

It's not an answer to Your questions, but it might help a little bit. go to the site and select application notes.

★ Doric Lenses Inc. photonics industry

Coherent:

 

[steve001]

Sorry I don;t know about lenses but I tried searching for this and came up with nothing.
Not even Google - tough to search for.

Lets say I want to manipulate a Laser beam after collimation. A typical (assume a decent beam is 1-1.5mrad). SO the aixiz (or whatever) focusing/collimating lens is between the diode and my optic I'm going to use to manipulate the beam.
Yes

To improve divergence of a 1-1.5mrad beam from a laser pointer would I place my secondary optics at it's focal from the Diode or the first lens? Or somewehere else?
Doesn't matter. You will need two lenses though. One to expand the beam and one to collimate the beam

What if I just wanted to manipulate the beam to change it's divergence... ?
For example... take a crappy 2mrad cheapie laser pointer and cut it down to 1mrad (but not collimate it)? Or expand the beam to 5mrad (for more of a flood effect)?
One lens either a negative lens or a positive lens

To sum up...

For all these tasks... what focal length lens would I need? Why?
Where would it need placed in the beampath to effect desired changes?
Is it's distance measured from the diode or the previous lens in the beampath?

That depends on how many times you want to expand the beam.
To figure that out divide the positive focal length lens by the focal length of the negative lens. Example 12 EFL / -6 EFL gives a beam expansion of 2x 30 EFL / -6 EFL gives an expansion of 5x. The same if they were both positive. EFL stands for effective focal length

Read up on Galilean and Keplerian beam expanders


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