Pros and cons of a beam expander

[swimminsurfer256]

Besides being able to focus the laser to a certain point, I was just curious as to other pros and cons of getting a beam expander.

Thanks!

 

[Prototype]

One pro is incredible divergence, there's a link somewhere that shows a 10mW red being seen from ~22mi away using a beam expander.

 

[vitalyx]

Please explain why divergence improves with a beam expander? How does it do it? Just makes a beam thicker?

 

[maxkillz]

I believe that a beam expander makes the initial beam diameter wider (thicker, whatever) and you can set the focus to where ever you want it. depending on the quality of the beam expander itself you can have a pin point dot 100yards away or 10 yards away. (if you want to go crazy 400m+ away). I can't really think of any cons as it makes it so your lasers burning range gets MUCH farther than it normally would be. maybe 10% loss if the lenses aren't coated right or dirty? other than that, if you have the money go for it

 

[vitalyx]

Thanks for explaining. I assume only certain hosts allow beam expander attachment?

 

[davidgdg]

Please explain why divergence improves with a beam expander? How does it do it? Just makes a beam thicker?

Assuming the beam is focused to infinity, divergence is proportional to beam width. Thus ten times the beam width equals one tenth the divergence. However, one problem with beam expanders is that it can be tricky to work out when the spot is focused to infinity - it needs two people, patience, mobile phones and a BIG space !
David

 

[Laser_Ben]

Simple

Pros: Lower Divergence
Cons: Larger Beam Diameter

Assuming you are dealing in physics (and not laser idiot logic) the divergence is inversely proportional to the diameter for a given source brightness, you CANNOT increase this source brightness with any optics outside of the cavity.

 

[vitalyx]

Pointing a laser at some remote object, say a few kilometers/couple miles away, and trying to get as small dot as possible while looking at it with binoculars works great for me.

 

[Ymerej]

Thanks for explaining. I assume only certain hosts allow beam expander attachment?

is this true? or is there an adjustable one out there that can be used for any handheld/portable host?

 

[Trevor]

is this true? or is there an adjustable one out there that can be used for any handheld/portable host?

It needs to be threaded for the beam expander to attach directly, or, failing that, you'll need to find another way to attach it (shims, etc.).

-Trevor

 

[Ymerej]

It needs to be threaded for the beam expander to attach directly, or, failing that, you'll need to find another way to attach it (shims, etc.).

-Trevor

thanks, i'll try to see i can work that out. another noob question, does a beam expander work for all wavelengths or theres a specific one for each?

 

[RA_pierce]

thanks, i'll try to see i can work that out. another noob question, does a beam expander work for all wavelengths or theres a specific one for each?

I don't know if all are coated but the LaserGlow X10DR is coated specifically for 532nm, so it will not work well for any other wavelength.

A broadband coating can be used that will allow high transmission at a wider range of wavelengths.

 

[Ymerej]

I don't know if all are coated but the LaserGlow X10DR is coated specifically for 532nm, so it will not work well for any other wavelength.

A broadband coating can be used that will allow high transmission at a wider range of wavelengths.

thanks for the answer!

+1 to you :yh: