Enlarging Beam diameter of green modul

[Danjoo]

Hi guys

Im looking forward to build a yellow pointer inpired by LPF user rog.
i want to build the yellow one in a MXDL host lathe, and milling at work is no problem.

I start with some experiments to find out how everything works.
First i build the setup on my desktop to see the yellow beam.

an there it it: thefirst problem!

Beam diameter of the green DX 5mw modul i want to use, is to small.
I guess its 1mm.
For the red i want to use a 16x diode in aixis housing, but if i focus this beam to infinity the beam diameter is about 3mm.

The dot on the wall is ok, its yellow, but the beams are not yellow.
I see a red covered green beam. Not a yellow beam.

I think its not easy possible to get a smaller red beam.

Then i think about making the breen beam bigger.
The frontend lens makes the focus, no changes on the beam diameter possible on that lens.

But in the modul is another lens right in front of the crystal.
i think about removing the glued crystal an put a spacer between the crystal and the first lens.

Did somebody tried this?

Its Possible to get a bigger beam with this modification?

Greetings

Daniel

 

[Benm]

Re: Beam diameter of green modul

The frontend lens makes the focus, no changes on the beam diameter possible on that lens.

Not by adjusting its position, but it should be possible if you replace this lens with a 'weaker' one. It would be placed further from the crystal/lens assembly resulting in a larger beam when focussed at infinity.

 

[Danjoo]

Re: Beam diameter of green modul

Any Idea where i can get a "weaker" one?
In this case i think weaker means bigger diameter of the roundness of the lens.
-->  http://www.novalasers.com/NOVAstore/pc/viewPrd.asp?idcategory=6&idproduct=30

i think original its a "Meniscus Lens" that means konvex inside, konkav outside.

I try some other leses instead oh that lens. The aixis one for example.
But this is not the right lens i guess, i think this meniscus lens ist required.
Also tested the LG22x lens, i know is coated for 405nm but it has also not the effekt i look for.

Somebody an idea where i can find one, maybe in some spezial sled?

Whats with the idea to replace the first lens wich is glued to the crystal base.
Is ther any chance to get a bigger diameter?

Any optik experts here?

king regards

daniel

 

[Benm]

By weaker i mean a focal point farther away.

What is the beam like that comes out of the lens glued to the crystals?

It might be an option to put a negative lens right after that and then a positive one further down the barrel... this would do pretty much the same as replacing the glued lens, without the problem of actually replacing it.

 

[Danjoo]

Hi benm,

The beam direkt after the lens wich is glued has also small diameter and is expanding. Maybe its a negativ lens? The lens on the end will focus this expanding beam to infinity.

Aktually i am at work and i try to build this spacer i talk about. In this prozess i do some lathe work on the crystal holder to get a clean diameter to mount my spacer. And finaly the glue break. aaarrghh

I think i will post some picts after my night shift...

 

[RA_pierce]

You will need 2 lenses.
A concave and convex.

First test the lenses to make sure they work for what you are trying do do.

If they do...
Remove both lenses.
Place the concave first.
Then the convex at the proper distance.

The concave lens will expand the beam and the convex lens will focus or collimate it.

I've done this with my laser, it will also improve the divergence.

 

[Benm]

If you have the mechanical space, you could even leave the existing lenses in place and put a beam expander (telescope) after them. You could for example expand the beam 3 times, giving a beam 3 times wider with 1/3rd the divergence.

http://www.mellesgriot.com/glossary/wordlist/glossarydetails.asp?wID=105

Has 2 nice diagrams that show how these work with 2 plano-concave lenses or a combination of a plano-concave and plano-convex lens. Note that the bundels on the far left and right are all paralel, just different in diameter.

 

[Danjoo]

Argh, on the lathe work i remove the crystal base, and later at home i loose the crystal somewere in my small lab orbit.

That means projekt stoppt til i get new modul from a new standstone order, cost me 2 weeks i guess.

At the moment its just a 1064 pointer!

I take a pic with my mobile phone, voila a 1064 beam visibl, with some cigarett smoke.

I post again when i have new modul.

Greetings

daniel

@benm
i dont have much space, this beam enlarging projekt is step one to build a yellow laserpointer.
I want the bigger beam out of the normal green laser barrel of this standstone modul.

 

[chopper]

This is a cool java applet for playing with lenses.
http://www.mtholyoke.edu/~mpeterso/classes/phys301/geomopti/twolenses.html

To start click 'beam' and then click where you want the beam.  Then click 'aperture' and place it in front of the lens to limit the beam size.  You can click on any object to manipulate it's properties.  If you want to simulate the convex/concave setup mentioned above, add two lenses.  They will both be convex.  Click one of them and the click and drag the focal point to the other side of the lens and it will change to convex.  You can mess with the focal points and positioning.  It's real handy...

 

[Danjoo]

thx alot, god link to understand this optik physiks.


now i collect as much different lenses i can that i have some when my new module arrives.

 

[diachi]

Be really careful with that IR pointer, it's much brighter/ more dangerous than it looks !

 

[Benm]

If you lost the crystal set, i reckon its 808 pump light, not 1064.. dull red to the naked eye, when abused, guaranteed to fry

 

[Danjoo]

With the camera and smoke i found the focus point and it burns well.
Thx for warning.

It is 808, ok.
I think i read somewhere that the cristal divides wavelengt than i calcutate 1064nm.

 

[rog8811]

For the red i want to use a 16x diode in aixis housing, but if i focus this beam to infinity the beam diameter is about 3mm.

Though I have not tried it with a standstone module, puting a SenKat red into a DX green module gave me a tighter beam. You will need to shorten the module as the focal length is quite different.

As you now have a spare module it may be worth a try

Regards rog8811

 

[Danjoo]

You put a red diode in the green optik module?

do i understand right?

 

[Danjoo]

I make some experiments to found the right lenses,
finally i find some usable stuff!

Lens 1 is from a cheap 5mw red pointer modul, its plano-konkave, beam goes in the plan side.
Lens 2 is from the LG 22x sled it looks like it have blue coating, its konkav-konkav with a very big diameter of the konkavnes!!??

I just put the lenses in a thing wich is able to hold the lenses in a line.
For the green laser i use a rominsen 30mw from dx.

I think its possible to put this in a barrel wich i have to made in front of the green modul.

I try to make a beam picture that makes its visible, that the beam is right kollimated.
Direkt at the optiks i blow some smoke on the experiment to make it visible in my daylight room.