What can you tell me about mounting FAC?

[T_Warne]

I have the 9mm diodes and cylinder lenses, now I just need info on how to set them up.

How do you do it? What do you use for adhesive?

~ should I glue them directly to the can? If not, how far away from the diode should the lens be?

I would like to use a temporary adhesive in my experimentation so that I can reposition or change the lens.

~Where can I buy small quantities (1oz,) of temporary optical adhesive? ( something like NBA107 ) Can a PHR be used cure 350–380 nm UV cure glue?


Thanks.
TW

 

[T_Warne]

:anyone:

 

[ElektroFreak]

I recommend a microscope w/manipulation tweezers and some epoxy. With a 9mm diode, you'll need to decan the diode. You'll obviously want to be EXTREMELY careful not to get any epoxy on the die. I'd place two tiny spots of epoxy on each side of the heatsink material next to the die face. Then attach a suitably cut piece of narrow-gauge singlemode glass fiber (the cylinder lens you speak of) sideways across the die face without touching the die itself at any point during the process. Once it sticks, let it set and then carefully place another tiny dot of epoxy over the original dots for good measure. The fiber should be as close to the die as possible without touching. It will be a challenge, most definitely. Good luck!

Here's some pictures of a FAC lens on a c-mount of mine:

EDIT: I read a little more deeply into what you're asking, and I'm not sure if we're talking about the same thing.. I've personally never seen a FAC lens on a 9mm diode before, so if we're not on the same page here, post a picture of your lenses so that I or someone else here can get a better idea of what you're describing..

 

[T_Warne]

ElektroFreak, thanks for the reply.

These are the cylinder lenses I received from Heruursciences. I Haven't a clue how to use them. I think this may be a case of me jumping into the deep end of the pool without my water wings... I'm in way over my head.

" Cylinder lenses, Have fast, medium and slow lenses, if focusing close to burn/cut get FAST if collimating for long distances get SLOW only $10.00 each."

 

[LarryDFW]

T_Warne;

The pictures help to visualize the mounting options.

I am not too familiar with 9mm mounts (Meridith I assume).

The small cylinder lens (fast) can be mounted on the can with a quality epoxy to reduce the fast axis divergence (perpendicular to the fast axis).

After you do that, then a short Focal Length lens can be added to collimate the entire beam. This focal length has to be more than the distance from the laser diode + the thickness of the small cylinder lens. This lens is the one that has to be adjustable for focus.

Meridith uses a spring system to hold the diode in place. That probably needs to change for mounting the two lenses you need.

LarryDFW

ElectroFreak: How was the small optical fiber cut in half ??

 

[ElektroFreak]

T_Warne;

The pictures help to visualize the mounting options.

I am not too familiar with 9mm mounts (Meridith I assume).

The small cylinder lens (fast) can be mounted on the can with a quality epoxy to reduce the fast axis divergence (perpendicular to the fast axis).

After you do that, then a short Focal Length lens can be added to collimate the entire beam. This focal length has to be more than the distance from the laser diode + the thickness of the small cylinder lens. This lens is the one that has to be adjustable for focus.

Meridith uses a spring system to hold the diode in place. That probably needs to change for mounting the two lenses you need.

LarryDFW

ElectroFreak: How was the small optical fiber cut in half ??

I don't believe that it is cut in half. From what I've seen the light just passes through the cross-section of the fiber, which at that scale has a similar effect as a standard cylinder lens.. The reason for working at that scale so close to the diode die is so that all possible power is captured.

I would think that you could get decent fast axis collimation with a cylinder lens like you've got there, T_Warne. You'd just have to experiment with the lenses, and I'd recommend getting an IR detector card. I think these can be had easily on ebay, if not elsewhere. They allow you to see the IR beam spot clearly without the need for IR sensitive optical equipment (cameras. etc..)

 

[RA_pierce]

I'm no optics expert, but I think what you need to do is mount the lenses in relation to the axis they are meant to correct.

Have you used multimode diodes before?
If you have, I don't meant to insult your intelligence.

Basically, the multimode diodes produce a rectangular beam. The fast and slow axis diverge at different rates.
You need to determine which is the fast and which is the slow axis.
Use the smaller cylindrical lens to correct the fast axis and one of the larger ones to correct the slow axis.
The goal is to get the fast and slow axis to diverge at similar rates so the beam can be collimated more effectively.

 

[T_Warne]

Thanks for the input, gentlemen. This is my first attempt at anything on this level of DIY. I have never worked with loose lenses like these before.

The diodes are definitely multimode. They produce a line that spreads out very quickly. Am I correct in my assumption that the length of the line is the fast axis and the width of the line is the slow?

"Meridith uses a spring system to hold the diode in place. That probably needs to change for mounting the two lenses you need."
I will turn a mount up on the lathe so that the LD is held in the back by a threaded retaining plug. Something like this: http://www.o-like.com/b2b_cpinfo.asp?id=964

"I'd recommend getting an IR detector card. "
That sounds like a really good idea.

"Have you used multimode diodes before?
If you have, I don't meant to insult your intelligence."
No, I have not used them before; and no offense taken. I'm a definite NooB and happy to receive any help or suggestions that anyone has to offer.


Can anyone point me in the direction of pictures or diagrams of lens setups?

How about a good temporary adhesive? I'm sure that this will take a few attempts at getting right and I don't want to damage the lens getting it off to reposition it.

Thanks again.

 

[LarryDFW]

T_Warne;

Silicone sealant is a good temporary adhesive.

Use it only on the ends of the cylindrical lens, since it might affect the surface clarity.

Once you correct the fast axis (the one that diverges the most), then you can use a large plano-convex lens to focus the entire beam. It does need some adjustment means.

I do not think you need to use more than one cylindrical lens.

LarryDFW

 

[suiraM]

If you just want to burn things, a single cylinder lens can be glued to the can. The smallest one that will cover the glass window of the diode can will do. You have to determine which direction is the fast axis, as someone explained. Then you stick it in a Meredith module and enjoy. Not too complicated.

However, you may want to consider saving the cylinder lenses for a C-mount diode or a diode bar, because a regular glass lens will do a good job with most 9mm diodes, so you would sort of be wasting a specialty lens on a laser that doesn't really need it.

If you want max burning ability, you really need to pick up a good book on optics. The spot size is far more relevant than the output power. With the right focusing optics, a 5mW laser will light a match. With a simple lens, that is not going to happen.

If you don't want to read up on it, get a Meredith glass module and a 40x microscope objective lens. Get the module roughly collimated, and align the objective so that the beam is reasonably dead centre. Then put something you want to burn at the working distance of the microscope. Play around with the module until you get the smallest spot.

If you still want to improve on it, then use the cylinder lens (and read up on the optics anyway).

 

[LarryDFW]

Ted;

Did you get one of the Hi-Power lenses from the other vendor ?

If so, I would try it alone, as suiraM mentioned.

Since it has a short focal length,
it will do a good job of focusing before the fast axis spreads to far.

LarryDFW

 

[T_Warne]

Larry,
What Hi-Power lens from which other vendor? I have experimented with a Meredith in a DIY heatsink, but I am not particularly fond of the setup.

The rig that I have had the best luck with is a collimation lens from Hurrer mounted into a piece of aluminum rod. The diode fits into a 9MM pocket and is held in place by a threaded plug.

I've kind of given up on the cylinder lenses for now. I lack the patience, a steady enough hand, as well as the ability to place the lens with precision. My attempts so far have been disappointing to say the least.

 

[LarryDFW]

Ted;

The lens assembly like the one in my avatar.

It is 9mm in diameter like all the Aixiz lenses.

It does have to be ~2mm from the actual laser,
so it would have to be almost to the diode in the aluminum rod mount system you had the photo of.

LarryDFW