Nearly finished my first build, couple of questions about focussing

[samwhiteUK]

OK, so as stated, I've nearly finished my first build, its taken a bit of time but I absolutely love it! :drool:

I've read that you can use a magnifying glass to focus the laser, so I have a couple of questions.

First, what is the range of movement needed to focus, i.e. how much would I have to move the glass to change the focus from right in front if the laser to infinity? Roughly speaking, I mean I know this will depend on the strength of the glass etc.

Second question is if I need to use the lens in the aixiz module as well? Could I benefit from using both? And if I do use both, how do I focus the aixiz module? To infinity? Close?

Final question is about focussing to infinity, if I try, the dot is never quite as focussed as it is if I use it close up. This doesn't really come as a shock, but can I get it closer, maybe to extend burning range? Would I use two lenses for this as mentioned before? My guess I suppose is that nothing can be done, as another lens would reduce the power too much, but I'd like to be pleasantly surprised by someone telling me that something can be done!

 

[ultimatekaiser]

ok.

A magnifying glass can be used if clean, but the distance will vary with the power (curvature) of the lensing, though the micro scratches in it will likely give you a crappy beam profile. I would recommend buying a lens for use in the module from a member here or from DTR's shop for use with the wavelength you're using. this will focus it better, and you will get less power loss. they're inexpensive and easy to use, as they just screw in from the front of the module. if you use a magnifying glass you'll have to start far away and move in until the dot shrinks to its minimum size for max focus, go to far and it will grow again as the photons will be crossing over each other in the air as the focal point moves forward. For an infinity focus it down until the dot is as close to its starting diameter as possible. All lasers naturally diverge and get bigger over distance like a flashlight. This is normal, you just want to get it as close as possible and again, a lens designed for this is recommended. You'll get a cleaner beam and less divergence, it'll be built in, and AR coated to pass as much of the laser as possible, which leads to your other question. you could use multiple lenses to get better divergence, but it can only get so good in relation to the lens's properties and diameter. Look up how a beam expander works or a camera focus. you'll get the idea... :beer: but the more optics that are in the way, the more loss you will incur.

 

[Eudaimonium]

OK, so as stated, I've nearly finished my first child, its taken a bit of time but I absolutely love it! :drool:

I've read that you can use a magnifying glass to focus the laser, so I have a couple of questions.

First, what is the range of movement needed to focus, i.e. how much would I have to move the glass to change the focus from right in front if the laser to infinity? Roughly speaking, I mean I know this will depend on the strength of the glass etc.

Second question is if I need to use the lens in the aixiz module as well? Could I benefit from using both? And if I do use both, how do I focus the aixiz module? To infinity? Close?

Final question is about focussing to infinity, if I try, the dot is never quite as focussed as it is if I use it close up. This doesn't really come as a shock, but can I get it closer, maybe to extend burning range? Would I use two lenses for this as mentioned before? My guess I suppose is that nothing can be done, as another lens would reduce the power too much, but I'd like to be pleasantly surprised by someone telling me that something can be done!

Can you show us a picture of what you have so far?

How exactly are you "nearly" finished without an Aixiz module, what is the diode in?

I'm just having hard time picturing your setup, if you can post some pictures it'd be great, we could help you easily.

But in any event, YES it'd be great if you had an aixiz module. It's sorta essential.

 

[samwhiteUK]

Can you show us a picture of what you have so far?

How exactly are you "nearly" finished without an Aixiz module, what is the diode in?

I'm just having hard time picturing your setup, if you can post some pictures it'd be great, we could help you easily.

But in any event, YES it'd be great if you had an aixiz module. It's sorta essential.

I have an aixiz module at the moment, I was just wondering if I could add/swap with a magnifying glass to improve focusing.

Here's the build at the moment:

As you can see, the end if the module could be screwed in completely and a magnifying glass could be mounted inside the end, or, as I will do now, have the end of the module attached to the end of the flashlight, which can turn as it unscrews.

I currently have one of these lenses, is this as good as I am reasonably going to get? 3-Element Collimating Glass Lens Assembly Coated for 630-660nm (Red) & 808nm IR Lasers - Detailed item view - OdicForce Lasers Online Shop

 

[Eudaimonium]

If you already have 3 element glass lens in there, it's good, but I don't understand why do you want anything else to focus it.

I will assume you do not know you can twist the knob at the end of your module (part holding the lens) to thread the lens in and out and change focus to whatever you want - close focal point for burning or long for pointing.

 

[samwhiteUK]

If you already have 3 element glass lens in there, it's good, but I don't understand why do you want anything else to focus it.

I will assume you do not know you can twist the knob at the end of your module (part holding the lens) to thread the lens in and out and change focus to whatever you want - close focal point for burning or long for pointing.

I know that that can be used to focus.I was wondering if there was anything else that could be done to IMPROVE the focus.

I stated in my previous post that I knew the module could be screwed in and out, and I also mentioned that the end of the flashlight could be attached to the end of the module, so the focus knob on the module could be turned by the end of the torch . I thought it should be clear that I was doing this to make a focus knob and not just for a giggle.

 

[Eudaimonium]

Sorry for misunderstanding, but you just kinda wrote it a bit confusingly,

What do you mean by "improve" the focus? What do you mean, the focusing mechanism, the beam profile, the focal point distance?

It's not getting much better than this, you cannot get a "thinner" beam than this.

 

[samwhiteUK]

By improve the focus, I meant reduce the divergence of the beam over distance, but it is clear now that this is good as it will get I'm not bothered, I still love it! :drool:

Thanks for the help! :beer:

 

[Eudaimonium]

Divergence is directly related to beam diameter. If you wish to get better divergence, you need to expand the beam diameter.

That's probably not gonna be easy. Or cheap.

 

[SKeeZ]

I would strongly suggest not using a magnifying glass for focusing for a few reasons:
Power drop through a thick magnifying lens can be as much a 1/3 your power. so if you have a 600mW laser, it will only get 400ish after the magnifying glass. #2 magnifying glasses are bulky and low quality usually, you dont need the same precission for reading a book as magnifying a burning laser. also, it is usially very easy to focus a laser with the lens that comes attached to most modules.