Question About Corrective Optics

[HighPowerObsession]

Im not obsessed; I just dont want to spend $500 on a laser that projects a flat line on anything more then 20 feet away.

 

[RedCowboy]

I like to burn and I have used the cylindrical pairs, but for an easy fix, if you like to burn that is, just use a 3 element and a SANWU 3X expander. Make sure to ask for an adaptor to fit the M9 x 0.5 threaded 3 element lens body.

Hard way I used UV curing glue and set the lenses running with my laser safety glasses on and used a 405nm laser to cure the glue.

The easy way.

I used washers as spacers to set the 3 element focus to about 15 feet, then screw on the expander.

Both ways makes reaching out to burn easier, the expander gives you a nice looking zoom cone too.

SAFETY GLASSES THAT ATTENUATE THE WAVELENGTH YOU ARE USING MUST BE WORN !!!

Here's the expander working.

---------------------------------edit------------------------------

Sorry I forgot about this thread, I lost a bunch of pics and videos and build threads a while back and forgot I had this. >>>>> http://laserpointerforums.com/f65/n...pts-videos-builds-more-97325.html#post1420377

 

[94Z28]

Im not obsessed; I just dont want to spend $500 on a laser that projects a flat line on anything more then 20 feet away.

Only giving you a hard time...

I would think some epoxy could work; but I can bet that gluing to metal pieces of anything outside of a metal bonding epoxy is easy to knock-off the metal... and i'm not sure if these pairs generate any heat around them, but if so that can also play a factor..

I hope you get something figured out bud, I was making fun of the Obession in your username and that instead of HighPower you are more worried about Divergence now... NAME CHANGE NEEDED!! lol...



/e... Yeah, RedCowboy's way is the one method I could see doing with glue, because he still has something protecting the pairs from being open to elements or getting bumped.

 

[RedCowboy]

It's pretty strong and there are different formulations.
405nm is not perfect, 385nm would be better, but I just spend some extra time with the 405nm and they hold pretty darn strong. So far none that I installed have ever broken loose and it took a lot of force to break the test lens loose, best way is to twist, but you still could break the glass.

 

[HighPowerObsession]

Ok burning is a whole other thing. To give you an idea about what my goal is, I want a high powered green laser (NDG7475 1.4W 520nm) and a high powered blue laser (NUBM07E 5W 465nm) for aesthetics since I think those beams and colors are amazing.
I also want a laser that is exceptional at burning like the 1W 405nm (BDR-209), but if I can get something even better I'll definitely take it. I actually prefer to get something else since 405nm is not appealing aesthetically to me at all.
So all this divergence talk is relating to the NDG7475 and a burning laser I want (I'll be purchasing the NUBM07E from JL in the PL-E Pro so I'll be using a 3-element and BE on that regardless).

Now that we have that out of the way, the thing I don't like about using the 3-element & 3X BE method is Id be loosing 30% power and I'd HATE loosing that 400mW in the NDG7475 since I have heard the 3-element really dims the brightness with that particular diode compared to the G2. I think corrective optics is the perfect solution to the NDG7475 divergence problem since it wont decrease the power like the 3-element would. For the burning laser, I don't mind so much about using the 3-element & BE, but I'm either going to go with the BDR-209 WITHOUT corrective optics or 3-element/BE OR I'm gunna go with the NUBM44 WITH corrective optics or 3-element & BE. So Red Cowboy, which of those options would be better for burning at long distances like popping a balloon at 100+ feet and other crazy stuff like that?

 

[steve001]

Hmm ok maybe I don't understand how hard it is to align then. I though you would just have to move them closer or further apart until the dot is as round as you can get it (there's obviously more to it than just that, but I didn't think it would be a super hard thing to do). And as far as portability goes, it seems if you just glued them in place they would stay their and you can move the laser all around and they wouldn't fall all the mount or anything. Have you tried doing it before?

A better solution to the square correction optics are round beam correction optics. Round ones are shaped like typical round lenses; with that type of lens shape one is free to orient them precisely as needed. Now one still needs to machine an optical housing and lens mounts..., that's going to cost. I've used an adhesive for lens mounting. It holds securely and can be peeled away if needed.
http://www.beaconadhesives.com/cg527.html

 

[CDBEAM777]

Funny thread.....Been using corrective optics for years. Epoxy works fine...no problem....you really gotta apply a lot of pressure to break the lens free !!! That is not a problem....ever....!

As far as alignment....ya....it is a PITA !!....but then...SO WHAT....It just takes some time to get the distance between the Cylindrical lenses just right...

And yes...there ARE other alignments demands !! The beam MUST pass thru the corrective lenses....at the center !!
And....and the MultiDiode bar shape MUST be vertical as it passes thru the Cylindrical lenses....

Demanding to align...yes....worth the effort...YES !!

Maybe I am just used to these demands....and we are old friends !!! I suppose !!

NOW...another challenge is where to epoxy the Cylindrical lenses to....so they are in the correct position relative to the diode...that is a machining challenge....but .....see my attached builds....the adaptor has also been designed, machined and proven to work.

And finally....A BIG, BIG yessss....why would one spend a pile of money...only to deliver a bar at 20 feet....seems stupid to me...when we have a proven solution for Hand Held units !!

Later...Beam Out !

 

[steve001]

Funny thread.....Been using corrective optics for years. Epoxy works fine...no problem....you really gotta apply a lot of pressure to break the lens free !!! That is not a problem....ever....!

As far as alignment....ya....it is a PITA !!....but then...SO WHAT....It just takes some time to get the distance between the Cylindrical lenses just right...

And yes...there ARE other alignments demands !! The beam MUST pass thru the corrective lenses....at the center !!
And....and the MultiDiode bar shape MUST be vertical as it passes thru the Cylindrical lenses....

Demanding to align...yes....worth the effort...YES !!

Maybe I am just used to these demands....and we are old friends !!! I suppose !!

NOW...another challenge is where to epoxy the Cylindrical lenses to....so they are in the correct position relative to the diode...that is a machining challenge....but .....see my attached builds....the adaptor has also been designed, machined and proven to work.

And finally....A BIG, BIG yessss....why would one spend a pile of money...only to deliver a bar at 20 feet....seems stupid to me...when we have a proven solution for Hand Held units !!

Later...Beam Out !

As I mentioned a few replies back, round cylindrical optics would be a better solution.

 

[diachi]

Cost, size (Need to mount them in your host, and fabricate those mounts), alignment and of course trade offs involved with beam correction are all issues. There's no free ride when it comes to beam correction, you always need to make some sort of trade off, most of the time it's acceptable or just not an issue.


There's no reason it can't be done as others have shown - it's just not practical or necessary for everyone or every application.

 

[HighPowerObsession]

At this point, I'm kinda over corrective optics; they just seem to be not worth the hassle. I don't know who to believe as far as how easily they can be moved and I don't feel like having to pay a huge premium to get them installed in a build. If the optics can get moved easily, that is a huge issue since I'll be transporting these lasers alot and even though they wont get dropped, they will get bumped and tossed around a bit in backpacks and such (while being in a protective medal/foam briefcase as well).

Anyway, I think BE are a better route to go down, but I just hate using 3-element lens since there is that massive drop in power. I wonder if I used a NUBM44 build with a G2 lens and a 10X BE if that would be enough to tame the beam and make the "dot" an actual dot and not a line or long bar at far distances. I was just checking out this thread of a guy who I THINK is using the NUBM44 diode with a 20X BE. I don't know if he was using a 3-element or not, but if he wasn't, that incredible. Yeah that's 20X and I'll be using a 10X at most, but still its impressive how well it can tame the beam from a diode that has such horrid divergence. So anyway, the question now is in a NUBM44 build would a G2 lens and 10X BE give me a solid dot at far distances or would I have to use a 3-element as well to get that desired affect?

 

[diachi]

At this point, I'm kinda over corrective optics; they just seem to be not worth the hassle. I don't know who to believe as far as how easily they can be moved and I don't feel like having to pay a huge premium to get them installed in a build. If the optics can get moved easily, that is a huge issue since I'll be transporting these lasers alot and even though they wont get dropped, they will get bumped and tossed around a bit in backpacks and such (while being in a protective medal/foam briefcase as well).

Anyway, I think BE are a better route to go down, but I just hate using 3-element lens since there is that massive drop in power. I wonder if I used a NUBM44 build with a G2 lens and a 10X BE if that would be enough to tame the beam and make the "dot" an actual dot and not a line or long bar at far distances. I was just checking out this thread of a guy who I THINK is using the NUBM44 diode with a 20X BE. I don't know if he was using a 3-element or not, but if he wasn't, that incredible. Yeah that's 20X and I'll be using a 10X at most, but still its impressive how well it can tame the beam from a diode that has such horrid divergence. So anyway, the question now is in a NUBM44 build would a G2 lens and 10X BE give me a solid dot at far distances or would I have to use a 3-element as well to get that desired affect?

The optics won't move easily if you use the right epoxy, that stuff is hard. If they do move it's because they've had a lot of force applied and have broken off entirely.

Simply using a beam expander won't make the dot round, it'll still be rectangular, you'll just have a wider beam at aperture and better divergence thus a smaller far field dot. Turning a rectangular multi-mode beam into a round beam using lenses alone is not straight forward and you need to sacrifice power to do it - the best way to do it is by coupling it to a fiber, but that has tradeoffs too.

 

[HighPowerObsession]

Ok but there is still the problem of finding a reliable person to build me a laser with corrective optics at a reasonable price. And I don't even know what "coupling it to a fiber" means, but I'll look into it I guess. I'd rather stick with what people have done before (like the guy in that thread) especially since I'm not looking to experiment with a bunch of different lens and optics and stuff. How did that guy get such a perfect small dot so far away if simply using a BE won't achieve that?

 

[diachi]

Ok but there is still the problem of finding a reliable person to build me a laser with corrective optics at a reasonable price. And I don't even know what "coupling it to a fiber" means, but I'll look into it I guess. I'd rather stick with what people have done before (like the guy in that thread) especially since I'm not looking to experiment with a bunch of different lens and optics and stuff. How did that guy get such a perfect small dot so far away if simply using a BE won't achieve that?

Coupling to a fiber means passing the beam into a piece of fiber optic cable.

Do you mean in the picture where he has the dot on a tower nearly 1km away? Doesn't look like a perfect small dot to me - that looks to me like it's a good couple of feet across, and not necessarily round - the quality isn't good enough to determine what shape it is accurately.

 

[HighPowerObsession]

Yeah the 900m shot; who cares if its a foot or two across, it doesn't matter to me what someone at the site of the dot sees. In fact, its probably better that way because if it was a very small dot, I wouldn't be able to tell that my laser was even hitting it. I just don't want that god awful line to be projected on anything more than 20 feet away. When I saw the pictures in this thread (NUBM44 would be even worse than that), it immediately killed it for me until I found out that I could get something like that guy did on the tower 900m away. If I had a NUBM44 build that could project a dot like that and that far away, that would be PERFECT....I think you guys think I have higher expectations than I really do. Btw that thread with the green laser isn't even that good of example of how bad the line can be.

Now all I need to know is what it takes to achieve what that guy in the thread achieved with the tower. I already messaged him but who knows if he is going to respond.

 

[Sta]

HPO, my NUBM44 with sanwu 3x expander and 3-element lens does not appear to project a line at any distance. At short distance it is a stubby bar and at long distance it looks like a dot.

 

[RedCowboy]

Cylindrical correction of the rapidly diverging axis is the right first step, I use a G2 lens and I use a sanuw G2 when I finish with his 3X expander.

After the rapidly diverging axis is corrected install a beam expander aligned to the beam, spacial filtering can be used to clean up the MM beam.

For more power:

Next is to use 2 NUBM44 diodes with G2 lenses and cylindrical correction that combine via a PBS cube, a wave plate can be used on 1 beam prior to the cube or not if you don't mind a + shaped beam, but this makes spacial filtering harder if you don't use the wave plate, then align a beam expander.

This is to make the best use of affordable MM diodes on a budget.

A ring of a dozen 405nm diodes articulated into a cone intersecting a sliding lens pair could produce a nice bundle of beams with bundle width and convergence point both being adjustable.

I would love to spend money on some projects, but right now bigger issues loom and take the fun out life, some bigger diodes would make things easier.

As for power wasting, you have to trade some power for beam correction, otherwise you have a bright flashlight, yes the 3 element/expander only does consume more power than the G2/cyl pair/expander set up and is not as good, but is easier for people to make quick use of.

As for the nice looking build with the round dot, unless he has some spacial filtering hidden in there then the expander is likely clipping the corners of the bar/square beam, but they are not the most energetic portion and again you trade some power for beam quality.

I don't care is it's splashy and bar shaped, I just want to concentrate the power into the smallest bar at the focus point as possible.