650nm BEST LENS FOR LOWEST DIVERGENCE?

[FiveTwentyThreeHundredmW]

Just got a single mode 650/660nm laser. Uses one of the open-can LPC diodes. Amazingly tight beam. The divergence is insane low! Using the lens on the left which I don't know what kind it is?....(on the right is a 3 element lens for comparison). Anyone know what kind of lens is on the left? The dot also has a line running through it....

I can really appreciate the beam quality for these diodes, they have got to be among the best. Even across my apartment, focused at infinity the dot is soooo small. I'd estimate 0.5-0.6mRad.

 

[DTR]

The one on the left looks like one of my lens barrels so it is probably a G-2 but it could be a G-1. The China G has a little larger lip.

 

[FiveTwentyThreeHundredmW]

The one on the left looks like one of my lens barrels so it is probably a G-2 but it could be a G-1. The China G has a little larger lip.

Hey DTR! I had a 240mW 520 which had a lens that looked exactly the same. It was a G lens. So makes sense. But...I thought G are used for getting more power while having a worse beam. But this is a lower power (less than 250mW) red. I bought it strictly for low divergence and beam quality. Purely for low divergence. And it's quite awesome now (focused at infinity this laser's dot is smaller than my Spartan 637nm 90mW). But I want the best lens for it. Would a 3 element be better? Take out the lines on the dot, and make it a wee bit tighter? ^____^

 

[DTR]

With low divergence single mode diodes for the most part they can actually get better spot size and power advantage but they do usually have a little more splash. It is mainly multimode diodes where you get into the trade off between spot size and power.

 

[FiveTwentyThreeHundredmW]

How would a lower powered single mode diode have more splash? My 1.6W 445 has diode output that covers a backyard but my 650 is a bulging oval that's not even visible after 20 feet...hmm

Focused, it's got a super small dot even 25 feet away...but it's got a line on the dot. What do you think a 3 element would do? I have this laser purely for low divergence (it still lights up my place, and next to my 1.6W 445 it honestly doesn't do too bad.) No fog in that photo and the cam exaggerates the lasers....but still...

 

[FiveTwentyThreeHundredmW]

With low divergence single mode diodes for the most part they can actually get better spot size and power advantage but they do usually have a little more splash. It is mainly multimode diodes where you get into the trade off between spot size and power.

1. So with a 150-250mW single mode 650...is it worth trying the 3 element glass? Will the dot get noticeably smaller?

2. FYI, the "mystery lens" looks like it only has one optic in the barrel. I also noticed wrapping teflon tape on the threads is tough. I got some cheap tape and it easily falls off unless you wrap it tight (how it should be done anyway) but going tight is hard without the lens slipping. Anyone have strategies for wrapping lenses? :beer: The lens is very snug and a spring is not necessary either. But on my 445 1.6W 501B, the lens is very smooth, almost loose but just barely snug. It looks like the heat may have sealed the tape to the threads? But isn't the tape heat resistant? I could use a spring with my 445, but the 650 the lens is very tight with tape.

 

[FiveTwentyThreeHundredmW]

I got a roll of teflon tape on Amazon for 45 cents, free shipping. It's gone now from the site. But what a STEAL.

Just taped the lens for my 2 501B lasers, it is PERFECT! Focus is so smooth yet firm. Took a while to learn how to wrap the threads but I got my own method down now.

I noticed the 3 element barrels are smaller and are still very easy to turn even with tape...they could use a spring too or double-wrapping. The G barrels seem wider.

 

[hakzaw1]

wow
triple posting--
you may hear from somebody about that

teflon tape can ONLY be used for lenses IF you know how to make it impossible to get into the diode or diode window

adding a focus knob helps- you can add a very tiny dot of silicon glue to keep it in place in the focus knob- so it wont move-other wise changing the focus ( & I somehow get the feeling you do that a LOT) will not make you remove the knob and lens to 'start over' -- there is a 640 diode that is said to have the best of all- bright shade of red and super thin beam which makes it even brighter - side by side it atkes 2W of 650 to 'look' tyhe same brightness of 1 w of 640 Mierlight sells a 500mW 640 showlabby for only $1500at Greedbay

Norty UK has a YTUBE vid of two identical PJs with the two reds- equal in preceived brightness-

GL hak




then tape or spring where the lens goes into the module

 

[Pman]

Its not in good form to post again right after posting. You should edit the prior post instead
I rarely use Teflon tape myself. Concerned about any coming loose and burning. Just be really careful wrapping.

 

[FiveTwentyThreeHundredmW]

Its not in good form to post again right after posting. You should edit the prior post instead
I rarely use Teflon tape myself. Concerned about any coming loose and burning. Just be really careful wrapping.

wow
triple posting--
you may hear from somebody about that

teflon tape can ONLY be used for lenses IF you know how to make it impossible to get into the diode or diode window

adding a focus knob helps- you can add a very tiny dot of silicon glue to keep it in place in the focus knob- so it wont move-other wise changing the focus ( & I somehow get the feeling you do that a LOT) will not make you remove the knob and lens to 'start over' -- there is a 640 diode that is said to have the best of all- bright shade of red and super thin beam which makes it even brighter - side by side it atkes 2W of 650 to 'look' tyhe same brightness of 1 w of 640 Mierlight sells a 500mW 640 showlabby for only $1500at Greedbay

Norty UK has a YTUBE vid of two identical PJs with the two reds- equal in preceived brightness-

GL hak

then tape or spring where the lens goes into the module

Sorry for the triple post.

I own 3 501B lasers, 2 have G lenses and 1 has a 3-element. In my experience the lens barrels all need tape and/or a spring. The G's seem less loose but it's still a problem. Lens barrels of course are not a tight fit (understandable since you'd have too much metal-to-metal contact and thread wear and tiny metal shavings. However, the amount of play/wobble in the fit is always unacceptable. With no lens or spring, the wobble throws the beam angle around and it's impossible to hold a focus point. The lens moves at the slightest move of the host. These lasers are well-made, awesome products and deserve a stable, snug lens fit and proper focus rotation.

A spring adds tension and helps hold a focus, but the wobble is still totally there when rotating, throwing your beam angle. Keep in mind the lens can also move forward-backward a tiny bit which ruins the focus too.

My first 501B had teflon tape and no spring. One wrapping takes away ALL wobble and play. But it was still too easy to rotate. I added a spring and it was fine. But I got paranoid about the spring hitting the diode. I re-wrapped the lens with two layers and it's fantastic.

My other two 501Bs had the G lenses with springs and no tape. Rotating the lens throws the beam angle horribly. I took the springs out and wrapped one layer on the threads, and it's snug and tight. Zero wobble.

After noticing the same lens fit with 3 lasers (the wobble and play, which I understand based on the design) I just don't see how people could use it like that. Teflon tape is dirt cheap. I got a roll for under $1. After 30 mins of practice I have a method of wrapping tightly. The tape does not slip. And it's easy to scrape away the bits that cover the lens. The fit is perfect. It is so easy to fix what seems like widespread "issue". And the tape is very easy to work with. If you mess up you can get it all off in one or two big peices, even after you pressed it into the threads. And it never gets into the module threads. It stays on the lens barrel.

Teflon tape is a complete score, IMO. Dirt cheap, clean/neat, removes ALL wobble and play. Wrap one or two layers for desired tightness. Without it or a spring the laser is seriously handicapped...

And yes, I do like to adjust the focus point of my laser. It's a feature of the design. I should be able to do it all day if I want, including removing the lens and using it like a "flashlight"

I don't know about others but I want my laser to hold it's focus point and have a straight beam. But to each their own? lol :beer:

 

[hakzaw1]

I did not mean that a lot of focusing was a bad thing-- only that IF you are going with Teflon tape take care that is cannot get off the threads and into a bad place AND more importantly IF anyone using tape EVER sees anything odd in the spot STOP at once and make sure it is not some tape that has gotten in the wrong place--

hak

 

[FiveTwentyThreeHundredmW]

I did not mean that a lot of focusing was a bad thing-- only that IF you are going with Teflon tape take care that is cannot get off the threads and into a bad place AND more importantly IF anyone using tape EVER sees anything odd in the spot STOP at once and make sure it is not some tape that has gotten in the wrong place--

hak

True- I was nervous about anything getting close the diode...my 650nm has the open-can LPC...and I can see the lasing chip, looks like a tiny iridescent grain of sand...I know how sensitive they are Luckily the tape is a score for me. My 445 has a closed can but I'm still paranoid about anything touching that diode window... :beer:

 

[steve001]

Just got a single mode 650/660nm laser. Uses one of the open-can LPC diodes. Amazingly tight beam. The divergence is insane low! Using the lens on the left which I don't know what kind it is?....(on the right is a 3 element lens for comparison). Anyone know what kind of lens is on the left? The dot also has a line running through it....

I can really appreciate the beam quality for these diodes, they have got to be among the best. Even across my apartment, focused at infinity the dot is soooo small. I'd estimate 0.5-0.6mRad.

The answer to this question is simply a longer positive focal length lens. Experiment with some cheap lenses from Anchor Optics.