Huge 445nm beam

[Howie]

I just hooked up a Flexmod and set the current to 900mA for a 445nm diode for the scanner I'm putting together. This was the first diode I've installed, ever, so I'm glad it actually worked!!

So I fire it up and the "dot" was like a 4 inch by 1 inch stripe from about 6 feet away. It was pretty bright but HUGE! I was using the stock acrylic Aixiz lens and only powered it up for a few seconds.

Would the lens be the cause for the huge beam? I have a few glass lenses around here somewhere that are actually for the 445s. Think thats the problem or is there another cause for the crazy divergence?

 

[Coherent Light]

Your Diode is out of focus. You will not to adjust the focus by screwing the lens in and out until focused.

 

[Kulhu]

yea you need a glass lens for the 445, and the glass must not reflect too much light or it will kill the diode.

 

[Howie]

Cool, thank you.

I'll need to find a better heat sink for the driver before I run it for any length of time but I'll switch to the glass lens and work on the focus when I do.

 

[Bionic-Badger]

Also don't run it with your acrylic lens in the mean time. They melt from the intense radiation of your class 4 laser, and the vapors can affect the diode's window.

Glass 405nm lenses can be purchased for about $10 from Aixiz. Get the full-threaded version (linked) because then you can attach a focusing module to it. Also make sure that the coating really is made for 405nm. There have been some sent out that were mistakenly for red lasers. A 405nm AR coating will have a goldish tint to it when white light reflects off the front. A red AR coating will look bluish.

 

[Toaster]

I have been told I have a huge beam before.

You see, what I did was read up on how to make my beam smaller. I got tired of scaring people whenever they looked at it.

I looked at Jayrob's glass lens comparison and from what I seen, for the 445nm, the 445 glass lens looked like a better cleaner dot than the 405 glass lens. The 405 however has more power coming through it.

Here is the quote from the thread:
* Stock projector lens: 352mW's - Wide spreading thin wings... not desirable.
* 405-G-1: 360mW's - Not too bad... Most power, but same side splash that is much more noticeable than with blu-ray because of the visibility of the 445... (a good lens choice)
* New AixiZ 445 lens - Nearly the same as AixiZ 405 (within a few mW's - about 5% less)
* AixiZ 405 glass: 315mW's - This is the one for me! Very nice clean dot! (better than I had hoped for anyway) Still fairly good power.
Edit: I added a couple of more lens power comparisons. (no pictures for these two)
* Normal AixiZ glass lens (red): 272mW's... The dot and beam looks the same as AixiZ 405 glass. I believe it is the same optics but with a different coating...
* AixiZ acrylic (back opened) gave 293mW's. But I don't think acrylic is an option because it will most likely degrade quickly. But just to show the power comparison...

There you go! Enjoy

Oh Also, you can get the lens from Jayrob, he is a pretty cool dude.

 

[Morgan]

The difference between the 445nm Aixiz glass lens and Jayrob's 405-G-1 lens is that the Aixiz is a 3 element lens, (i.e. has three glass lenses). They are AR coated to include the 445nm wavelength. In fact, 405nm and 445nm are close enough to probably be covered by the same coating and often you will now see them stated as broadband coated for both. I'm not certain we are absolutely sure that early lenses, stated to be coated for 445nm, are only coated for this wavelength but it is likely this wouldn't make much difference in use. Prior to the 445nm diodes they were only ever quoted as AR coated for 405nm as this was the wavelength they were used with.

The Jayrob lens, and the LarryDFW lens as it happens, (they use the same lens), is a short focal length, single lens. This means it is closer to the diode and therefore usually outputs a narrower beam and catches more of the light emitted. This is one reason why the power output is higher but because the 445 diodes are multimode, and emit a bar of light, distortions are created with this lens causing the undesireable splash and poor beam shape. They are, however, much better suited to the high power blurays as these have a much narrow emitter.

To summarise:

When using the Casio 445nm diodes -

For best beam shape, without using other corrective optics, use the Aixiz 3 element AR broadband coated lens.

For best power output and therefore better burning, (15% more than the Aixiz), use the Jayrob or LarryDFW lens.

When using the high power Bluray diodes -

Jayrob or LarryDFW lenses win hands down!

M

 

[Flaminpyro]

Morgan you forgot to tell them if they want to scare someone, don't use a lens at all :crackup:

The difference between the 445nm Aixiz glass lens and Jayrob's 405-G-1 lens is that the Aixiz is a 3 element lens, (i.e. has three glass lenses). They are AR coated to include the 445nm wavelength. In fact, 405nm and 445nm are close enough to probably be covered by the same coating and often you will now see them stated as broadband coated for both. I'm not certain we are absolutely sure that early lenses, stated to be coated for 445nm, are only coated for this wavelength but it is likely this wouldn't make much difference in use. Prior to the 445nm diodes they were only ever quoted as AR coated for 405nm as this was the wavelength they were used with.

The Jayrob lens, and the LarryDFW lens as it happens, (they use the same lens), is a short focal length, single lens. This means it is closer to the diode and therefore usually outputs a narrower beam and catches more of the light emitted. This is one reason why the power output is higher but because the 445 diodes are multimode, and emit a bar of light, distortions are created with this lens causing the undesireable splash and poor beam shape. They are, however, much better suited to the high power blurays as these have a much narrow emitter.

To summarise:

When using the Casio 445nm diodes -

For best beam shape, without using other corrective optics, use the Aixiz 3 element AR broadband coated lens.

For best power output and therefore better burning, (15% more than the Aixiz), use the Jayrob or LarryDFW lens.

When using the high power Bluray diodes -

Jayrob or LarryDFW lenses win hands down!

M

 

[Morgan]

Sorry flaminpyro!

Of course, if you want to scare someone, don't use a lens at all.

Rectified!

M

 

[Toaster]

Morgan, What lenses are you talking about. Rather than using the name of the supplier can you use the name of the lens? Jayrob sells many lenses.

 

[Benm]

The acrylic lenses are no good for these diodes... i tried, and it developed a black spot right in the middle of beam in virtually no time. Using the aixiz glass lens for red now, waiting on the one for blue to arrive.

Beam quality is better even with the wrong coating too - its still a line, but less rings/artifacts around it using the glass lenses.

 

[Morgan]

I did use the name of the lens. It is the, "Jayrob 405-G-1". That is the name of the lens as stated above. There is also the, "405-G-2", and the, "650-G-1". the 405 states the wavelength for which they are AR coated as does the 650 in both names. As mentioned above though the 405nm coating will likely work just as well with 445nm.

You'll find them here -

http://laserpointerforums.com/f39/jayrob-build-kits-lenses-other-stuff-listed-here-44227.html

... and here -

http://laserpointerforums.com/f64/fs-405-g-1-glass-lens-mod-31-increase-vs-aixiz-22497.html

... Larry DFW's lens is here -

http://laserpointerforums.com/laser_pointer_forums_3/forum/showthread.php?t=22493<br

Seems to be a broader coating on Larry's but I've not used them so I have no figures and it only looks like the first post has been updated since the 445s came out so you'll have to do some searching yourself for more information.

M

 

[Benm]

I don't know about the 405 coating... it seems to work for most people, but aixiz also makes a lens with 400-445 nm broadband coating now... at least, in the listing it says "This glass lens is now coated to work AR with 400-455nm applications." so that idicates its different from the previuous 405 glass lenses.

405nm glass lens for AixiZ 12X30mm laser module - eBay (item 380137309450 end time Sep-30-10 13:34:45 PDT)

 

[millirad]

^ Good point, the new lens has a broader band pass spectrum and therefore should transmit higher energy/milliwatts.

(For other builders who are learning), it is a lens and needs to be incorporated/installed into an Aixiz threaded module.

 

[Morgan]

Thanks for clarifying Ben, I wasn't sure how far the experimenting had actually gone but the wording would indicate a different coating.

M

 

[Benm]

I wonder if there is any way to tell the old and new lenses apart... The item history lists 597 sold, of which about 100 since the beginning of july. I figure they are sold the old ones under the same ebay listing, and i have no idea when they changed the coating.

Aixiz makes pretty nice lenses, but one downside is that there is no marking or part number anywhere to tell them apart. Bluray and red coatings are sortable by looking carefully, but i doubt this would be possible for AR 405 against AR 400-455... perhaps if you have them side by side, but not if you have only one.