Roithner Lens 27 small fl Lens

[daguin]

What does the "spot" look like? How "clean" is it? What is its shape?

Peace,
dave

 

[Spyderz20x6]

I think it can damage the laser diode...
The AR coating reflects violet light...

 

[Danjoo]

I make a few shots, not sure how to descripe proper how it looks.

Laser in tripod 2 meter to the wall,foot rule on the wall to compare.
I have ingrain wallpaper on the wall.
Cant really compare because is my one and only short fl lens.
Another one from lightpath is coming.  :

In pic two the spot looks off center.

Pic 5 has no viollet ball in reall, the camera cant get the spot without this effect.
Its a normal clean spot, besides the shape of the diode output or the optik bythemself make it looks like the beamspot have a line crossing it.

Pic 6 is with mobilphone.

Hope this pictures give a impression.

@spyder
If the diode get damaged from the wrong ar coating idk.
Is this approved info that it hurts diode?

Thanx

daniel

 

[Spyderz20x6]

I make a few shots, not sure how to descripe proper how it looks.

Laser in tripod 2 meter to the wall,foot rule on the wall to compare.
I have ingrain wallpaper on the wall.
Cant really compare because is my one and only short fl lens.
Another one from lightpath is coming.  :

In pic two the spot looks off center.

Pic 5 has no viollet ball in reall, the camera cant get the spot without this effect.
Its a normal clean spot, besides the shape of the diode output or the optik bythemself make it looks like the beamspot have a line crossing it.

Pic 6 is with mobilphone.

Hope this pictures give a impression.

@spyder
If the diode get damaged from the wrong ar coating idk.
Is this approved info that it hurts diode?

Thanx

daniel

Yes...
It degrades the chip by reflecting photons back into it.

 

[andythemechanic]

[quote author=Danjoo link=1230869534/0#18 date=1231131380]I make a few shots, not sure how to descripe proper how it looks.
...

Yes...
It degrades the chip by reflecting photons back into it.
[/quote]

I asked at roithner if they have specs for the coating or can do different coatings or deliver the lens uncoated, lets see what they reply, could still be that the coating is broadband.
What about reflection from an uncoated lens? I know that for a plane surface reflection is about 4% but for a curved lens?
Do you thinks thats enough to damage a diode?

 

[brtaman]

Actually just because the AR coating is optimized for 635 on this lens, does not mean that it will reflect more power back into the diode. The meredith glass module lens which quite a few members used for BR devices was also optimized for around 6XXnm.

Why this is so, is pretty simple:

Diode has a theoretical output of 190mw before lens:

With acrylic a theoretical 160mw passes past lens. Therefore there is 30mw of light being left behind.

The roitner lens on the other hand is more efficient and allows 175mw to pass. Only 15mw stays behind.

Even with the "wrong" AR coating the lens is able to pass more light, therefore decreasing strain on the die. I think that the AR coated lens that you were referring to spyderman, is the Aixiz triple element glass lens, where all there lenses are AR coated, with this lens there is a dramatic reduction in output and consequently more strain on the die. However, I still think it be best to just wait for IgorT's group buy like daguin said. Broadband coating (IIRC), more efficient and most importantly wont cost an arm and a leg. Shouldn't be too long now.

 

[Spyderz20x6]

Actually just because the AR coating is optimized for 635 on this lens, does not mean that it will reflect more power back into the diode. The meredith glass module lens which quite a few members used for BR devices was also optimized for around 6XXnm.

Why this is so, is pretty simple:

Diode has a theoretical output of 190mw before lens:

With acrylic a theoretical 160mw passes past lens. Therefore there is 30mw of light being left behind.

The roitner lens on the other hand is more efficient and allows 175mw to pass. Only 15mw stays behind.

Even with the "wrong" AR coating the lens is able to pass more light, therefore decreasing strain on the die. I think that the AR coated lens that you were referring to spyderman, is the Aixiz triple element glass lens, where all there lenses are AR coated, with this lens there is a dramatic reduction in output and consequently more strain on the die. However, I still think it be best to just wait for IgorT's group buy like daguin said. Broadband coating (IIRC), more efficient and most importantly wont cost an arm and a leg. Shouldn't be too long now.

Oh, ok...
I was looking at the roithner link danjoo gave us, and i mixed up lens 27 with another lens and thought it was triple element...

 

[artix]

Thinks about it...

If the lens lets more light through, how can it do more damage?

 

[Spyderz20x6]

Thinks about it...

If the lens lets more light through, how can it do more damage?  

I wish i had thought of that

 

[Laser_Ben]

The other lenses melt when you put too much power through them, that means they are absorbing the light. These lenses reflect the light instead of absorbing it, even though less light is lost in the process.

 

[Danjoo]

Iam still happy with this lens.
I just start think about damaging the diode by reflections.
But the point from brtmann and artix sounds logical to me.
If i get more light out its hard to imagine the the damage is higher.

What i do here is nothing against Igor.
I hope nobody take me wrong.

If Igors Lens is ready I buy for sure a few.

But i think is good if we have more lens-test data in the forum.


OT
For next eperiment i have choosen this lens: Its caoted for 400-600nm.
Order is three weeks ago, hope it come soon.

The lightpath Lens: 352330-a
http://www.thorlabs.com/catalogPages/744.pdf scroll down.
But this baby is really expensive...
/OT

 

[tacomanmcjab]

Have you tested this lens with a red yet?

 

[diachi]

Have you tested this lens with a red yet?

yeah, I would like to see the results with a red too .

-Adam

 

[Danjoo]

I have tested red already.

Its the last post on page1 of this thread.

For the beam its the same like for blue ry its smalller beam diameter.
Questions open? let me know



Daniel

 

[IgorT]

Last days of cristmas holidas i remember all the stuff i order the nights online. :
Time ago i buy a Lens 27 from Roithner laser in austria.

Daniel

Hey, Daniel, could you help me out a little?


I am preparing a detailed analysis of my two lenses, with beam specs (dia, aspect ratio), various projections (die artifacts from 405nm diodes), and stuff like that.

Basically, it'll be a comparison of my short FL and medium FL lens to a ThorLab's lens (identical to short FL, but 3 times more expensive), to Meredith (again same lens as short FL, but wrong coating), and hopefully to this one...


What i would need would be some specific photos. Since i'm getting very close to finish line, i'd like to do this quick, and if you could email me, i would appreciate it a lot!


Thanks!



EDIT: 3000th post?

 

[Danjoo]

Email sendet!


Daniel