Sharp 490nm GH04850B2G 55mW Laser Diode

[badboybilly]

He probably hasn’t got around to it yet, soldering and pressing 400 plus diodes, testing and what not, The acrilic comes with any module, just purchase the 2element 520 coated seperatly, in my experience with the 488 the 2ellement does an exceptional job at eliminating all the artifacts!

 

[RedCowboy]

The 520 2 element is AR coated for green and the 490 diode is more blue than green, the acrylic may melt, I ordered with a G2 but may use a G7 as both are 400-700 coated or there about.

 

[badboybilly]

This is why it apparently works so good!

 

[RA_pierce]

He probably hasn’t got around to it yet, soldering and pressing 400 plus diodes, testing and what not, The acrilic comes with any module, just purchase the 2element 520 coated seperatly, in my experience with the 488 the 2ellement does an exceptional job at eliminating all the artifacts!

I find that the artifacts introduced by the acrylic and 3-element lenses are worse than the native artifacts of the diode.
The acrylic lens creates bright splash exiting at about 30-45 degrees from the beam that is brightest along the fast-diverging axis and the 3-element glass makes "wings" with a similar pattern.
This is because the acrylic lenses create internal reflections when used with highly elliptical, fast-diverging diodes and the metal spacer within the multi-element glass lenses aren't sufficiently blackened to eliminate reflections from the fast axis (which gets clipped).
The acrylic lenses also seem to accumulate dust more quickly, probably due to static attraction to dust.

Because of this, I prefer to use a G lens which provides the most power and doesn't make the beam spill out all over the place.
I'll take the rectangular artifact over the ugly mess created by the acrylic and multi-element glass lenses. My $0.02.

The 520 2 element is AR coated for green and the 490 diode is more blue than green, the acrylic may melt, I ordered with a G2 but may use a G7 as both are 400-700 coated or there about.

What's the coating specification of the 2-element lens?
These new diodes may appear "blue" but the wavelength may fall within the specifications for the green coating.

 

[RedCowboy]

This is why it apparently works so good!

@ BBB: What gets reflected back into your diode you can't see, as far as you know it works so good. :crackup:


@ RA Pierce: I don't see exact specs, just that DTR sells one for 400-500 which covers 490 and the 520 just says 520, I will likely go with a G2 or G7

The 520 2 element may not reflect a significant amount but I can say that I don't know, I wouldn't say it works so good without knowing it was not going to burn the coating or reflect back into the diode.

https://sites.google.com/site/dtrlpf/home/glass-lenses

 

[badboybilly]

Looking back I suppose it’s possible I’m clipping the full output with the 5mm exit hole, I don’t have the laser in hand anymore but just look at the dpss quality dot!

https://youtu.be/YaxCEn8SQfc


This video is even better divergence don’t get any better than this!

https://youtu.be/N1MV5pAhIVg

 

[RedCowboy]

I see some reflections.

 

[DTR]

I will do a comparison between the two element and three element lenses here in a bit. I can do either with these and yes the no lens option does have an acrylic by default.

 

[Shotgundrums]

I will do a comparison between the two element and three element lenses here in a bit. I can do either with these and yes the no lens option does have an acrylic by default.

Excellent, thank you:beer:

 

[paul1598419]

I haven't pressed one yet, so I can't say for sure which resolves the rectangular artifact and which gives less splash in the output. I really dislike that box sitting just to the side of the focused dot more than a little splash. If anyone finds a lens that eliminates all reflections I am certainly interested in getting some, but I have not found one that does that myself, yet.

 

[DTR]

Can't really see any difference between the two element and three element but on both the box reflection is small and pretty faint in comparison. If I get a chance I will see if there is any power difference between the 2EG and the 3EG.

G-2


2EG


3EG

 

[badboybilly]

Looks like the 2 element is the winner to me!

 

[RedCowboy]

Looks like the 2 element is the winner to me!

Naw, the 3 element is tighter.

-----edit-----

That is a pretty blue, I would like to see a 1 - 2 watt beam of it.

 

[Shotgundrums]

My PLP520-B1 build has a 2EG and it made a dramatic difference with the square reflection.

 

[RedCowboy]

I'm going to try a G7.

 

[badboybilly]

My PLP520-B1 build has a 2EG and it made a dramatic difference with the square reflection.

It sure does buddy, also less loss than the 3 element, The pictures say it all!

G2-G7 if you like the box reflection!