NUBM07E 465nm 2.9W Diode Test (Hitting 470nm+)

[RedCowboy]

Yes and everyone says something different it seems, but I also found that technical definition, but I just say rapidly diverging axis when talking about correction or lens clipping to keep it simple.

 

[paul1598419]

Yeah, that is less confusing, I guess. I just didn't want the wrong information being perpetuated.

 

[Alaskan]

I'm so confused then, from what I think I see, the minima side is the slow axis, the wide the fast for this diode, I've been told they swap at a distance, for some diodes, but I don't see that happening with the green 1W 7475T diode. I can't say what this diode does, mine died.

 

[RedCowboy]

Yeah, that is less confusing, I guess. I just didn't want the wrong information being perpetuated.

I appreciate that and I would rather say it right, but I need to know when a particular diode behaves opposite from another where the technical definition is not mutually reflective of the beam characteristics, but I do appreciate the info and I would like to state it correctly.
Thanks.
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Alaskan, look at a 7876 or M-140 or nubm44 with a 3 element.

Focus to infinity and see how when you hold it with the wide part of the ribbon facing you, that is you look down and rotate the laser until the beam looks wide, now look at the distant line, it will be tall and skinny, dead opposite of how it started.

Rotate 90 degrees and you will see the narrow side that will produce a short wide line in the distance.

The shape of the emitter is opposite of the divergence ratio.

When I fire my G2 lensed nubm44 into the 1st concave cylindrical it looks wide and short in the distance, Horizontal line, but like a little letter l going into the concave lens, Vertical line. Every blue MM diode I have ever seen is like this and although efficiency is up so is divergence.

 

[Alaskan]

Due to the low divergence of my expanded NUBM44 it makes my ability to see what is happening difficult, but I think I can see that it does change orientation by 90 degrees when spotting 300 feet away, but I don't see it happening with my NDG7475T 1 watt green 520nm laser at that distance.

 

[RedCowboy]

The 520's may be a little closer to a square pn junction, with the blues it's just the shape of the pn junction we see lensed up close, the more powerful they get the wider they get, but it's the height portion that diverges very rapidly.

p.s. I got a message back Dave at LSP about 6x pairs, I will get a price for 2, 5, and 10 sets and decide if it's worth buying in bulk, if not everyone can just order directly. Do you want a set right away?
The 07E is pretty, but I am loving the power of the 44 corrected into a useful beam, it is addicting and I want more. :eg:

 

[Alaskan]

I could use another pair, yes. Thanks!

 

[Pi R Squared]

Alaskan, look at a 7876 or M-140 or nubm44 with a 3 element.

Focus to infinity and see how when you hold it with the wide part of the ribbon facing you, that is you look down and rotate the laser until the beam looks wide, now look at the distant line, it will be tall and skinny, dead opposite of how it started.

Rotate 90 degrees and you will see the narrow side that will produce a short wide line in the distance.

The shape of the emitter is opposite of the divergence ratio.

:thinking::wtf: I mostly use my lasers inside over short distances 20' or less, I had never noticed this.

Alan

 

[paul1598419]

RedCowboy, if the price is good, I definitely want a set. Let me know. Thanks.

 

[DTR]

This thread has a ton of tests and discussion on correction and the possible backfill issue.:beer:
NUBM07E 465nm 2.9W Diode Test

 

[lazeristasUVISIR]

:thinking::wtf: I mostly use my lasers inside over short distances 20' or less, I had never noticed this.

You really need to focus a laser at a distance where you want to observe the effect.

 

[RedCowboy]

RedCowboy, if the price is good, I definitely want a set. Let me know. Thanks.

They are 55.00 AUD, 1 USD = 1.358 AUD so that's about 40 bucks US, however he has to get more in. There is a small price break at 10 pairs, but right now they are out of stock.

 

[jors]

Yeah, that is less confusing, I guess. I just didn't want the wrong information being perpetuated.

A Diodes 'Fast Axis / Slow Axis' demystified / discussion...

 

[RedCowboy]

To employ a cylindrical pair the above chip would be rotated, that is the module/diode, would be rotated 90 degrees so that the far field line looks horizontal ( as focused through a G2 ) and what strikes the 1st concave cylindrical looks like a tall thin line, it seems wrong but it's not and that 1st concave cylindrical will make the far field horizontal line look even wider. Center it where your original focused line from your G2 was centered.

The 2nd convex cylindrical is moved foreword and back causing that far field horizontal line to shrink and expand until you have it set where is has shrunk to an optimum infinity beam, also centered.

NOTE: You can see why clipping the fast diverging axis robs power as it is the more energetic.

 

[logsquared]

To employ a cylindrical pair the above chip would be rotated, that is the module/diode, would be rotated 90 degrees so that the far field line looks horizontal

Actually, no need to rotate 90deg. Correction actually takes place on the slow axis. The orientation of the diode in the picture will produce a "-" horizontal line in the far field with the orientation shown.

The blue "pill" shape on the picture is what strikes the collimation lens. This gives the "l" shape right after the lens. The beam turns to the "-" shape in the far field because the collimator lens basically images the die at a distance. Look on the front of the "LD chip" the small rectangle is the die shape. This is what is imaged at the far field.

Hope this helps.

 

[RedCowboy]

Are you sure about that?
This is where the definition is different depending on who you ask, as I have read it it's actually determined by the construction of the junction, the rapidly diverging axis may be the slow axis, I have heard it both ways, but I know you want a far field horizontal line focused when you set up cylindrical pairs and the line that strikes the 1st concave cylindrical looks tall and narrow even though it is wide and short just 15 feet away.

I will try to find the definition by the junction construction, because it is not always the rate an axis diverges that dictates its denotation rather the junctions construction, or so I have read.

IF the BLUE OVAL is what it looks like 10mm in front of the G2 then YES, leave it just like that.
I thought that was showing what it does down stream and the junction rectangle behind it is what you see up close, but if its the shape of the blue oval then it's just like it needs to be. But I think the shape of the junction is what you see up close, a horizontal line and the blue oval is the far field, in which case it needs to be rotated.

As far as an image of the emitter that's fine for a single mode but MM is different, just look at the raw output on the wall then screw in the lens, what was long becomes short.

Is the definition different if it's a single mode vs a MM?
https://www.rp-photonics.com/broad_area_laser_diodes.html

No matter what I know what to do with it, I want a MM diode focused through a G2 to be producing a wide short horizontal line at the longer distance and a letter l shape into the 1st concave cylindrical. Regardless of what we call the axis, and I have heard it both ways, could single and MM make a difference, I know the emitter picture will be reproduced with a single mode in most cases, but uneven diverging MM diodes maybe not.