Confirmed - Osram PLT4 - A "new blue" wavelength :)

Some of you may have been following this thread (http://laserpointerforums.com/f51/h...ojector-450nm-640nm-non-dpss-green-64072.html) Well, I finally got a hold of my 3.8mm module (well sort of, it still needed a tad of modifying to fit the enlarged can... errrr "enlarged tiny diode can"). Fired the diode up, focussed with an Aixiz acrylic, and decided to put it to the diffraction grating test!

A quick note first. I'm using my tool here (Calculator: Determine Wavelength (nm) Using Diffraction Grating), which is based on solid math thanks to Cyparagon. What is not quite as *solid* is my ability to precisely measure the two crucial distances that this wavelength math requires.

So what? I bring that up to emphasize that fact that I wouldn't trust the final indicated value of the individual wavelengths. A few mm of error in measurement can make a pronounced difference in the indicated wavelength.

What can we trust? We can trust the relative difference between this PLT4, and our beloved A130 "445" diodes. That's where error isn't a concern, because it was fairly plain to see, and easy to measure, that there were at least 15mm of difference in the distance of the their dots from each other. When you crunch the math:

1000 lines per mm
102 cm from surface

Distance between the dots? (this is what matters)

For the A130 diode: 51 cm between dots (suggesting 447nm)
Calculator: Determine Wavelength (nm) Using Diffraction Grating

For the PLT4: 52.5 cm between dots (suggesting....wait for it.... 457nm!)
Calculator: Determine Wavelength (nm) Using Diffraction Grating

Pretty cool! Remember, these wavelengths may not be correct individually, but the difference between them (IE, the PLT4 being ~10nm higher) should be solid



EDIT / UPDATE:
I now have a shot with a 473nm added into the mix (far right dot)


Some final thoughts:
- It's not a drastic visual difference, but I can see it without much trouble, as long as I'm paying attention.
- My camera can't pick up the difference, because all blue 445-range beams look pink to it, the attached beamshot is fairly useless as a result (though you can sort of see the difference, even though the camera totally skews the colour of both)
- The beam specs are better than a typical A130 445, but worse than a 658 singlemode. It's a rectangular beam, but it's a "better" rectangular beam than our usual 445s.
- I'm running it at the mid-point (100mA) between typical (80ma) and max current (120ma) as per the datasheet. It gets warm, but not hot.

Awesome

Cant wait to see this in a finished build!

+:beer:

Nice!

I was thinking about this today; when you were going to test this diode.

Awesome results!

That's awesome. Have you lpm'd it yet?

And I love your tool (lol)
When I do a diffraction grating test I use a know wavelength like green usually to verify accuracy with the lines/mm and distance to wall.

That diode makes the 445nm unit look violet! Nice photos! Neat find!

Hey- did you get that package yet?

Meatball said:

That diode makes the 445nm unit look violet! Nice photos! Neat find!

Hey- did you get that package yet?

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Not yet - but I'm sure it will arrive shortly

UPDATE: By strange fluke of the universe, I ended up in possession of a 473nm that isn't mine. (shipping mistake, and the correct recipient gave me instructions to test the 473nm pointer's power since it was here). So I added it to the photo of wavelengths.

Looks like this OSRAM is dead in the middle of a 445 and a 473 - which makes me happy

LEFT: A130 (typical "445" diode)
MIDDLE: This OSRAM PLT4
RIGHT: 473nm CNI

How's the output look dotwise? Is it a line or fairly symmetrical?

qumefox said:

How's the output look dotwise? Is it a line or fairly symmetrical?

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It's a line. Much better than a 445, but nowhere near as symmetrical as a 658.

Ah, so it's probably like the 20mW 635's I have. I think we'll probably see that only diodes originally developed for optical drive use will have near guassian beam characteristics. So i'm not really too surprised.

qumefox said:

Ah, so it's probably like the 20mW 635's I have. I think we'll probably see that only diodes originally developed for optical drive use will have near guassian beam characteristics. So i'm not really too surprised.

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I think as a general rule that probably makes sense - but there are some notable exceptions. The HL63133DG has almost identical (maybe even better) beam specs vs a LOC, yet it definitely was never intended for optical drives. Essentially, it has the same intended purpose as this OSRAM blue (IE, pico projectors)

Very VERY nice rhd; +1 if I can (I don't know if I can)... 457, I end up seeing that out of my ArIons... definitely have to look into getting one of these diodes... I'm guessing cracking open a ShowWX is the only way at this point, and then the interesting aspect of getting it mounted into a host

I wouldn't be suprised if in 5 years we'll have 5W R-G-B diodes in a single can with all the pico projector madness going on.

grenadier said:

I wouldn't be suprised if in 5 years we'll have 5W R-G-B diodes in a single can with all the pico projector madness going on.

Click to expand...

I don't think that would be desirable from an optics perspective though?

Wow, do want. 460nm handheld? I'm in.

-Trevor

rhd said:

I don't think that would be desirable from an optics perspective though?

Click to expand...

How so?

grenadier said:

How so?

Click to expand...

You'd have three emitters inside a can, but they wouldn't literally be the same point of emission, so you wouldn't get a coherent white beam. I'm not even sure you'd get three beams side by side. My sense is that you'd probably get some sort of wonky mess of an output.

That said, I don't know much about "microlensing", but that might be a solution if you wanted to stack three emitters in close proximity, just get the appearance of a single beam. Totally speculation though.