(Provisional) Group Buy: Laser Diodes A150V

[300EVIL]

Excuse my ignorance, but seeing as the LD in these projectors is only used as an illumination source to light phosphors, how do you figure judging the blue balance of the video output is in any way an indication of the LD wavelength?

Well, It does use the raw diode output as well for the blue spectrum. The phosphor is used for green. However, I'd imagine it would be very hard to distinguish the output wavelength of the LD's just from the projectors output as it's always a mixture.

The only way to truly tell would be the spectrometer method, looking for peak wavelength output or actually pulling the diode arrays from both projectors and look at the output of both, comparatively, with a spectroscope or a good diffraction grating.

[-bart-]

Project the thinnest vertical white line on both projectors.
Project the lines in such a way that they overlap pixelperfect.

Shoot a photograph though a grating, if you have one.
Preferably low lines/mm grating , high megapixel camera.
If you see two distinct blue lines, you have two wavelenghts.

You can calculate the exact wavelength using the white green and red lines as a reference.

[300EVIL]

Project the thinnest vertical white line on both projectors.
Project the lines in such a way that they overlap pixelperfect.

Shoot a photograph though a grating, if you have one.
Preferably low lines/mm grating , high megapixel camera.
If you see two distinct blue lines, you have two wavelenghts.

You can calculate the exact wavelength using the white green and red lines as a reference.

Bingo...

(15 Characters)

[Phatslug]

Good idea, I did similar, projecting the thin line through a grating. While doing that, I've already seen the same 'violet' blue on both projectors.

Making sure the projection size is exactly the same, the disctance between the RGB lines is also exactly the same, so I'm confident, this is 445nm as well. Bad news

[JohnYayas]

This would have been a good experiment for the Mythbusters.

[Phatslug]

I also did the other test now, shooting the pixel matched lines of the two projectors via the grating. The blue lines match.

When I disadjust the two projectors lines a little, you can also see each projectors RGB lines next to each other. Looks the very same as well. Hm.

[-bart-]

For best results, keep the camera + grating as far away as possible from the projection surface.

[Phatslug]

Yes, done that as well with no change. I just couldnt take any decent pitcures that way.

[dnar]

.

[Stoney3K]

OK, so there's some certainty that the A150 is using 445nm just as the A140 would.

Then again, 460nm and 445nm would be quite close to each other in the diffraction pattern when you compare the distance between the R, G and B lines. 445 and 460 would only differ by a fraction of a mm.

This does raise some questions: Where does the A150 get its additional brightness and what happened to Nichia's announcement on 460nm diode lasers?

BTW, great job on aligning the two projectors together. All you need now is a pair of polarizers, RealD glasses, and Flight Simulator.