Nichia to Ship Green Diode Laser

[aryntha]

Well, sure wish it was actually happening right now, even if it meant harvesting $500 projectors. But I think it'll be a year or so until we actually get our hands on one.

 

[seoguy]

One thing to remember is, even though 510 might look green, it's not gonna be as bright as 532nm. In photopic vision 510nm should be about as bright as yellow lasers (about 590nm).

Did you forget about Rayleigh scattering?

The shorter wavelength of the 510nm laser is going to make the actual brightness of the beam nearly 20% brighter than a 532nm laser, which should at least partially offset the perceived brightness difference due to different sensitivity of the human eye based on wavelength under photopic vision conditions.

And compared to a yellow laser, the difference is even more pronounced - a 510nm beam will have an actual brightness nearly twice that of a yellow laser!

You also base your response on photopic vision - but many of us don't have lasers powerful enough for the beam to be seen outside in direct sunlight. And the very first green LD's will most certainly not be that strong!

Rather than pure photopic vision, most folks are going to be viewing their lasers in either subdued lighting, or outside at night - where either scotopic vision, or mixed-mode (rods & cones) will be in effect instead.

While in broad daylight, the peak sensitivity of pure photopic vision is 555nm (and 532nm seems somewhat brighter than 510nm), in scotopic vision (at night), the peak sensitivity shifts to 505nm, VERY close to the 510nm wavelength of this new diode!

Even in subdued lighting (such as at dusk) when both rods and cones are active, the much higher sensitivity of the rods results in peak sensitivity shifting to blue. See this graph -

This increase in apparent brightness is based just on human eye sensitivity alone. Add-in the extra "boost" that a 510nm LD would get in actual beam brightness due to Rayleigh scattering, and I would guess that, under normal laser viewing conditions or at night, with lasers of equal power, a 510nm LD would kick a 532nm's ass in visible beam brightness!

Yellow at affordable price? prolly never as is asaik is not needed in a projector.

Don't be so sure! Didn't some manufacturers (Sharp?) announce new HD-TV models with extra "yellow" pixels - and TV commercials bragging about colors so vivid..."we can't show them to you on your TV"? If high-end quad-color TV's take-off, how long before the manufacturers start demanding yellow LD's for projectors?

I also noticed that these first greens are rated for 50mw @ 10,000 hours lifespan. I wonder what would happen if we put one of these in a large heat sink, and only wanted 100-200 hours out of it, how far could we push it to? :thinking:

Perhaps Nichia needs to send some "samples" to IgorT?

.

 

[HaloBlu]

I've been wondering what the peak for photopic was. Thank you. Would you have a link to the source?

 

[RA_pierce]

I would guess that, under normal laser viewing conditions or at night, with lasers of equal power, a 510nm LD would kick a 532nm's ass in visible beam brightness!

I would be surprised if 50mW of 510nm is much brighter than 50mW of 532nm.
Perhaps we should ask aryntha, who has a 515nm 30mW.



With higher brightness/mW versus 445, projectors won't be needing as much green power.
I don't think there will be another "craze" like there was/is for the 445nm diodes.

I will definitely be going for a diode green but it will not replace my DPSS greens.
Diode may win it for input to output power efficiency and compactness, but DPSS has better beam characteristics and spectral "purity."

 

[heruursciences]

Don't know about brighter, but definitely prettier. 514 is a nice emerald green, 510nm will be just a tad bluer, and when balenced with 445 blue and 660nm red you will have a crazy color gamut that mixed gas lasers would envy. If only they could make tiny beam sizes to fit tiny galvo mirrors nicely...

 

[Pontiacg5]

We would be able to match beam sizes for combining a lot easier with three diodes instead of 2 diodes and a DPSS.

And portable whites would be so much easier, I'm going to build one when my 638 gets here, but I would love to swap the DPSS green for a diode

 

[jmgallego]

I've been wondering what the peak for photopic was. Thank you. Would you have a link to the source?

And I, what was the isotopic peak! Great chart!

Thanks!

 

[awlego]

Any news on what pico-projectors might actually be containing these diodes the price point of them?

 

[cistercian]

I have been waiting a long time for this.No rush...I will wait until they are common and inexpensive.And then build or buy a high power one.It will be fun to compare them to DPSS beam quality in the future.I wonder if DPSS greens will become rare in the future...I guess we will see!

 

[aryntha]

I have been waiting a long time for this.No rush...I will wait until they are common and inexpensive.And then build or buy a high power one.It will be fun to compare them to DPSS beam quality in the future.I wonder if DPSS greens will become rare in the future...I guess we will see!

I really doubt it. At this point, I think there's a possibility that more cheap DPSS greens have been made, than people that want them.

It's amazing though, since I remember how exotic the tech was 10 years ago. 473s were just about to start to follow that trend, and then, bam - 445... I'm not sure how "cheap blue" is going to play out now, since 445 seems to be "blow your eyes out powerful" or nothing at all.

 

[RA_pierce]

I really doubt it. At this point, I think there's a possibility that more cheap DPSS greens have been made, than people that want them.

It's amazing though, since I remember how exotic the tech was 10 years ago. 473s were just about to start to follow that trend, and then, bam - 445... I'm not sure how "cheap blue" is going to play out now, since 445 seems to be "blow your eyes out powerful" or nothing at all.

I am using my 445 less and less. It's hard to enjoy it with safety goggles and it's hard to enjoy it when it "blows my eyes out" every time I turn it on.

Lower power on the way. ~1W of 445 is just too much. I'm thinking about getting rid of this one. Just like I did the 2.5W 808. Too much power in a portable is not fun.

I will be glad if these green diodes are single mode and Class IIIb.

 

[millirad]

You'll be OK, once your eyes adjust for the intensity. J/K
Seriously though, why not just put your 445 into a scanner? Perfectly nice power level when scanned right?

 

[RA_pierce]

You'll be OK, once your eyes adjust for the intensity. J/K
Seriously though, why not just put your 445 into a scanner? Perfectly nice power level when scanned right?

Ehh... not really into scanners.
I'm planning on building a 2W RGB labby in the future.
Right now I just want to enjoy some color.

 

[seoguy]

I've been wondering what the peak for photopic was. Thank you. Would you have a link to the source?

I actually came across that # quoted in numerous sources while researching this.

But due to the complexities involved, the actual curve has been somewhat of a moving target over the years.

In fact, the photopic curve even varies by the field of view! The very center of the fovea (0.35 degrees field of view) is completely lacking in "S" cones. As a result, a wide field of view (10 degrees) is more sensitive to blue and violet than a narrow (2 degrees) one. The previous curve was for the former, as that is how someone is going to be viewing a laser beam.

Doing some digging, I have learned that at least 10 genetic variants of the "L" and "M" cone photopigments have now been discovered! (And each with it's own response curve! ) Based on this, there has been some recent work theorizing that the photopic curve may actually be somewhat flat on top, and peak at 545!

I would be surprised if 50mW of 510nm is much brighter than 50mW of 532nm.

Unlike photopic, the scotopic curve is well-defined. The prior graph was log-scaled to get both to fit, and thus made the curve look more rounded. Here it is with normal scaling -

It peaks at 505nm, and as you can see, drops-off quite steeply at longer wavelengths! This LD is only 5nm away from that peak! - while a 532 DPSS is over 5x farther away (down that steep slope!) Add to that the extra "boost" it also gets from Rayleigh scattering, and there is no doubt that under scotopic viewing conditions, 510nm would be brighter than 532!

Up against a 50mw DPSS, my money would still be on the new LD! I think the color would be prettier as well!

Diode may win it for input to output power efficiency and compactness, but DPSS has better beam characteristics and spectral "purity."

But wouldn't a 510nm perhaps give you a better color gamut? :thinking:

My understanding was that the yellow-tinged green of a 532nm DPSS kinda "sucked" for color rendering in projectors, and was only being used because it was readily available?

It appears I'm not the only one coming to this same conclusion...

514 is a nice emerald green, 510nm will be just a tad bluer, and when balenced with 445 blue and 660nm red you will have a crazy color gamut that mixed gas lasers would envy.

We would be able to match beam sizes for combining a lot easier with three diodes instead of 2 diodes and a DPSS.

And portable whites would be so much easier, I'm going to build one when my 638 gets here, but I would love to swap the DPSS green for a diode

Agreed!

And perhaps get a prettier color range as well!

And I, what was the isotopic peak! Great chart!

Thanks!

Your welcome!

Isotopic? Nuclear vision? :thinking: Is that like Superman?

Searching for what you meant, I did find a blog incorrectly referring to night vision as "isotopic".

If you are talking about night vision, that's scotopic - the curve for that one is the graph I just posted above. It peaks at 505nm - which is one of the reasons I think that the beam of this 510nm LD would look so awesome at night!

It's amazing though, since I remember how exotic the tech was 10 years ago. 473s were just about to start to follow that trend, and then, bam - 445... I'm not sure how "cheap blue" is going to play out now, since 445 seems to be "blow your eyes out powerful" or nothing at all.

They are going to need some lower-power blues, to go with those greens in projectors.

I will be glad if these green diodes are single mode and Class IIIb.

Well, those initial ones are not "death-ray" Class IV's, but rated for normal operating 50mw APC, so definitely Class IIIb!

.

 

[Prototype]

1.)But wouldn't a 510nm perhaps give you a better color gamut? :thinking:

My understanding was that the yellow-tinged green of a 532nm DPSS kinda "sucked" for color rendering in projectors, and was only being used because it was readily available?



2.)They are going to need some lower-power blues, to go with those greens in projectors.


Well, those initial ones are not "death-ray" Class IV's, but rated for normal operating 50mw APC, so definitely Class IIIb!

1. By spectral purity I assume they meant the wavelength shift range is a lot smaller. It's only a few nm for DPSS vs. the +/-10nm diodes can have.

2.Low powered 445nm diodes exist, and are in use in the laser pico projectors. Osram makes a 3.6mm can 50mW 445nm diode. There's also the Nichia 50mW diodes. While these may be costly for us, remember that the main companies buying these are spending a huge amount of money buying them in bulk, and have the money to throw around.

 

[RA_pierce]

But wouldn't a 510nm perhaps give you a better color gamut? :thinking:

My understanding was that the yellow-tinged green of a 532nm DPSS kinda "sucked" for color rendering in projectors, and was only being used because it was readily available?

Yes, the gamut should be better, but I am not interested in it's use in projectors.
I think that the 510nm diode would make a nice, stable, and bright pointer for night use. I plan on getting a telescope soon and I think a cool green guide would be spectacular. It would definitely beat DPSS for stability in outdoor operating temperatures.

The thing I like about DPSS is that it looks so "clean" compared to the output of diodes. I don't know how to describe it but it looks "more" monochromatic and the profile is much sharper. Diodes are a bit unreliable when it comes to exact wavelength...

And thanks for the explanation on the scotopic curve.

I'm ready for these diodes. Are we there yet?... oke: