how 520nm brightness vs 532nm in an RGB buld

I haven't personally seen it yet, an am trying to decide on a direction to go in my latest build. I'm needing to buy a considerable amount of green and originally planned a combination of the two, but am now thinking perhaps all diode would be preferable as far as reliability goes. However for the application, brightness is everything. My clients will not mind any differences in shade, but my 20W for example projector must compare in brightness side by side to a 20W projector using 532nm dpss.

I've seen lots of discussion as to how 520nm compares to 532nm in colours, particularly how yellow is not quite as nice, but gains of some interesting shades when mixed with blue. However I'm wondering specifically about brightness.

As it's a shorter wavelength, it's in theory less visible than 532nm watt for watt. But there are also other factors such as dpss lasers not coming up to peak power under fast modulation, which has traditionally been a big problem.

So I am wondering if anyone with firsthand experience can comment on the brightness in an rgb build vs 532nm ? Has anyone actually removed a working 532nm module and replaced it with the same power of 520nm for comparison ? I'm interested to hear how it compares both on it's own, and when mixed with other colours. I understand the differences in shade and resulting colour mixes, and think I could live with less yellow and better cyans. But I'm more interested in how it affects raw brightness in the real world.

As an example would a 3 watt projector comprising of 1 watt each of red, green and blue, be brighter or less bright if the green were 520nm vs 532nm, when taking into account 532nm's performance under modulation ?

Really appreciate any input, as I need to make a decision on this quite soon and having not seen it personally am finding myself really unsure of which direction to go.

add approx. 20-25% more 520nm, to achieve comparable 532nm brightness (watt for watt).

not from personal experience, but from what info. / feedback ive gotten on this subject.

my $.02

i have one of the laserwave 1W 520nm greens. it is very bright, however the the beam specs as supplied are not as good as a decent 532.

i added a set of anamorphic prisms external to the module and a spatial filter. now it has a very nice beam.

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Originally Posted by carlos3621

add approx. 20-25% more 520nm, to achieve comparable 532nm brightness (watt for watt).

not from personal experience, but from what info. / feedback ive gotten on this subject.

my $.02

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m0f,
I think the relative visual brightness of the 520nm vs the 532nm will be less important than beam quality because you need a lot (relatively) of power. I am still a little surprised at all these reports that 520 nm beam quality is not comparable if not superior to 532nm, DPSS output. On DTR's site where a 445 and a 520 diode are projected through the same lens, the 520nm beam is slightly better and a well corrected 445 beam will outperform any Chinese laser I have used. Nevertheless, be that as it may because when you want 5-10W of green then you need to knife edge multiple 520nm diodes and then even equal performance will deteriorate. When two equally powerful beams terminate in the same size spot, but one starts fatter then that one will appear less brilliant and 4-6 knife edged diodes will be fatter. Many of the several watt and lower DPSS lasers are polarized and you can PBS combine them to double the power with the same beam specs and often for less cost than a laser with twice the specified power. I would go with 1-2 DPSS lasers.

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Originally Posted by swamidog

i have one of the laserwave 1W 520nm greens. it is very bright, however the the beam specs as supplied are not as good as a decent 532.

i added a set of anamorphic prisms external to the module and a spatial filter. now it has a very nice beam.

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Do u happen to know if the lightspace 520nm
Green modules are prism corrected?

sorry. i do not know.

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Originally Posted by carlos3621

Do u happen to know if the lightspace 520nm
Green modules are prism corrected?

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Hmmm.. They say its 1.6 mrad but im not so sure..

Like Planters mentioned it will have a lot to do with beam size and divergence.

If I were building a 20 watt here is what I would do before spending 5 grand on a green....

First determine how many watts of green I need.

Second, figure out the max watts of 520 that will fit the galvo mirrors I want to use with the divergence i want.

Third, order a 1 watt diode from DTR and set up two RGB's with 532 in one and 520 in the other. Match all the powers and divergence of both greens as close as possible. Fog up the shop and run tests with different colors and just green. If the green looks weak turn up the 520 or down the 532 till they look even. Measure the powers to see how much more, if any, 520 is needed.

for high power green, I agree with Planters, better using 532nm. you will got better beam.
for 1W, 2W green, we advise choose 520nm instead of 532nm.
It's lifetime, it's Analogue, Also you can using 520nm building 10pcs RGB projector the same, but using 532nm, 10pcs is different each other.
Picture is one of our customer using our 638+520+462 building projector
Best regards!
Bridge

It depends on how you do things........ We have different manufacturers in the 520nm each with their individually beamparameters. I,m pretty sure with the right optics you can get the same low divergence as a 532nm. It all depends on which manufacturer you choose, and what the budget is. Divergence is a mayor factor when it comes to visibillity of a laserbeam. If all the beamparameters are the same like divergence , beamsize at aperture etc i would go for 520nm. You will have a little less nice yellow but you have perfect modulation and its less fragile then a DPSS. There is a reason why Chinese companies like laserwave promoting their 520nm greens ;-)

98% here thinks the 520nm are worse in beamquallity but it depend on how you do things. We can do blue,s 462nm in 0.5mrd but the price is higher. The 520nm can be a low divergence too but it will be more expencive then a dpss or 520nm from china. Its the same with red multimode and single mode. A Single mode red 1 watt can be done in 0.65mrd full angle and so when comparing it with a 1.3 watt/1.3mrd multimode you need 4 watt to have the same brightness according to science. You have a tighter beam with going single mode so you have way better graphics too. Its more expencive but in the end your better off. It looks more expencive at first but its not, its just how you look at things.

But because the focus is always on power people prefer to buy a multimode red since its cheaper and it sounds better when you can say to the guy that hires you that you have more power then what the guy next door has.

Take your pick what the wife allows you to spend:p:

Perfect: Low divergence with beautiful yellow: DPSS green with a PICO driver (heat and cool)
Fraction less perfect: Low divergence 520nm with less yellow.
average : 520nm/green from china (typical 1-1.3mrd)
Budget range : 532nm/0.7mrd from china with problems after 1 year but with nice yellow :)

Hi Edision, remember we compare beam during Frankfurt in 2013 year?
Our OEM-V series green sold large quantity each year, I am 100% sure more than all lasers you sold. :).
When you sold large quantity each year, you couldn't face a few pcs power down, pleasure is most of reply is active.
Why we advise customer choose 520nm in middle power 520nm, not because our 532nm, it is because 520nm lifetime, Analogue better than 532nm, just like I said, if you do 10pcs RGB projector using 532nm, the color, balance is the same, I give you big thumb, can you? 520nm is only less nice yellow, for 532nm, maybe you want yellow is green or blue, eachi projector is different, :).
Best regards!
Bridge

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Our OEM-V series green sold large quantity each year, I am 100% sure more than all lasers you sold.

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I,m sure you sold more greens since i don,t do 532nm greens :p 532nm is a DPSS and we don,t do DPSS. I had a 3 laserwaves in the past and all had problems but i have seen the new 532nm-V-S series and i was quite impressed with the overal quallity. Laserwave has a more convinient driver since it runs on standard voltage supply like 5V and 12V compared to the OEM-F series from CNI. I went in the past with CNI OEM-F,s because of the quallity of the Head. But with the new V-S ones i might give it a shot in the near future. But i will wait and see the reviews on PL first before i buy one.........

Because we are a relitively small company we aren,t selling the quantities that laserwave can do. We don,t have the manpower or the cashflow that laserwave has. Even if we had the manpower and cashflow we can,t beat china because the manufacturing cost or higher. Living expences and wages are 5 till 10 higher and also my morgage. Because we are relatively small and don,t do mass production we are flexible and have direct contact with the customer. Our modules are also upgradeble so if someone buys a green 1 watt he doesn,t need to buy a new module when he wants to upgrade his power. So we are thinking on the long therm.;)

Oh for people that complain where this thread is going , please read the post from bridge about who is the biggest seller. Totally irrelevant but i couldn,t resist to comment on that.

Back to the real subject........?

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Originally Posted by edison

Back to the real subject........?

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Oh, the irony...

Look up the response of the eye...peaks around 555 nm so 520 nm will appear less bright for sure. A good DPSS crystal laser will have supperior beam quality to any mumtimode diode or it should anyway. :) The diodes should modualte better and be way more reliable IF NOT OVERDRIVEN! Phil

Yes your absolutely right phil, with a good driver dpss is sure the perfect choice. Unfortunally chinese green aren,t available with good drivers. I replaced several chinese greens with a Pico heat and cool driver to have perfect linear modulation and rock stable in hot and cold weather.

CNI OEM-F heads are available with a heat and cool driver but again with that bulky powersupply. With 520nm its now only a short time before a real 532nm direct diode arrives i think. Fingers crossed its single mode and 532nm/200mw :cool: Then we are really moving forward :)

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Look up the response of the eye...peaks around 555nm so 520 nm will appear less bright for sure. A good DPSS crystal laser will have superior beam quality to any multi mode diode or it should anyway.

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Yes, the eye will see the 532 as a little brighter, but this will be a relatively small effect. I believe the beam quality will overwhelm this. I STILL don't understand this problem with the 520 beam quality. It should be at least as good as the 445 and when I correct a 445 to fit onto a 5mm aperture scanner it is always a better far field beam than any commercial DPSS I have used. Even when you correct the beam of a DHOM, Laserwave or a CNI to a 5 mm aperture the blue is better and it is multi mode. Is it possible that no one is actually correcting these 520nm diodes and just collimating them? What are the exit beam dimensions from these 520nm modules?

Edison,
You are correcting these 520nm diodes with a prism pair or a cylinder pair, right?

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Originally Posted by planters

Yes, the eye will see the 532 as a little brighter, but this will be a relatively small effect. I believe the beam quality will overwhelm this. I STILL don't understand this problem with the 520 beam quality. It should be at least as good as the 445 and when I correct a 445 to fit onto a 5mm aperture scanner it is always a better far field beam than any commercial DPSS I have used. Even when you correct the beam of a DHOM, Laserwave or a CNI to a 5 mm aperture the blue is better and it is multi mode. Is it possible that no one is actually correcting these 520nm diodes and just collimating them? What are the exit beam dimensions from these 520nm modules?

Edison,
You are correcting these 520nm diodes with a prism pair or a cylinder pair, right?

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FWIW, i just received confirmation from Lightspace, that they now DO correct their 520nm modules, with prisms.

our new 1W 520nm, 17mm@17m, full beam sizes test not only center brightness beam sizes test.
if someone just want to buy and like do test and share his test openly, we can do special prices for him.
any interesting, please contact with me, bridge@laser-wave.com, skype: bridgetan1980
Best regards!
Bridge

Thanks everyone for the input. More than anything I needed a sanity check, and in thinking it through over the last few weeks have covered pretty much everything talked about in this thread. This thread has really helped me in coming to a decision though and so I do think the dpss route is best to start with and will almost certainly pbs at least 2 knife edged 520nm in there in the near future. For now I think I will be combining one of my existing dhom 1W's running about 1.6W via pbs in to a 5W, to hopefully get around 6.5W of 532nm to start with.

The OEM-N and MGL-N series of CNI's do have heating and cooling drivers and so that's what I've been leaning towards over the past couple of weeks. I think for my usage, which does include some outdoor shows in the mountains, the added stability of a hbridge tec driver will make all the difference.

Planters, thanks for the reminder about how knife edging the diodes together will not necessarily increase the power density of the beam. That's one thing I was overlooking in considering 520nm. The added longevity and ease / low cost of repair should a single diode quit is mainly what I found so tempting about the 520nm.

As far as visibility goes, despite being theoretically a less visible wavelength, I was more or less curious of the improved modulation characteristics would make up for it. But didn't factor power density into the equation.

Edison, the single mode diodes as nice as they are, I don't think are for me as 99% of my jobs are beam shows, with the need for massive power due to big lighting and led walls. Though in your example the power density of a 1.6W built with single mode diodes can match that of a much higher powered laser built with multimodes, I think is much more important for graphics than it is for strictly beam shows. In my case of needing to match up 6-7W of green I have a feeling despite the power density being similar, 1.6W of single mode red wouldn't work as well as 6W of multimode even at the same power density. So I do think multimodes have their place. Using mpe and the safety scan lenses as an example, a tight lower powered beam at mpe is less exciting than a fat higher powered beam at mpe. And great point about the necessity of a heating and cooling driver for stability, I fully agree. Which is my main reasoning for choosing cni despite the fairly high price comparatively. Driver size isn't so important in my example as my case is quite large, and I will be removing a dhom driver which is quite large. The oem drivers also don't seem to be overly huge to me, perhaps they've recently redesigned them (though size is relative to individual requirements)

Once again, thanks everyone for your help. It's helped me pretty much be settled now on purchasing a couple of 5W dpss greens to start with. The added power density being one of the huge factors I had overlooked.

Miles

Ahhh your waving beams from left to right ;) Well then i would do a 520nm setup since that matches the red and blue at best. DPSS CNI can have between 0.7mrd and 1mrd so its a little thight. Keep in mind that DPSS is fragile, lots of people have problems with their dpss heads. Since you don,t need a superthight beam to match that red, maybe its good to concider a 5 - 6 watt 520nm. ;)

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Originally Posted by 142laser

Look up the response of the eye...peaks around 555 nm so 520 nm will appear less bright for sure. A good DPSS crystal laser will have supperior beam quality to any mumtimode diode or it should anyway. :) The diodes should modualte better and be way more reliable IF NOT OVERDRIVEN! Phil

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Just a question regarding the apparent brightness of 532 vs 520 - that the peak around 555nm is in daylight where as isn't it nearer 505-510nm at night / in the dark ? I was wondering if therefore (in theory) - in the dark the 520nm green would appear to be 'brighter' or more defined or am I missing something here ?

In the dark any lightsource (laser or not) is looking brighter then in broad day light. Since 532nm is close to the "eyepeak" of 555nm , the 532nm is always brighter the 520nm. But since most green 532nm have poor modulation and are not heat and cool drivers and compare it with the 520nm that has the exact same power but perfect modulation (assume the driver is designed perfectly) then the 520nm wins. You still missing the bright yellow line though. A DPSS is still the way to go because of the better beamquallity but with a good driver.


Viasho recently launched their new OEM module and that comes with a Heat and Cool driver. CNI OEM-F has also heat and cool on request. Laserwave is stuburn and are convinced that they can go without........ We asked many times (begged:p) do a heat and cool driver but in the end of the day its their choice. Viasho went with a Vacuumcleaner on top of their modules with the size of an 1995 mobile phone while laserwave and CNI went with a different construction so no fan is needed and is allot smaller in size. Viasho disappeared from the market for a while but i think he will be back soon.

He made a very good move by going OEM-F /laserwave style with Heat and cool. If the beam is less then 1mrd in divergence with a 4-5mm beam as standard we have a nice green that,s for sure. Many people have already projectors with 532nm in it so they will stick with that so they can mix and match.

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Originally Posted by markmtts

Just a question regarding the apparent brightness of 532 vs 520 - that the peak around 555nm is in daylight where as isn't it nearer 505-510nm at night / in the dark ? I was wondering if therefore (in theory) - in the dark the 520nm green would appear to be 'brighter' or more defined or am I missing something here ?

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I have always wondered if the vision of peoples watching a laser show is photopic or mesopic (scotopic not for sure). If mesopic, certainly the 520nm line will appear equal or even brighter than the 532nm line!

Hmmm ..
This has been covered before, but .. interesting ..
Attachment 44815

From this:
http://webvision.med.utah.edu/book/p...ics-of-vision/

I think the chemistry of the rods and cones will not shift and when looking straight at the light I believe the photopic curve will dominate.