how 520nm brightness vs 532nm in an RGB buld

[m0f]

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.

[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

[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.

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

[planters]

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.

[carlos3621]

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.

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

[swamidog]

sorry. i do not know.

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

[carlos3621]

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

[logsquared]

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.

[bridge]

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

[edison]

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:

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