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Visibility of 445nm laser beam

CopperSulfate

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I am looking to buy the SF501B from Sci-Fi Lasers. I am trying to decide what power to get. I have never owned a blue laser nor have I seen one in real life. I have a 50mW 532nm from Ledshoppe that I use for night-time demonstrations along with star-pointing. But I would love to get a blue one to increase my collection. My main questions are how visible is the beam of a 1W blue laser compared to a 50mW green laser? And would it be worth it spending extra to get a higher powered laser (1.5W-1.8W or 2.2W-2.4W) instead of a 1W?
 



Hap

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Lux Nitida

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Besides that link to the comparative tool Hap posted which is a useful link to bookmark, here is a picture of my 2.3W 445nm and 100mW 532nm for a side-by-side for you. The other laser is my 50mW (107mW peak) DL Spartan 589nm on the right.

Also this link here takes you directly to the comparative tool: Relative Laser Beam Brightness Calculator: (418nm 1mw) vs. (645nm 1mw)



I will also include this outside pic without the termination bloom overloading my camera's sensor. Same lasers as stated above. Forgive me for the wide looking beams of the 445nm and 532nm, I was holding those by hand with my 589nm on my tripod at the time lol.

 
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Laser Chick

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If the audience is more than 50 feet away from you, I would go with ~ 1.5W to ensure that they can see the beam.
 

Pman

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Glad you call your 589nm a "golden yellow" and not yellow. Everyone I've shown my 589nm to says it looks golden yellow, golden, golden orange or orange. As with any color the shade can change dramatically with different backgrounds or next to other wavelengths.
I have a combined red/green uit from.O-like that actually looks more yellow than golden. 593.4 must look really orange in comparison but I don't have one.
Anyways, what are we talking about again;) Without looking it up I believe it takes about 500mW to equal the beam brightness of a 50mW 532nm although that depends on what wavelength blue. Also, I wouldn't be expecting a nice sharp beam like you get with the 532nm. I've always liked this diode (the PLTB450B) as it offers a better beam divergence):
https://sites.google.com/site/dtrlpf/home/diodes/osram-pltb450-1-4w-450nm

but I doubt that is an option that the seller you are looking at has. You can always ask though.
 

Lux Nitida

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Glad you call your 589nm a "golden yellow" and not yellow. Everyone I've shown my 589nm to says it looks golden yellow, golden, golden orange or orange. As with any color the shade can change dramatically with different backgrounds or next to other wavelengths.
I have a combined red/green uit from.O-like that actually looks more yellow than golden. 593.4 must look really orange in comparison but I don't have one.
Anyways, what are we talking about again;)


I was surprised the first time I saw how orange the 589nm looked in a photo next to my other lasers, like my first photo above. The only way I can get my camera to come close to its real color is when photographed by itself.





In reality it is golden yellow, same color as a low pressure sodium street light. I think it is beautiful to behold but you really have to see it in person to appreciate it best. I don't have a 593.4nm but do want to acquire one in the future just to be able to compare them and of course to have both of these DPSS "yellows". Anyway, to the OP, I agree with Laser Chick I would go with at least 1.5W to ensure good beam visibility for others if that is your intention. I love the visibility from my 2.3W it can be seen quite a distance away and at many different angles. Just be sure you get solid safety glasses, don't cheap out with safety at these kind of powers, one slip and permanent eye damage is guaranteed. At minimum something like these OD 4+ is what you want for safety: Eagle Pair® 190-540nm & 900-1700nm Laser Safety Goggles I use OD 5+ myself and when burning close-in it is still hard to look at the dot at times on the 2.3W 445nm. :beer:
 
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GSS

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And yes safety glasses just like Lux said, wow we all forgot:tsk: OMG forgot to say nice pics and showing OP the comparison.
 
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