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445 violet/blue laser question

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YammyTheCat

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I searched but I couldn't really find any answers . My question is that I've heard that blue lasers look rectangle and not round. If I have the laser not focused or infinity and I shine it on a wall half a mile away would it look rectangle or still be so small that it you can't tell either way. Also wondering how well the beam would look at night from a 445 1W violet laser, and would the beam look rectangle? Sorry I'm new to blue lasers. Thanks.
 
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Mohrenberg

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none of the beams actually look rectangle.
When focused, they're all round.

I'm assuming they're referring to the raw output that comes from the diode. When shined on a wall it will be rectangular
 
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trussmonkey25

trussmonkey25

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Mohrenberg said:
none of the beams actually look rectangle.
When focused, they're all round.

I'm assuming they're referring to the raw output that comes from the diode. When shined on a wall it will be rectangular
Click to expand...
All mine come out rectangular infinity or spread out. Some may be clipped by the size of the lens
 
TaterMay

TaterMay

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Mine, too, are all rectangular when shining at a distance, even when using a 3-element lens. I suppose it depends on the diode. The NDB7875, NDB7A75(the worst of these 3), and M140 diodes are all rectangular, for sure. What type of lens are you using?
 
Pi R Squared

Pi R Squared

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445nm isn't violet, it's blue, 405nm is violet. Yes any 445nm is rectangular, but when focused you won't notice it, but when unfocused or far away yes it will be rectangular. Something like a half a mile away I expect the dot would be very large.

Alan
 
Mohrenberg

Mohrenberg

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Pi R Squared said:
445nm isn't violet, it's blue, 405nm is violet. Yes any 445nm is rectangular, but when focused you won't notice it, but when unfocused or far away yes it will be rectangular. Something like a half a mile away I expect the dot would be very large.

Alan
Click to expand...

Yeah, i was referring to looking at the beam, like 3 or 4 feet away.

A square beam coming off a laser would be trippy though lol
 
Pi R Squared

Pi R Squared

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Cel said:
Are you sure?
Aren't there single-mode 445nm diodes? Or are they rectangular too?
Click to expand...

I think there's only one single mode 450, the 120mW PL450B. I don't think there's any single mode 445, if there is I am sure someone will tell us.

Alan
 
Pi R Squared

Pi R Squared

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LeHap said:
Quick search gave me this:
Single mode laser diode at 445nm

Don't know if that's what you're looking for :)

-Alex
Click to expand...

That is exactly what we were looking for, thanks for posting that. I had no idea there was a 50mW single mode 445nm diode. It would have been nice if they were reasonably priced, $290. :eek: I don't think I'll be buying one. The single mode 120mW 450nm is really cheap.

Alan
 
NightExplorer96

NightExplorer96

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Pi R Squared said:
That is exactly what we were looking for, thanks for posting that. I had no idea there was a 50mW single mode 445nm diode. It would have been nice if they were reasonably priced, $290. :eek: I don't think I'll be buying one. The single mode 120mW 450nm is really cheap.

Alan
Click to expand...

Oh ok lol, your welcome! :wave:

-Alex
 
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doubleone44

doubleone44

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There is also the NDB7242E diode somebody on the forums is selling (I think they are still being sold). These are multimode, but with single mode-like divergence (really low from what I've hear). These are 445nm 50mW diodes (possibly the same as listed above)
 
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