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power threshold for lateral visible beam

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ashenfang

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Im curious what the power threshold is before one can start to see the beam from behind and to the side of the source. I see pics all the time of laser night shots where the beam is clearly visible from all angles. Are these shots taken with longer exposure times?
 





I live in an arid climate and I can hardly see my 250mw red beam at night, which is good, because the dot is spectacular. However, reds just don't make very visible beams (unless you are at sea level... maybe... or in a moister climate)

250mw is pretty much the maximum for current cheap red technology... I would just go with a greenie
 
In a dark room I can see my 5mw DIY 635's beam if I look down the host. My LPC's beam is clearly visible from any angle and it's being driven at a modest 200ma for ~190mw of output.
 
hanzyfranzy said:
250mw is pretty much the maximum for current cheap red technology... I would just go with a greenie
Click to expand...

I have an LPC-815 build that begs to differ with you.

IMG_0026.JPG


But i'll agree on the last part... mW to mW, green is going to beat pretty much everything else as far as visibility.. at any angle.

And yes that LPC build is still alive.. and it has about 30 hours on it now. It's actually what's doing the red in the lumia wheel video I did last night.

 
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@qumefox how many mA are you running the lpc-815 diode and are you using a glass lense?
 
qumefox said:
I have an LPC-815 build that begs to differ with you.

IMG_0026.JPG


But i'll agree on the last part... mW to mW, green is going to beat pretty much everything else as far as visibility.. at any angle.

And yes that LPC build is still alive.. and it has about 30 hours on it now. It's actually what's doing the red in the lumia wheel video I did last night.

Click to expand...

Well, there are always freak diodes, which is how companies sell "300mw" red lasers. They choose from the batches the abnormal diodes that can, out of shear luck, withstand extra power. I guess I was just talking about the average diode...
 
May only be 14% brighter.. but it is brighter. This one is running around 500mA and the optics are some I got off ebay a long time ago, but of all the lenses I had the one I used tested as having the lowest losses. It's been so long since I got it that I couldn't even tell you what seller it came from.

I do NOT recommend driving LPC's this high though. This particular one only got set this high because the pot got bumped when assembling the laser. It was originally set at 420mA and doing around 275mW. However I have plenty of LPC 815 sleds's, so I was not going to dismantle the pressed together build and risk breaking it until it died. But so far, it hasn't died, but I think it's probably a freak diode because i've had other identical diodes LED at lower currents.
 
Down here in the often humid Louisiana, I can see a 20mw 405nm at night :D No fog or anything and some ambient light. It looks like a grey streak.
 
LIKE THIS?
4772-more-fog-time-beam-backyard-2010-038.jpg

Yes there is fog and a bit of light from the early sunrise, but those beams are quite east to see in the night sky, 500 mW 405nm, 500 mW 445nm, 75mW 473nm, 260mW 532nm, 70mW 589nm, 285mW 650nm!

btw, about 10% as many mW's will be easy to see in the dark here by the Pacific.
 
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yep, i have a 293mW lpc at 420mA, using aixiz 650 glass, i do want a 650-g-1 though just to compare, I heard it's basically the equivalent of a 405-g-1 tho...
 
scopeguy20 said:
LIKE THIS?
4772-more-fog-time-beam-backyard-2010-038.jpg

Yes there is fog and a bit of light from the early sunrise, but those beams are quite east to see in the night sky, 500 mW, 405nm, 500 mW 445nm, 260mW 532nm, 70mW 589nm, 285mW 650nm!

btw, about 10% as many mW's will be easy to see in the dark here by the Pacific.
Click to expand...

What kind of camera did you use for that? Mine sees 405 as blue and 650 as pink.. and it bugs the crap out of me, so i'd like to get one that better represents the wavelengths as they really appear.
 
scopeguy20 said:
LIKE THIS?
4772-more-fog-time-beam-backyard-2010-038.jpg

Yes there is fog and a bit of light from the early sunrise, but those beams are quite east to see in the night sky, 500 mW, 405nm, 500 mW 445nm, 260mW 532nm, 70mW 589nm, 285mW 650nm!

btw, about 10% as many mW's will be easy to see in the dark here by the Pacific.
Click to expand...

I hate you.. But i love you at the same time.:na:

Freaking Epic Picture right there. That just made my eyes light up.:drool: The 589nm is just flat out sick.

Mind if i use that picture as my wallpaper on my computer.:).?
 
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