Red Laser mW

[VegasSteve777]

What size (mW) RED laser would be equal to the very visible beam of a 30mW greenie (Deal Extreme 30mW)??

Looking for a red laser that puts out a visible beam into the night skies!!

~Steve~

 

[TorchBoy]

Off the top of my head I think the eye is about five times more sensitive to green light that red, so "about 150mW."

 

[aaron_inc]

ive got a 200mw 660nm red and its about as bright as 5mw green so youre either looking at an outrageously powerful 660nm or a few hundred milliwatts of 635nm.
either way it will be pretty expensive.

 

[Daedal]

I have read in a couple places that 635 is twice as bright as 660, and that to get the brightness of green, u need 4 times the power of a greenie. But that is all at the point of termination, that has nothing to do with the beam. The beam is a lot less visible on a red laser because the small reflections from red are almost invisible to the human eye, while green is very visible to a human eye because our eyes are very sensitive to it.

Hope that helps;
DDL

 

[TorchBoy]

I have read in a couple places that 635 is twice as bright as 660, and that to get the brightness of green, u need 4 times the power of a greenie. But that is all at the point of termination, that has nothing to do with the beam. The beam is a lot less visible on a red laser because the small reflections from red are almost invisible to the human eye, while green is very visible to a human eye because our eyes are very sensitive to it.

Hope that helps;
DDL

You're not quite making sense there Daedal. Yes the eye is more sensitive to green light, but what reason do you have for asserting the beam is less comparatively visible than the point of termination of the beam?

 

[Ashton]

I doubt it's as bright as a green, but mu pulsar 150 (~135mw (Average, never tested)) makes a visible beam at night. My Atek >200mw makes a visible beam in a very dim ROOM!!!

Though again, I have no greenie of my own, so I cannot attest to their brightness.

 

[Daedal]

You're not quite making sense there Daedal. Yes the eye is more sensitive to green light, but what reason do you have for asserting the beam is less comparatively visible than the point of termination of the beam?

Well, I suspect that the nature of the red light in small quantities is rather too dim and would be ignored. it is the same as a faint glow from a covered lamp or something. The light is there, but it is very dim and hard to see. I could be wrong, or it could just be my eyes, but when there's a very faing glow of something, even in a dark room, the eye tends to filter it out when a camera would grab it with no problem.

Hope I'm making sense;
DDL

 

[TorchBoy]

Oh, I see what you're probably getting at (no pun intended). Red light isn't as visible to our peripheral vision, thanks to rod cells in the retina not working the same as cone cells.

 

[Ragnarok]

Yes, there are several factors that put red at a disadvantage to green as far as beam visibility, especially at night.

1. Green is more visible than red in photopic (color) vision.
2. Green is more visible than red in scotopic (night/BW) vision.
3. Green light is scattered much more by the atmosphere than red.

Even if you have projected spots of equal apparent brightness, red beams will be less visible than green. To maximize red beam visibility, use "shorter" red wavelengths, i.e. 635nm - and lots more of it.

 

[VegasSteve777]

Thanks for the replies......Still fuzzy on what RED laser would put out the same beam as my new DX 30mW into the night skies for star pointing.....A Wicked Pulsar 150mW??
~Steve~

 

[SenKat]

No - the Wicked runs at 650nm - if you had a 120mw 635nm red for example, you would have more of a shot seeing the beam than you would with the 650nm Pulsar - red can be uber powerful, and yet you would be unable to see the beam unaided, unless there was a heavy fog, or smoke type of situation involved....