5mw red laser beam

[gbp007]

I have a portable red laser pointer which is 635nm and also 5mw but i cant see the beam ..What is the minimumrequired amount so that im able to see a red beam ?

 

[stevetexas]

Visibility depends on the amount of particulate matter/humidity in the air, wavelength and power of the laser,  and how dark it is.  
Unlikely that you'll be able to see a 5mw red without smoke/fog...

 

[styropyro]

That's weird, I have a 5mW 635nm and a 5mW 650nm from AixiZ and the beams are actually pretty clear in a dark room(considering its a 5mW red). But I'm starting to wonder if they are putting out more than they say. I'll try to get some pictures tonight, I hope my camera will be able to pick it up.

 

[stevetexas]

it isn't [highlight]impossible [/highlight]to see the beam, just not easy. it also depends on the axis from which you view it.
if you look along the laser down the length of the beam (parallel to the beam) it will be much more visible than looking perpendicular to it.

 

[Crossfire]

I cannot see the beam on my AN 635nm 5mW red unless there's a small bit of smoke in the room. Even in a dark room, if it's clear, the beam is not visible.

 

[gbp007]

Well im guessing with a little bit more like a 10mw red laser pointer then it would be easy to see the red beam just as easy as you see it with a 3mw green laser pointer ?

 

[Things]

actually a 10mw red beam will be about as bright as a 1>mw green beam, so you'd have to have a pretty high powered red to see it like a greenie.

 

[stevetexas]

Even my 100mW, and 180mW reds are not as bright as a 5 mW green :'(

 

[Crossfire]

And remember, 635nm is more visible than 650nm or 660nm.  For a 10mW to be any sort of visible it probably have to be 635nm.

 

[Aseras]

hell I've seen beams on 1mw Hene ( 633nm ) with the right conditions.

Try a pinch of flour. flour reflects everything. it's good for a quick test since it'll linger, but it makes a HUGE mess.

 

[flogged]

5mW @ 635 nm is not going to have a terribly visible beam. If you carefully sight down the laser in a dark room the beam should be very faintly visible. Another thing with reds is the forward scattering is stronger than with green lasers. What this means is if you look towards the laser the beam is often more visible.

With reds is if there's any kind of crud in the air - just a little haze, smoke, fog.. whatever, the beam is MUCH more visible.

I've got a homemade red pointer that's about 25mW (possible more.. I really want to get it tested to see what the actual power is) @ 635nm and the beam is faintly visible, even in very clear air. However this is only when looking down the beam, you can't really see it from the side in clean air.

The sky is blue because shorter wavelengths are scattered more by the atmosphere, so as you head towards the blue part of the spectrum, on a mW per mW basis, the laser will have a more visible beam.

What all this means is if you want a red with a visible beam in clean air go for the highest power you can get your paws on