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power threshold for lateral visible beam


Well-known member
Jun 28, 2007
I hate you... ....The 589nm is just flat out sick.

Mind if i use that picture as my wallpaper on my computer.:).?
Sure n/p, I have it on my E-Bay MasterCard too!
Camera is Nikon Coolpix 7600 using auto exposure, Also, I forgot at first to list the Spyder III 473nm which does about 60- 102mW and I think the color w/b better with about 80mW of 445nm, btw

Also, here's a indoor beam shot for ya...
Only 2 lasers used, a Blue 473nm and a PGL III R/G -GH
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Oct 4, 2010
Besides the relative insensitivity of the human eye to red light as opposed to green, there is another reason why red laser beams are harder to see: they are actually much dimmer. We see a laser beam from the side because of light scattering due to dust in the air, and red light is scattered much less by dust than shorter wavelengths. That is why the sky is blue and sunsets are red.

From a the top of Pack Monadnock in southern New Hampshire, you can just see the top of the Prudential tower in downtown Boston. From that distance, the red lights on top of the building can easily be seen, but the much brighter white lights on the building appear faint. Again, dust scattering of different wavelengths is the reason.

Now you know.


Well-known member
Sep 16, 2007
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...

The 650-G-1 is great for high power reds.
It makes a great beam that is thinner than what you get with the Aixiz lenses and you get 20-25% more power. I recommend it if you want the most from your laser.

My 300mW LOC pen has a lot of hours on it but is still going strong.

One thing to note is that the harder you push these diodes, the longer their wavelength shifts. Mitsubishi rates them at 655nm-660nm. They will shift pretty close to 670nm as you push them and as they warm up, so any increase in power after a certain point will not really get you much more brightness.

Using a high-transmission lens like the 650-G-1 is a good idea since you can get just as much power with less heat generated, a longer lifetime, and the wavelength doesn't shift so much since you don't have to drive it as hard.

On topic - the beam of a laser is least visible when viewed perpendicular to the direction of the beam. Most of the light is scattered forward and backward, so it is easiest to see the beam when you are at the source or viewing from the "business end."

You will need several Watts of any wavelength to get a bright beam viewed at any angle for a reasonable distance in excess of 1/8 mile. Slight humidity helps. Dense fog does not.
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