red beam ???

hello guys, i would like to know how powerfull red laser is needed to see some nice red beam...
cheers

milantheone said:

hello guys, i would like to know how powerfull red laser is needed to see some nice red beam...
cheers

Click to expand...

This is VERY dependent on the conditions of the air and your eye. How much moisture is in the air? How much "dust"? How well do YOU see the 660nm wavelength? Is it shining toward you? Is it shining away from you? Are you looking at it from the side?

I can see the beam of a 1mW red cat toy if I spray some "smoke in a can" into the air.

Peace,
dave

Ok, since you are so willing to help:

How powerful should the red laser be to see a nice red beam under the following conditions, with average 660nm wavelength eyesight.

1) Its 12 AM, and its dark
2) No fog
3) You live in south florida (so its kinda moist in the air)
4) No smoke
5) Not much dust
6) Outdoors
7) No lights... no street lights... nothing, just you and the stars.
8) The beam is pointing away from you (and if theres a big difference, also the beam is pointed towards you).

9) You are not looking at it from the side
10) Your friend is looking at it from the side (can he see it?)

all right...  i mean generaly at night without fog.... laserman covered it all

cheers

laserman22 said:

Ok, since you are so willing to help:
How powerful should the red laser be to see a nice red beam under the following conditions, with average 660nm wavelength eyesight.
1) Its 12 AM, and its dark
2) No fog
3) You live in south florida (so its kinda moist in the air)
4) No smoke
5) Not much dust
6) Outdoors
7) No lights... no street lights... nothing, just you and the stars.
8) The beam is pointing away from you (and if theres a big difference, also the beam is pointed towards you).
9) You are not looking at it from the side
10) Your friend is looking at it from the side (can he see it?)

Click to expand...

With the above condition AND MY EYES (which are old), it would take about 50mW for ME to see the beam shining away from me. It would take a bit less if it was shining toward me. Your friend would be out of luck though.

If you added moisture into the air (or smoke, or incense, or spray deodorant, etc.) the beam would appear bright

Peace,
dave

Thanks.

so 50mw could be enough to point at stars like with green one???

why not add 150mw to that for under 50 dollars from DX?

haha

http://www.dealextreme.com/details.dx/sku.11315

this one looks good and the price is unbelievable...

one question remain can i order it if i am from UK??????

it was written : these lasers may be purchased only if you are NOT a citizen of the United States and you are NOT currently living in the United States.

so what about UK, customs???
does anybody have experience???
cheers

milantheone said:

http://www.dealextreme.com/details.dx/sku.11315

this one looks good and the price is unbelievable...

one question remain can i order it if i am from UK??????

it was written : these lasers may be purchased only if you are NOT a citizen of the United States and you are NOT currently living in the United States.

so what about UK, customs???
does anybody have experience???
cheers

Click to expand...

You can get it in the UK. I'm in Glasgow and I have one sitting on my desk mocking me , and wanting batteries :

If you plan on burning anything you NEED goggles.

-Adam

milantheone said:

so 50mw could be enough to point at stars like with green one???

Click to expand...

You can point at the stars, but NOT like a green one. Green light is right in the middle of our eye's ability to perceive light. It is therefore MUCH easier to "see." Although the energy being produced by a 50mW red is the same energy that is being produced by a 50mW green, the green will be MUCH, MUCH, MUCH "brighter"

You really cannot compare the brightness of a red to a green. You are comparing apples to hazelnuts.

Peace,
dave

For some reason my eyes do not do well with 660nm light. Blu-ray (405nm) is MUCH brighter to me, as far as the beam goes. Even a 300mW red doesn't look very bright to me. Yet, I can see the beams of my hene's fairly easily, which is 632.8nm and they are only a few mW at the most. But, the beam from a HeNe is also much more concentrated.

In clear dark conditions my 20mW 532nm is brighter than my 300mW 650nm.

milantheone said:

so 50mw could be enough to point at stars like with green one???

Click to expand...

Hi.

The green light appears 7 times brighter than the 660 nm red. My 150mW green laser is clearly visible in the air, when it's cold dry and dark. 150mw times 7 is the power you need to make a 660nm red laser as visible through the air as the green one. If you can find a 1050mW 660 nm red laser, this laser is as visible as a 150mW green. I have a 16x DVD burner 635nm laser. It is barely visible through the air at the same conditions as above even if it burns white paper when focused.

br.

Vidar

Low-Q said:

[quote author=milantheone link=1229198493/0#6 date=1229201291]so 50mw could be enough to point at stars like with green one???

Click to expand...

Hi.

The green light appears 7 times brighter than the 660 nm red. My 150mW green laser is clearly visible in the air, when it's cold dry and dark. 150mw times 7 is the power you need to make a 660nm red laser as visible through the air as the green one. If you can find a 1050mW 660 nm red laser, this laser is as visible as a 150mW green. I have a 16x DVD burner 635nm laser. It is barely visible through the air at the same conditions as above even if it burns white paper when focused.

br.

Vidar[/quote]

yes buddy i really can imagine that your 150mw greenie is clearly visible, but do you know that i can see nice beam in the dark night with my 10 and 20mw greenie as well????.. which means that 150mw red could be fine by your marvelous theory  

milantheone said:

[quote author=Low-Q link=1229198493/0#13 date=1229282010][quote author=milantheone link=1229198493/0#6 date=1229201291]so 50mw could be enough to point at stars like with green one???

Click to expand...

Hi.

The green light appears 7 times brighter than the 660 nm red. My 150mW green laser is clearly visible in the air, when it's cold dry and dark. 150mw times 7 is the power you need to make a 660nm red laser as visible through the air as the green one. If you can find a 1050mW 660 nm red laser, this laser is as visible as a 150mW green. I have a 16x DVD burner 635nm laser. It is barely visible through the air at the same conditions as above even if it burns white paper when focused.

br.

Vidar[/quote]

yes buddy i really can imagine that your 150mw greenie is clearly visible, but do you know that i can see nice beam in the dark night with my 10 and 20mw greenie as well????.. which means that  150mw red could be fine by your marvelous theory  
[/quote]
Yes, 10 and 20 mW greenie is visible but you can't expect to use that one, or a 150mW red (depends on the wavelength), for star pointing, if anyone around you is suppose to see clarely where you point - unless you tell them where the beam is - pointless, right? A 150mW greenie is clearly visible, but not VERY visible. I'll explain later.**

**To double the visibility, I mean how your eyes and brain receive and process light information respectively between two different light intensities, you have to increase the power by a factor of 10. Which means that a 150mW greenie appears to be twice as visible as a 15mW greenie. Funny how practice and theory works well together here

A 660nm laser, which is even duller than a 635nm laser at the same power, needs quite much power to be clearly visible through the air. 1W or more. Visibility also depends on how the air, the humidity in it, dust etc. responds to the wavelength going through it.

Br.

Low-Q