1000m 50mW laser reflection experience? Need help from the PRO's

Depens on how fast your laser dot grows big

if your laser is about 1.5mRad the dot will be about 150 millimeters diameter after 100 meters

weeba2kv said:

Depens on how fast your laser dot grows big

if your laser is about 1.5mRad the dot will be about 150 millimeters diameter

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Maybe a beam expander would be good for this long range situation, also you should get a a larger mirror than your beam will be, so it will be easier to actually hit the mirror.

beam expander is pretty expensive

weeba2kv said:

Why ? well why not , :thinking: 231344 video's on you tube and 100 treads in LPF LOOK I CAN BURN A MATCH why ?

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hampsterMSR said:

Thank you

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hampsterMSR said:

There's no logic purpose about doing this, it's not like i'm going to find the Cancer cure by doing this, so... Why? pleasure, fun, curiosity.

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Using pseudonomen137's Diameter Calculator for Laser Beams! and estimating a beam diameter of 1mm and a beam divergence of 1.2mrd will produce a spot size of 1201 mm or 3.94 feet. If this person thinks they'll see a beam shooting up into the sky they are mistaken using 50 mW to do this. Even in humid conditions they won't see much. Perhaps a diffused glow.

If I were this person and before I set about doing this experiment what I'd do is have someone shine the laser and have myself at 100 meters perpendicular to the beam to see how visible this beam is. If the beam is clearly visible proceed out another 100 meters.... This way you'll get a good idea of what could be expected if the beam never diverges, however it does and that's why I wondered why.

Yes, I often wonder why people spend so much money too buy a laser just so they can burn something.

steve001 said:

Using pseudonomen137's Diameter Calculator for Laser Beams! and estimating a beam diameter of 1mm and a beam divergence of 1.2mrd will produce a spot size of 1201 mm or 3.94 feet. If this person thinks they'll see a beam shooting up into the sky they are mistaken using 50 mW to do this. Even in humid conditions they won't see much. Perhaps a diffused glow.

If I were this person and before I set about doing this experiment what I'd do is have someone shine the laser and have myself at 100 meters perpendicular to the beam to see how visible this beam is. If the beam is clearly visible proceed out another 100 meters.... This way you'll get a good idea of what could be expected.

Yes, I often wonder why people spend so much money too buy a laser just so they can burn something.

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Thank you for your reply , I agree with your last sentence too.

steve001 said:

Yes, I often wonder why people spend so much money too buy a laser just so they can burn something.

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I'm absolutely amazed how that's usually question #1 from anyone who sees a powerful handheld laser for the first time:banghead:

hampsterMSR said:

Thank you for your reply , I agree with your last sentence too.

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I think you'd have more fun constructing beam Galilean and Keplerian type beam expanders.
It may also interest you in see how far you can see a reflection off a reflective road sign or a mirror. Custom Signs - USA Traffic Signs Flourescent yellow school crossing signs work just a little bit better than plain reflective white signs.

Personally I've seen a 5 mW green laser reflected off a window at 3 miles.

Beams expanders will increase the distance of reflection