What are some good ways to do distance checks?

[matticusnicholas]

What the title says.

I'm curious about how far my laser can actually travel while still being able to see the dot. The problem is my eyes can't focus that far. I was wondering what are some good ways to check the viable distance of your lasers?

 

[Ramsey_innovations]

A safe way to do it would be to setup a video camera pointing at a wall with some sort of a scale or ruler for size reference. Then go some distance away and point it at the scale while recording video. You may need to use some safety goggles or a light filter in front of the lens on the camera to prevent flooding depending on the laser and camera being used.

 

[OutlawKing]

I have a reflective fire lookout tower (closed for winter) approx 2 miles away according to my range finder and my green 55mw hits it easy i was also thinking about positioning a mirror up there aswell. You could also buy some reflective glint tape put it on somthing easy to see from your known distance point

 

[Kookapeli]

You could get a pair of binoculars

 

[steve001]

What the title says.

I'm curious about how far my laser can actually travel while still being able to see the dot. The problem is my eyes can't focus that far. I was wondering what are some good ways to check the viable distance of your lasers?

You need to define the parameter of this experiment more precisely and the particular wavelength of light. Green will be the most visible naturally.
For instance.
Naked eye only ?
Using a telescope, spotting scope... ?
Off of a highly reflective material such as glass, or traffic sign or light in color matt surface or shiny surface ?

I've seen a green 5mw reflection off a window that was 3 miles distant. That's a round trip of 6 miles

 

[Roger O]

You can see the flame of a candle from 6 miles if you have a good telescope. I think the most important parameter is the maximum allowable divergence of the beam at the max distance.

 

[Scotty 757]

If only the earth was still flat like it used to be..

 

[Roger O]

, Right you are! However, since a lot of people with safety on their minds will shine their lasers out of a 2nd story window (~20 feet above ground level), which when plugged into the formula for distance to the horizon (d=~3.856*√h) is 5.96 miles, which as they say is close enough for government work!