Minimum laser power to cause problems
keesje wrote: I only read the first 35 posts, so maybe it has come up. What is minimum l@ser power that could be used to cause problems in a cockpit?
The FAA, working with experts, set various levels. Less than 50 nanowatts per sq. cm. (0.05 microwatts per sq. cm.) is deemed to not cause distraction. At this level, the light does not stand out against other nighttime lights seen from the sky.
Glare occurs around 5 microwatts per sq. cm. It is hard or impossible to see around the glare.
Flashblindness occurs around 100 microwatts per sq. cm. These temporarily blind a pilot and can leave afterimages lingering for seconds or even minutes.
Note that the above is irradiance: light power spread over an area. This is different than beam power, which is how pointers are measured (how much light comes out, irregardless of whether the beam is tight or spreads out a lot).
The eye is most sensitive to green light. If you have a green beam and red beam of equal power, the green appears much brighter (therefore distracting/glaring) than the red one.
A green pointer of 5 milliwatts (the legal limit to sell as a pointer in the U.S.) can cause flashblindness to about 250 feet, glare to about 1,200 feet, and can be a distraction over 2 miles away.
A green pointer of 125 milliwatts has a visual effect 5 times greater, so it causes flashblindness to 1300 feet, glare to 1.1 miles, and can be a distraction over 11 miles away.
There is NO reason to ever aim a pointer at or near an aircraft. (Well, one legitimate consumer reason, which is to signal a search-and-rescue aircraft when one is truly lost.)
Hope this answers your question.