Does laser power decrease with distance?

Actually, yes! Laser irradiance (power per unit area, sometimes also called intensity) is proportional to the inverse of distance squared. The idea that the inverse square law does not apply to lasers is a common misconception.

How far does a laser pointer reach?

In total darkness we can see a <5mW 650nm laser around 500 – 1km away when it shines on a white surface. The divergence will make that projected dot 1km away a large dot that reach 20–30m in diameter, and very faint. Green YAG laser pointers at the same power, is in comperison visible up to 4–5km away.

How is laser pointer power measured?

You can use a photodiode or thermopile to measure laser power. Photodiodes are much more sensitive and they’re the only solution for very low powers. The complete power range of PD sensors (with and without attenuating filters) is from 10 pW to a few Watts.

How far can a laser beam travel in space?

Each laser has the power of about four laser pointers and must be detected by a spacecraft an average of 137 miles (220 kilometers) away. Even the ultra- precise assembly of the satellites isn’t enough to guarantee the laser transmitted from each spacecraft will be aligned well enough to hit the other spacecraft.

Can a laser reach the moon?

The typical red laser pointer is about 5 milliwatts, and a good one has a tight enough beam to actually hit the Moon—though it’d be spread out over a large fraction of the surface when it got there. The atmosphere would distort the beam a bit, and absorb some of it, but most of the light would make it.

Are green lasers illegal?

Those handheld green lasers pointers may not be as harmless as you thought. And yes, lasers above 5 mW are commercially available in the United States, but it is illegal to market them as Class IIIa devices.

Can a laser pointer hit a plane?

You should NEVER aim a laser pointer at or near an airplane, helicopter or drone (drones are legally considered aircraft and you may blind or damage the operator’s camera). It is not safe, you may be arrested, and you may help get laser pointers banned.

How does a laser measure distance?

In a nutshell, laser measurement tools are based on the principle of reflection of a laser beam. To measure a distance, the device emits a pulse of laser in the direction of an object, for example a wall. The time necessary for the laser beam to get to the object and go back determines the measurement of the distance.

What is the difference between the red and green laser pointers?

The 1 mW red pointer has a glare distance of 255 feet, compared to the same power green laser, which can cause glare at 490 feet. Similarly, the bottom two bars show that the green laser has much longer visual interference distances than the blue laser — even though they both are the same power and thus have the same NOHD distance.

How far can you see with a laser pointer?

Laser pointers have the potential to reach vast distances when the conditions are right. If there is nothing in the way and there is no reason for the laser light to be obscured by the sun or other things, then it can go pretty far. It’s even possible to shine a laser light and for it to be seen many miles away.

How does the power of a laser affect hazard distances?

If a laser’s power is increased, the hazard distances are longer by the square root of the power increase. Going from a 5 mW to a 500 mW laser is a 100 times power increase — but the hazard distances only become 10 times as long. (The square root of 100 is 10.) However, note that in general, the higher the laser power, the higher the divergence.

Can lasers reach this far up in the air?

Knowing that lasers have the potential to reach this far up in the air is interesting. The fact that they can potentially still be visible at that far of a distance is pretty remarkable. It’s also important to know that you should never shine a laser pointer at an airplane or any other type of vehicle.