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SNIPER 101 Part 85 – LASER Rangefinder Advantages and Limitations

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All right let’s look at lasers laser of course is an acronym it stands for light amplification by stimulated emission of radiation in case you didn’t know that’s why it’s in all capital letters it’s a laser K a laser rangefinder is pretty simple it operates on time-of-flight principle it’s a very simple equation your distance is going to equal your rate times the time okay so if you know the rate of the speed of light which in most circumstances is about 186,000 280 miles per second and you know the time is going to send a pulse of the laser in a narrow beam towards a target it’s going to measure the time taken by the pulse to be reflected off of the target and return back to the center to find your distance pretty simple.

How Laser Rangefinders works?

How it works using a laser rangefinder is also very simple you simply point and click so that’s not very hard and there are certain advantages of a laser rangefinder that are very nice they’re very quick and easy to use you point you click and quick and easy and it can definitely give you very precise measurements to the target most lasers are at least within 5 meters of the target as far as your accuracy some are even as close as half a meter and so that’s very precise and of course they don’t require the knowledge of the object’s dimensions in order to range accurately like when you’re using the milling reticle you have to know how big the target is with laser it doesn’t matter you just point and click and you got it and also that means you can now range trees and Hills for example if you use an ax ranging reticle you can’t just make the assumption all pine trees are 40 feet tall that’s not they vary in size all rocks are exactly 3 feet wide no you’re not going to be able to arrange a rock using your milling reticle but you will be able to arrange it using a laser so those are the main advantages of a laser there are limitations that you have to be aware of when using lasers.

This is going to affect which laser you’re going to purchase so pay close attention there’s a thing called beam divergence it’s important to understand now despite the beam being really narrow at first you know the laser beam seems like it’s perfectly straight but it’s eventually going to spread out over longer distances due to beam divergence now beam divergence of an electromagnetic beam is an angular measure of the increase in the beam diameter or the radius with distance from the optical aperture or the antenna aperture from which the electromagnetic beam is coming out of okay so like most electromagnetic beams electromagnetic radiation is basically light okay as some light is visible some light is invisible but a lasers are subject to divergence which is measured in terms of milliards just like your you know your scope reticle is going to be measured to millions in angular measurement or degrees and for our applications the lower divergence a beam is going to be better this is going to be one aspect that separates high-quality lasers from low-quality lasers when you pay for a high dollar one versus a cheap one is your beam divergence how narrow it keep setting

Qualities of laser rangefinders

How concentrated it is now neglecting the divergence due to poor beam quality your divergence of the laser beam is going to be basically proportional to its wavelength and inversely proportional to the diameter of the beam at its nose point but to make a long story short you’re going to have beam divergence it’s going to spread out eventually and it’s not going to be able to give you that pinpoint reflection that you’re going to need to range a target at long range so spend a little more money on a good laser and that’ll minimize that problem there is another effect they need to be aware of this is another big limitation to using laser rangefinders is atmospheric scintillating or beam wander effects okay no atmospheric skin elation is basically it’s going to occur when you have different air densities due to thermal gradients in the air you know different temperatures air are going to have different densities and this is going to kind of act like a lens and this is going to you know deflect the path of the beam just like a lens of glasses going to be a different density than the air that’s why it bends a light right so you’re going to have just atmospheric scintillating bending your beam and divergence combined with these atmospheric inflation effects and other beam wander effects that there’s a lot of different things that can happen these are going to all potentially deflect the laser beam away from the target especially when you get further out there!

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