Laser Rangefinders: Unfolding The Mystery Of How It Works
A laser rangefinder brings many benefits to its users in many sports, which are hunting, golfing and even mountaineering. For a hunter, this really useful tool brings multiple benefits such as increasing their chances of making a clean shot which is a more merciful way of hunting, or even help you understand the terrain better.
As for bowhunters, a laser rangefinder would fall within the category of one of the most needed equipment, although there are other equipment needed for shooting accuracy. Also, a rangefinder is convenient to travel with where it is lightweight and durable. There are many methods how a rangefinder can benefit you in so many ways!
All laser rangefinders work using the same concept, where they emit laser beams which bounces off your target object. Later, the high-speed clock would measure the total time taken for the beam to leave and return to the unit. Since the beam travels at the speed of light, a simple time measurement can be used to calculate the distance travelled. The distance would usually be shown to the user through the screen.
Now, I would go through the process of how it works, one by one.
Beam Divergence onto the target
First things first, the beam from your laser rangefinder has to reach the intended target. The basic concept is this: the further the target, the greater the beam dispersion (as opposed to the beam being focused). However, the result is that smaller beam divergence would give you greater ranging precision and the more “focused” the laser beam, the greater the ranging distance.
Therefore, the ability of your rangefinder to “focus” its beam would be an indication of how far it can range. But, beam divergence would not be the only factor to consider if your rangefinder is smart in analyzing such readings and making up for such situations.
Reflecting from the target
It is important to note that there are several factors that affects the accuracy of the rangefinder’s reading and cause the reflection to not be that accurate. The factors include target properties (surface condition) and atmospheric condition.
So, at this stage, when the beam strikes the object, the reflected beam would be received by the rangefinder to calculate the distance. The principle here is that the more available light which comes back to the rangefinder, the easier it is to take the readings.
Do note that the effect of beam scatter, atmospheric distortion and interference can vary the length of time required for the light to be reflected. This would mean that the rangefinder would have different readings in a different environment.
Calculating the distance
After the beam reflected off the object back to its source, the rangefinder would measure the time taken for the beam to make its journey to the object and back. Based on the speed of the beam and the elapsed time, the device would measure the distance to the target.
This calculation method is named the ‘time of flight’ principle. Since laser beams travel at the speed of light, the total time required for the beam to return to the rangefinder is really small. Therefore, this makes it really difficult to measure the time taken, which means that laser rangefinders are limited in the level of precision of measurement where it can determine distances in meters. However, there are some cutting-edge rangefinders which can accurately determine distances in millimeters.
Displaying it to you
How a rangefinder analyzes a result and decide to display it to you depends on how it is programmed. For the older rangefinders, it would use the first reading approach, where the unit would receive the first beam that is reflected back and calculate the corresponding distance.
Another method is termed the closest spike method, where the rangefinder looks for the closest peak rather than the closest single reading. Objects which are scattered in pattern such as rain or fog cannot pass the ‘threshold’ that is set in the rangefinder.
Depending on the range you want to see, different method of how the rangefinder display the results to you would be ideal. For example, the highest spike display method, where the rangefinder would look through an entire set of readings in the same distance and determine what you intend to range. This approach is good when ranging reflective targets around 340 to 350 yards.
If you would like to range even further, it would be wise to get a rangefinder that uses the largest cluster method or the furthest spike method.
Usually, laser rangefinders would display the information through an LCD or OLCD screen, which is similar to your cell phones. You may get the information including your intended target’s distance, speech and degree of inclination.
After understanding how a laser rangefinder work, I hope it would help you significantly in how you operate it. There are still some common mistakes you need to avoid in ensuring that you get the maximum benefit from your rangefinder. Amongst others, you have to ensure that your target is not out of range, where you have to understand that the maximum range estimate on your rangefinder only applies to highly reflective surfaces.
Other factors include not accounting for the elevation angle of your target, which can be resolved by having an angle compensator fixed in your rangefinder. Keeping your rangefinder in good condition is a helpful habit which you should cultivate so that the rangefinder can give you the most accurate reading possible.
Only when you have an accurate reading of the measurement, you can reflect on how far you need to shoot. If you have any tips or tricks you want to share, feel free to comment below!