# The principle of laser rangefinder, how to buy laser rangefinder

2022.02.14

Laser rangefinders, do you understand? Classification of laser rangefinders, laser rangefinders are divided into three categories, one is a handheld laser rangefinder, which has a short measurement distance, generally 20-250m, with high measurement accuracy. Generally 1-2mm, widely used. Long-distance laser rangefinder, the measurement distance is long, generally 500-2000 meters, the accuracy is relatively low, generally 0.5-1 meters, mainly used for electric power, environmental protection, forest, animal and plant protection, field survey and other field long-distance measurement . Laser ranging sensors are highly accurate and can be integrated with other equipment, mainly for industrial and online monitoring.

Its principle: the principle of triangulation, the laser beam emitted by the semiconductor laser irradiates the target. The receiver collects the light reflected by the target and focuses it on the photosensitive element. As the distance from the target changes, the angle of the reflected light passing through the receiver lens changes, and the position of the light focused on the photosensitive element also differs.

The principle of time measurement is to measure the distance in the time it takes for a light-emitting laser to strike an object and return. Stable detection is possible without affecting the surface state of the workpiece. Check the time t of receiving the reflected light of the laser in the right picture, and calculate the distance Y. The calculation formula: 2Y (round-trip distance) = C (speed of light) T (time to receive the reflected light).

The principle of confocal measurement is that there is a lens inside the measurement section. The lens has a fixed focal length, and the focal length of the lens is set to f. When using this lens to focus light, when the height is f, the focus will coincide, and the light will converge to 1 point. As the height deviates from f, the light gradually becomes blurred. The focal position is the position where the amount of reflected light passing through the pinhole is strong. Determine the height of the tuning fork (lens) when the amount of reflected light is strong, and you can see at a glance whether the target object is located at a focal distance f from it. By reading the position of the tuning fork (lens) at this time with high accuracy by the internal sensor, the distance to the target can be measured. Because it measures the focal height, accurate measurements can be achieved regardless of the target's material, color, and inclination.

Factors to consider when choosing a laser rangefinder: measurement accuracy (how big is the error); use site (indoor or outdoor, for forestry, surveying or fishing, etc.); the range of the measured distance (whether the measured distance is a few meters or a few meters) Hundred meters, several kilometers).

There are three misunderstandings in choosing a laser rangefinder: blindly consider the price; there is an old Chinese saying, "one penny gets the goods", which may not be completely correct, but it still makes sense. In recent years, Chinese rangefinder manufacturers have sprung up like mushrooms, with many brands emerging. The quality of rangefinders varies, and the country has not issued relevant national standards. Therefore, the market is very chaotic, so we should not only consider price when choosing products. There must be a reason for the low price. It depends on whether the product has a certificate, whether the product design is reasonable, and whether it is anti-drop; the laser level of the product, some products cannot let children look directly at the eyes, which may damage the eyes.

Blindly pursuing high prices, the price of laser rangefinders is very confusing in the market. Many users may think that high-priced products are good when purchasing, so they blindly pursue high prices. In fact, it is necessary to consider ranging range, ranging accuracy, measuring distance, function, laser, etc., but the price is not the key. If you are a user, first take a look at the product functions of the laser rangefinder, and then choose a laser rangefinder suitable for engineering use after the actual experience.

Blind pursuit of high indicators, any product has its own technical indicators, which of course represent relatively high performance. In recent years, the accuracy and range of rangefinders have been continuously improved. Many surveying and mapping professionals feel that their work must maintain extremely high precision, so they desperately pursue high precision and high measurement range when purchasing.

When purchasing, the user should choose a rangefinder according to actual needs. For example, ordinary personal users can choose a rangefinder with good performance and a lower price depending on how far the range is and whether high precision is required. Secondly, see if the ranging range is suitable for your own use. Distances of more than a few kilometers are used by some professional surveying and mapping industries. There is absolutely no need for ordinary users to blindly pursue high positions and cause waste.