What is Distance Meter?

In large-scale engineering activities, people always need to measure the distance inevitably. When people measure distance, they mostly use the distance meter, which is not only convenient to use but also accurate in the measurement process. So what is a distance meter? How does the distance meter work? Below we will introduce the knowledge about the distance meter in detail, including the definition and working principle of the distance meter, hoping to help friends in need.

Distance meter basic

A distance meter is a tool for measuring length or distance, and it can be combined with angle measurement equipment or modules to measure parameters such as angles and areas. There are many forms of distance meters, usually a long cylinder, composed of the objective lens, eyepiece, display device (can be built-in), battery, and other parts.

Working principle of distance meter

1. The distance meters on the market are mainly divided into three categories: laser distance meters, ultrasonic distance meters, and infrared distance meters. We introduce and analyze the principles of these three distance meters.
2. The laser distance meter is an instrument that uses a laser to accurately measure the distance of the target. When the laser distance meter is working, it emits a very thick laser beam to the target, and then the photoelectric element receives the laser beam reflected by the target. The timer measures the time from emission to reception of the laser beam and calculates the distance from the observer to the target. The laser distance meter is the most commonly used distance meter at present. Laser distance meters can be divided into handheld laser distance meters (measurement distance 0-300 meters) and telescope laser distance meters (measurement distance 500-20000 meters).
3. The accuracy of the laser distance meter mainly depends on the calculation accuracy of the time between the instrument's laser emission and reception. Laser distance meters can be divided into conventional laser distance meters with an accuracy of about 1 meter (mainly used for outdoor sports, hunting, etc.) and those used in surveying and mapping, land measurement, construction, engineering applications, military, etc.
4. The ultrasonic distance meter works based on the characteristics of ultrasonic reflection when encountering obstacles. The ultrasonic transmitter emits ultrasonic waves in a certain direction and starts timing at the same time. When propagating in the air, the ultrasonic wave will return immediately when it encounters an obstacle on the way. When the ultrasonic receiver receives the reflected wave, it will immediately interrupt and stop timing.
5. After emitting the generated ultrasonic wave, the distance meter continuously detects the echo reflected by the obstacle,  measures the time difference between the emitted ultrasonic wave and the received echo, and then calculates the distance L. Because the ultrasonic wave is less affected by the surrounding environment, the measurement distance of the ultrasonic distance meter is relatively long, and the measurement accuracy is relatively high. At present, the range of use of ultrasonic distance meters is not very large, but the price is relatively high, usually around several hundred yuan.
6. The speed of ultrasonic propagation in the air is greatly affected by temperature, humidity, air pressure, so the measurement error is large. And because the ultrasonic wave has a longer wavelength and a shorter propagation distance, the measurement distance of the general ultrasonic distance meter is relatively short and the measurement accuracy is relatively low. However, due to the characteristics of fan-shaped propagation of ultrasonic waves, its detection range is larger than that of photoelectric distance meters, and it is widely used in safety protection, cable height measurement, obstacle detection, and other fields in actual engineering.
7. A distance meter is an instrument that adjusts the external light for accurate distance measurement, and the measurement range is usually 1-5 kilometers.

It uses the non-diffusion principle of infrared propagation: when the infrared ray passes through other substances, the refractive index is very large. When the infrared ray is emitted from the distance meter and meets the reflector, it takes time for the infrared ray to propagate, which is received by the distance meter, and then the distance can be calculated based on the time from sending out to receiving infrared rays and the propagation speed of infrared rays.

Working process: The modulation signal frequency “f” generated by the main control oscillator is amplified and added to the light-emitting tube, and the infrared modulated light is emitted through current modulation, and then emitted from the emission optical system to the mirror of the mirror station. After being reflected, the returned light is received by the receiving optical system, reaches the silicon photosensitive diode, and then undergoes photoelectric conversion, and finally obtains a high-frequency ranging signal.

In the automatic infrared distance meter, a logic command circuit is set for program control. The novel distance meter developed in recent years uses a microprocessor system, which can not only complete the above-mentioned program control but also develop a variety of other automatic test functions, including various methods of distance measurement and self-test, etc.

Feature of distance meter

1. It can be measured at a long distance in the case of no reflector and low reflectivity.
2. With a synchronous input terminal, multiple sensors can be measured synchronously.
3. Wide measurement range and short response time.
4. Compact design, easy to install and operate.
5. It can measure the distance of various objects (without a mirror).
6. Increase the filter to measure the high-temperature measured object.
7. Visible light is easy to align with the measured object.

The way to use the distance meter

1. Battery insertion/replacement: Press and hold the removal button, and push to the left to remove the back cover. Open the battery compartment cover to install or replace the battery. This signal is displayed on the screen when the battery is low. Insert batteries with correct polarity and use only alkaline batteries. Insert the back cover along the slot until it clicks into place. When the instrument is not used for a long time, please take out the battery to prevent the battery from rotting.
2. Turn on/off the distance meter and press the red “READ” key briefly, then the light, battery level, and buzzer will be displayed on the display until the first work command is issued. The instrument can be switched off from any menu at any time. When no key is touched for 150 seconds, the instrument will automatically shut down.
3. Clear key. (red OFF/CLEAR) The clear key can restore the instrument to the normal mode, that is to say, it will restore the zero position. The “Clear” key can be used before measurement/calculation or after measurement/calculation. Within a function (area or volume), the “Clear” key can be used to go back to the previous command and take a new measurement.