What is a laser level transmitter?

A laser level transmitter is also called a laser level meter. Industrial Accurate, non-contact, and uninterrupted real-time monitoring of material height. Designed for material level and liquid level. A laser level transmitter is a continuous or high-speed pulsed laser beam emitted by a semiconductor laser.

The laser beam meets the surface of the object to be measured and reflects. The light return is received by the laser receiver. And accurately record the time difference between laser emission and reception. In order to determine the distance from the laser radar to the measured object. Laser level transmitter is similar to radar/ultrasonic level sensor.

Laser Level Transmitter

The laser level transmitter is a non-contact level gauge. The product is powerful, sturdy and durable. It has excellent accuracy and high stability. It achieves accurate, non-contact and uninterrupted real-time monitoring of material height. Industrial site and process, river water level monitoring, material height monitoring and other occasions have very broad applications.

Laser level transmitter Main features:

  • Abundant output interfaces: TTL, RS232, RS485, 4~20mA, CANBUS, ModBus, 0~5V, 0~10V;
  • Ultra-wide power supply voltage: 6~36V DC;
  • The resolution is 0.1mm, and the single acquisition accuracy is better than 1mm;
  • Protection grade: IP67 (anti-salt fog, mildew, anti-collision treatment);
  • Built-in over-current automatic recovery, anti-reverse connection, anti-surge and lightning protection;
  • Non-contact measurement technology, less affected by the working environment, easy to install, layout and back-end control;
  • In an outdoor environment, it can still maintain high measurement accuracy and reliability;
  • The sensor can be processed into a fully sealed, convenient to use in harsh environments;
  • It can be powered by vehicle power supply and industrial DC power supply;
  • Stable power consumption, very low power consumption (when there is no current alarm, the power consumption is less than 1W);
  • Standard industrial bus interface, with operating software to realize all-round industrial automation control;
  • Liquid level and material level height monitoring;
  • It can be equipped with Bluetooth, GPRS, WIFI, rechargeable lithium battery and other functions.

Extended reading: Float Level Sensors – Single and Multipoint

Laser level transmitter data:

Shortest distance0.05m
The longest distance [indoor]SLDS-M02A: 60m
Precision±1mm; single measurement accuracy is better than 1mm
Output frequencyUp to 8Hz
laserVisible laser
Laser classClass Ⅱ safety laser
Laser wavelength635nm~650nm
Spot diameter[email protected]
Laser life>50000h
AnnotationPlease do not stare into the beam, avoid contact with the laser, according to EN60825-1:2003-10 standard
Input voltageDC6-36V
Whole machine power consumption<1W
Digital outputRS485, RS232, TTL, CANBUS, ModBus
Analog output4-20mA, 0~5V, 0~10V
Instrument size80mm*63.4mm*32mm
Shell materialAluminum black anodized
Protection levelIP67
Operating temperature-15℃…+50℃
storage temperature-30℃……+70℃

Laser level transmitter Applications:

Application range:

  • Liquid asphalt, polymerization reactor vessel (high pressure),
  • Reactor vessel (vacuum), molten glass, ferrous and non-ferrous metals,
  • Alloy polystyrene, nylon, polychloride and other core blocks, talcum powder or lime powder,
  • Ore, waste rock in ore chute, wet or dry wood chips;
  • Mining, chemical industry;
  • High-risk areas such as pharmaceuticals, papermaking, plastics, oil and gas, etc.

Restrictions on use: poor accuracy or uselessness under foggy conditions

ElementFactors that extend the measuring rangeFactors that shorten the measuring range
Target surfaceThe brightly reflective surface, such as reflectorDim and matte surface, green and blue surface
Air particlesClean airDust, fog, heavy rain, blizzard
Daylight intensityDark environmentThe target is brightly illuminated
  • Rough surface: When measuring rough surfaces (such as plaster walls), aim at the center of the shiny area.
  • Transparent surface: Please do not measure on the surface of transparent objects, such as colorless liquids (such as water) or glass (no dust).
  • Oblique round surface: The measurement can only be performed when the target area is large enough to accommodate the laser spot.

Extended reading: Hydrostatic Level Measurement

Extended reading: What is Modbus Protocol?

Laser level transmitter working principle

The laser level transmitter adopts the phase method laser ranging technology. Using the frequency of the radio band, the laser beam is amplitude modulated and the phase delay produced by the modulated light going back and forth to the measuring line is measured. Then according to the wavelength of the modulated light, the phase delay represented by this is converted distance. That is, the indirect method is used to measure the time required for the light to pass through the measuring line.

The distance D from the surface of the material is proportional to the time travel T of the pulse:


Where C is the speed of light

Since the distance E of the empty tank is known, the level L is:


According to the range and full scale information set by the user, the processor calculates the percentage of the current material level, and then outputs 4-20mA or 0-5V analog signals, RS485 Modbus digital signals, and warning alarm relay switch signals in proportion.


  • The measuring beam has a small divergence angle and good directivity;
  • Large range, long-distance measurement, minimum blind spot;
  • Not affected by the temperature of the medium;
  • Non-intrusive measurement, non-contact measurement;
  • Fast measurement speed, suitable for fast-changing liquid level and material level measurement;
  • Easy to use, programmable measurement;
  • Accurate measurement and high precision are suitable for high-demand projects;
  • The resolution is ten times higher than the general table;
  • The beam angle is small, suitable for long-distance positioning and avoiding obstacles.


  • Easy to be interfered by the light source in the test band and absorbed by the dark object;
  • Slightly more expensive

Extended reading: Ultrasonic Level Switch-External Mounted

Laser-level measurement has gained popularity in industrial applications. The advantage of laser level measurement is an accurate and simple measurement without contact with the measured material. Even materials with a low dielectric constant can be easily measured with a laser transmitter.

The laser beam is very narrow (divergence <0.3°), and a small spot is formed on the surface, which is usually less than 30cm even at a long distance. The figure below shows a typical installation on the storage bin. The laser transmitter is mounted on the reel using a rotating flange to ensure precise alignment to the bottom of the silo. In order to strengthen the protection, a dustproof tube is also used. For plastic applications, it is important to use metal mounting plates or flanges and ensure that they are properly grounded to the silo to help eliminate static buildup.

Extended Reading: GWR Level Sensor for High Temperature & High Pressure

Extended reading: Radar Level Sensor Advantages and Disadvantages

In order to use water resources rationally, real-time detection of the water level of various water areas is particularly important, so the demand for water level gauges is huge.

The laser level meter is a new type of distance measuring equipment with the advantages of high accuracy, fast response, large range, non-contact measurement, etc. It is suitable for my country’s rivers, lakes, reservoirs, hydraulics, ship locks, rivers, urban water and other liquid level monitoring occasions.

Extended reading: Ultrasonic level transmitter for Hazardous Liquids

Extended reading: Capacitive water level sensor

More Featured Liquid Level Measurement

SI-LT Magnetostrictive level transmitter with Local Digital Display
SI-100 Magnetostrictive Level Sensor
SI-U02 Multi-Point Liquid Level Float Switch

SI-U01 Float Level Sensor
ULT-200 Ultrasonic Level Detector
ULT-100A Ultrasonic Level Transducer
SMT3151TR Submersible Level Transmitter–2Mpa,200m
SI-80 Radar Level Sensors
SIRD90 Radar Level Transmitters, Non-Contact

SIRD70 Guided Wave Radar (GWR) Level Transmitters
RF Capacitance Level Transmitter

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Sino-Inst offers over 50 level transmitters for level measurement.

About 50% of these are liquid level meters, 40% is the tank level sensor.

A wide variety of level meters options are available to you, such as free samples, paid samples.

Sino-Instrument is a globally recognized supplier and manufacturer of level measurement instrumentation, located in China.

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