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Laser Sensor [Working Principle, Types, Features, Applications]

Laser Sensor [Working Principle, Types, Features, Applications]

A laser sensor is a type of non-contact sensor defined as an electrical measurement device used to sense small objects and the exact location of the target objects. This sensor uses a laser to produce light in a straight line.

Laser light contains light waves of similar wavelengths. For this reason, the beam moves in a parallel direction.

This light can be used to transmit information over long distances. Laser sensors are considered as photoelectric sensors, but they use a laser light beam to detect the object or even its exact distance. 

The light of this type of sensor can be a point (point laser) or linearly (line laser). The point type is used to detect distances and the linear type is used to measure the dimensions of objects. 

These sensors are divided into different types with digital or analog output with different resolutions and accuracy. Laser sensors can be used in many cases where there is a significant distance between the sensor and the object along with dust or bad environmental conditions. 

What is Laser?

A laser is a device that emits light from very narrow parallel beams that have a certain wavelength. This device consists of light collecting or activating materials that are located inside the light intensifying housing.

This material amplifies the light beam generated by an external energy source (either electricity or light).

What can Laser Sensor Detect?

Laser sensors can measure length, distance, thickness, vibration and speed.

The working principle of laser sensors

The working principles of all laser sensors are based on the Triangulation Principle. Some laser sensors are designed and manufactured for metal and polished objects and some for completely dark objects. 

Laser sensor is widely used in industrial and agricultural production, national defense and military, medical and health, scientific research, and other aspects and applications.

The sensor consists of a laser, optical parts, and photoelectric devices used to convert the measured physical parameters such as length, flow, speed, etc. into optical signals, and then use a photoelectric converter to convert the optical signals into electrical signals output.

Major types of Laser sensor

Laser sensors are mainly divided into Laser Displacement sensors and Laser Distance Sensors. Laser Displacement sensors are divided into reflective, through-beam, and retro-reflective models. 

These models utilize the visible laser beam, but their detection methods are different.

Laser Displacement sensors

A laser displacement sensor uses laser technology for accurate and non-contact measurement purposes. It consists of a laser, a laser detector, and a measurement circuit and can be used to measure the position, displacement, and other changes of the target object. 

This sensor can also be used to measure exact geometrical measurements such as displacement, thickness, vibration, and other quantities of the object. The working principle of this sensor is based on the laser triangulation method that is well suited for high-precision and short-distance measurement, and the laser echoes analysis method that is proper for long-distance measurement. 

The major types of laser displacement sensors include: reflective, through-beam, and retro-reflective.

Reflective laser sensor:

This sensor, also called a transmitter/receiver, contains an emitter to emit laser light and a receiver for the light-receiving task. 

To detect targets, the sensor emits a laser beam, then these beams of lights reflect from the surface of the target object and receive the reflected beam of lights to detect the target object.

Through Beam laser sensor:

In this sensor optical axis create a signal beam between a transmitter made of a laser light emitter part and a receiver made of a light-receiving part. 

The sensor recognizes the target objects by recognizing whether the beam of the laser signal emitted from the transmitter is interrupted by the target.

Retro-reflective laser sensor:

In this sensor, there is a reflector and signal beam created between this reflector and sensor. When the target object interrupts this signal beam, sensors receive the reflected light by the surface of the object and therefore the object can be detected.

Laser Distance Sensor

Laser Distance Sensor, which is used to measure distance, uses a narrowed beam of light to measure the distance to the target. 

These types of laser sensors are able to detect the distances of any solid object And produce an output signal. The sensor consists of a laser light-emitting, a receiver lens, and a light-receiving (CMOS) located on the head of the sensor. 

A laser beam emitted to the surface of a target by the sensor and then receives the reflected light. If there is a change in the position of the received light, the sensor can detect the change in the distance of the target. 

This method forms a triangle that consists of the path of the laser beam from the light source to the point of reflection on the surface of the measured target to the light-receiving element. Consequently, it is called the triangulation method.

There are absolute distance measurement methods including pulse laser ranging and phase laser ranging, and micro displacement measurement methods including triangulation laser ranging and interferometry laser ranging for the measurement of the target's distance.

Features and Advantages of laser sensor

  • Large measurement range
  • High Operating distance
  • Stable measurements
  • High accuracy and speed
  • Small size and quick installation
  • Easy and smart settings
  • Ability to work in all industrial environments
  • Accurate positioning
  • Detects a wide range of materials
  • Accurate measurement of contactless distance using laser technology
  • Resistant to interference and environmental noise

Laser Sensor Application

  • Expressway toll station for counting and protecting vehicles
  • Over-limit recognition of vehicle width and height
  • Measure the distance and position on the robotic paw when choosing a product to lift or place
  • Measure the wire diameter
  • Check the availability of goods and parts
  • Measure the distance between 2 sheets
  • Measure the height of stacked goods, measuring length in the wood and packaging industries
  • Car control and safety
  • Tiny hole detection
  • Power tool control
  • Piece deviation control
  • Detection of small parts
  • Align the railway track
  • Quality Control
  • measure Brake rotor thickness
  • Welding head position
  • check the wood thickness
20th Mar 2022 Saeed Abd

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