What is Laser Sensor & How it Works?

Laser application

Laser Sensor

  • A laser sensor is a measuring value recorder that uses laser technology.
  • The physical measured value is transformed into an analogue electrical signal by a laser sensor.
  • A laser sensor senses an item using laser light or rays.
  • Laser sensors transform light energy into electrical energy if we think of them as transducers.
  • The contactless measurement method employs a laser sensor.

Describe the Laser

  • Laser is an acronym of Light Amplification by Simulated Emission of Radiation.
  • The energy is magnified to a very high intensity in a laser.
  • A laser sensor produces energy in the form of light that is similar to the electromagnetic spectrum’s optical region.

Working principle of Laser

Laser sensors working principle is based on triangulation.

What does the “Laser Triangulation Principle” mean?

  • A laser sensor’s distance measurement.
  • This hypothesis predicts that the laser beam will make contact with the target.
  • Once the laser sensor makes contact with the object, some of the lasers light will be reflected back.
  • This point’s location will be determined by the sensor’s receiver.
  • The laser point inside the receiver will move around depending on the distance, as will the angle of incidence.

Technique of triangulation

         The time it takes for light to reach an object and be reflected is measured by these time-of-flight distance sensors. Triangulation is an alternative technology that uses the angle of reflected light to calculate a distance to an object. The fundamental geometry of triangulation is shown below.

A laser emits a tiny point of light that bounces off of an object and onto the camera’s image plane.

laser Triangulation Principle

         The laser beam should be pointed so that it is parallel to the ray that passes from the center of focus to the edge of the image in a pinhole camera. This provides a measurement of the distance between infinity at one edge of the image and the distance at the other edge

Operation of a Laser Sensor

         The object that has to be sensed is incident with a laser beam. A little bright dot would be how laser would seem because it is a highly focused beam of light.

         Some light will be reflected back by the target object when the laser beam strikes it and the object is intended to be detected. A photodetector, for example, in the sensor’s receiver detects this reflected light. Internal circuitry in the sensor with photodetector, amplifier would handle the signal processing.

Operation of a Laser Sensor

Classification Based on Laser Triangulation Principle

  • Based on their functionality and intended application, laser triangulation sensors can be split into two groups.
  • In displacement and position monitoring applications where great accuracy, stability, and little temperature drift are required, high-resolution lasers are frequently used. These laser sensors are often employed in closed-loop feedback control and process monitoring systems.
  • Proximity type laser triangulation sensors are substantially less expensive and are frequently employed in counting applications or to identify the presence of a part.

Uses for Laser Triangulation Sensors

         The most typical use of laser triangulation sensors is general positioning.

They are perfect for both static and active feedback positioning applications due to their quick, highly linear response. The flexibility for process and quality control monitoring is provided by large operating distance and measurement range.

  • Road profiling for paving and concrete.
  • Train track alignment
  • Robot placement
  • Position of the welding head

         Due to their high frequency response and lack of mass, non-contact laser triangulation sensors are the best choice for measuring moving targets. Laser sensors are made with 20 kHz frequency response and a 40 kHz sampling rate, making them perfect for high speed applications like:

  • Analysis of spindle run-out
  • Piezoelectric characterization
  • Measurements of ultrasonic vibration
  • Continuous process observation
Laser sensor application


Laser types based on application

The following list includes many sensor types that rely on laser light to operate.

  • Distance sensors using laser
  • Sensors for laser displacement
  • Projector laser
  • Photoelectric laser Sensors
  • Edge Detection Sensors for laser
  • Laser-powered curtains
  • Sensor for laser positioning

Advantageous of Laser sensors

  • The measurement made by the laser sensor is quite precise.
  • Laser sensors have a high beam direction and a low light divergence angle.
  • For laser sensors, the brightness level is high.
  • The range of a laser sensor can reach many kilo meters.
  • Laser sensors have a narrower frequency range than regular light.
  • Laser sensors perform contactless measurement, which doesn’t stop the process.
  • For laser sensors, both digital and analogue outputs are provided.
  • All industrial settings are suitable for the usage of laser sensors identifies a variety of materials.
  • Installing laser sensors is simple.
  • Resistant to noise from the surroundings and interference.

Disadvantageous of Laser sensors

  • Analog measurement equipment is less expensive than laser sensors.
  • Due to the need to maintain extremely precise calibration, laser sensors are exceedingly fragile.
  • A very high degree of precision is not required in all procedures. Laser sensors are therefore inappropriate there.
  • Laser sensors may harm vision.

Applications of Laser sensors

  • Object’s location Quality assurance
  • Lining up the train tracks
  • Wire diameter measurement
  • Position of the welding head
  • Brake rotor thickness measurement
  • Vehicle tally
  • Restrict your knowledge of the vehicle’s height and width.
  • Determining the separation between two sheets
  • Control of power tools
  • Measuring the thickness of wood
  • Controlling deviations during quality control inspections of the timber thickness

What is meant by sensors used in Blue Laser Technology

  • When normal sensors with a red laser diode are performing to their maximum capacity, the sensors are employed since they have a blue laser diode.
  • The blue laser produces a small light spot on the target surface because of its shorter wavelength, which prevents it from penetrating the surface and produces stable and accurate results.
  • This technology is best applied to glowing metals that are extremely hot as well as organic and (semi-)transparent items.
  • Red colored laser, operates at 670nm wavelength, was subject to certain limitations. With different wavelength blue violet laser operates at wavelength of 405nm will enables the measurement of certain application like vibration on engine manifold.
  • Blue laser sensor measurements on red-hot incandescent objects over 700 °C and transparent items like glass and plastics.
  • These surfaces are measured accurately by blue laser model due to their signal stability.
  • Red colored laser, operates at 670nm wavelength, was subject to certain limitations. With different wavelength blue violet laser operates at wavelength of 405nm will enables the measurement of certain application like vibration on engine manifold

Laser sensors in Manufacturing/ Industries Application

Molding Injection

  • Verification of part ejection
  • Prior to the following cycle, it is essential to verify that the target has been successfully removed from the mold in order to increase manufacturing cycle efficiency and avoid downtime.
Molding Injection
  • The laser Sensor works to steadily detect the target from practically anyplace within 5 m thanks to its capacity to retain fine detection across long distances.
  • By measuring the distance to the floor or top of the stack, sensors are utilized to assist palletizing robots with product stacking and positioning.
  • Conventional sensors may be affected by the different colors or materials of the products being stacked or the floor, which could lead to inaccurate readings and possibly damaged products as a result of product placement.
  • The laser Sensor is able to consistently detect the distance regardless of the surface finish use of TOF (Time of Flight) Technology.

Tapping Apparatuses

  • Monitoring tapping machines for tool breakage
  • Because standard sensors cannot withstand the debris and cooling liquids near the tool, tapping machines often have to adopt additional processes to check for tool fracture.
  • The laser Sensor may be installed far from a dangerous situation and still reliably keep an eye out for tool breakage.
Tapping Apparatuses


Processes for Cutting and Rolling

Processes for Cutting and Rolling
  • Control of material tension throughout the roll-to-roll process
  • With traditional thru beam type photoelectric sensors, top, middle, and lower levels of sheet material must be detected. This requires time-consuming tasks including installation, wire routing, and optical axis alignment.
  • Several sensors can be readily avoided because to the laser range and analogue output, which significantly improve tension control.

Heaters for Forging/Billets (Induction Heaters)

  • Finding hot metal after it has been ejected from a heater
  • It employs program to ignore ambient effects, allowing it to accurately identify targets that are burning hot.
  • Also, the sensor may be placed far away from the hot target thanks to its 5 m (16.4′) detection distance.
Heaters for Forging, Billets


Big Filling Machines and Sintering Machines

  • Measuring the amount of stuff in a hopper
  • While employing traditional methods, dusts and mists have always been a difficulty for level detection.
  • Moreover, spaces between the materials occasionally caused hopper level measurements to be miscalculated.
  • The laser sensor can detect the level of the material in the hopper steadily and accurately with TOF (Time of Flight) Technology and an adjustable beam point.
Big Filling Machines and Sintering Machines

Presses of Transfer

  • Detection of material depletion
  • To detect material runout, thru-beam type sensors have to be positioned both above and below the press mould
  • However, buildup of dirt and grease on the lenses soon leads to problems.

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Presses of Transfer

Electronic Shutters

  • Detection of forklift approaches
  • While installing conventional thru-beam type photoelectric sensors, wiring and alignment required a lot of time and work.
  • By offering long-distance reliable detection with minimal wiring and no alignment required thus decreases this time and effort.
Electronic Shutters

Robots Palletizing -Robotic stacking feedback for height detection

  • By measuring the distance to the floor or top of the stack, sensors are utilized to assist palletizing robots with product stacking and positioning.
  • Conventional sensors may be affected by the different colors or materials of the products being stacked or the floor, which could lead to inaccurate readings and possibly damaged products as a result of product placement.
  • The laser sensor is able to consistently detect the distance regardless of the surface finish thanks to the use of TOF (Time of Flight) Technology.
Robots Palletizing

Process of Winding Sheets

  • Interior sheets are available in a range of hues, substances, and even patterns like mesh.
  • Conventional reflecting sensors fail when the mesh has holes or when the substance or color of the sheet changes.
  • Due to its unique position-based detecting technique and capacity to extend its beam spot size to disregard holes, the LR-T is unaffected by any of these issues.
Process of Winding Sheets

Metallic Surfaces, like Engine blocks

  • Detection of engine block holes
  • It was often necessary to utilize touch sensors to determine whether a hole was processed correctly in the automotive industry due to the intricate shapes of engine blocks and other metallic components.
  • The laser can now be utilized to save inspection time and be mounted in an unobtrusive location due to its capacity to reliably detect holes over extended distances.
Process of Winding Sheets

Welding Apparatus

  • Component presence/absence detection before welding
  • As sensors had to be placed far from the target to avoid being damaged by weld spatter, the identification of big portions during the welding process has always been problematic.
  • The laser Sensor is able to reliably detect targets at a greater distance.
Welding Apparatus

Casting Die

  • Aluminum melt level detection in die casting
  • The heat and vapor from the melted metal caused sensor problems and damage when using standard level detection techniques.
Casting Die
  • The laser Sensor can be placed far from the possibly harmful heat because it can detect shiny metal levels up to 5 m (16.4′) away. Some laser Sensor has an analogue output for more accurate level control. Also, the analogue output enables you to use various set points for level control that is more exact.

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