Laser sensors

Back to Basics tutorial: Lasers can be used in non-contact distance sensors. In industrial machinery or for plant-floor applications, triangulation-based laser displacement sensors are used most often. Laser-based triangulation displacement sensors combine high resolution and comparatively long ranges. See diagram and sensing primer.


Machine Control, Instrumentation
Principle of triangulation: As the target moves across the laser sensor field of view, left to right in the diagram, the change in the distance between sensor and target flattens the angle of the returning light from A to B. As the position of the beam on the receiving array changes, so does the measurement.

Lasers can be used in non-contact distance sensors. In industrial machinery or for plant-floor applications, triangulation-based laser displacement sensors are used most often. Laser-based triangulation displacement sensors combine high resolution and comparatively long ranges.


Sensor manufacturers generally offer versions with 10 µm resolution and ranges to 1 m.


Triangulation technology (see diagram) uses a laser light source to project a well-collimated beam onto the target. Light reflected by the object passes through a lens that focuses the reflected beam onto a receiver. Changing the distance between sensor and target changes the angle of the returning light and the position of the beam on the receiving array, typically a charge-coupled device (CCD) line. The CCD signal feeds a microcontroller, which provides measured values as output using analog signals.


To limit signal noise, laser measurement sensors perform internal sampling, sometimes called integration or averaging. During sampling, the device averages multiple readings for smoother, more accurate output. Integrating more samples creates higher resolution, but increases the measurement time.


Faster decisions, response


Advanced sensing arrays and fast microprocessors speed response times. Some sensors project a laser line, rather than a laser point, bringing in more data to smooth over and tune out irregularities.


Author Information
Stephen Petronio is photoelectric product manager with Baumer Electric.


Primer on sensing

To understand performance of various sensor technologies for different applications, it can be helpful to review terms used to describe sensor measurements, suggests sensor manufacturer Baumer Electric.


Resolution corresponds to the smallest possible distance change that causes a detectable change in the output signal.


Repeat accuracy is defined as the difference of measured values in successive measurements.


Linearity is the deviation from a proportional linear function (straight line). It is given as a percentage of the upper limit of the measuring range (full scale).


Reaction time is defined as the time required by the sensor’s signal output to rise from 10% to 90% of the maximum signal level. For sensors with digital signal processing it is the time required to calculate a stable measured value.


Temperature drift : Ambient temperature changes cause measured values to drift. Temperature drift is nearly proportional to temperature change.

The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by Control Engineering subscribers. Vote now (if qualified)!
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
Maximize ROI with integrated control system approach; Microcontrollers vs. PLCs; Power quality; Accelerate and rewire IIoT; Traits for excellent engineers
HMI effectiveness; Distributed I/O; Engineers' Choice Award finalists; System Integrator advice; Inside Machines
Women in engineering; Engineering Leaders Under 40; PID benefits and drawbacks; Ladder logic; Cloud computing
Programmable logic controllers (PLCs) represent the logic (decision) part of the control loop of sense, decide, and actuate. As we know, PLCs aren’t the only option for making decisions in a control loop, but they are likely why you’re here.
This digital report explains how plant engineers and subject matter experts (SME) need support for time series data and its many challenges.
This article collection contains several articles on how advancements in vision system designs, computing power, algorithms, optics, and communications are making machine vision more cost effective than ever before.

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

Control room technology innovation; Practical approaches to corrosion protection; Pipeline regulator revises quality programs
Cloud, mobility, and remote operations; SCADA and contextual mobility; Custom UPS empowering a secure pipeline
Infrastructure for natural gas expansion; Artificial lift methods; Disruptive technology and fugitive gas emissions
Automation Engineer; Wood Group
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me