Laser Displacement Sensors

KEYENCE's laser displacement sensors enable non-contact measurement of a target's height, position, or distance. By pairing multiple sensors, measurements such as thickness and width can also be performed. High-accuracy displacement sensors can be grouped into two categories: confocal and laser triangulation. Both provide accurate, reliable solutions for non-contact measurement, but depending on the application one type may offer an advantage over the other.

Download Catalogues

Products Lineup : High Precision Measurement (Reflective Distance Sensors)

CL-3000 series - Confocal Displacement Sensor

The CL-3000 Series confocal displacement sensors are compact 1D laser displacement sensors that use a unique method to ensure high-precision measurement on any material or surface. Using a confocal sensor enables stable measurement on materials ranging from dark rubber to clear films without having to adjust mounting or measurement settings. The sensors are designed with only the lens inside the heads, making them both compact and lightweight, which is ideal for installation in narrow spaces or on robots. All electronics are kept away from the measurement location in the optical unit, providing a stable result that is unaffected by heat or electrical noise. Equipped with features like quad spot processing and optical axis alignment, this series is well suited for a variety of industries and applications, including position or thickness measurement, and it can accurately measure on curved, uneven, or even rough surfaces.

Catalogues Price

LK-G5000 series - Ultra High-Speed/High-Accuracy Laser Displacement Sensor

The laser triangulation displacement sensors of the LK-G5000 Series offer high speed and high accuracy for non-contact displacement measurement applications. The sensors utilise advanced hardware such as the RS-CMOS and HDE lens pack to provide reliable results on a range of materials by ensuring the returned light is always in focus. This technology creates a sensor with superior linearity (0.02% of F.S.) and repeatability (0.005 µm). With a max sampling speed of 392 kHz, the LK-G5000 Series can reliably monitor vibrations or catch small changes in fast-moving targets. The head lineup is designed to support a variety of industries and applications, allowing users to select the ideal sensor based on their requirements for measurement range, accuracy, and beam spot size.

Catalogues Price

LK-G3000 series - High-speed, High-accuracy CCD Laser Displacement Sensor

The LK-G3000 Series laser displacement sensors employ high-accuracy Li-CCD and ernostar lensing to provide a flexible solution for measuring displacement. This series offers a broad range of sensor heads to support applications requiring high accuracy or large standoff and has a maximum range of 1 metre. The sensors are equipped with a function (ABLE) that automatically adjusts the settings to optimise the reflection from different surfaces, making it possible to measure translucent, rubber, or metal materials stably.

Catalogues Price

Products Lineup : Reflective Distance Sensors

IL series - CMOS Multi-Function Analogue Laser Sensor

IL Series CMOS multi-function analogue laser sensors are reflective laser displacement sensors that provide the best-in-class detection ability and stability at a reasonable cost. Stable detection is possible without tuning for workpiece types or their surface conditions, so the IL Series can be added to production lines to help make setup, changeover, and product changes easier. With a wide-ranging lineup of sensor heads, including high-accuracy models and long-range (up to 3.5 m) models, these laser sensors can be applied to diverse applications thanks to their broad dynamic range and environmental resistance. 1 μm repeatability allows for use in high-tolerance detection setups that previous sensors could not stably provide.

Catalogues Price

KEYENCE's 1D laser displacement sensors enable non-contact measurement of a target's height, position, or distance. By pairing multiple sensors, measurements such as thickness and width can also be performed. High-accuracy displacement sensors can be grouped into two categories: confocal and laser triangulation. Both provide accurate, reliable solutions for non-contact measurement, but depending on the application, one type may offer an advantage over the other.

Descriptions of the various types, measurement principles, and advantages of 1D laser displacement sensors can be found below.

Multi-colour Confocal Method

Confocal displacement sensors emit and receive light on the same axis. Multi-colour confocal sensors use a light source that emits multiple colours (wavelengths) of light that each have a unique focal distance. The sensor measures the distance to the surface by detecting which colour is currently focused on a target. KEYENCE's CL-3000 Series sensors utilise a brighter light source than conventional models, producing stable measurement results throughout the full range, regardless of the surface's reflectivity.

Laser Triangulation Method

Laser triangulation-based displacement sensors utilise the return angle of light reflected from the target to calculate position. Laser light is emitted from the sensor and is reflected off the target surface. Some of that reflected light is focused by a lens onto the receiving element in the sensor head. Depending on the target's distance from the sensor, the return angle of the light will change, striking a different position on the receiver, which can be detected. The LK-G5000 Series employs a high-resolution CMOS to stably measure small changes in displacement.

Confocal Surface Scanning Method

Surface scanning confocal laser displacement meters utilise a tuning fork to rapidly vibrate an objective lens. This moves the focal point of the laser up and down through the measurement range at high speed. The reflected light is focused on a pinhole, where some of the light passes through to the light-receiving element. When the light is focused on the target, more intense light passes through the pinhole, and the objective lens' position is recorded and correlated back to the target position. KEYENCE's LT-9000 Series uses a tuning fork to scan in the z-axis and an oscillating unit to scan in the x-axis, producing high accuracy and stability while employing an ultra-fine beam spot of ø2 µm.

Benefits of Laser Displacement Sensors

One of the major reasons that these sensors can measure targets with diverse materials and characteristics is that they can perform highly precise, non-contact measurements. The optimal laser displacement sensor can be selected to match the application or target material (such as transparent or glossy targets).

If the target is made of metal or some other hard material that does not scratch easily, it can be measured with a caliper, micrometer, or other such instrument that touches the target directly or with an LVDT or other such contact displacement sensor in an inline situation. However, errors may occur due to the measurement pressure when the target is soft. For delicate targets whose quality is affected by contact, such as wafers, thin films, and sensitive hairline metal surfaces, non-contact laser displacement sensors can be used to measure without worrying about errors and target damage. Since they allow for stable, non-contact measurement even of transparent or glossy surfaces, laser displacement sensors enable a wide range of possible applications.

Accurate device positioning is necessary for the automation of processes such as coating, welding, and component mounting. The compact, lightweight head of KEYENCE’s multi-colour confocal method laser displacement sensor can be easily installed on devices and accurately determines the distance to the target, allowing for highly precise position control without sacrificing device operation.

Separating the spectroscope unit and leaving the lens as the only key part in the head has given the CL-3000 confocal displacement sensor a compact and lightweight head that can be installed easily in machines. Measurement is performed with light along the same axis, so the heights of narrow gaps in targets can also be measured with no blind spots. Furthermore, the head generates no errors due to heat or electrical/magnetic noise, ensuring stable measurement. For device control, laser displacement sensors can measure target height at high speeds, feeding back this information to control devices. This allows for heights of stepped targets or targets that are slightly tilted during conveyance to be measured in real-time. The result is that quality can be maintained in automatic processes.

Laser Displacement Sensor Case Studies

Thickness measurement of glass (patterned on one side)

When the surface reflectance differs between the glass surface and the pattern surface, tracking errors traditionally occur at the pattern surface when the thickness is measured with laser displacement sensors positioned on each side of the glass. The CL-3000 confocal displacement sensor uses a multi-colour confocal method that measures the position where the projected light is in focus, allowing for stable and highly precise measurement unaffected by differences in the intensity of the light reflected from the target. This minimises the effect of tracking errors, improving the inspection cycle time.

Dispenser nozzle height measurement and control

Ensuring advanced, high-accuracy, automatic coating requires not only a sophisticated dispenser robot but also a high-performance displacement sensor that moves together with the nozzle, working as the eye of the dispenser. Installing the CL-3000 Series confocal displacement sensor so that it follows the dispenser nozzle enables nozzle height control through real-time measurement and feedback of the target height. The compact and lightweight head can be installed easily next to the dispenser nozzle and reduces residual vibration when the operation stops. The multi-colour confocal technology uses a coaxial system to provide a wider measurement range and ensures stable height measurement and feedback control without being affected by the transparent, mirror, or glossy surfaces of materials or by shapes such as concaves, differences in height, and inclined or rounded surfaces.

Frequently Asked Questions About Laser Displacement Sensors

CL-3000 Series confocal displacement sensors can stably measure not only transparent glass but also a wide variety of target materials and shapes with high precision. Of course, the non-contact measurement eliminates the concern of damaging the glass. With the CL-3000 Series, up to six heads can be connected simultaneously to a single controller. For example, the glass's flatness can be checked stably by measuring the four sides and the centre of the glass with a system consisting of one controller and five heads or by measuring six ends with four to six heads. Furthermore, as discussed above, all sensors are compact and lightweight, making them suitable for mounting in narrow spaces or robotic arms. The electronics are kept away from the measurement location in the optical unit, thus providing a stable result that’s unaffected by both heat and electromagnetic noise.

Generally, diffuse reflections occur due to the laser light penetrating the inside of the PCB or its solder mask, which is a lacquer-type material that usually comes in several different colours. The semi-transparent nature of the solder mask paired with different colours could potentially cause diffuse reflections when it is measured with a laser displacement sensor. This may lead to unstable measured values. KEYENCE CL-3000 Series confocal displacement sensors can emit laser light at multiple wavelengths to calculate and measure just the wavelength band of the light that brought the surface of the target into focus. Stable measured values can be obtained with high precision even for PCBs and other such targets easily penetrated by light—glass, silicon wafers, micro lenses, etc. The advantage of this technology is that it can even enable you to measure the surface displacement of a soap bubble without physically affecting the surface.

The purpose of a distance displacement sensor is to measure the amount of movement or displacement of an object concerning the reference point. Thanks to their design, these sensors usually measure displacements in the micron and even nanometre range, with some models being capable of measuring finer than the nanometre range. The purpose of these sensors, at least in the manufacturing sense, is to provide precise measurement of position—a feature that has many applications.
Measuring position can tell us about the object’s movement. For instance, it can be used to monitor machinery operating within a certain range and for quality control. The latter is perhaps the most interesting, as it’s associated with metrology, allowing us to check the product’s exact measurement specifications by measuring displacement.

Several factors play a crucial role in determining the adequate sensor for your application, ensuring the device and its measurement method suit your specific need. Range, resolution, and accuracy are, by far, the most important factors when selecting your displacement measurements.
However, as seen above, not all measurement methods suit all materials, and some sensors are better at scanning certain materials over others. You should also consider sampling speed, especially if you’re measuring dynamic displacement—in which case you’d want a sensor with an adequate sampling speed.

Though they’re both non-contact laser displacement sensors, confocal and laser triangulation sensors operate on fundamentally different principles, which makes them suitable for different applications. Laser triangulation relies on emitting the light onto a surface and measuring the light the surface reflects onto the receiving element. Any changes in the angle of reflected light are proportional to the displacement in the target surface.
Confocal sensors, on the other hand, transmits a variety of wavelengths of lights and looks at which wavelength is in focus on the target surface. As the focused wavelength changes, we can determine the change in the position of the target. However, thanks to their design, which includes a series of optical lenses housed inside a cylindrical tube, confocal sensors tend to be more stable compared to laser triangulation sensors. However they also tend to be slower, giving the edge for high-speed applications to laser triangulation sensors.

The Selecting a Measurement Sensor site introduces proven solutions in various industries, including automotive, film & sheet, and electric & electronic components for laser profilers, as well as our other laser displacement sensors and measurement systems. Applications can also be explored by measurement types, such as thickness, width, height, height difference, and 3D inspections.

More Details

CL-3000 Series A New Concept in Non-Contact Thickness Measurement

Thoroughly explains the measurement principle as well as how the functions and performance of the CL-3000 Series confocal displacement sensors solve problems with conventional thickness measurement. If you are concerned about thickness measurement, this is the only guide you need.

Technical Guides

CL-3000 Series Confocal Displacement Sensor Application Suite for Automotive & Metal Components Industries

The ultra-compact head of the CL-3000 Series confocal displacement sensors enables high-precision measurement on any material or surface. Diverse applications using this characteristic in the automotive and metal components industries are contained in this guide.

Technical Guides

"We want to measure with high accuracy..." Two points to help customers with these concerns

Depending on setup conditions, laser displacement sensors may not achieve the accuracy listed in the specifications. Using laser displacement sensors that employ general triangulation as an example, this guide explains the causes of measurement errors, and methods to eliminate errors and increase stability.

Technical Guides


This guide contains a wide range of measurement methods: thickness, width, height/step, outer diameter, stroke, run-out/vibration, eccentricity, warpage/flatness, angle, gap/clearance, target meandering, radius, inner diameter, positioning, profile, and 3D shape.

Technical Guides