Product Details Supplier Info More products

Chris Jones, managing director at Micro-Epsilon, discusses the drive towards the miniaturisation of displacement measurement sensors.

This particularly concerns integrated electronics and smarter sensors that offer an abundance of features and increased functionality, he said.

Displacement can be measured in various ways by using a number of different physical measuring principles.

Some years ago, displacement sensors were still relatively large in their housing design, with separate, discrete electronics.

However, new technologies and production systems are now enabling miniature sensors to be produced with integrated electronics.

Established in Hanover, Germany, in 1968, Micro-Epsilon was originally a manufacturer of strain gauges, the start of the company’s displacement measurement product range.

In the mid-1970s, it was already recognised that the future for Micro-Epsilon was in non-contact displacement measurement technology.

In contrast to contacting systems, non-contact sensors operate wear-free and so provide more reliable results over longer periods.

Modern production systems require minimal cycle times and so require very rapid acquisition times from displacement sensors, which in turn can only be guaranteed by utilising non-contact measurement techniques.

In the case of sensitive objects that are adversely affected by contact, non-contact sensors are ideal as they measure the distance to the object from a safe range.

The requirements for the performance and reliability of the displacement sensors are very high.

Important application criteria are measurement frequency, accuracy, temperature stability and resolution.

Since the start of its own development efforts, Micro-Epsilon has attempted to establish as comprehensive a portfolio as possible in the field of displacement measurement.

In the non-contact displacement measurement area, the company’s range today includes the traditional electromagnetic methods: capacitive, inductive and eddy current.

Laser triangulation, time-of-flight and confocal sensors are provided for optical displacement measurement.

This means customers always obtain an optimum solution for their measurement task, since a narrow product portfolio does not restrict their choice.

Current trends in displacement measurement technology indicate that smaller, more intelligent sensors with integrated electronics are now required.

In mechanical engineering, the requirement for extremely compact sensors is always an important factor, especially if installation space is restricted or if the sensor needs to be lightweight.

This is also the case in terms of integration of more electronics and intelligence in the sensor.

This means that sensors are more frequently required to perform the signal conditioning directly in the sensor, therefore reducing component count while offering faster measuring speeds.

Eddy current sensors can be used with all electrically conductive materials.

As eddy current penetrates insulator materials, even metal behind an insulating layer can be used as a measuring object.

A special coil winding means that very compact sensor designs are possible, which can still be used across high temperature ranges.

All eddy current sensors are insensitive to dirt, dust, moisture, oil and pressure.

Micro-Epsilon’s miniature eddy current sensors are recognised worldwide.

With sensor diameters from 2mm and cable diameter of just 0.5mm, these sensors are said to be the smallest standard manufactured eddy current sensors in the world today.

Due to their ultra-compact design and by using new inorganic materials in their construction, the eddyNCDT ECT sensors provide almost unlimited scope in terms of the external design and geometrical shape of the sensor.

This means sensors can be adapted to suit virtually any application requirements.

EddyNCDT ECT sensors offer mechanical robustness, resulting in longer service intervals and higher temperature stability.

The complete circuit electronics can be integrated into the sensor, providing an even more compact measurement solution for OEMs and machine builders.

The sensors are also suitable for harsh operating environments, including high vibration, impact shocks and operating temperatures as high as 350C.

Sensors have been produced with extremely low thermal drift and with temperature errors of less than 20 parts per million per degree Kelvin.

Capacitive sensors are said to offer the highest precision of any non-contact sensor technology.

The latest electronics make it possible to offer resolutions in the picometre range.

Generally, these sensors are used to measure against conductive targets, but certain insulators can also be measured.

Capacitive sensors are designed as guard ring capacitors.

In practice, almost ideal linear characteristics are achieved by using these sensors.

However, a constant dielectric constant between sensor and target is required for a constant measurement; the system reacts sensitively to dielectric changes in the measuring gap.

As thermally induced conductivity changes have no influence on the measurement, the principle is also reliable where there are strong fluctuations in temperature.

Micro-Epsilon’s new-generation capaNCDT CSH sensor utilises a ceramic substrate that provides high-temperature stability.

Virtually unlimited sensor geometries can be developed using this technology.

For example, an extremely flat sensor has been produced with an installation height of 4mm.

This technology overcomes the previous limitations of cylindrical sensor designs.

To date, a maximum resolution of 0.037nm has been achieved using these sensors.

By integrating smart electronics in the sensor itself, laser triangulation sensors are an example of how much smaller sensor systems are becoming.

Most conventional sensors require a separate electronics unit, as well as the sensor itself.

Micro-Epsilon’s optoNCDT 1302 and 1402 sensors have a very small housing in which the complete electronics are integrated without sacrificing sensor performance.

The two series include 12 different measuring ranges between 5 and 600mm.

Other sensors in the range can measure up to 2m.

The advantage of using this measuring principle is the relatively large stand-off distance from the target that it offers.

For hot or moving targets, it is advantageous to be able to measure from a large stand-off distance.

Using the optoNCDT laser sensors means that very small spot sizes can be achieved, which is often critical to the application.

The spot size can be in the range of a few micrometres and so can also be used for targets of similar size.

Extremely high resolutions are possible when using confocal chromatic measurement technology.

Resolutions in the nanometre range are typically achieved by expanding the colour spectrum.

As the colour, which is in the focal point, is used for distance information, confocal sensors have a very small measuring spot that enables measurements on particularly small objects.

Therefore, even the finest scratches on a surface can be measured reliably.

The beam path of the sensor is compact and concentric.

This means that measurements inside bore holes or test tubes, for example, are possible.

For measurements such as these, the confocal miniature optoNCDT 2402 sensors, which have a sensor diameter of 4mm, are ideal.

Five sensor models cover a measuring range from 0.4 up to 6.5mm and achieve a resolution of 0.016um.

These sensors have been unrivalled since their launch in 2007.

With the launch of the optoNCDT 2402 sensor, a reduction of the diameter from 23 to 4mm was made in one step.

Thickness measurement of transparent films, boards or layers is possible using these sensors.

In contrast to other methods, the system only requires one sensor for a measurement of this type.

As the measurement is only performed using white light, no laser safety regulations apply.

The sensors can also be used in potentially explosive areas and in systems that are susceptible to EMC.

Micro-Epsilon

With over 45 years experience and more than 15,000 customers worldwide, Micro-Epsilon understands the need for accurate, robust, intelligent sensors and measurement systems.

With over 45 years experience and more than 15,000 customers worldwide, Micro-Epsilon understands the need for accurate, robust, intelligent sensors and measurement systems.

If you are measuring any type of displacement / position, temperature, speed or colour parameters, Micro-Epsilon sensors and systems provide market-leading performance, together with the fastest measuring rates, highest operating temperature ranges and smart interface capabilities. From simple, low cost sensors to high volume, customer-specific OEM solutions, Micro-Epsilon will have athe correct measurement solution for your application.

Using both contact and non-contact measurement techniques, Micro-Epsilon boasts one of the largest ranges of displacement sensors including 1D, 2D & 3D laser optical, confocal chromatic, eddy current, capacitive, inductive, draw-wire and time-of-flight technologies. Measuring ranges are from nanometers to kilometers!

For temperature measurement, there is a comprehensive range of non-contact infrared temperature sensors and thermal imaging cameras capable of measuring up to that include intelligent software packages to support configuration, analysis and management during the application. LED analysers, fibre optic sensors and Colour recognition sensors measure true colour using L*A*B and CIE.

Micro-Epsilon sensors are used throughout almost all industries: from automotive to aerospace, motorsport to metal production, semiconductor to subsea. Whether it’s an R&D, test, inspection, OEM or a process control application, Micro Epsilon measurement engineers can provide the right measurement solution.

View full profile