2.2 Capacitive sensors
Measuring systems

Capacitive sensor systems

For ultra precision in distance, position and motion measurement.

Need help selecting the right capacitive sensor system?

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When your product or application needs  accurate and reliable motion or position control engineering, capacitive measurement can provide an outstanding solution. With proven performance advantages such as outstanding accuracy and high speed, you can achieve the system performance you need.

As a world-leader in precision systems, we offer a range of sensors to meet your wishes: resolution, speed, ease of integration or all three.

We have experts in-house with unique experience on the integration of sensor systems plus short lead times and the ability to customize to your requirements, to bring your high-tech products to market in a way that achieves lasting ROI. For scientific instrument makers, our know-how brings the benefit of a partner who guarantees measurement confidence and traceability.

Our capacitive sensors feature

  • The highest resolution at the fastest bandwidth in the industry.
  • Analogue and digital outputs.
  • Simple user interface.
  • Variety of user platforms, such as ethercat.
  • High vacuum compatability.
  • High temperature environments.
  • Customisation based on your requirements.
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capa probe verzamelfoto-1
State-of-the-art systems can be supplied standard or custom made as your application demands.
CPL490_CPL590
CPL490 - CPL590
CPL190_290-1
CPL190
cpl230WithProbes-1
CPL230
CPL350 with Probe-1
CPL350

Scroll to the right for more driver info

Driver name
 CPL490 CPL190/290 CPL230 CPL350 CPL590
Max. resolution 0,05nm @1kHz 0,05nm @100Hz 0,07nm @100Hz 0,07nm @100Hz 0,11nm @1kHz
Typical res. @15kHz 0,0007% F.S. 0,003% F.S. 0,004% F.S. 0,004% F.S. 0,003% F.S.
Max. bandwidth 50 kHz 15 kHz 15 kHz 15 kHz 15 kHz
Measurement range 10 - 100 um 10 um - 12,5 mm 10 um - 12,5 mm 10 um - 12,5 mm 10 um - 12,5 mm
Typical linearity 0,2% F.S. 0,2% F.S. 0,5% F.S. 0,5% F.S. <0,1% F.S.
Number of channels 1 - 3 1 - 8 1 - 6 1 1 - 8
Typical thermal drift 0,02% F.S.*/C 0,04% F.S.*/C 0,04% F.S.*/C 0,04% F.S.*/C 0,02% F.S.*/C
Other features Easy DAQ connection CPL290 comes with dual range Embeddable OEM design Embeddable OEM design Up to 4 selectable ranges
* F.S. = full scale
CPL490 CPL190/290 CPL230 CPL350 CPL590

The CPL490 is our most highest performing capacitive sensor system for very high precision and/or very high speed measurements. With resolutions up to 10 times higher compared to our other systems, this represents the most precise capacitive displacement system in the world. At 1 kHz bandwidth, resolution is as low as 50 picometers. At 50kHz bandwidth, a remarkably high frequency for capacitive measuring systems, the precision is still less than 0,3 nanometers.

Probe choices
Probe Model Sensing Area (mm) Range Type Range (µm) Near gap (µm) Resolution (nm) @1 kHz @10 kHz @15 kHz @50 kHz
2G-C8-0.5 0.5 Fine 10 20 0,05 0,07 0,09 0,26
    Standard 50 25 0,17 0,27 0,35 1,0
    Extended 100 50 0,38 0,80 1,0 3,3
2G-C8-1.2 01.2 Fine 50 25 0,15 0,20 0,22 0,63
    Standard 100 50 0,33 0,40 0,52 1,7
    Extended 200 100 0,68 1,0 1,3 3,8
Probe brochure

Probe brochure CPL490

application example

SEM focus

SEM focus - An integrated probe system was developed for stage focusing. A tailored probe design with 45° surface was required to fit the available space; the probe was encapsulated to improve reliability and prevent charging issues. The probe was optimised to allow on/off switching within 1 ms. A dual range option was offered for high precision focus measurement with sub-nm accuracy. The system was supplied for a UHV environment with vacuum feed through.

info

The CPL190 and CPL290 series set an industry standard for the combination of outstanding bandwidth, accuracy and resolution. With bandwidths of up to 15 kHz, it offers signal-to-noise ratios that are low enough for a resolution in the sub-nanometer range. A modular system structure supports up to 8 channels per system, synchronized and without crosstalk. This system is ideal for high-precision applications both in the laboratory and integrated into instruments or machines. The series is available in both a single range (CPL190) and a double range (CPL290).

Probe choices

 

Probe Model Sensing Area (mm) Range Type Range (µm) Near Gap (µm) Resolution (nm) @1 kHz @10 kHz @15 kHz
C3,C5 0,5 Fine 10 20 0,14 0,40 0,5
    Standard 50 50 0,50 3,0 4,0
    Extended 60 60 1,0 5.0 -
C3,C5 0,8 Fine 25 75 0,5 1,2 1,5
    Standard 100 100 1,0 3,5 5,0
C5,C8 2,0 Ultrafine 10 20 0,08 0,15 0,25
    Fine 50 75 0,3 0,6 1,0
    Standard 250 125 1,0 4,0 5,0
    Extended 500 125 3,0 8,0 10
C8 3.2 Fine 50 125 0,4 1,0 1,6
    Standard 500 250 3,0 6,0 10
    Extended 1250 250 15,0 20 30
C9,5,R20 5.6 Fine 50 225 0,4 08 1,3
    Standard 500 500 3,0 7,0 10
    Extended 2000 250 10 20 30
C18 13 Fine 2000 2000 30 35 40
    Standard 3200 2000 40 50 60  
R45 19 Standard 2500 5000 70 90 100
    Extended 6000 3000 120 160 180
C25 21 Standard 8000 5000 100 130 150
    Extended 12500 5000 180 230 250

 

Probe brochure

Probe brochure CPL190/290

Application Example

Disk drive run out

Disk Drive Run Out - In production (100%) measurement of disk drive writing heads was required to minimise run out. Reducing this enables smaller track widths to be written and higher storage densities to be achieved. Extremely high resolution (sub-nanometre) was needed on very small targets (smallest target 0,2 mm). A tailored probe design was applied with a sensing area very close to the edge of a flat probe; a fork design was used to enable measurement of difficult to access locations. Eurocard design was realised for easy integration into the customer electronics.

info

The CPL230 capacitive measuring systems offer high performance in a compact format; ideal for embedded or OEM applications. With one to six sensors available in a small footprint, they offer an adjustment free solution designed for easy integration. Available multi-channel format; channels may be synchronized for analysis of a common target.

Probe choices
Probe Model Sensing Area (mm) Range Type Range (µm) Near Gap (µm) Resolution (nm) @1 kHz @10 kHz @15 kHz
C3,C5 0,5 Fine 10 20 0,14 0,40 0,5
    Standard 50 50 0,50 3,0 4,0
    Extended 60 60 1,0 5.0 -
C3,C5 0,8 Fine 25 75 0,5 1,2 1,5
    Standard 100 100 1,0 3,5 5,0
C5,C8 2,0 Ultrafine 10 20 0,08 0,15 0,25
    Fine 50 75 0,3 0,6 1,0
    Standard 250 125 1,0 4,0 5,0
    Extended 500 125 3,0 8,0 10
C8 3.2 Fine 50 125 0,4 1,0 1,6
    Standard 500 250 3,0 6,0 10
    Extended 1250 250 15,0 20 30
C9,5,R20 5.6 Fine 50 225 0,4 08 1,3
    Standard 500 500 3,0 7,0 10
    Extended 2000 250 10 20 30
C18 13 Fine 2000 2000 30 35 40
    Standard 3200 2000 40 50 60
R45 19 Standard 2500 5000 70 90 100
    Extended 6000 3000 120 160 180
C25 21 Standard 8000 5000 100 130 150
    Extended 12500 5000 180 230 250
Probe brochure

Probe brochure CPL230

Application Example

Spindle Error - A multichannel system was required for the machine tool sector to determine critical performance parameters including radial and axial error motions, thermal drift and distortion due to environmental vibrations.  Hardware developed can be synchronised with customer encoders or index pulses and employs an integrated temperature module. The system offers a dual range option for either standard or ultra-precision machines. Integrated data acquisition is employed for the highest accuracy, undisturbed by electrical influences.

 

info

The CPL350 capacitive measuring systems offer high performance in a compact format; ideal for embedded or OEM applications. With one sensor available in an extra small footprint, it offers an adjustment free solution designed for easy integration.

Probe choices
Probe Model Sensing Area (mm) Range Type Range (µm) Near Gap (µm) Resolution (nm) @1 kHz @10 kHz @15 kHz
C3,C5 0,5 Fine 10 20 0,14 0,40 0,5
    Standard 50 50 0,50 3,0 4,0
    Extended 60 60 1,0 5.0 -
C3,C5 0,8 Fine 25 75 0,5 1,2 1,5
    Standard 100 100 1,0 3,5 5,0
C5,C8 2,0 Ultrafine 10 20 0,08 0,15 0,25
    Fine 50 75 0,3 0,6 1,0
    Standard 250 125 1,0 4,0 5,0
    Extended 500 125 3,0 8,0 10
C8 3.2 Fine 50 125 0,4 1,0 1,6
    Standard 500 250 3,0 6,0 10
    Extended 1250 250 15,0 20 30
C9,5,R20 5.6 Fine 50 225 0,4 08 1,3
    Standard 500 500 3,0 7,0 10
    Extended 2000 250 10 20 30
C18 13 Fine 2000 2000 30 35 40
    Standard 3200 2000 40 50 60
R45 19 Standard 2500 5000 70 90 100
    Extended 6000 3000 120 160 180
C25 21 Standard 8000 5000 100 130 150
    Extended 12500 5000 180 230 250
Probe brochure

Probe brochure CPL350

Application Example

Automotive bearing

Automotive Bearings - In production  a 100% measurement of bearing shell thickness was required. Measurement was to be carried out in the feeder resulting in a large variation in the position to the probe. This required a large stand-off and probe range, while maintaining sub-micron accuracy. Probes were calibrated against the convex/concave surface to eliminate linearity error caused by the small bearing shell radius. In a subsequent application, a CPL230 was implemented for up to 6 channels per machine to measure eccentricity. Synchronisation was applied to avoid cross talk.

Info

The CPL590 is our compact digital system offering exceptional long term stability for high precision and/or high speed measurements. With a 2U size driver unit, it offers EtherCAT, SPI and USB plus up to 4 calibrated ranges for a single probe. These can be switched digitally (remotely) or with a push button on the front of the driver.

Probe choices
Probe Model Sensing Area (mm) Range Type Range (µm) Near Gap (µm) Resolution (nm) @1 kHz @10 kHz @15 kHz
C3,C5 0,5 Fine 10 20 0,14 0,40 0,5
    Standard 50 50 0,50 3,0 4,0
    Extended 60 60 1,0 5.0 -
C3,C5 0,8 Fine 25 75 0,5 1,2 1,5
    Standard 100 100 1,0 3,5 5,0
C5,C8 2,0 Ultrafine 10 20 0,08 0,15 0,25
    Fine 50 75 0,3 0,6 1,0
    Standard 250 125 1,0 4,0 5,0
    Extended 500 125 3,0 8,0 10
C8 3.2 Fine 50 125 0,4 1,0 1,6
    Standard 500 250 3,0 6,0 10
    Extended 1250 250 15,0 20 30
C9,5,R20 5.6 Fine 50 225 0,4 08 1,3
    Standard 500 500 3,0 7,0 10
    Extended 2000 250 10 20 30
C18 13 Fine 2000 2000 30 35 40
    Standard 3200 2000 40 50 60
R45 19 Standard 2500 5000 70 90 100
    Extended 6000 3000 120 160 180
C25 21 Standard 8000 5000 100 130 150
    Extended 12500 5000 180 230 250
Probe brochure

Probe brochure CPL590

Application example

6DOF machine controlSix degrees of freedom machine control - the application required a stage to be moved with high accuracy in six degrees of freedom. The CPL590 was chosen as this fully digital measurement system could be directly integrated into the ethercat control loop under development.  Six channels were synchronised to each other. This combined with the high resolution and bandwidth enabled succesful delivery of a ground breaking precision machine.

02.2 Capacitive systems application

How does capacitive measuring work?

At the center of a capacitive probe is the sensing element. This generates the electric field which is used to sense the distance to the target.

A guard ring surrounds the sensing element and focuses the electric field toward the target. Electronic components are connected to the sensing element and guard ring. All of these assemblies are surrounded by an insulating layer and encased in a stainless steel housing.

Capacitive sensors use a high frequency electric field for sensing, usually between between 500 kHz and 1 MHz. The field is focused by the guard ring resulting in a spot size about 30% larger than the sensing element diameter. A typical ratio of sensing range to the sensing element diameter is 1:8. This means that for every unit of range, the sensing element diameter must be eight times larger. For example, a sensing range of 500µm requires a sensing element diameter of 4000µm (4mm). This ratio is for typical calibrations. High resolution and extended range calibrations will alter this ratio.

The amount of current flow in the electric field is determined in part by the capacitance between the sensing element and the target surface. Because the target and sensing element sizes are constant, the capacitance is determined by the distance between the probe and the target, assuming the material in the gap does not change. Changes in the distance between the probe and the target change the capacitance which in turn changes the current flow in the sensing element. The sensor electronics produce a calibrated output voltage which is proportional to the magnitude of this current flow, resulting in an indication of the target position.

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