As part of its wide range of non-contact position measurement products and systems, Ixthus Instrumentation provides exclusive sales and technical support for ADE Technologies Inc, the USA-based capacitive gauge and sensor specialist. Now available on request from Ixthus, a 12-page guide aptly named the Introduction to Capacitance Gauges provides an overview of the characteristics and benefits of the technology.
ADE Technologies' range of capacitance gauges, sensors and instruments are used for high- and ultra-high-precision measurement in typical resolution ranges from 0.1 to 50nm over distances up to 10mm. As highly durable non-contact devices, capacitive probes have an almost limitless life and their high bandwidth is well suited to continuous and rapid position feedback in servo systems as well as exacting and highly stable dimension measurement for metrology.
As a company with several decades of design experience in this field, ADE Technologies has developed a specialised guard field that effectively shields the sensor element, overcoming the undesirable interaction with unwanted grounded surfaces and electric fields that can cause problems in measurement consistency.
With the advent of nanotechnology and MEMS device manufacture, and through increasing standards of high-precision measurement being required for manufactured goods, capacitance gauges and sensors are being used more and more. Single or multiple probes are used by end-users and OEMs as part of metrology and calibration systems, or for high-precision position feedback in manufacturing and test equipment. As well as measurements in ambient air and vacuum, it is possible to apply the technology in oil.
Applications for capacitive gauges and sensors include focal plane control on optical systems, precision spindle run-out for rotating machine condition monitoring, accuracy measurement of linear and rotary position stages (positional, flatness, straightness), and vibration measurement systems. One area of use is critical thickness measurement of wafers for semiconductor manufacture and similar applications are found in flat panel, photovoltaic and DVD manufacture. Most consist of dual fixed capacitive gauge heads measuring the differential distance and the flatness of substrates, which are traversed through the probe heads and measured in several positions, with a thickness between 120 to 500microns and resolution to 0.01microns.