Measurements in maximum precision and high speed for Industry 4.0

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In the Industry 4.0, automation and data exchange in manufacturing technologies: Cyber-physical systems, network devices, network connectivity, cloud computing and cognitive computing. sensors must provide high-precision results and perform high-speed measurements in order to ensure reliable quality, for any industry. [1] Optical measurement technology [2]is becoming more important for production and inspection processes, as it is non-contact and independent of the target material and surface properties.

 

+ Confocal chromatic technology [3]consists in two lenses (or curved mirrors) are arranged confocally one to another when their focuses match. With the confocal chromatic measuring principle, white light is split into different spectra by lenses and focused on an object through a multi-lens optical system. The lenses are arranged such the light is broken down by controlled chromatic aberration into monochromatic wavelengths dependent on the displacement.

+ The confocal chromatic measuring system [4]is used for fast distance and thickness measurement. Different sensor models and controller interfaces open several fields of application, e.g. in the semiconductor industry, glass industry, medical engineering and plastics production.

+ Main features for confocal chromatic measurement system:

  • Wear-free measurement and passive sensor design.
  • Highest precision with submicrometer resolution.
  • Fast surface compensation.
  • Adjustable measuring rate up to 70kHz.
  • Distance measurement and thickness measurement.
  • Extremely small spot size.
  • Configuration via web interface.
 

+ The confocal chromatic measuring technique [5]enables multi-layer thickness measurements of transparent materials, distance measurements, intensity evaluation and measurements within recesses and boreholes. The confocal chromatic measuring procedure is ideally suited to in quality control processes line.

+ The confocal chromatic measuring principle [6]enables high precision displacement and distance measurements. Including on diffuse and reflecting surfaces. Very small objects can be detected due to the small measurement spot size. The axial beam path avoids shadowing effects, enabling measurements even in sleeves and recesses. With the 90° version, geometrical features can be measured inside holes and recesses.

 

The principle enables thickness measurements of transparent materials such as glass. The thickness value is detected to micrometer accuracy using only a single sensor. The controller provides an editable and expandable materials database. Material-specific parameters such as refractive indexes can be adapted using the web interface. Multi-peak measurements enable the evaluation of up to 6 peaks, which is how multi-layer objects such as laminated glass can be measured.

+ The controllers [7][8](applied in the quality control of electronic productions) provide an excellent signal-to-noise ratio enabling measurements at high accuracy. They are among the fastest controllers worldwide and are frequently used for dynamic monitoring tasks. The fast surface compensation regulates the exposure cycles in order to achieve high signal stability which is particularly favorable when measuring surfaces with different reflection characteristics.

+ The great advantages of confocal chromatic measurement systems [9]are that surface properties and material of the target object have almost no influence on measurement accuracy. High precision measurements are possible on reflecting surfaces such as high-gloss or polished metals and liquids, on matt surfaces such as plastics and black rubber, as well as on transparent materials such as glass and plastic plates. The extremely small measurement spot, depending on the system, only a few µm, enables the measurement of bonding wire and small contours of mechanical parts.

+ As samples of applications [10][11]we can use it for quality control of medical tablet stamps and dies, in stainless steel tubes for catalyst production, measuring dental samples confocal and automatic contour and parts measurement.

In high precision inspection of finest surface structures, confocal chromatic measurement systems are used for displacement as well as distance measurements and intensity evaluation. Surface properties of the smallest precision parts can be determined to micrometer accuracy using this method. For example, scratches can be reliably detected. Based on the determination of the distance, surface topographies of objects can be performed.

 
Multi-layer, laminated and curved glass for example for airplanes, automotive and architectural applications, solar cells, flat screens and smartphone displays

When a measurement object [12]consists of different materials such as metals and plastics, the reflectivity highlights the differences in the materials although the distance values do not change. Unevenness and scratches influence the degree of reflectance and become visible. The system detects the changes in the signal intensity and produces an exact image of the target and its fine structures. Perform measurements using signal intensity, enables the visualization of the finest of structures. With constant exposure time, additional information about the surface evaluation can be made which would not be possible with just distance measurement.

When manufacturing multi-layer, laminated and curved glass [13][14]for example for airplanes, automotive and architectural applications, solar cells, flat screens and smartphone displays; precise thickness measurement of each layer is very important. Confocal sensors are the best for these tasks. If some production defetcs do not comply with the specifications, there is a risk of increased stress which might lead to deficiencies or delamination of the glass.

Compact, high speed and easy to integrate sensors ensure highest reliability in almost any area where high precision is demanded from machine monitoring to fully automatic quality control of the final product.

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