optical metrology

The measurement of objects by measuring machines with optical sensors is termed optical metrology.

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Optical metrology for digitising components
Stereo camera system for high-resolution, digital 3D models

What is optical metrology?

Optical metrology measures components and other items inspected without contact by acquiring the measurement object from all sides using sensors. Here 3D scanners are used as sensors; these scanners are a combination of a projector and a stereoscopic camera. This projector projects a striped pattern on the item inspected, this pattern is acquired by the two cameras from different angles; the position of the point in space can then be determined. It is possible to create 3D models of the object measured from the data acquired.

Optical metrology at Quality Analysis

At Quality Analysis, we have high-precision 3D scanners from Carl Zeiss GOM Metrology, with which we can scan measurement objects up to a maximum size of 3 meters. However, we can also scan very small components with a size of only a few millimeters. For evaluation, we use GOM Inspect Pro - a software that can be used to implement practically all application possibilities of optical metrology.

The measurements can be carried out either in our inspection rooms or on your premises. As a certified 3D measurement service for GOM Metrology and an accredited test laboratory, you can always rely on the absolute reliability of our measurements. We are happy to pass on our expertise to you and train your employees in the use of your own measurement technology.

Advantages of optical metrology

During the optical measurement of an object, there is no contact between the object and the sensor at any time such that even soft or very delicate items can be acquired. Furthermore, optical measurement can be (partially) automated with the aid of robots and turntables, such that, combined with the high speed of the scans, it is excellently suited to quality assurance in series production.

Disadvantages of optical metrology

It is a disadvantage that the optical measuring systems can often not acquire transparent and highly reflective surfaces without problems. In this situation it is necessary to prepare the item inspected using a special scanning spray. Here we use, among others, sublimating scanning sprays such that no residues are left on the component scanned. At the moment, the accuracy of optical systems is lower than that of tactile metrology. The accuracy is in the area of a few hundredths of a millimetre.

Where is optical metrology used in practice?

GOM Inspect as analysis software for the evaluation of STL data
© Carl Zeiss GOM Metrology GmbH

Today, optical metrology is used in many areas. Worthy of mention in particular are quality assurance and quality monitoring in numerous industrial sectors, as well as reverse engineering. It is also easier to plan the production of end products if 3D scans of the individual components are available. Shape and position tolerances can be depicted clearly in a false-colour image using 3D models. Based on the CAD data, it is also possible to depict graphically the exact deviations in a nominal-actual comparison.

Practical application examples

Automotive industry

In the automotive industry, optical metrology plays an important role not only for initial sampling and quality control of classic sheet metal components and steel castings, but also during the general inspection and dimensional inspection of battery trays and their components. This application is becoming increasingly important with the emergence of electric mobility.

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Plastics industry

In the plastics industry, currently the primary area of interest is the measurement and digitisation of injection moulded and die-cast components.

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Summary: optical metrology

Optical metrology covers all measuring machines using which the measurement object is measured by means of optical sensors. These sensors are mostly 3D scanners that combine a stereoscopic camera and a projector.

Your Contact

Sascha Falter

Sales

+49 7022 2796-733
s.falter@qa-group.com

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