Optical metrology

Optical metrology refers to the method of non-contact measurement of surface geometries using photogrammetry. This process captures entire surfaces, not just individual measurement points.  Optical metrology is particularly well-suited for comprehensive component analysis. Non-contact, fast, and with very high point density, this method digitizes and analyzes the component surface using a 3D scanner—either in our accredited measurement rooms or directly at your site. The range of components extends from prototypes and sheet metal to injection-molded and die-cast parts and battery trays.

The inspection and quality assurance of individual components can also be fully automated using optical measurement methods. To do this, a robot loads the test piece into the 3D scanner or coordinate measuring machine, and the measurement begins. This type of automated surface analysis is particularly useful when large quantities of individual components need to be inspected during ongoing production or when work must be performed under dust-free or sterile conditions.

Optical metrology is suitable for a wide range of workpiece inspections, such as geometric dimensional inspections, surface comparisons , or initial sampling . The main obstacle to optical inspection is the need for higher accuracy. In such cases, tactile measurement methods—which are accurate down to the micrometer range but take more time—are superior. Which advantage prevails must be decided on a case-by-case basis. As a rough guideline, the measurement method used should be at least five times more accurate than the highest just-acceptable tolerance. If you’re still unsure which method is best suited to your needs, simply contact us—we’d be happy to help.

Yes, our measurement systems are portable and are therefore ideal for on-site measurements at your facility. If, for logistical, time-related, or production-related reasons, you are unable or unwilling to have the testing performed in our accredited test facilities, we will be happy to come to you and perform all necessary measurements on-site. If your parts can’t come to us, we’ll come to you!

Optical metrology has five key advantages over tactile methods:

1. Sensitivity to contact

Many workpieces and materials used in modern industries, such as the electronics industry, are extremely sensitive to contact. Optical 3D measurement technology is therefore ideal for them, since—unlike with tactile methods in industrial metrology—the test piece is never touched by the sensors during measurement. This completely rules out any damage caused by the measuring device itself.

2. Live parts

Optical measurement technology is particularly important in the automotive and e-mobility sectors, as non-contact measurement is, of course, especially crucial for live components. Optical metrology plays a key role primarily for the following purposes:

• Vehicle connection points
• Busbars
• Distortion of the entire battery
• Incoming inspection of individual components to be installed
• Development (stress testing, simulation of charging cycles, etc.)

There is a wide range of possible applications; one of the key advantages is that the method is non-contact and therefore non-destructive, which means that the surface of a component cannot be damaged, or—in the case of live parts (cells, batteries, sensitive materials)—must not be touched.

3. Highest data density

Optical measurement methods provide a data density that far exceeds that of tactile methods. With a 3D scanner, such as the one we used, individual coordinate points on the test specimen are no longer measured; instead, a three-dimensional image is created. Such a result cannot be achieved with tactile measurement technology, even with thousands of measurement points.

4. All data is always available

With optical metrology, all features from the scanned area are captured and made available in a 3D model. This information can be accessed at any time. This means that even after the measurement is complete, additional features can still be measured from the model. With tactile metrology, the component would have to be clamped and measured again for this purpose.

5. Time savings thanks to optical metrology

In practice, even scanning a few hundred measurement points poses a major challenge—not because it is technically unfeasible, but because it is extremely time-consuming; such inspection processes can take several hours. It goes without saying that such inspections in ongoing production must be limited to random sampling. Optical metrology, on the other hand, are very precise and fast, since measurement and digital transmission occur almost in real time. They are suitable for solving very complex and critical measurement tasks. An optical measurement, by contrast, takes only a few minutes or even just seconds.

Die optische Messtechnik liefert also eine hohe Datendichte in kürzester Zeit. Warum setzt man dann nicht überall auf sie?

OPTISCHE VS. TAKTILE MESSUNGEN - WAS IST GENAUER?

Diese Frage ist leicht zu beantworten: die taktile Messung ist genauer. Während mit taktilen Verfahren auf mehr als einen Tausendstel Millimeter genau gemessen werden kann, reicht die Auflösung optischer Messsysteme "nur" für Messungen im Bereich einiger hundertstel Millimeter. Das ist für viele Anwendungen aber nicht präzise genug.

SPIEGEL UND GLAS

Einige Oberflächen benötigen aufgrund ihrer Beschaffenheit eine Vorbehandlung für eine Untersuchung mittels optischer Messgeräte. Um auch bei hochglänzenden und durchsichtigen Flächen homogene und hochgenaue Daten zu erzeugen, muss das Werkstück mit einem Mattierungsspray bearbeitet werden. Dieses Spray wird sehr dünn aufgetragen und beeinflusst die Messgenauigkeit darum nicht. Alternativ kann in manchen Fällen auch auf die taktile Messung ausgewichen werden.