InfiniteFocus is a highly accurate, fast and flexible optical 3D measurement system. With only one sensor, users verify dimensional accuracy and measure surface roughness of their components. Based on the technology of Focus Variation the range of measurable surfaces is almost unlimited. By means of Vertical Focus Probing, which is an extension of Focus-Variation vertical surfaces are probed laterally as well. Components are traceably measured in high accuracy, with a high vertical resolution and in high repeatability. The robust measurement principle of Focus-Variation in combination with a vibration-isolating hardware enables the form and roughness measurement of also large and heavy components. All axes of InfiniteFocus are equipped with highly accurate encoders ensuring precise stage movement. With an automation interface, InfiniteFocus is also applied for fully automatic measurements also in production.
Up to now, geometries such as bore holes of injection valves in the automotive industry were difficult to measure optically. The lateral probing of components with vertical surfaces was limited to tactile measuring systems, CT solutions or complex customized solutions. This changes with Vertical Focus Probing, an extension of Focus-Variation technology. Based on areal measurements, the optical probing of components over the entire surface is possible.
Different optical measuring methods allow the measurement of components with different flanks. The spectrum of measurable flanks or slopes has so far covered 0° - 85°, whereby in industrial practice, Focus-Variation has established itself as the most suitable method for steep flanks. However, this technology has also reached its limits for components that show flanks steeper than 85°. Nonetheless, Bruker Alicona has been constantly developing Focus-Variation for 15 years and has complemented their optical measurement principle with a new technique, Vertical Focus Probing. Even surfaces with slopes of more than 90° can now be optically touched and measured in 3D.
Different technologies allow the measurement of components with different flanks. Here: Surfaces with 0°, 60° and 90°
Reflected light can also be detected by the objective when measuring slopes steeper than 90°
Vertical Focus Probing is based on the use of partial light. This means that in addition to coaxial light, light from different directions is used. As a result, individual light rays diffusely reflected from vertical surfaces are captured again by the objective, enabling the traceable and repeatable measurement of flanks with more than 90° in a high-resolution.
How high the proportion of reflected light rays is, depends on the geometry and the roughness of the surface to be measured as well as on the light source used. The objective also plays a role, as, depending on its diameter, an objective can also capture reflected light from surfaces that show flanks steeper than 90°. This is where the numerical aperture (AN) comes into play, which is defined by the objective diameter and the working distance. It influences how much the measurable slope of a surface can still exceed the 90° mark.
Vertical Focus Probing, like Focus-Variation, is based on the vertical scan of the surface to be measured. The focus information curve is evaluated for each position. The difference to Focus-Variation is that in Vertical Focus Probing not only one, but several Z-values are calculated for each measuring point (XY). These Z-values represent the vertical surface.
Coordinate measuring machines are verified according to EN ISO 10360. Part of this process is, among other things, the measurement of the bidirectional length measuring error of e.g. ball bars. Typically, tactile methods are very well suited for this purpose, since they can probe the ball laterally. For optical methods this was not possible until now. With Vertical Focus Probing, this is changing: balls can be probed at the equator, which makes it possible to determine the distance.
Vertical Focus Probing can be used for a wide range of applications in dimensional metrology, respectively in all areas of the manufacturing industry and production. Among others, the tooling industry, precision manufacturing, the automotive industry as well as the aerospace sector benefit from new measurement possibilities whenever it comes to components with vertical surfaces. Features such as holes, bores, reference surfaces, contours, lengths etc. can thus be optically measured with high accuracy, in high resolution and short measuring times.