Researchers at Fraunhofer IPM have integrated the digital holographic sensor HoloTop NX into a coordinate measuring machine for what the institute describes as the first time worldwide. The host platform is the Leitz Infinity 12.10.7, a CMM from Hexagon's PMM-C series, connected to the sensor through Hexagon's SENMATION system for fully wireless, automatic sensor exchange.
A comparison test on a 75 × 75 mm² test object illustrates the scale of the difference. HoloTop NX generated more than 700 million 3D measurement points in under two minutes. The same CMM measuring tactilely at maximum accuracy recorded 729 points in roughly four minutes. Both methods achieved accuracy of under 1 µm.
What's new here is the combined mode: the system can switch between optical and tactile measurement within a single setup, and Fraunhofer IPM says the two data sets can be fused at high accuracy. A zero-point clamping system installed at the Fraunhofer IPM facility also allows parts to be transferred between the CMM and other carrier systems, such as machine tools, without losing positional reference.
HoloTop NX captures coin-sized surfaces in about one-tenth of a second and generates up to 9 million 3D points per exposure. The sensor uses multiwavelength digital holography to map surface topographies on rough and structured surfaces. Its working distance is 120 mm, and it can also operate outside of focus across a range of several centimeters. Fraunhofer IPM says this would allow mirror optics to be fitted for multi-angle inspection, similar in principle to a tactile star probe.
The institute previously deployed HoloTop NX on machines from Hermle and Stäubli as well as Hexagon platforms. Fraunhofer IPM is now soliciting industrial partners for feasibility studies involving precision components.
