With firmware versions 1.11 and 1.12, Heliotis is consistently advancing the Gen4 platform for heliInspect and heliCam. In addition to numerous detailed improvements, users benefit in particular from higher measurement accuracy of the heliInspect white light interferometers, a larger vertical measurement range, new integration options, and additional functions for the heliCam Lock-in cameras. <\/p>\n\n
As usual, all improvements are available to existing customers via a firmware update \u2013 no hardware replacement is required.<\/p>\n\n
The measurement accuracy of a white light interferometer is not determined by optics and mechanics alone. Equally decisive is how the interference signals are captured during the scan and subsequently evaluated. With firmware 1.11, two fundamental improvements were therefore introduced that address precisely these points. <\/p>\n\n
In previous firmware versions, the measurement frames recorded during a scan were already linked to the current encoder position of the scan axis. This allowed deviations from a constant scanning speed to be largely compensated for during reconstruction. <\/p>\n\n
With the new Encoder-Based Reference Mode, data acquisition is taken a step further. Measurement frames are no longer recorded at a fixed frame rate and then assigned to an encoder position. Instead, the scan axis triggers each recording directly at a defined encoder position. As a result, the measurement frames are created during acquisition at equidistant intervals of \u03bb\/8. <\/p>\n\n
In addition to further improved position assignment, the signal processing in the heliSens image sensor also benefits from this, as the Lock-in demodulation takes place under ideal sampling conditions. Together with the new CenterOfMassPhaseFusion, the Encoder-Based Reference Mode forms the basis for the significant improvement in repeatability shown in the next section. <\/p>\n\n
With firmware 1.11, surface reconstruction was expanded to include the new CenterOfMassPhaseFusion extraction mode. The algorithm combines the robust and unambiguous position information of the coherence envelope with the significantly more precise phase information. It thus combines the advantages of both evaluation methods: a large unambiguous measurement range with simultaneously maximum measurement precision. <\/p>\n\n
While this algorithm previously had to be called as a separate processing step from the heliAlgo library, it is now integrated directly into the standard evaluation of the Gen4 platform and is available as a native extraction mode via the API. Applications thus benefit from the improved reconstruction without additional implementation effort \u2013 regardless of whether they access the camera via GenICam, HALCON, MATLAB, Python, or other software environments. <\/p>\n\n
Together with encoder-based referencing, CenterOfMassPhaseFusion enables the significant improvement in repeatability shown in the following section.<\/p>\n\n
The combination of encoder-based referencing and the new CenterOfMassPhaseFusion reconstruction mode significantly improves repeatability, especially for high-precision step height measurements. While the previous improvements already contribute individually to higher measurement quality, their combination achieves the best results. <\/p>\n\n
The following comparative measurement shows the standard deviation of repeated step height measurements for various data acquisition and reconstruction methods. Depending on the measurement task and configuration, repeatability can be significantly increased compared to the previous standard evaluation. <\/p>\n\n
The values provided refer to the repeatability of individual image sensor pixels relative to a reference plane. In contrast to many published data sheets, no averaging is performed over larger areas or several hundred pixels, meaning the measurement results conservatively reflect the actual performance of the system. The measurements were carried out on a heliInspect H8 Ultra without active vibration damping. <\/p>\n\n