Vision metrology versatility

Up until the late 1970s, the contour projector, or optical comparator, was the mainstay of automated two-dimensional inspection systems. Since then, while there have been many advances in comparator technology, video-based electronic image analysis has jumped to the forefront for non-contact inspection and measurement tasks. A read on…

- Shreyansh B Hippargi

Driven by advances in optics, cameras, electronics, and software, video metrology systems have increased in performance, speed, and versatility. The ability to automatically collect and analyse hundreds, or thousands, of accurate measurement points makes the purchase of a video-based, noncontact metrology system a high Return On Investment (ROI) decision.

Vision versatility

Three key factors make automatic video measuring systems an attractive investment:

1) Measurements are fully automatic, eliminating the variation in judgment from one operator to the next.

2) They provide very high accuracy and repeatability compared to traditional, manual methods.

3) The most advanced Video Measurement Machines (VMM) integrate additional sensors, such as tactile probes and lasers, to enable the measurement of features that cannot be measured using the optical sensor alone.

It is this latter capability—the ability to use additional sensors—that sets OGP (Optical Gauging Products) SmartScope® systems apart from other video measuring machines on the market today. The schematic picture (refer to image 1) gives a brief idea of how a multisensor system works. The camera can measure all the features that it can see. It can, for example, see Dia B and C and thus measure them. It also sees the top surface A, so it can check the distances within that plane. The camera, however, will be unable to see Dia D and the bottom surface E. So, to measure Dia D, a touch probe is used. Similarly, the height of bottom surface E relative to top surface A can be measured with the help of a probe. Similarly, areas like side grooves and cuts can be measured with the help of a touch probe.