TEST & MEASUREMENT FEATURE
PRECISION LASER
MEASUREMENTS W
henever considering the benefits of non-contact precision laser
measurement devices it is always important to remember one simple concept: quality. Quality is crucial if you are to satisfy your customers and retain their loyalty so they keep purchasing your product in the future. Quality is keenly felt by manufacturers
in the 21st century. We are all under pressure to make ever more complex products with tighter tolerances in a cost effective and reliable way whilst ensuring quality is at the forefront. Customers quite rightly expect quality products that are competitively priced, longer lasting and more fuel efficient. We assume the panels, doors and seals on our cars will be correctly fitted to ensure they are water and wind tight. Even the hardiest of flyers amongst us like a smooth touchdown thanks to precisely fitted landing gear. Then there are the regulators who
require improvements in safety and reductions in carbon, noise and waste. Non-contact precision laser
measurement devices play a big part in helping manufacturers meet demands for both quality and regulatory improvements.
LASER MEASUREMENT IN ACTION The holy grail of profile measurement is being able to reliably report the surface of a component in a lot of detail or - to put it more simply - take lots of pictures of its surface. For example, GapGun – Third
Dimension’s non-contact handheld and automated laser measurement devices - uses laser triangulation technology to
Above: Non-contact precision laser
measurement devices help improve engine efficiency in the aerospace sector
When it comes to quality control, checking a product using precision laser measurement increases efficiency and saves manufacturers time, money and resources, explains Dennis de Roos, chief sales & marketing officer of Third Dimension
collect measurements by projecting a laser stripe across the surface of a part to determine the measureable feature. At the same time, an integrated camera system takes images of this static laser stripe. As the angle is known between the camera and the laser projection, an algorithm calculates the dimensions of the surface over which the laser falls and the camera sees. This measured data is then output to point cloud format to generate a digital copy of the surface. Image processing is then used to
convert the images of the profile into a series of points which can be used to extrapolate the shape of the feature. These points allow the system to analyse the measured surface. Because a laser is a clean form of structured light, measured data is highly reliable and can be used as a stable light source for data analysis. GapGun scans a component’s profile to
measure features that include angle, radius, edge break or scratch, for example. Measured data is then recorded for statistical process control and traceability purposes and transferred to a computer, enabling the operator to rectify any mistakes in real time on the production line. This ensures components are the correct size
/ INSTRUMENTATION
and fit together accurately without compromising the quality, cost or time to complete the build. The beauty of non-contact laser
measurement devices is that they offer a repeatable set of rules that do not require subjective interpretation. This means manufacturers can precisely measure lots of profiles and surface finishes quickly, repeatably and in well-defined ways.
A LONG HISTORY Today’s non-contact precision laser measurement devices are a world away from where the quality control industry was 40 years ago. Back in the 1980s, manufacturers
inspected products using traditional contact measurement devices such as micrometers and Vernier calipers (invented in the 17th century), which needed to touch the surface of a product to determine its dimensions. However, there are a number of drawbacks to using a device which has to physically touch the part it is measuring. Firstly, the part could be damaged or marked. Secondly, if a part is unfixed, hinged,
or designed to move, contact is likely to introduce an inherently unstable measurement result which is unlikely to
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