City University and Sencon to develop quality control tool

The sensor and control systems developer is collaborating with the university to build low-cost optical sensing systems capable of measuring the absolute thickness of coatings on cans.

This will enable manufacturers to more accurately check that cans are the correct colour and provide sufficient defence against contamination.

Manufacturers currently calibrate a film’s thickness using capacitive sensors. This technology relies on electrodes and electronics to detect changes in the amount of stored electric charge – or capacitance – when the sensor is placed near a film.

Prof Panos Liatsis, head of City University’s information engineering and medical imaging group, said the problem with this technique is it can only be used to calibrate a ‘relative measurement of thickness’.

Liatsis said the new optical-based technology will ideally achieve absolute measurements. Their system will be based on a Michelson interferometer, which principally studies the way a light beam changes spectra once it is reflected from an object.

The team believes the wavelength of light reflected from film coatings will give it the data it needs to determine absolute thickness.