Man vs. Machine
By Thorsten Rother, YXLON International GmbH and Keith Bryant, Smart Loop
This discussion has gone on in bars and offices for many years, ever since men raced against the early automobiles, now it carries on when they face each other over a chessboard. When someone has a car with Parking Assist it can provoke many adverse comments from friends and soon our cars will have auto drive systems. If you believe Professor Stephen Hawking this will end in the nightmare scenario when AI makes Man obsolete. “It (AI) will take off on its own and redesign itself at an ever increasing rate. Humans are limited by slow biological evolution, so couldn’t compete and would be superseded”.
Within the x-ray world a similar debate has rumbled on, also for a long time, basically the merits of fully automated in line 2D and 3D x-ray versus off line 2D systems. It falls quite neatly into those who believe a human interface causes issues with results and those who believe that the human interface is needed to make accurate judgement calls on viewed images. The crux which we will investigate here is can a fully automated system be consistent and accurate enough and work with almost no false fails or passes, which cause issues within the factory or with customers. Or does the flexibility of an off line system allow the human at the GUI or human interface to have the ability to make the correct judgement call on a defect.
In line Computed Laminography has been in use for the inspection of printed circuit boards for many years and 2D Off Line has been around a long time in electronics too, Fein Focus being the original system in the 1970’s. Technology has moved on dramatically, but the basic split remains. In Line is about throughput and repeatability with no human intervention, it needs programming and also fine-tuning to get the best from it and the production line stops if it breaks.
2D Off Line requires an operator to make the key decisions in many cases, unlike In Line it can zoom in and out and show angled views to allow the operator to fully inspect potential fails. However it is not really fast enough to do 100% inspection in anything but small batch shops.
Principle of computed laminography
Laminography was originally developed for medical applications for imaging with X-rays. By a coordinated movement of X-ray source and sensitized film in opposite directions above and below the patient, a certain plane within the patient, the so called focus plane, is being projected onto the same position during the entire scan and thus gives a sharp image. For all other planes the position of the projection moves during the scan and they are therefore blurred. However, with this technique only one layer can be imaged per scan. In modern digital laminography the film is replaced by a digital flat panel detector, which acquires many images during the movement. By means of a computer these images are superimposed to generate a blurring tomogram as with the classical technique. However, by applying an appropriate shift before superimposing the images, it is possible to obtain sharp images from many other layers and such to receive a full 3 D image of the object. This reconstruction technique is called tomosynthesis.