What is X-Ray Inspection Resolution?
Here are a few things to think about before you ask that question.
During my years in the x-ray world I have been asked that question thousands of times and I provide the industry standard answer of some number in microns or how many line pairs per mm. Both methods are totally valid and industry acceptable measurements of x-ray system resolution.
The problem I have always had with this answer is this, both are measurement results that are exacted under the most controlled circumstances imaginable. An individual that has an in-depth understanding of x-ray imaging techniques performs these measurements: penetration, power and magnification are optimized to perfection. This individual in most cases is also an expert on the imaging software suite in question. On top of that the gauges used for taking these measurements are made of very low-density materials and have their own inherent limitations, which limit the use of higher kV and mA settings.
The major reason both of these measurements are not the end all is both are dependent upon magnification, you will always see the “at maximum magnification” behind the Line Pair Per mm (lp/mm) and overall system measurement results. The reason for this is without the magnification it would be impossible to see the extremely small details of the test gauge on the system monitor.
The second reason these two measurements can be deceiving is power or really the lack of power needed to image these two extremely low-density gauges. X-ray tubes with small spot sizes perform best at low power, a 5 micron x-ray tube will provide the best images at 4 or five watts of total power, increase the total wattage to image denser samples and the iso watt control of the x-ray tube will open up the spot size to dissipate the heat on the anode as total power to the x-ray tube is increased. When the spot size is enlarged your resolution has just been decreased from that starting number of say 60 lp/mm to say 20 lp/mm.
If your typical sample has a density above the density of the lp/mm gauge or requires a larger field of view with magnification less than system maximum you can’t assume that you are going to get the maximum resolution results during daily use on your production floor.
I am sure you are getting the idea here … these numbers are not real world numbers and should only be used as a starting point.
So… you’re thinking “ how do I chose an x-ray vendor or x-ray system manufacturer if I don’t use the industry standard measurements as the deciding factor?
The answer is simple; send your typical samples to the x-ray system manufacturer to get a demo. By using your real life samples the x-ray system will be adjusted out of the maximum resolution range into a more realistic operating range for the power required and magnification to image your samples. By using your typical samples you will get to see what the true resolution of the x-ray system will be on your production floor, which is really the only number you care about anyway.
For more information please don’t hesitate to contact us. We’d be happy to prepare a complete report with the x-ray inspection images of your samples.