Development and investigation of different measurement principles for focal spot size below 5 μm

The aim of this work package is to propose an appropriate measurement procedure for focal spot sizes below 5 μm based on existing line and hole gauges. The selections will be based on a catalogue of criteria for both the nanometre gauge and the performance of the measurement procedure. The evaluation will include real measurements with different X-ray sources (e.g. Excillum NanoTube N1, Yxlon FXT-190.61 or X-RAY WorX XWT-190-TCNF) using the same setup as well as a comparison with standards for the measurement of focal spot sizes beyond 5 μm.

Dimensional metrology of nanometre gauges

The aim of this work package is to provide traceable methods to characterise nanometre gauges used for the measurement of the spot size, shape, and position of target designs. Different types of structures will be considered as gauges. The structures can be line and edge structures. Possible structures are e.g. Siemens star, sub-micron slits (JIMA type standards) and ring gauges. The spot size would be from 100 nm to 5 μm. Target uncertainty for the spot size measurement is 10 %.

This work package will survey the requirements for the calibration gauges and develop tools and measurement strategies for unfilled and filled gauge structures. the selected structures (line and edge) will be prepared for measurements and measured. Uncertainties will be estimated for all measurements. The results will be validated by comparison of the developed methods.

Numerical algorithms for spot size image evaluation and optimisations through simulation tools

The main objective of this work package is to implement numerical algorithms for the determination of the focal spot size, shape and position, to be integrated within a stand-alone tool made available for public use. The tool and the methods will be applicable to images issued from software any existing X-ray CT system. In order to support the development and to evaluate the limits of the algorithms, available simulation tools will be used.

Validation of the developed measurement method

The aim of this work package is to validate the developed measurement method and make recommendations outlining key points for method description and application. A measurement plan and procedures will be developed, activities will be centred on actual data acquisition and on result evaluation and analysis. Validation will primarily test reproducibility and repeatability of results across different operators on various systems and comparability to established methods where applicable.  Based on results a new draft standard will be created incorporating results and additional recommendations will deal with any difficulties encountered during application of the developed procedure or steps of the procedure warranting further clarification in order to minimise chance of user error.