JACoW is a publisher in Geneva, Switzerland that publishes the proceedings of accelerator conferences held around the world by an international collaboration of editors.
@inproceedings{smith:icalepcs2023-thmbcmo30,
author = {W. Smith and M. Arce and M. Bär and M. Gorgoi and C.E. Jimenez and I. Rudolph},
title = {{Using ArUco Codes for Beam Spot Analysis with a Camera at an Unknown Position}},
% booktitle = {Proc. ICALEPCS'23},
booktitle = {Proc. 19th Int. Conf. Accel. Large Exp. Phys. Control Syst. (ICALEPCS'23)},
eventdate = {2023-10-09/2023-10-13},
pages = {1264--1268},
paper = {THMBCMO30},
language = {english},
keywords = {EPICS, detector, HOM, MMI, controls},
venue = {Cape Town, South Africa},
series = {International Conference on Accelerator and Large Experimental Physics Control Systems},
number = {19},
publisher = {JACoW Publishing, Geneva, Switzerland},
month = {02},
year = {2024},
issn = {2226-0358},
isbn = {978-3-95450-238-7},
doi = {10.18429/JACoW-ICALEPCS2023-THMBCMO30},
url = {https://jacow.org/icalepcs2023/papers/thmbcmo30.pdf},
abstract = {{Measuring the focus size and position of an X-ray beam at the interaction point in an synchrotron beamline is a critical parameter that is used when planning experiments and when determining if a beamline is achieving it’s design goals. Commonly this is performed using a dedicated UHV "focus chamber" comprising a fluorescent screen at an adjustable calibrated distance from the mounting flange and a camera on the same axis as the beam. Having to install a large piece of hardware makes regular checks prohibitively time consuming. A fluorescent screen can be mounted to a sample holder and moved using a manipulator in the existing end-station and a camera pointed at this to show a warped version of the beam spot at the interaction point. The warping of the image is caused by the relative position of the camera to the screen, which is difficult to determine and can change and come out of camera focus as the manipulator is moved. This paper proposes a solution to this problem using ArUco codes printed onto a fluorescent screen which provide a reference in the image. Reference points from the ArUco codes are recovered from an image and used to correct warping and provide a calibration in real time using an EPICS AreaDetector plugin using OpenCV. This analysis is presently in commissioning and aims to characterise the beam spots at the dual-colour beamline of the EMIL laboratory at BESSY II. }},
}