Speaker
Description
We report a technique for fabricating optically transparent x-ray optics by laser drilling precision pinholes in diamond membranes. This work supports a novel diagnostic under development at SLAC which will profile the Coulomb field of relativistic electron bunches with attosecond-um spatio-temportal resolution.
Diamond is chosen for its specific transmission window extending from RF through UV (relevant for preserving the space charge field of the electron bunch). It is also very robust, however, thin free-standing diamond is challenging to process. In this proceedings, we describe a laser drilling setup with integrated laser-profiling measurements capable of generating <30um holes in 2um thick, 2mm diameter diamond membranes. A Ti:Sapphire laser was focused on the membrane, mounted on a three-axis positioning system. A python code automatically performs knife edge scans of the gaussian intensity profile to plot the waist at multiple z positions, mapping the complete waist profile versus propagation distance. The membrane is then positioned at the z location of the desired hole diameter, and the laser power is increased past the ablation limit to create a precisely sized pinhole at the target location.
This technique enables cnc fabrication with micron accuracy without requiring complex lithography or mechanical drilling, and is broadly applicable to precision micro-machining of thin, brittle substrates.
Funding Agency
This work was supported by US Department of Energy contract nos. DE-AC02-76SF00515, the DOE-BES Accelerator and detector research program, and DOE-BES, Chemical Sciences, Geosciences, and Biosciences.
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