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"Femtosecond laser ablation of cadmium tungstate for scintillator arrays "

Richards, S, Baker, MA, Wilson, MD, Lohstroh, A and Seller, P (2016) "Femtosecond laser ablation of cadmium tungstate for scintillator arrays " Optics and Lasers in Engineering, 83. pp. 116-125.

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Ultrafast pulsed laser ablation has been investigated as a technique to machine CdWO4 single crystal scintillator and segment it into small blocks with the aim of fabricating a 2D high energy X-ray imaging array. Cadmium tungstate (CdWO4) is a brittle transparent scintillator used for the detection of high energy X-rays and γ-rays. A 6 W Yb:KGW Pharos-SP pulsed laser of wavelength 1028 nm was used with a tuneable pulse duration of 10 ps to 190 fs, repetition rate of up to 600 kHz and pulse energies of up to 1 mJ was employed. The effect of varying the pulse duration, pulse energy, pulse overlap and scan pattern on the laser induced damage to the crystals was investigated. A pulse duration of ≥500 fs was found to induce substantial cracking in the material. The laser induced damage was minimised using the following operating parameters: a pulse duration of 190 fs, fluence of 15.3 J cm−2 and employing a serpentine scan pattern with a normalised pulse overlap of 0.8. The surface of the ablated surfaces was studied using scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy and X-ray photoelectron spectroscopy. Ablation products were found to contain cadmium tungstate together with different cadmium and tungsten oxides. These laser ablation products could be removed using an ammonium hydroxide treatment.

Item Type: Article
Subjects : subj_Mechanical_Engineering
Divisions : Faculty of Engineering and Physical Sciences > Mechanical Engineering Sciences
Authors :
Richards, S
Baker, MA
Wilson, MD
Lohstroh, A
Seller, P
Date : 1 August 2016
DOI : 10.1016/j.optlaseng.2016.03.004
Copyright Disclaimer : Copyright © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (
Uncontrolled Keywords : Micro-machining; Femtosecond laser; Sub-surface damage; Brittle materials; Structured scintillators
Depositing User : Symplectic Elements
Date Deposited : 11 May 2016 13:24
Last Modified : 31 Oct 2017 18:17

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