SEDL / STP / STP1038-EB / STP24440S

Cluster Beam Deposition for Optical Thin Films

Waddell, EM
Pilkington Defence Systems Barr & Stroud, Anniesland Glasgow,

Monachan, BC
Pilkington Defence Systems Barr & Stroud, Anniesland Glasgow,

Lewis, KL
Pilkington Defence Systems Barr & Stroud, Anniesland Glasgow,

Wyatt-Davies, T
Pilkington Defence Systems Barr & Stroud, Anniesland Glasgow,

Pitt, AM
Pilkington Defence Systems Barr & Stroud, Anniesland Glasgow,

Pages: 11    Published: Jan 1988

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Abstract

A study has been carried out of the deposition of films of barium fluoride using cluster beam techniques. The effect of different aspects of the deposition process has been assessed including deposition temperature, cluster source geometry and acceleration voltage. X-ray measurements suggest that a transition temperature exists between 200 and 300°C above which dense oriented films of excellent crystallinity are produced. At lower temperatures the films are of a different orientation, are less than theoretical density and are optically inhomogeneous. However an enhancement of laser damage threshold at 1.06μm has been observed for films produced at 200°C. The transition temperature itself can be influenced by cluster source geometry and acceleration voltage used during deposition. The films have been used for anti-reflection of ZnSe substrates and, under optimum conditions, have laser damage thresholds at 10.6μm significantly in excess of the uncoated substrate material.