{'fraction_non_alphanumeric': 0.010526315789473684, 'fraction_numerical': 0.0, 'mean_word_length': 5.166666666666667, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Ion beam milling of thin films for optical fabrication

The work reported here examines the roughness evolution of several thin films including gold, copper, aluminum and silicon; all applied to fused silica substrates. The films were deposited by an ion beam sputtering process and ranged in thickness from a few hundred nanometers to several micrometers. Roughness evolution during ion milling was evaluated by exposing the thin films to an argon ion beam and measuring roughness at regular intervals until the thin film was completely removed. These results suggest that roughness evolution depends on initial film roughness as well as depth of material removed.