{'fraction_non_alphanumeric': 0.025684931506849314, 'fraction_numerical': 0.005136986301369863, 'mean_word_length': 4.909090909090909, '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}}
Direct observation of terahertz wavefront converted by a metal hole array

Wavefront conversion by a metal hole array (MHA) has been experimentally observed via a visualization of the continuous-wave terahertz (THz) field. At the resonant frequency of the MHA, curved wavefront of the THz wave (125 GHz) emitted from a horn antenna has been converted to a plane wavefront. Near field visualization at the MHA surface (transmission side) revealed that the field re-emitted from the MHA oscillates in phase. We experimentally confirmed that the MHA acts as a planar THz wave collimator.