{'fraction_non_alphanumeric': 0.01568627450980392, 'fraction_numerical': 0.0, 'mean_word_length': 4.941860465116279, '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}}
Properties of the white-welsh mirror system.

The imaging properties of the four-mirror system of White and Welsh are investigated in the paraxial approximation. Expressions are derived for the total light flux reaching the exit slit from any point within the system. These expressions are used to obtain the flux from three different types of line sources symmetrically situated within the system. Finally, the performance of the system as used with a specific condensing system and spectrograph is evaluated.