{'fraction_non_alphanumeric': 0.007183908045977011, 'fraction_numerical': 0.0, 'mean_word_length': 5.2792792792792795, '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}}
Survey of fiducials, edges and the backside surface for the measurement of aspheres and freeforms

In addition to the aspheric or freeform surface a lens or mirror also contains other structures such as edges and fiducials. These surfaces are important for the production process including the assembly of the optical system. It is demonstrated how these structures can be measured with a high precision cylindrical coordinate measuring system involving an optical and a tactile probe system. The measurements reveal a reference coordinate system which defines the position and orientation of the freeform surface which is also a necessary requirement for the measurement of the freeform surface.