{'fraction_non_alphanumeric': 0.01791359325605901, 'fraction_numerical': 0.002107481559536354, 'mean_word_length': 5.551724137931035, '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}}
Optical imaging of high-frequency focused ultrasonic field using a Nomarski interferometer coupled with multichannel lock-in detection

Abstract. We present a nondestructive optical technique for quantitatively imaging a focused ultrasonic field in continuous-wave mode within clear media. We used a Nomarski interferometer configuration coupled with a couple charge device array and multichannel lock-in detection. A two-dimensional full-field image of pressure amplitude can be obtained in only one acquisition. This method was experimentally demonstrated with a high-frequency ultrasonic transducer and experimental measurements of acoustic pressure obtained at 27 MHz. This technique is very interesting because it does not introduce any disturbance in the ultrasonic field and does not need any scanning mechanisms to acquire images. It can be useful for probing high-frequency acoustic fields and for calibrating HF-piezo-electric transducers.