What is it about?
A photorefractive effect of mixtures of flexoelectric liquid-crystal (flex LC) was investigated and applied to a laser ultrasonics.
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Why is it important?
In this study, a laser ultrasonic measurement system using a flexoelectric liquid crystal mixture was demonstrated. Photorefractive flexoelectric liquid crystal (PR-flex LC) show that a gain coefficient was measured as 1400 cm–1 and a response time was 960 microseconds, both with an applied electric field of 2.0 V/mm. The flexoelectric liquid crystals do not show spontaneous polarization unless an electric field are applied so that uniformly aligned defect-free firms have been obtained in flexoelectric liquid crystals. The experimental results of acoustic time-of-flight measurements in a target aluminum (Al) plate are presented by using an adaptive two-beam interferometer with a PR-flex LC cell. The acoustic velocities in the longitudinal and transverse waves propagating through this plate can be measured by using measured time-of-flight in both waves and the thickness of Al plate. The measured velocities are compared with the nominal values with good agreement. The parameters in an adapted interferometer with a PR-flex LC are appropriate for remote ultrasonic detection immune to the vibrations in an industrial environment.
Perspectives
Optical systems using liquid crystals are simpler than those using conventional interferometers, making them suitable for miniaturization. For a laser ultrasound system using liquid crystals to be practical, it is important to increase the sensitivity and durability of the liquid crystals.
Dr. Takeo Sasaki
Tokyo University of Science
Read the Original
This page is a summary of: Photorefractive flexoelectric liquid crystal mixtures and their application to laser ultrasonics, Optical Materials Express, February 2023, Optical Society of America (OSA),
DOI: 10.1364/ome.484412.
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