1:30 PM - 1:45 PM
[5p-C22-2] Variable-Focus Liquid Crystal Lens Using Ultrasound Vibration
Keywords:lens, Ultrasound, liquid crystal
Optical liquid crystal devices require transparent electrodes using indium tin oxide (ITO) to apply an electric voltage and control the molecular orientation. However, ITO needs the rare metal indium and it is difficult to realize a high electric conductivity and transparency simultaneously. Our group has proposed a novel technique to control liquid crystal molecular orientation using acoustic radiation force without using ITO electrodes. In this report, an optical variable-focus liquid crystal lens using ultrasound was discussed.
An ultrasonic liquid crystal lens was fabricated. The lens has no moving mechanical parts and a simple structure; a nematic liquid crystal layer with a thickness of 0.05 mm is formed between two circular glass plates (diameters:15 and 30 mm; thickness: 0.7 mm). Polyimide orientational films was formed on the surface of two glass plates so that the liquid crystal molecules oriented perpendicularly to the glass plates. An annular PZT ultrasonic transducer (outer diameter: 30 mm; inner diameter: 20 mm; thickness: 1.0 mm) was bonded on one of the glass plates.
By exciting the transducer at the resonance frequencies of 36.1 kHz, the concentric flexural vibration mode with the half wavelength of approximately 11 mm was generated on the liquid crystal lens. The acoustic radiation force acting the surface of the glass plates changed the molecular orientation of the liquid crystal, and the incident light to the lens was refracted and the transmitted light could be focused on the target. The focal point could be controlled by the input voltage. The shorter response time could be obtained with the thinner liquid crystal layer.
An ultrasonic liquid crystal lens was fabricated. The lens has no moving mechanical parts and a simple structure; a nematic liquid crystal layer with a thickness of 0.05 mm is formed between two circular glass plates (diameters:15 and 30 mm; thickness: 0.7 mm). Polyimide orientational films was formed on the surface of two glass plates so that the liquid crystal molecules oriented perpendicularly to the glass plates. An annular PZT ultrasonic transducer (outer diameter: 30 mm; inner diameter: 20 mm; thickness: 1.0 mm) was bonded on one of the glass plates.
By exciting the transducer at the resonance frequencies of 36.1 kHz, the concentric flexural vibration mode with the half wavelength of approximately 11 mm was generated on the liquid crystal lens. The acoustic radiation force acting the surface of the glass plates changed the molecular orientation of the liquid crystal, and the incident light to the lens was refracted and the transmitted light could be focused on the target. The focal point could be controlled by the input voltage. The shorter response time could be obtained with the thinner liquid crystal layer.