A sound producing diaphragm of low density, low heat capacity, a large coefficient of thermal expansion and a large Young's modulus is located adjacent the end of an optical fiber transmission line element which is adapted to propagate modulated light and transmit the light outwardly therefrom particularly from the end region thereof to the surface of the diaphragm. The diaphragm absorbs light transmitted from the end region of the fiber optical element which heats and cools in response to the light energy absorbed thereby to expand and contract and produce a sound field. As a transducer in a telephone receiver, the diaphragm is mounted in the earpiece with the end of the optical fiber transmission line located in close proximity thereto and having an enlarged end which includes an anti-reflective coating so that light propagated along the fiber is transmitted to the diaphragm and not reflected back down the fiber.
In an optical telephone wherein amplitude modulated light is converted to sound by applying the modulated light to an enclosed volume of gas wherein the volume and/or pressure of gas varies in synchronism with the instantaneous energy of the modulated light and wherein an optical fiber is used as the transmission element, the improvement is provided by the means to more uniformly distribute the optical energy in the gas cell causing an improved and more efficient conversion of the modulated light directly into sound. The means can be provided by covering the light entering side with a positive lens and positioning the optical fiber at the focal point of the lens.
The sensitivity of the earphone of an optical telephone that contains a gas filled tube that reacts to small changes in temperature caused by amplitude variations in light to create sound is improved by replacing the gas tube opto-acoustic converter with a strip of a material that reacts forcefully when heated and cooled so that the sensitivity of the optical telephones opto-acoustic converter can be increased and transmission quality improved.
An optically driven actuator, such as a microactuator, is provided in which light is used to cause linear or angular mechanical or micromechanical motion. The actuator includes a solid light-absorbing and expanding member having an internal partially absorbing and partially reflecting cavity; and a waveguide for directing optical energy into the cavity to cause the light-absorbing and expanding member to expand, thereby resulting in displacement of the actuator. The mechanical or micromechanical motion may be used in optical power control elements, switches, shutters and the like, or perform other functions in combined optical waveguide and electrical or electronic systems.
A method and apparatus for dilating blood vessels in vasospasm through the use of high frequency wave, e.g., hydraulic or acoustic waves. The invention is suitable to treat any vasospasm, including any vasospasm intractable to medication, including cerebral vasospasm, which currently is not susceptible to any mechanical or chemical treatments. The apparatus for dilating blood vessels includes a catheter having a fluid-filled lumen, a wave generator arranged within the catheter lumen for generating a wave front that propagates through the fluid in the lumen and is transmitted from the distal end of the catheter to propagate through the fluid in the blood vessel, and an energy source connected to the wave generator to provide energy to produce the wave front.
A method and apparatus for dilating blood vessels in vasospasm through the use of high frequency wave, e.g., hydraulic or acoustic waves. The invention is suitable to treat any vasospasm, including any vasospasm intractable to medication, including cerebral vasospasm, which currently is not susceptible to any mechanical or chemical treatments. The apparatus for dilating blood vessels includes a catheter having a fluid-filled lumen, a wave generator arranged within the catheter lumen for generating a wave front that propagates through the fluid in the lumen and is transmitted from the distal end of the catheter to propagate through the fluid in the blood vessel, and an energy source connected to the wave generator to provide energy to produce the wave front.
