Abstract: A device for compensating for changes in temperature and strain in electro-optic modulators without altering the voltage field effects. Devices for modulating light intensity in response to a varying electrical signal are particularly useful with optical fiber information sensing systems. Such modulators basically receive a light signal, collimate and polarize the light, then pass it through a wave plate to cause circular polarization. The light signal then is passed through a modulator material which rotates the beam polarization in response to varying voltage signals imposed on the modulator. Unfortunately, changes in temperature and strain also change the state of polarization. I have now found that by transmitting the light signal through two equal crystals in series that are rotated 180.degree. from each other, a uniform strain or temperature change will result in canceled polarization effects. Thus, effects of changes in temperature and/or strain are canceled without affecting the voltage field effects.

Abstract: A system for transducing a signal voltage into an optical signal, transmitting the optical signal via an optical fiber to a remote location in the form of light attenuation frequency and interpreting the light frequency at the remote location to the amplitude and wave form of the signal voltage. The electro optic modulator includes an elongated piezoelectric member which changes length when an electric field is imposed across it. A mirror is attached to a free end of the piezoelectric member and strains or alternately moves toward and away from a partially reflecting surface at the end of an adjacent optical fiber. Light is introduced into the fiber with a portion reflected back by the movable mirror and part by the end of the fiber. A detector at the second end of the optical fiber receives the reflected light.

Abstract: A device and method for modulating light intensity in response to a varying electrical signal which is particularly useful with optical fiber information sensing systems. The device includes a number of components positioned in seriatim in an elongated cavity in an insulating body. Means for receiving a light signal, such as from an optical fiber, is positioned at one end of the cavity. A lens receives the light and collimates it into a narrow collimated beam directed through the cavity. The beam is polarized, retarded by a wave plate to circular polarization and passed through a modulator material which is capable of rotating beam polarization in response to varying voltage signals imposed on the modulator through electrodes thereon. A mirror at the end of the modulator reflects the beam back through the system.