Abstract: A device and system for purifying a fluid is provided. The system includes a tank having an interior space and a media container disposed within the interior space. A valve is provided that cooperates with an element within the interior, the valve being movable between an open and a closed position. The valve being biased to the open position when the element is not positioned within the interior space, wherein the interior space is fluidly coupled to the atmosphere in the open position. The valve further being configured to move to a closed position when the element is positioned within the interior space.

Abstract: A device and system for purifying a fluid is provided. The system includes a tank having an interior space and a media container disposed within the interior space. A valve is provided that cooperates with an element within the interior, the valve being movable between an open and a closed position. The valve being biased to the open position when the element is not positioned within the interior space, wherein the interior space is fluidly coupled to the atmosphere in the open position. The valve further being configured to move to a closed position when the element is positioned within the interior space.

Abstract: A laser transmitter with a feedback control loop for minimizing noise. The novel laser transmitter includes a laser, an external reflector adapted to form an extended cavity to the laser, and a feedback control loop adapted to detect noise in the laser and in accordance therewith, adjust the optical phase of the extended cavity such that the noise is at a desired level. The optical phase of the extended cavity is adjusted by adjusting an operating parameter of the laser, such as its bias current. In an illustrative embodiment, the feedback control loop is adapted to compute the rate of change of the noise with respect to bias current and in accordance therewith, adjust the bias current of the laser such that relative intensity noise and interferometric intermodulation distortion are simultaneously minimized.

Abstract: A method for minimizing the generation of interferometric intermodulation distortion in an analog fiber optic link that employs a directly modulated diode laser as its optical source. This is accomplished via the reduction of frequency chirp in the current-modulated diode laser source (32). To reduce frequency chirp, the diode laser (32) is coupled to an external reflector (52), so that an external laser cavity with a long, passive section is formed. Specifically, the frequency chirp of this extended laser cavity is reduced from that of the original diode laser by the ratio of the optical path length in the external cavity to that in the diode. The external reflector (52) can also be integrated, via splicing, to the fiber pigtail (54) of the laser transmitter (50) so that the compact geometric form factor of a diode transmitter is preserved.

Abstract: A telemetry system for receiving data from large arrays of sensors, in which the sensors are located in an unprotected environment, is implemented using fiber optic components. Laser sources, located in a protected environment, transmit light through the boundary separating the protected environment from the unprotected one. The light is then split into a number of beams and fed to electro-optical modulators, where it is modulated in response to electrical signals received from the sensors. The modulated light signals are then wavelength-division multiplexed and transmitted back through the environment boundary, where they are amplified, demultiplexed and converted to electrical signals. Multiplexing reduces the number of boundary penetrations, and the use of highly stable electro-optical modulators eliminates the need for signal conditioning electronics at each sensor.

Abstract: A telemetry system for receiving data from large arrays of sensors, in which the sensors are located in an unprotected environment, is implemented using fiber optic components. Laser sources, located in a protected environment, transmit light through the boundary separating the protected environment from the unprotected one. The light is then split into a number of beams and fed to electro-optical modulators, where it is modulated in response to electrical signals received from the sensors. The modulated light signals are then wavelength-division multiplexed and transmitted back through the environment boundary, where they are amplified, demultiplexed and converted to electrical signals. Multiplexing reduces the number of boundary penetrations, and the use of highly stable electro-optical modulators eliminates the need for signal conditioning electronics at each sensor.

Abstract: A mode preserving apparatus (11) comprising a supporting structure (13), an optical fiber (15), a pin connector (17) for positioning a first region of the optical fiber at a first location and a strain-relief mechanism (19) for positioning a second region of the fiber at a second location. A bobbin assembly (21), includng a first bobbin (23), is mounted on the supporting structure (13) for movement relative to the first and second locations. The optical fiber (15) extends along a path from the first location at least part way around the bobbin (23) to the second location so that movement of the bobbin (23) relative to the first and second locations alters the configuration of the path.

Abstract: An apparatus for launching separate mode groups comprising an LED (13) and a collimator (C.sub.1) for providing a first beam (19) of collimated light and an LED (15) and a collimator (C.sub.2) for providing a second beam (23) of collimated light. The beams (19) and (23) intersect and form an acute angle A. A light guide (R.sub.1) has a receiving face (27) at the intersection of the beams (19) and (23) so that the beams are launched into the light guide as first and second mode groups, respectively.