Abstract: A loudspeaker driver has a diaphragm connected to a surrounding frame by a roll suspension which extends around the diaphragm and within the frame. The roll suspension connects the outer edge of the diaphragm to the inner edge of the frame and flexes as the diaphragm is displaced to and fro axially relative to the frame. In order to provide for better integrity of the roll suspension during its displacement, and reduce unwanted deformation and concomitant distortion, the suspension roll is provided with pleats extending across the roll suspension transversely to the direction of axial movement of the diaphragm to create a series of undulations (peaks and troughs) around the perimeter of the roll suspension. In transverse cross-section, the roll suspension is parabolic. The roll suspension varies continuously between each peak and adjacent trough.

Abstract: A brake assembly of the type having a brake shoe platform and one or more brake plates mounted on the platform, each brake plate having a brake lining and a backing plate attachable to an outer surface of the platform, is characterized in that the platform has a series of circumferentially spaced apertures each adjacent its rear edge, and a series of circumferentially spaced recesses communicating with its front edge. The backing plate has two rear flanges each being L-shaped and having an inner portion depending from its inner surface and a rearwardly projecting outer tongue portion, these rear flanges being sized to pass through the apertures in the brake shoe platform. Also, the backing plate has two front flanges, each having an inner portion depending from its inner surface and an outer tongue portion, these front flanges being arranged to slide into the recesses at the front edge of the platform.

Abstract: Portable apparatus for measuring parameters of optical signals propagating concurrently in opposite directions in an optical transmission path between two elements, at least one of the elements being operative to transmit a first optical signal (S1) only if it continues to receive a second optical signal (S2) from the other (10) of said elements, comprises first and second connectors for connecting the apparatus into the optical transmission path in series therewith, and a device connected between the first and second connectors for propagating at least the second optical signal (S2) towards the one of the elements, and measuring the parameters of the concurrently propagating optical signals (S1, S2). The measurement results may be displayed by a suitable display unit. Where one element transmits signals at two different wavelengths, the apparatus may separate parts of the corresponding optical signal portion according to wavelength and process them separately.

Abstract: A laser for generating laser light pulses comprises a cavity containing an active optical gain medium (102) and a spectral filtering device (104), a delay device (110) for delaying light by a predetermined delay time (?t), means (106) for extracting a portion of laser light from the cavity, launching said portion into said delay means (110) and returning the delayed portion to the optical gain medium (102), control means (116) operable to activate the gain medium for a first time period (C1) to produce a first laser light pulse (LP1) having a duration that is less than the delay time (?t), and activate the gain medium for a second time period (C2) while a said delayed portion of the first light pulse that has been delayed by the delay means (UO) is traversing the gain medium (102), thereby to produce a second laser pulse (LP2) having a shorter duration and faster risetime than the first laser light pulse (LP1), and output means (108) for outputting the second laser light pulse (LP2).

Abstract: In a method of measuring cumulative polarization mode dispersion (PMD) along the length of a fiber-under-test (FUT), a polarization-sensitive optical time domain reflectometer (POTDR) is used to inject into the FUT plural series of light pulses arranged in several groups. Each group comprises at least two series having closely-spaced wavelengths and the same state of polarization (SOP). At least two of such groups are injected and corresponding OTDR traces obtained for each series by averaging the impulse-response signals of the several series in the group. The process is repeated for a number of groups. The PMD is obtained by normalizing the OTDR traces of all of the groups, then computing the difference between each normalized OTDR trace in one group and the corresponding normalized OTDR trace in another group, followed by the mean-square value of the differences. Finally, the PMD is computed as a predetermined function of the mean-square difference.

Abstract: An array receiver which reduces complexity and cost by exploiting multiuser information in signals received from a plurality of transmitting users preprocesses (40) samples of antenna signals (x1, x2 . . . , xN) from the antenna elements (22/1, . . . , 22/N) to form basis signals (yO, . . . , yM) together having fewer space-time dimensions than the space-time dimensions of the combined antenna signals. The receiver processes and combines the basis signals to produce sets of estimated received signals (z0, . . . , zM), each for a corresponding one of the users. Each of the basis signals comprises a different combination of the antenna signals. The receiver combines the basis signals to provide a user-specific output signal, and periodically updates parameters of the filters (40/0, . . . , 40/M) used for deriving each particular basis signal such that each user-specific output signal will exhibit a desired optimized concentration of energy of that user's received signal as received by the array antenna.

Abstract: In a method of calibrating a light delivery device (10) having a solid state light source (12), for example comprising LEDs of an LED array, and an intensity control unit (16) comprising LED array driver and a dimmer module for generating a control signal for controlling at least the intensity of the light source, the light source is temporarily connected by a light guide (24; 24, 26) to a radiometer (38) for detecting irradiance of the delivered light. The light delivery device has a memory (30) for storing control signal parameters and associated radiance levels. The light delivery device is calibrated by adjusting the control signal parameters, e.g.

Abstract: A linear electromechanical translation apparatus is provided of the type comprising first and second clamps fixed to a support, first and second elongate movable members each extending through one of the clamps, and an extension actuator connected between the movable members and adapted to move each one of the elongate movable members longitudinally relative to the other member as the extension actuator is extended or retracted. The apparatus is characterized in that the first elongate movable member has a rear end connected to a front end of the extension actuator, and the second movable member has a rear end connected to a rear end of the actuator and has a forwardly extending elongate portion which lies beside and parallel to the first elongate movable member. Both the clamp assemblies may be located forwardly of the front end of the actuator.

Abstract: First and second optical fibers are spliced by a mechanical splice-based connecting device having a portion whereby light leaked from the splice can leave the connecting device. A reference power level (PREF) of light leaked while only the first fiber is inserted into the connecting device, and a measured power level (PM) light leaked while both fibers are inserted are measured. Insertion loss of the splice is derived from the measured power level (PM), the measured reference power level (PREF) and a calibration factor (C) previously obtained by using the same or substantially identical measuring apparatus and connecting device to measure a corresponding calibration input power level (P?IN) and calibration reference power level (P?REF) with only the first fiber inserted, and a calibration measured power level (P?M) and output power level (P?F) of light coupled into a second fiber after the second fiber has been inserted.

Abstract: Apparatus for extracting light from an optical waveguide (12) by bending the waveguide to such an extent that a portion of any light propagating in the waveguide leaks therefrom comprises a bending unit (10) for bending a portion of the waveguide in dependence upon a control signal (S) and providing a detection signal (Pd) proportional to light leaked from the waveguide. A control unit (14) varies the control signal (S) in response to the detection signal (Pd) to cause the bending unit (10) to progressively decrease the bending angle and has a processor unit (46) which computes a rate of change (dPd/dR) of the detection signal (Pd) with respect to bending radius (R) and causes the bending unit to maintain that bending radius at which the aforesaid rate of change is substantially equal to a predetermined value.

Abstract: A wireless communication system includes a portable, typically hand-held transmitter which includes RF absorbing material and/or one or more dissipative parasitic antennas for reducing RF fields in close proximity to the operator to such an extent as to substantially preempt the effect of the operator presence, specifically the operator's hand, in field operation. As a result, the RF absorbing material and/or one or more dissipative parasitic antennas reduces the proportionate effect upon the RF radiation level caused by the operator's hand or other body part. The RF absorbing material may comprise a layer of such material upon a surface of a ground plane within a housing of the transmitter, and/or on an interior surface of the housing, and/or on an exterior surface of the housing. The dissipative parasitic antenna may comprise a printed antenna and resistive load integrated on the transmitter's printed circuit board or elsewhere in or on the housing.

Abstract: A hand-held colorimetric device (101) suitable for use by blind or color-blind individuals to determine the color of a surface-under-test (SUT), for example of a fabric, has an aperture (110) which, in use, is covered by the SUT (113) whose color is to be determined. Six LEDs (115A, 115B, 116B, 117A and 117B) arranged in pairs (115A/115B, 116A/116 B, 117a/117B) emitting red/orange, green, and blue light illuminate the SUT and diffuse reflections therefrom containing red/orange, green, and blue spectrum sample values are used to determine the luminous reflectivity and chromaticity values for the color of the SUT. The measured values are compared with colorimetric values of reference surfaces to determine the color of the SUT. The colorimetric device may output the name of the color aurally.

Abstract: An interferometric optical analyzer apparatus comprises a light source, an interferometer and a detection system for determining the linear response, and subsequently any optical parameter, of one or more optical elements using substantially unpolarized light. In one embodiment, the light source supplies substantially unpolarized coherent light over a predetermined range of optical frequencies. The optical element is coupled in one arm of the interferometer and the other arm of the interferometer is used as a reference. The unpolarized light is first passed through the interferometer then through a three-way polarization splitter unit to split the light into at least three light beams according to preselected polarization axes corresponding to three linearly independent states of polarization. The three light beams are coupled to individual detectors and a controller computes Jones matrix elements from the resulting electrical signals.

Abstract: A widely-tunable laser apparatus comprises a plurality of tunable lasers having different ranges that overlap to encompass a desired operating range of wavelengths (for example from 1250 nm to 1650 nm) of the widely-tunable laser apparatus. The tunable lasers are tunable synchronously and selectively with their respective outputs connected in common to sweep the output of the widely-tunable laser apparatus substantially continuously over said operating range. The tunable lasers share the same tuning means which has a plurality of independent channels, each for light from a respective one of the tunable lasers.

Abstract: A light delivery device (10) having a light source (12) and a variable aperture unit (18) is temporarily connected by a light guide (24; 24, 26) to a radiometer (38) for detecting irradiance of the delivered light. The light delivery device has a memory (30) for storing irradiance levels. The light delivery device is calibrated by adjusting the aperture to each of a series of predetermined settings, obtaining from the radiometer a corresponding series of delivered light irradiance levels measured thereby, storing the irradiance levels and aperture settings in memory, and applying a best fit algorithm to the irradiance measurements and aperture settings. Thereafter, a desired irradiance level can be set by selecting the best fit aperture setting. Output intensity levels may be measured at the same time as the irradiance levels and used to compensate for light source degradation when setting a desired irradiance level.

Abstract: A light source unit comprises a support for supporting a lamp unit, e.g., a gas discharge lamp or the like. The lamp unit has longitudinal and transversal fiduciary surfaces and the support has guide rails for guiding the lamp unit as it is inserted transversely with the longitudinal fiduciary surfaces sliding along a reference surface until transversal fiduciary surfaces engage one or more stops. The support may comprise a first part for supporting the lamp unit, a second part for supporting a light guide, and at least first and second light baffles between the first part and the second part, the first and second baffles each having an aperture for passing only a portion of light from the lamp unit incident upon the baffle, the arrangement being such that light from the lamp unit must pass through the apertures in both baffles to be incident upon the light guide.

Abstract: A remote-controlled audio system comprises sets of loudspeakers (14A-14D) connected to power amplifier units (22A-22D) in an audio distribution unit (10) to which several audio sources, such as a compact disc unit, a tape deck, etc., are connected. Remote units (34) are provided, one in each zone with a set of loudspeakers. The loudspeakers and the remote unit are connected to the audio distribution unit by four wires whereby audio and data signals and power are transmitted to the loudspeakers and the remote unit, respectively. Each power amplifier unit may have a pair of power amplifiers, each connected to one of the loudspeakers in the set, referenced to a first ground (1) and a second ground (2), respectively. The second ground (2) is maintained at a prescribed voltage relative to the first ground. The remote unit (34A) is connected between the “ground” terminals of the two loudspeakers of the set, i.e. those connected via the speaker cables to the first and second grounds in the audio distribution unit.

Abstract: Apparatus for measuring polarization mode dispersion (PMD) of a device, e.g. a waveguide, comprises a broadband light source (10,12) for passing polarized broadband light through the device (14), an interferometer (20) for dividing and recombining light that has passed through the device to form interferograms, a polarization separator (30) for receiving the light from the interferometer and separating such received light along first and second orthogonal Feb. 25, 2003 Feb.