Abstract: An improved apparatus and method for providing a measurement of the characteristic behavior of an acoustic wave in a bone of a subject. A preferred embodiment has first and second transducers and a mounting arrangement for mounting the transducers in spaced relationship with respect to the bone. The first transducer may transmit acoustic energy over a broad solid angle, thereby behaving as a point source of acoustic energy. Additionally or alternatively, the second transducer may collect acoustic energy over a broad solid angle, thereby behaving as a point receiver. A signal processor in communication with the second transducer provides a measurement that is a function of at least one of transient spectral or transient temporal components of the signal received by the second transducer.

Abstract: An apparatus for performing a measurement that characterizes the behavior of an acoustic wave in a heel bone. The apparatus is an integral unit having a base with a platform coupled to the base at a specified angle with respect to the base for receiving, centering and reproducibly orienting a foot. The apparatus has two transducer arms, each supporting an acoustic transducer in spaced relationship with respect to the foot of the subject and a member for mounting the first and second transducer arms in moveable relationship to the base so as to permit coupled two-dimensional motion of the first and second transducers over regions of the heel. The transducer units have transducer caps and an acoustically absorbing filler medium for emitting an acoustic wave with substantially the character of a point source over an opening angle of at least 30.degree..

Abstract: An apparatus and methods for determining a measure equivalent to broadband sound attenuation from transient or other measures derived from acoustic signals propagated through bone and, additionally, for using this measure for the calibration of an ultrasound bone analysis instrument. A synthetic mathematical filter corresponding to a given value of broadband ultrasound attenuation is applied to the signal propagated through a calibration of known or neutral acoustic properties. The value of the acoustic measure corresponding to the resultant waveform is determined and associated with the broadband ultrasound attenuation value corresponding to the synthetic mathematical filter. A model relating the acoustic measure to BUA values may thereby be established for subsequent clinical application.

Abstract: An improved apparatus and method for providing a measurement of the characteristic behavior of an acoustic wave in a bone of a subject. A preferred embodiment has a first assembly containing mounting means for mounting two transducers in spaced relationship with respect to the bone, and a second, hand-holdable assembly containing a display for displaying an output characterizing the behavior of the acoustic wave in the bone. In other embodiments of the invention, an acoustic signal propagated along a path through the bone is processed to determine the proximity of the path to an edge of the bone.

Abstract: An apparatus and methods for determining a measure equivalent to broadband sound attenuation from transient or other measures derived from acoustic signals propagated through bone and, additionally, for using this measure for the calibration of an ultrasound bone analysis instrument. A synthetic mathematical filter corresponding to a given value of broadband ultrasound attenuation is applied to the signal propagated through a calibration of known or neutral acoustic properties. The value of the acoustic measure corresponding to the resultant waveform is determined and associated with the broadband ultrasound attenuation value corresponding to the synthetic mathematical filter. A model relating the acoustic measure to BUA values may thereby be established for subsequent clinical application.

Abstract: An apparatus and methods determine externally in a vertebrate subject the porosity and non-connectivity of a bone. A preferred embodiment has an acoustic transceiver with a pair of acoustic transducers disposed in a specified spatial relationship with one another, such that an acoustic signal is transmitted from one to another via the bone. The transmission path through the bone corresponding to the acoustic signal analyzed by the system may be varied, with values derived from measures of acoustic transmission through differing locations in the bone stored in different locations of a memory. A location processor is provided for selecting a target location based at least in part on the values stored in the memory for defining a region of interest with respect to which a measure of bone porosity is determined.

Abstract: An apparatus and method determine externally in a vertebrate subject an index of porosity and non-connectivity of a bone. A preferred embodiment has first and second transducers and a mounting arrangement for mounting the transducers in spaced relationship with respect to the bone. A signal generator,in communication with the first transducer, causes the first transducer to produce acoustic signals, having energy distributed over a frequency range, that are propagated into the subject and received by the second transducer along a path the includes the bone. Finally, the embodiment has a signal processor, in communication with the second transducer, for providing a measurement that is a function of at least one of spectral or temporal components of the sisal received by the second transducer. The transducers act like a point source and point receiver.

Abstract: An apparatus and method for acoustic analysis of bone are disclosed which provide measurements of transient spectral or temporal characteristics using signal processing techniques, wherein ultrasonic bone index value measurements are derived so as to minimize differences among successive measurements taken of the same individual and to maximize differences in measurements taken of different individuals and provide outputs indicating the condition of bone.

Abstract: An automatic gain control circuit for an interferometer or a phase sensitive detector reduces sensitivity to fluctuations in amplitude of input signals. A pair of currents from the phase sensitive detector that represents a detected phase difference are input to an automatic gain control ratio detector. The output of the automatic gain control ratio detector is a function of the ratio of the difference and sum of the phase sensitive detector currents that is substantially independent of intensity or amplitude fluctuations of the input signals.

Abstract: An electro-optic device comprises a substrate of electro-optic material having at least one optical waveguide formed therein subjacent a main surface thereof for propagating an optical mode. A coplanar transmission line is formed on the main surface of the substrate and has at least first and second electrodes spaced apart by an electrode gap that is wider than the first electrode. The center of the waveguide is within the electrode gap and closer to the first electrode than the second electrode.

Abstract: An automatic masking system is used in an optical time domain reflectometer for implementing a method of compensating for relaxation transients in an optical receiver in the OTDR. The masking system drives an optical modulator that masks the optical reciver from high amplitude optical pulses in the return reflected light from a fiber under test. A masking pattern corresponding to the high amplitude optical pulses is generated from a first acquisition of data with the receiver unmasked from the return reflected light. The masking pattern is stored and used for generating a signal from the masking system to the optical modulator for blocking the high amplitude optical pulses in the return reflected light during a subsequent acquisition of data. In a third acquisition of data of the return reflected light, the optical modulator masks the receiver from the return reflected light.

Abstract: A measurement is carried out on a medium that propagates energy in a selected form by applying energy in the selected form to the medium, the power varying as a function of time in accordance with the elements of two Golay complementary sequences where one kind of element is represented by zero power and the other kind of element is represented by a predetermined non-zero power level and the successive elements of each sequence are applied at uniform intervals. Energy emitted from the medium in the selected form is received, and the variation as a function of time of the power emitted is correlated with the variation as a function of time of the power that was applied. Preferably, the level at which power is applied is varied both directly, in accordance with the elements of the two Golay complementary sequences, and in a derivative fashion, in accordance with the logical complements of the two Golay complementary sequences.

Abstract: A surface acoustic wave (SAW) device is fabricated to minimize or eliminate purious signals caused by bulk modes. A backing layer is provided on the bottom surface of the crystal substrate of the SAW device having an acoustic impedance nearly the same as that of the crystal substrate for a family of spurious bulk modes.

Abstract: A structure for compressing an acoustic surface wave into a symmetric higher energy density output surface acoustic wave. Conductive strips are placed in parallel upon a piezoelectric surface. When a symmetric input is generated at one side of the multistrip coupler, the energy of the input wave is compressed into the center channel and is presented at the output in a single moded symmetric form.

Abstract: A broadband electroacoustic converter incorporating a two-layer acoustic coupler is disclosed for efficiently converting between electrical signals carried on an electrical network having a specified electrical impedance and acoustic signals carried in a load medium having a specified acoustic impedance.