Abstract: In some aspects, the present invention provides a method of measuring bone condition using ultrasound waves. Embodiments can involve transmitting an ultrasonic signal through a portion of a bone to be measured to a receiver. The first and second harmonics of the detected signal can then be isolated. A duration difference can then be determined between (i) the detected signal or a first harmonic of the detected signal and (ii) a higher harmonic of the detected signal. Based on that duration difference, material conditions of the bone can be estimated. Methods according to the present invention can be significantly more robust and repeatable than known methods of measuring bone conditions.

Abstract: This invention relates to an acousto-optical tunable filter generally of the kind described in U.S. Pat. No. 6,266,462. More specifically, the invention relates to a filter and its construction, the filter including a support, first and second mounts at spaced locations on the support, an optical fiber having first and second mounted portions secured to the first and second mounts respectively and a filtering section between the first and second mounted portions, a signal generator operable to generate a periodic signal, and an electro-acoustic transducer having a terminal connected to the signal generator and an actuating portion, the electric signal causing vibration of the actuating portion, and the actuating portion being connected to the filtering section so that the vibration generates a transverse wave traveling along the filtering section. The filter has an improved damper to more effectively dampen waves traveling along the filtering section.

Abstract: An optical fiber is subjected to a series of traveling flexural waves propagating along a length of the fiber. At least a portion of an optical signal propagating within the optical fiber in a first propagation mode is coupled to a second propagation mode. The optical signal in the second propagation mode has a frequency which is equal to either the sum of or the difference between the frequency of the optical signal in the first propagation mode and the frequency of the traveling flexural waves.