USA As Represented by Secretary of the Navy

Joseph F Vignola

Brian H Houston

Douglas M Photiadis

John A Sterling

An exemplary inventive subordinate oscillator array (SOA) includes two or more vibration attenuation devices (oscillators) that are sequentially arranged (e.g., via beams in the SOA) so that their respective anti-vibratory influences overlap. To design the SOA, an optimal number N of oscillators is calculated according to the equation N=&#x3b7;Q&#x394;, where &#x3b7; is the modal overlap, Q is the quality factor, and &#x394; is the desired fractional bandwidth. Each oscillator is akin to a conventional dynamic vibration absorber (DVA) and is characterized by its own mass, stiffness, damping, and geometry (e.g., length, width, and height). The respective characteristics of the oscillators are selected and the oscillators are distributed so that the SOA, when suitably attached to a vibrative structure, attenuates the vibrations of the structure so as to approximately flatten the structure's vibrations over a frequency band of interest.

Manufacture methods relating to a subordinate oscillator array

An apparatus for measuring the amount of motion of the surface of a microscopic object includes a light source, an optical fiber for transmitting the light, and a collection objective. The optical fiber emits the light output through an aperture tapered to a diameter in the range of from 20 nm to 200 nm. The collection objective is positioned to receive both the direct component of the fiber light output and the Doppler-shifted reflected light of the fiber light output from the surface of the object. The direct component and the Doppler-shifted reflected light combine in the collection objective to form an interfered light signal that is output to a photo-receiver. The intensity of the interfered light signal is modulated by the relative phase shift between the two interfering beams and is proportional to the out-of-plane displacement caused by the surface motion of the object surface. The photo-receiver receives the interfered light signal and converts it to an electrical signal that is proportional to the light intensity and representative of the amount of the surface motion of the object. A signal processor processes the electrical signal and outputs the amount of surface motion of the object's surface. A tip altitude control system positions the output end of the optical fiber relative to the surface of the sample. A movable stage receives and secures the object in order to enable measurements to be taken at a plurality of locations on the surface of the object. In addition to measuring surface motion and detecting small mass changes on an object's surface, the invention may be used to measure high frequency surface phonons.

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Berwyn Heights, MD, United States of America

Joseph F Vignola