Abstract: An acousto-optic device which is incorporated into a fiber optic system to define, based upon device configuration, an element such as a phase modulator, optical tap, frequency shifter or mode coupler. The device comprises an acoustic transmission member having a groove therein which is secured in the Hertzian contact along a continuous portion of its surface with an optical waveguide so as to communicate acoustic signals from a transducer affixed on the member through the Hertzian contact area and into the optical waveguide. In one preferred embodiment the member comprises a capillary tube having a bore that is substantially the same diameter as the optical waveguide to which the device is to be affixed. A portion of the capillary tube is removed to expose the base, thereby defining a groove along the capillary substrate. In one preferred embodiment an acoustic transducer is deposited on the curved surface opposite the groove to focus acoustic signals from the transducer toward the groove.

Abstract: A shear acoustic transducer-lens system in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens.

Abstract: To facilitate the fabrication of acoustic printheads, arrays of spherical acoustic lenses are provided for bringing rf acoustic waves to essentially diffraction limited focii at or near the free surface of a pool of ink. These lenses produce focal patterns which are relatively free of localized amplitude variations, so they may be employed to fabricate acoustic printheads having relatively stable characteristics for acoustic printing.

Abstract: The output surface of an acoustic printhead having one or more concave acoustic beam forming devices for supplying focused acoustic beams to eject droplets of ink on demand from the surface of a pool of ink is planarized by filling those concave devices with a solid material having an acoustic impedance and an acoustic velocity which are intermediate the acoustic impedance and the acoustic velocity, respectively, of the ink and of the printhead. This not only facilitates the cleaning of the printhead, but also eliminates the edges upon which an optional ink transport or the like may tend to drag. The outer surface of the filler may be essentially flush with the face of the printhead, or the filler may overcoat the printhead.

Abstract: A printhead for an acoustic printer comprises one or more acoustic microlenses, each of which brings an acoustic beam to focus approximately at the free surface of a pool of ink for ejecting individual droplets of ink from the pool on demand. As used herein, an "acoustic microlens" is defined as being an acoustic lens having an aperture diameter which is less than an order of magnitude greater than the wavelength of the incident acoustic wave (i.e., the acoustic wave which illuminates the lens).

Abstract: The invention relates to a multi-layered piezoelectric acoustic transducer for generating layers of the same piezoelectric material are provided such tool alternate layers have different crystallographic orientations and different piezoelectric coupling coefficients. The layers may be provided so that alternate layers have crystallographic orientations which provide maximum electro-acoustic coupling and layers which provide minimum electro-acoustic coupling.

Abstract: Provision is made spatially stabilizing standing capillary surface waves in fixed and repeatable locations with respect to stationary external references. For spatially stabilizing such a wave on the free surface of a volume of liquid, the wave propagation characteristics of the free surface of liquid are periodically varied in a spatially stable manner at a spatial frequency equal to the spatial frequency of the standing wave or a subharmonic thereof, thereby locking the crests and troughs of the standing wave in predetermined spatial locations. A spatially periodic pattern of notches in a wall or base plate bounding the free surface of the liquid may be employed to physically modulate its wave propagation characteristics at a suitable spatial frequency. Alternatively freely propagating secondary capillary surface waves may be launched from spatially periodic sites along the free surface of the liquid to actively modulate its wave propagation characteristics at the diesired spatial frequency.

Abstract: Provision is made for selectively addressing inividual crests of traveling or standing capillary surface waves to eject droplets from the selected crests on command. To that end, the addressing mechanism of this invention locally increase the surface pressure acting on the selected crests and/or locally reduce the surface tension of the liquid within the selected crests. The preferred addressing mechanisms have sufficient spatial resolution to address a single crest substantially independently of its neighbors.Discrete addressing mechanisms having a plurality of individual addressing elements are especially attractive for liquid ink printing and similar applications, not only because their individual addressing elements may be spatially fixed, but also because the spatial frequency of their addressing elements may be matched to the spatial frequency of the capillary wave. Such frequency matching enables selected crests of the capillary wave to be addressed in parallel, such as for line printing.

Abstract: A nozzleless print head for ink jet printing and the like comprises one or more essentially planar surface acoustic wave transducers which are submerged at a predetermined depth in a liquid filled reservoir, so that each of the transducers launches a converging cone of coherent acoustic waves into the reservoir, thereby producing an acoustic beam which comes to a focus at or near the surface of the reservoir (i.e., the liquid/air interface). The acoustic beam may be intensity modulated to control the ejection timing, or an external source may be used to extract droplets from the acoustically excited liquid on the surface of the reservoir on demand. Regardless of the timing mechanism employed, the size of the ejected droplets is determined by the waist diameter of the focused acoustic beam.

Abstract: A noncontacting method of measuring periodic surface heating is described. The perturbation of an externally generated acoustic wave is measured. The acoustic wave is generated in the air above a sample to be studied. The acoustic wave is directed onto the sample surface, coincident with a modulated light beam. Absorption of the light beam results in the periodic heating of the sample, at and near the sample surface. The air in contact with the sample surface is in turn heated, and produces a periodic phase shift in the reflected acoustic wave. This phase shift is detected and gives a direct measure of the periodic heating of the sample surface. An acoustic microscope may generate the acoustic wave. The sample is placed in water. An acoustic microscope lens produces an acoustic wave in the water, which focuses onto the sample surface, coincident with a modulated laser beam. The light beam is guided onto the sample using an optical fiber.

Abstract: A scanning acoustic microscope is disclosed for the detection and location of near surface flaws, inclusions or voids in a solid sample material. A focused beam of acoustic energy is directed at the sample with its focal plane at the subsurface flaw, inclusion or void location. The sample is scanned with the beam. Detected acoustic energy specularly reflected and mode converted at the surface of the sample and acoustic energy reflected by subsurface flaws, inclusions or voids at the focal plane are used for generating an interference signal which is processed and forms a signal indicative of the subsurface flaws, inclusions or voids.

Abstract: An acoustic microscope comprising a transducer for transmitting acoustic signals towards the surface to be studied, and means for receiving at least one reflected signal from the surface; in many embodiments of the invention, signals are received from two separate points. The signals received are passed to a synchronous phase detection system for analysis. The signals may be received at the same phase detector input and separated according to their expected time of receipt relative to their time of transmission, or they may be received at separated points on the transducer related to their separated points of transmission. The separated return signals are compared on the basis of phase (and in certain embodiments, magnitude) differential either to each other or to an internally generated reference signal to analyze the surface characteristics of the material.