Abstract: A sound diffuser includes a front plate defining a plurality of sound exit holes. An outer frustoconical wall extends from the front plate, the outer frustoconical wall decreasing in diameter from the front plate. An inner frustoconical wall extends from the outer frustoconical wall toward the front plate, the inner frustoconical wall decreasing in diameter toward the front plate and defining a sound entry opening spaced apart from the front plate. A plurality of legs are coupled to at least one of the front plate and the outer frustoconical wall, the legs extending away from the front plate to contact a speaker cover. First and second straps operatively extend from the front plate, the first strap having a distal end with a fastener for connection to a speaker case. The second strap also has a distal end with a fastener for connection to the speaker case.

Abstract: The sound generating and transmitting apparatus is based on a radiator including at least a first, and possibly two or more, shaped reflecting surface(s) having a forward radiant axis. Each of the shaped reflecting surfaces defines sets of equivalent acoustic input locations, with each set being a ring of non-zero circumference centered on the forward radiant axis. The sound source is a distributed, functionally continuous sound source adapted to exploit this feature. In its preferred form the sound source is a sort of closed line array of loudspeakers providing a torodial shaped acoustic source to direct at the hyperbolic cone, the transducers being disposed in a circle with all of the loudspeakers oriented inwardly toward or outwardly from the forward radiant axis.

Abstract: The present invention provides novel filled silicone compositions comprising a nano-particulate metal oxide filler selected from nano-particulate monoclinic alpha-phase bismuth oxide, nano-particulate erbium oxide, and mixtures thereof. The new composite compositions exhibit a combination of outstanding performance characteristics in both the cured and uncured states. Thus, the uncured formulations are typically free flowing liquids which are self-leveling, which de-gas readily under vacuum, are readily colorable through the addition of pigments, and which cure at temperatures of about 60° C. The cured compositions possess outstanding acoustic characteristics which make them ideally suited for use in applications such as acoustic lenses for medical imaging and therapy. For example, the acoustic impedance of compositions provided by the present invention is closely matched to the acoustic impedance of human tissue.

Abstract: A device comprises an acoustic lens (100) with a variable focal length and means (12) for directing incoming acoustic waves onto the lens. The acoustic lens comprises a curved boundary between two fluid media (1, 2) in which the acoustic waves have different propagation velocities. Means (5, 6, 7) are provided for applying a force directly onto one of the fluid media (1) so as to induce a displacement of the boundary (M1, M2). Such arrangement of the acoustic lens makes it possible to achieve rapid variations in the focal.

Abstract: An improved acoustic lens and an improved ultrasonic transducer system comprising an improved acoustic lens and related methods are provided. The improved acoustic lens may have a uniform loss along an elevation axis or may have a loss along the elevation axis that provides for an apodization of an acoustic signal. The improved acoustic lens may be a multi-component lens. In a two-component lens embodiment, the inner lens component, for interfacing with a transducer, may have a concave outer surface and the outer lens component may have a flat or convex outer surface. In a three-component lens embodiment, the inner lens component, for interfacing with a transducer, may have a concave outer surface, the middle lens component may have a concave outer surface and the outer lens component may have a flat or convex outer surface.

Abstract: A loudspeaker includes a frame, a magnet coupled to the frame and a diaphragm secured to the frame. An acoustic lens may be positioned in front of the diaphragm. An aperture extends through the acoustic lens. The acoustical directivity pattern of the loudspeaker may be modified by the acoustic lens to improve the uniformity of the off axis vs. on axis sound pressure level.

Abstract: This invention provides a lens system for a loudspeaker. The loudspeaker may include a driver unit and a waveguide attached to the driver unit. The loudspeaker further may include a lens system. The lens system may include a plurality of plates. The plates may be positioned to divide an interior of the waveguide into a plurality of acoustic paths of substantially equal length. The acoustic paths may bend the propagation of one or more acoustic elements of a sound wave so that each acoustic element arrives at a plane substantially at the same time.

Abstract: A speaker grille is disposed in front of a speaker having a diaphragm and reproducing the sounds of 1 kHz and higher. The speaker grille is provided with a sound opening which includes a sound opening portion that opposes a region extending from the edge portion of a diaphragm to the fixing portion o n the outer circumference of the diaphragm of the speaker. The speaker grille offers superior sound characteristics, and at the same time a sufficient mechanical strength.

Abstract: A sound focus speaker adopting a gas-filled sound lens enhances efficiency of transferring sound from a source to target area and of protecting a spread of transferred sound. The sound focus speaker includes a gas-filled sound lens, sound sources for generating sound and a sound-absorption room for surrounding the sound lens and the sound sources. Sound emitted from the sound focus speaker is focused at specific distance to make a focus point and not spread to the outer of the focus point from forming a sound area.

Abstract: The invention relates to a waveguide loudspeaker with adjustable controlled dispersion which comprises a duct fonned by flat, concave or convex walls round a diffraction throat, and which finishes in a mouth and where reflection can occur before or after the diffraction throat. The mouth is folded back in relation to the throat and has dimensions and shape chosen for the simultaneous application of at least two of the three fundamental principles for sound diffusion, namely diffraction, reflection and absorption. Also, the invention concerns a method to obtain a loudspeaker having means to vary and set at least the degree of diffraction and reflection for the reproduction of wide bands of mid/high frequencies with a limited horn or waveguide length.

Abstract: A sound reproduction system is disclosed which minimizes unwanted acoustic reflections and the resulting comb-filter effects but which still maintains a broad and uniform directional characteristic throughout the region in the listening room in which listening positions are located.

Abstract: A loudspeaker includes a frame, a magnet coupled to the frame and a diaphragm secured to the frame. An acoustic lens may be positioned in front of the diaphragm. An aperture extends through the acoustic lens. The acoustical directivity pattern of the loudspeaker may be modified by the acoustic lens to improve the uniformity of the off axis vs. on axis sound pressure level.

Abstract: A backload horn-type omnidirectional speaker is provided wherein deterioration of sound due to wound horn portions is prevented such that the listener can enjoy natural sounding music regardless of the position from which the music is listened to.

Abstract: This invention provides a lens system for a loudspeaker. The loudspeaker may include a driver unit and a waveguide attached to the driver unit. The loudspeaker further may include a lens system. The lens system may include a plurality of plates. The plates may be positioned to divide an interior of the waveguide into a plurality of acoustic paths of substantially equal length. The acoustic paths may bend the propagation of one or more acoustic elements of a sound wave so that each acoustic element arrives at a plane substantially at the same time.

Abstract: An electro-dynamic phased array acoustic lens having an array of cells, each of which may be separately controlled to alter characteristics of an incident acoustic wave. Because each cell of the acoustic lens controls the delay and amplitude of the acoustic wave passing through that cell, such an acoustic lens may be used in combination with a single-element transducer to control the characteristics of acoustic waves with a similar degree of control, or more, as that provided by a phased multi-element transducer array. The acoustic lens may also be used in combination with a multi-element transducer, such that all elements of the transducer may be fired at the same phase and amplitude. In other words, an ultrasonic wave that passes through a given cell of the acoustic lens is phase offset as determined by that cell. The acoustic lens may be used in an ultrasonic ablation system to control the ultrasonic waves used to ablate the tissue.

Abstract: In video equipment, a video equipment speaker device that is almost invisible from a viewer and capable of placing, toward the front of the center portion of the screen, an acoustic image from a speaker 2 provided on at least either an upper or lower portion of a screen is provided. A speaker device 1 includes the speaker 2, a sound duct 3 positioned forward of the speaker 2 to externally output sound, a speaker baffle 4 provided in the vicinity of edges forming an opening of the sound duct 3 and formed to outwardly reflect the sound, a fin 5 provided forward of the speaker baffle 4, sound space 6 formed between the speaker baffle 4 and the fin 5, and slits 7 outwardly opened from the sound space 6.

Abstract: A speaker assembly includes a speaker mounted within a housing having a front plate and a base plate. The speaker is inclined with respect to the front plate. The base plate includes one of an inclined type structure, a convex type structure, a radial rib type structure having radial ribs, and an uneven structure having projections. The front plate includes holes of certain shapes such as having two half holes formed on opposite sides of front plate and communicating with each other through a common opening formed between the two half holes.

Abstract: A passive system for speech enhancement in a motor vehicle includes a headliner adapted to be disposed in an occupant compartment of the motor vehicle. The passive system also includes at least one passive sound reflector disposed in or near the headliner and being sound-reflective and shaped to direct or focus speech between front and rear seat occupants in the occupant compartment of the motor vehicle.

Abstract: A laminated composite panel-form loudspeaker consists of a peripherally stiffened laminated composite radiating panel on which a preselected number of transducers are mounted and a rectangular frame carrying a flexible suspension device which supports the panel radiator. The laminated composite radiating panel comprises a predetermined number of orthotropic laminae with predetermined specific moduli and stacking sequence. The peripheral edge of the laminated composite radiating panel is reinforced with strips of which the rigidities are determined in such a way that beneficial natural normal modes of the radiating panel are excited and satisfactory operation of the panel radiator over a desired acoustic frequency range achieved. The standing waves at the peripheral edge of the stiffened radiating panel are damped out via the use of the flexible suspension device.

Abstract: An apparatus for the redistribution of acoustic energy is provided which comprises a lens having a reflective surface defined by the surface of revolution (R1) of an elliptical arc (A1) rotated about a line (L) through an angle (&agr;1) and the surface of revolution (R2) of an elliptical arc (A2) rotated about the line (L) through an angle (&agr;2). Each elliptical arc (A1) and (A2) constitutes a portion of an ellipse (E1) or (E2) having a focal point located at a point (F1) on line (L), and shares an end point (P) which lies on the reflective surface and the line (L). The angle (&agr;1) is chosen such that the surface of revolution (R1) is convex with respect to an adjoining surface (S1) and the angle (&agr;2) is chosen such that the surface of revolution (R2) is concave with respect to the adjoining surface (S1).

Abstract: An apparatus for the redistribution of acoustic energy is provided which comprises a lens having a reflective surface defined by the surface of revolution R1 of an elliptical arc A1 rotated about a line L through an angle .alpha.1 and the surface of revolution R2 of an elliptical arc A2 rotated about the line L through an angle .alpha.2. Each elliptical arc A1 and A2 constitutes a portion of an ellipse E1 or E2 having a focal point located at a point F1 on line L, and shares an end point P which lies on the reflective surface and the line L. The angle .alpha.1 is chosen such that the surface of revolution R1 is convex with respect to an adjoining surface S1 and the angle .alpha.2 is chosen such that the surface of revolution R2 is concave with respect to the adjoining surface S1.

Abstract: An acoustic lens device is provided for use in facilitating oral communication in a space which is acoustically challenged. The lens device includes at least one acoustic reflector for positioning proximate to a dashboard of a passenger portion of a transport vehicle. The reflector is formed by an upper portion with an ellipsoidal surface obtained when an ellipse having two foci on an axis extending in a substantially vertical direction is rotated about the axis. In consequence, the upper portion encloses at least one of the two foci such that each of the at least one reflectors is disposed at a predetermined distance from the other with parallel axes. The first loci is disposed such that voice signals emitted from the mouths of persons seated in the front passenger compartment are directed from the first foci to the device. Accordingly, a sound pressure of a voice signal reaches the axis of the at least one reflector and is focused by the device and directed to the second focus in the back passenger portion.

Abstract: The acoustic lens system is used for ultrasonic imaging in an ultrasonic system which displays an image of an object while transmitting ultrasonic waves and receiving the ultrasonic waves reflected from the object, and has a half field angle .omega. expressed as follows: ##EQU1## wherein the reference symbol v.sub.0 represents the velocity of sound in the medium located on the incidence side of the first lens surface and the reference symbol v.sub.1 designates the velocity of sound in the medium located on the emergence side of the first lens surface. Accordingly, the acoustic lens system according to the present invention is remarkably excellent in the performance thereof in respect of field angles, aberrations, aperture angles, attenuation, etc., and has an advantage to permits further reducing acoustic attenuation and preventing spurious images from being formed due to multiple reflections by arranging antireflection films on the lens surfaces.

Abstract: An acoustic lens for the transformation of a planar wave into a spherical segment-shaped wave, and vice versa, is disclosed. In order to avoid aberrations, the lens is fashioned rotationally symmetrical relative to its center axis and biconcavely, the lens surface adjoining the medium in which the planar wave propagates is produced by the rotation of a section of a straight line, the lens surface adjoining the medium in which the spherical segment-shaped wave propagates is produced by the rotation of a section of an ellipse, and the angle between the straight line and the center axis as well as the angle between the major half-axis of the ellipse and the center axis are selected such that a planar or spherical segment-shaped wave entering into the lens propagates in the lens as a conical wave whose aperture angle is equal to double the angle at which the minor half-axis of the ellipse intersects the center axis.

Abstract: A speaker unit for a television receiver includes speakers SP.sub.L, SP.sub.R arranged at the back of a television screen surface, sound reflectors for reflecting the sound from the speakers substantially in a forward direction from the television screen surface, and acoustic lenses provided on a surface coplanar with the television screen surface for controlling the sound radiating direction. A high quality sound with a sense of ambience and compatibility with the television picture may be produced without enlarging the size of the television receiver cabinet.

Abstract: An interlayer for use in sound-insulating laminated glasses which is in the form of a laminated film of two kinds of resin films (A) and (B), each comprising a polyvinyl acetal acetalized with an aldehyde having 6 to 10 carbon atoms for the film (A) or with an aldehyde having 1 to 4 carbon atoms for the film (B), or is in the form of a resin film (C) comprising a mixture of the two kinds of polyvinyl acetal resins. The interlayer mitigates the coincidence effect to prevent the reduction of TL value without impairing the basic characteristics required of laminated glasses thereby permitting the interlayer to exhibit outstanding sound-insulating properties over a wide temperature range for a prolonged period of time.

Abstract: A temperature compensation system that adjusts the temperature of an acoustic lens fluid in a prescribed manner to maintain the index of refraction of the fluid constant relative to the surrounding water thereby maintaining the focal length of the lens constant over its operating temperature range. The system comprises two temperature sensors, a programmed lens fluid temperature prescriber and an error amplifier all cooperating to direct a servomechanism system to adjust a temperature control system to either heat or cool the lens fluid to the prescribed temperature so that its index or refraction and focal length are held constant.

Abstract: In an acoustic lens apparatus of this invention, a lens surface formed on an ultarsonic medium has a longitudinal wave lens portion constituted by a first aspherical surface at its central area, and a transverse wave lens portion constituted by a second aspherical surface at its peripheral area. The ultrasonic medium includes a piezoelectric transducer for generating ultrasonic waves at its surface opposite to the lens surface. The ultrasonic medium is arranged so that the lens surface opposes a sample, a coupler medium is filled in the gap between the surface and the sample.

Abstract: A focussing element for use in a lenseless, focussed transducer for producing a semi-focussed, ultrasonic beam comprises a body formed of electrical insulating material and a plurality of piezoelectric elements disposed in one end of the body, each element being planar, extending outwardly from a common axis, and being disposed at a predetermined angel to the common axis whereby to define a common focal point on the axis, and electrical conductors secured to the piezoelectric element for electrically exciting the elements.

Abstract: A number of embodiments of silencing devices for marine propulsion units using acoustical lenses that are positioned across either the air inlet device, the air exhaust device or both. The acoustical lenses direct the sound waves in such a way so as to effect silencing while, at the same time, ensuring that water will not enter the engine combustion chambers. The invention is shown in conjunction with both outboard motors and inboard mounted engines.

Abstract: An acoustic lens for use in an acoustic microscope including a solid state medium for propagating an acoustic wave having a wavelength .lambda. and having opposed end surfaces, an electric-acoustic transducer applied on one end surface of the solid state medium and having a radius a, and a spherical lens portion formed in the other end surface of the solid state medium and having an aperture of a radius w. The length l and the aperture radius w are normalized by the transducer radius a such that Z=l.lambda./a.sup.2 and W=w/a. Values of Z and W are selected from such a region in a first quadrant of the Z-W coordinate system that desired power and/or phase are obtained. The region neighboring the point Z=1 and W=1 is excluded.

Abstract: A noise reducing apparatus is disclosed, comprising a lens-type hollow body consisting of a plurality of inclined hollow tubular passages. The lens-type hollow body has a plane incident surface and a curved emission surface and the length L.sub.2 of the hollow tubular passage is optimized in accordance with relevant dimensional parameters of setting of the lens-type hollow body in a sound field, to reduce noise from a spot sound source efficiently.

Abstract: An underwater communicator comprising a transmitter for transmitting acoustical energy between mediums having differing impedance. The transmitter includes first and second ends. The first end is exposed to a first medium while the second end is exposed to a second medium. In the preferred embodiment, the transmitter is formed from a material having a substantially identical impedance to the second medium. An acoustical lens is positioned adjacent the first end of the transmitter. The acoustical lens has a substantially planar front face and a substantially concave shaped rear face. The acoustical lens includes a plurality of spaced vertically extending plates. The vertically extending plates form a substantially right angle with the front face of the acoustical lens. A plurality of spaced plates intersect the vertically extending plates and form an acute angle with the front face of the acoustical lens, thereby forming a plurality of inclined passageways.

Abstract: Arrangements are disclosed for generating a well defined traveling wave beam substantially unaffected by diffractive spreading. In different embodiments, the beam can be an electromagnetic wave, particle beam, a transverse beam, a longitudinal beam such as an acoustic beam, or any type of beam to which the Helmholtz generalized wave equation is applicable. Pursuant to the teachings herein, a beam is generated having a transverse dependence of a Bessel function, and a longitudinal dependence which is entirely in phaser form, which results in a beam having a substantial depth of field which is substantially unaffected by diffractive spreading.

Abstract: A lens incorporates two reflective shells. One shell's surface is generated when a parabola is rotated around a line which lies in the parabolic plane perpendicular to its axis of symmetry. The other shell's surface is generated when an ellipse is rotated about a line lying in the elliptic plane and passing through one focal point at a finite angle to its major axis. The parabolically-generated shell has a characteristic focal curve while the elliptically-generated shell has both a characteristic focal curve and a focal point. The lens incorporates these shells which are aligned so that they have coincident focal curves and axes of rotation. Plane wave radiation travelling parallel to the axis of rotation of the lens will be focused at the focal point of the elliptically-generated shell. Conversely, a transducer placed about this common focal point and can produce radiation which will be converted into a plane wave radiation.

Abstract: An enclosure for a transduction element incorporates a geometrically shaped acoustically reflective shell. This acoustically reflective shell is shaped so that the inner surface thereof is at a least a section of that shape generated when a parabolic structure is rotated around a line which, lies in the plane of the parabolic structure, is perpendicular to the major axis of the parabolic structure. Such geomtrically generated shapes will have one distinct focal curve. A transduction element placed about this focal curve will, in operation, cause acoustic radiation to be produced which will be characterized by a plane wavefront of coherent radiation. Said device may alternately act as a transducer which produces a 360 degree beam width by placement of a plane wavefront producing transduction means at a position above the acoustically reflective shell and parallel to the plane of the distinct focal curve.

Abstract: An acoustic lens arrangement having at least one transducer for the generation and/or for the reception of a plane acoustic wavefield. The arrangement includes a focusing surface for focusing the acoustic wavefield in an object region and at least one medium for the low-loss transmission of the acoustic wavefield between a transducer, the focusing surface and the object region to be investigated. The longitudinal axis of the focusing surface is inclined relative to the direction of the normal to the acoustic wavefield in such a manner that when the longitudinal axis is positioned normal to the surface of the object region, the acoustic beams incident thereon form a critical angle .theta..sub.R with the normal to the surface of the object.

Abstract: Disclosed herein is a sound wave control device which is shaped in a lens form or a prism form from an acoustically rigid porous material, wherein numerous paths having different path lengths are provided and the apparent medium density is varied. This second wave control device is used to improve the sound quality and the directivity of the sound waves from a speaker and the directional control of noises.

Abstract: An acoustic lens for use in an ultrasonographic probe is made of a material including silicone rubber mixed with particles of titanium oxide having diameters ranging from 0.08 to 0.20 .mu.m. The particles are mixed at a ratio in the range of 30 to 65 wt %.

Abstract: A lens system for directing and focussing acoustic energy from an array of acoustic transducers on a small target can be made lightweight, low in absorption and dispersion by incorporating plastic Fresnel lenses with prisms into a monolithic tray of the same plastic with one lens for each transducer.

Abstract: An ellipticized singlet azimuth versus elevation optimized and aperture eemized nonspherical acoustic lens antenna of very low or even minimal F-number providing balanced astigmatism for wide angle acoustical applications in underwater sound is described. The acoustic lens has an elliptical periphery and surfaces defined by a system of nonlinear partial differential equations, the surfaces acting together to produce two perfect primary off-axis foci F and F' at a finite distance in back of the lens and two perfect conjugate off-axis foci F.sub..infin. and F'.sub..infin. in front of the acoustic lens at infinity; i.e., the lens simultaneously focuses energy from the primary foci F and F' into two off-axis parallel ray plane wave sonic beams directed towards infinity at equal but opposite angles with respect to the acoustic lens axis.

Abstract: A device for focussing or collimating a beam of acoustic radiation comprises a body of acoustically transmissive material having first endface (12) coupled to a source of acoustic radiation (16, 18). The radiation is internally reflected by the side surface 20 of the body, this surface being of a shape such that it brings the radiation to a focus F after transmission through a second surface (14).

Abstract: An ultrasound imaging apparatus and transducer means which produces a converging beam pattern focused along the axis of the transducer with increasing beam concentration towards the furthest point of convergence of the beam pattern.

Abstract: An ellipticized singlet azimuth versus elevation optimized and aperture eemized nonspherical acoustic lens antenna of very low or even minimal F-number providing balanced astigmatism for wide angle acoustical applications in underwater sound is described. The acoustic lens has an elliptical periphery and surfaces defined by a system of nonlinear partial differential equations, the surfaces acting together to produce two perfect primary off-axis foci F and F' at a finite distance in back of the lens and two perfect conjugate off-axis foci F.sub..infin. and F'.sub..infin. in front of the acoustic lens at infinity; i.e., the lens simultaneously focuses energy from the primary foci F and F' into two off-axis parallel ray plane wave sonic beams directed towards infinity at equal but opposite angles with respect to the acoustic lens axis.

Abstract: A unidirectional dynamic microphone provided with a first sound path to the forward side of the diaphragm and a second sound path to the rear side of the diaphragm, a Helmholtz resonator disposed in the first sound path having a sound entrance, and a diffraction lens mounted ahead of the Helmholtz resonator and partially shadowing the sound entrance to the Helmholtz resonator for the purpose of increasing the high frequency response of the microphone.

Abstract: The invention provides a highly focussed ultrasonic wave throughout a large depth of field without any mechanical motion. One embodiment of the invention providing two focussed fields includes a front to back arrangement of a converging lens, a transducer without any backing material to dissipate ultrasound, a converging lens, and a transducer. To focus in the far field, the front transducer transmits and receives via the front lens. To focus in the near field, the rear transducer transmits and receives via both lenses which collectively focus in the near field.

Abstract: An ellipticized singlet azimuth versus elevation optimized and aperture eemized nonspherical acoustic lens antenna of very low or even minimal F-number providing balanced astigmatism for wide angle acoustical applications in underwater sound is described. The acoustic lens has an elliptical periphery and surfaces defined by a system of nonlinear partial differential equations, the surfaces acting together to produce two perfect primary off-axis foci F and F' at a finite distance in back of the lens and two perfect conjugate off-axis foci F.sub..infin. and F'.sub..infin. in front of the acoustic lens at infinity; i.e., the lens simultaneously focuses energy from the primary foci F and F' into two off-axis parallel ray plane wave sonic beams directed towards infinity at equal but opposite angles with respect to the acoustic lens axis.

Abstract: The fabrication of ultrasonic-wave lenses and prisms using low-surface tension (poor adhesion) polyalkene sheet (such as polyethylene) as an impedance-matching quarter-wave anti-reflective layer is made possible by the use of certain very low surface-tension cements.

Abstract: A differential property sensitive acoustic lens for non-destructive materials evaluation is described which in a preferred embodiment comprises first and second substantially semicylindrical shaped portions of fused silica disposed in closely spaced relationship along an axial plane, a substantially spherical depression defined in one end of each semicylindrical portion and a flat defined on each semicylindrical portion at the other end, a piezoelectric transducer attached to the flat of each semicylindrical portion, and a paraffin coated aluminum film of preselected thickness disposed between and in laminar contact with the semicylindrical portions for preventing acoustic and electrical cross talk between the transducers and between the semicylindrical portions.

Abstract: The invention provides a highly focussed ultrasonic wave throughout a large depth of field without any mechanical motion. One embodiment of the invention providing two focussed fields includes a front to back arrangement of a converging lens, a transducer without any backing material to dissipate ultrasound, a converging lens, and a transducer. To focus in the far field, the front transducer transmits and receives via the front lens. To focus in the near field, the rear transducer transmits and receives via both lenses which collectively focus in the near field.