Showing papers on "Interdigital transducer published in 1985"

Receiver for a spread spectrum communication system having a time-multiplexed convolver

Abstract: A convolver having at least a first interdigital transducer for generating a first surface acoustic wave in response to an input signal and a second interdigital transducer for generating a second surface acoustic wave counter to the first surface acoustic wave in response to a time reversed-time multiplexed reference signal. A segmented summing bus having a plurality of fingers extending into the interaction region of the first and second surface acoustic waves generates a plurality of samples indicative of the convolution of the first and second surface acoustic waves. The convolver also includes a pair of acoustic horns, one disposed between the segmented summing bus and each of the interdigital transducers and a ground bus having a plurality of filler segments extending intermediate the fingers of the segmented summing bus.

Piezoelectric ultrasonic transducer with flexible electrodes adhered using an adhesive having anisotropic electrical conductivity

Abstract: An ultrasonic transducer includes a piezoelectric member consisting of either a unpolarized piezoelectric polymer material or the like, or an in-advance polarized piezoelectric polymer material or the like, a first flexible substrate on which a first electrode set and their connecting leads are formed, these being bonded to one surface of the piezoelectric member, and a second flexible substrate on which a second electrode and its connecting lead are formed, these being bonded to the other surface of the piezoelectric member, wherein the piezoelectric member is sandwiched between the first electrode set and second electrode. The electrodes can apply a voltage to polarize the unpolarized piezoelectric polymer material in a manufacturing process of the piezoelectric member, or apply a drive voltage to the finished ultrasonic transducer. Also disclosed is a method of manufacturing the ultrasonic transducer.

Reinforced piezoelectric transducer and pressure sensor using such a transducer

Abstract: A piezoelectric transducer including a polarized piezoelectric material film, which also has a reinforcing material incorporated into the mass and which prevents any deformation of the film in certain given directions. The invention also relates to a pressure sensor using such a transducer. This sensor can be used both as a pressure sensor and as a pressure gradient measuring device.

Ultrasonic transducer with a multiple-folded piezoelectric polymer film

Abstract: An ultrasonic transducer includes a piezoelectric polymer film (14) folded as at least two layers and having electrodes on both the surfaces thereof. The ultrasonic transducer is responsive to a signal, applied across electrodes, to produce an ultrasonic wave to be focused at one spot so that it is converted to an electric signal. In this ultrasonic transducer, a groove (24) or through holes (42) are formed on and along the folded area (22) of the piezoelectric polymer film.

Sheet-like piezoelectric element

Abstract: Sheet-like piezoelectric element in which a plurality of slits (15) are formed between the comb-shaped electrodes 13,14 alternatively projected in a zigzag shape from a pair of therminals (11, 12) arranged oppositely, a piezoelectric layer of composite piezoelectric material is filled into the slits (15), a DC voltage is applied between the terminals (11,12) to polarize the adjacent layers in reverse directions to each other, and the electrodes (13,14) have a thickness corresponding to that of the piezoelectric layer. The element may be used for an electro-mechanical transducer or a thermal-electric transducer.

SAW Properties of PLZT Epitaxial Thin Films

Abstract: Thin films of PLZT with (111) orientation were epitaxially grown on c-plane of sapphire by rf-magnetron sputtering. The poling treatment was carried out under an applied field along direction of PLZT and SAW was excited along the same direction by an interdigital transducer. The coupling constant k2 was about 0.85% for the fundamental mode of SAW at normalized thickness Kd=0.42. The result indicates that the piezoelectric effect of the present PLZT thin film is as strong as BaTiO3.

Acoustic Lamb wave‐electric field nonlinear interaction in YZ LiNbO3 plates

Abstract: The nonlinear electroacoustic effect has been investigated for acoustic Lamb wave propagation in a YZ LiNbO3 plate under a uniform bias electric field. A theoretical model is briefly outlined, which shows how the effect can be interpreted in terms of second and third order material constants. The strength of the nonlinear interaction has been experimentally evaluated through measurements of the change in phase velocity of Lamb modes produced by the bias field. The experiments were performed in the frequency range 8–33 MHz on most of the Lamb modes excited in a 1.25‐mm‐thick plate by an interdigital transducer with a periodicity λ=0.396 mm. The results evidence a strong dependence of the nonlinear effect on the order and symmetry of the analyzed modes.

Measurement and Mapping of Elastic Anisotropy of Solids Using a Leaky SAW Excited by an Interdigital Transducer

Abstract: Abstmt-Methods of measuring the acoustic properties of solids using acoustic beams in a liquid generated by interdigital transducers (IDT) are described. An IDT can radiate acoustic waves into a liquid in oblique directions with respect to the substrate, and the wave fronts can be arbitrarily controlled by designing the IDT shape. When the acoustic beam is incident on the solid sample-water interface near the Rayleigh angle, the reflection field is equal to the superposed fields of the specular reflection and the reradiation from the leaky surface acoustic wave (SAW) excited on the sample. One normal IDT pair on a piezoelectric substrate is used to measure the acoustic properties of a solid sample. The velocity and the attenuation of the leaky SAW on the sample can be obtained by measuring the trailing field due to the reradiation. A new method for focusing the beam from an IDT and mapping a leaky SAW velocity on a solid sample surface is shown. An interdigital electrode is divided into several sections, each of which is positioned to form a one-dimensional Fresnelphase-plate interdigital transducer (FPP IDT) on a piezoelectric substrate. It has been found that the FPP IDT generates a converging beam onto a focal plane, and the present system is suitable for measuring the two-dimensional variation of the leaky SAW phase velocity on a sample surface. T

The Electric-Field Problem of an Interdigital Transducer in a Multilayered Structure

Abstract: A computational technique for the determination of the potential distribution of an interdigital transducer in a layered nonpiezoelectric environment is presented. Firstly, the problem is reduced to a dual boundary value problem for the potential distribution and the jump in the current density in the place of the interdigital transducer. Secondly, an iteration scheme to solve this dual boundary value problem is outlined. It is based upon an iterative minimization of the integrated square error made in the boundary conditions on the transducer fingers. Finally, numerical results for some representative configurations are presented.

Flat passband etched groove saw filter

Abstract: An acoustic surface wave device is configured as a bandpass filter. The device employs two interdigital transducer pairs for input and output. Each transducer pair has a slant finger geometry. The fingers are electrodeposited into grooves etched into the substrate. The grooves are deeper at the high frequency side of the substrate. The grooves enhance the electromechanical coupling of high frequency components and thus provide a flatter amplitude response curve.

Piezoelectric SAW device with a corrugated surface

Abstract: An acoustic surface wave device is configured as a bandstop filter. The device has groups of sinusoidal corrugations cut into the top surface of a piezoelectric substrate between the input and output sets of interdigital transducers. The groups of corrugations selectively scatter certain surface acoustic wave spectral components traveling between the input and output transducers. The scattered components are converted to bulk vibration and do not impinge upon the output transducer; other components travel from input to output transducer relatively undiminished. Thus, a band of scattered surface acoustic spectral components is filtered from the input spectrum.

Efficient, damage resistant LiNbO3 acousto‐optic waveguide deflector

Abstract: An efficient, damage resistant, guided wave deflector in LiNbO3 has been fabricated by a combination of titanium diffusion, proton exchange in benzoic acid with lithium benzoate, and post‐annealing processes. The stability of the waveguide has been confirmed using x‐ray rocking curves. The insertion loss of interdigital transducer and the diffraction efficiency were found to depend on the wave number of OH absorption produced by proton exchange.

Efficiency of surface interdigital transducers on anisotropic media

Abstract: Excitation and detection of surface acoustic waves by means of interdigital transducers are studied here in the case of general anisotropic media with low piezoelectric coupling. Relations between mechanical wave amplitude and applied and detected voltage are established. The electromechanical coupling coefficient is calculated from the equivalent electrical circuit of the transducer for different quartz‐crystal orientations. Experimental results are given for different quartz‐crystal cuts, in agreement with the theoretical values.

Compensation of acoustic wave devices

Abstract: Compensation for the effects of environmentally caused changes and aging on piezoelectric acoustic wave devices is electrically provided by the application of a signal, such as a DC bias voltage, to the finger elements of an interdigital transducer formed on the surface of the acoustic wave device. This produces very large field concentrations at the finger edges which act to magnify the electric field and accordingly the electroacoustic effect which alters the acoustic velocity of surface acoustic waves, shallow bulk acoustic waves and reflected bulk acoustic waves propagating in a piezoelectric substrate between input and output interdigital transducers.

Transducer for SAW arrangements

Abstract: In a directional transducer for SAW filters on a piezoelectric substrate, the transducer is formed of a plurality of groups which are connected in half-groups to busbars for two phases. The half-groups are alternately distributed into two or more channels such that the finger electrodes of each phase form a more or less gap-free series as viewed over all channels. A common, meandering busbar for both phases is associated with each channel.

Microwave saw monochromator

Abstract: An acoustic surface wave device is configured as a bandpass filter. The device has similar groups of sinusoidal corrugations cut into portions of both the top and bottom surfaces of an otherwise flat piezoelectric substrate. A pair of input interdigital transducers is located upon one end of the top flat surface of the substrate. A similar pair of output interdigital transducers is located on the bottom flat surface of the substrate at the end opposite the input interdigital transducers. When an input RF spectral signal is applied to the input interdigital transducers, the transducers convert the electrical signal spectrum to a surface acoustic wave spectrum. When the surface acoustic wave spectrum strikes the corrugations cut into the top surface of the substrate, the corrugations selectively scatter certain spectral components into bulk vibration. The bulk vibration strikes the similar corrugations located upon the bottom of the substrate and the bulk vibratory energy is efficiently reconverted to surface acoustic vibration which propagates along the bottom surface of the substrate. The surface acoustic waves propagating along the bottom of the substrate are highly monochromatic because only certain special components of the wave propagating on the top surface are efficiently transduced by the two groups of corrugations to the bottom surface. The monochromatic surface acoustic waves propagating on the bottom surface are reconverted to an electrical signal by the pair of interdigital transducers located upon the bottom surface.

Surface acoustic wave transducer

Abstract: A single-phase unidirectional surface acoustic wave transducer comprising a piezoelectric substrate and a transducer having localized symmetry and constructed for establishing a predetermined separation between the centers of acoustic wave reflection and transduction on said substrate by selectively orienting the transducer on a specific cut of said substrate to achieve a separation between said centers in a continuum of achievable phase angles of 0°-360°.

Saw filter having response enhanced via dampening

Abstract: An electrical surface acoustic wave filter with a wafershaped substrate (1) of monocrystalline, piezoelectric material, in particular lithium niobate, wherein one substrate side supports interdigital transducers (IW 1, IW 2) with metallic electrodes mutually engaging in comblike fashion for the stimulation and coupling out of the surface waves and with plastic and/or elastic damping compounds (10, 11) for the suppression of disturbing wave reflections. The damping compound (10, 11) is applied indirectly or directly to the substrate surface between the active interdigital transducer area "b" and the adjacent long substrate edges (4, 5) of at least one interdigital transducer (IW 1), and that at least in the inactive interdigital transducer areas (a, a).

Pickup for optical disk

Abstract: PURPOSE:To reduce the size and weight of the titled pickup for optical disk by using a means which produces the surface acoustic wave through an optical waveguide to deflect the waveguide light, a tracking error detecting circuit, and a control circuit for a surface acoustic wave generating means respectively. CONSTITUTION:An interdigital transducer IDT 29, for example, is used as a surface acoustic wave generating means. When the frequency of a surface acoustic wave 28 produced by the IDT 29 is changed, the deflecting angle of the waveguide light 24' which is deflected by the surface acoustic wave is changed. Thus the position of the light radiated from a condensing diffraction grating 27 is changed and then the light illuminating position is changed on the surface of an optical disk 40. Therefore the tracking control is possible by changing the frequency of the surface acoustic wave in response to the tracking error signal and then changing the light illuminating position. Furthermore the surface acoustic wave generating means like an IDT, etc. can be set on an optical waveguide 22. Thus a miniaturized pickup for optical disk is obtained.

Interdigital transducer method of acoustic beam steering for bulk wave acousto‐optic Bragg cells

Abstract: A LiNbO3 acousto‐optic Bragg cell is described, which uses an interdigital transducer deposited on the x surface of the crystal so as to excite longitudinal bulk acoustic waves along a direction almost normal to the surface itself. By a proper choice of the periodicity of the transducer electrodes, a frequency‐dependent steering of the acoustic beam can be obtained, which allows the Bragg conditions to be satisfied over a wide range of frequencies. Results are reported relative to a cell operating in the frequency range 1.4–2.1 GHz, with a diffraction efficiency of approximately 2% per watt of acoustic power.

Piezoelectric transducer and pressure sensor using such a transducer

Abstract: OF THE DISCLOSUREPIEZOELECTRIC TRANSDUCER AND PRESSURE SENSOR USING SUCH A TRANSDUCER The invention relates to a piezoelectric transducer comprising a polarized piezoelectric material film, which also has a reinforcing material incorporated into the mass and which prevents any deformation of the film in certain given directions. The invention also relates to a pressure sensor using such a transducer. This sensor can be used both as a pressure sensor and as a pressure gradient measuring device. (Fig 9)

Wide-band transducer for acousto-optic Bragg deflector

Abstract: A wide-band transducer for an acousto-optic deflector is described. The transducer is a chirped-frquency interdigital transducer with electrodes tilted to satisfy the isotropic Bragg condition. A s...

Acousto-Electro-Optic Effects in SAW Devices

Abstract: Acousto-optic and electro-optic devices can be used in many ways as signal processing devices like modulators, correlators, deflectors, etc. the fact that most of the processors can be done with either of the two types of devices, they often compete. However, the two effects can be combined to give an acousto-electro-optic device. the limitations that they might have separately can be overcome in this way. This type of device can be implemented in a bulk wave device or SAW. structure of SAW devices allows a variety of ways in which to apply the necessary electric field. A dc voltage can, for instance, be applied to an interdigital transducer. When a light beam passes under the transducer, the change in refractive index will diffract the light in the same way as an acoustic wave, launched from an identical transducer would. The only difference is the absence of a Doppler shift in the light frequency. tic pulse now interacts with the light beam at the same time, a combined effect will be seen. The electro-optic interaction will affect the phase of the detected pulse. In y-cut, z-propagating LihbO3,

Observation of thermo‐optic and photorefractive effects during acousto‐optic interaction in Ti:LiNbO3 waveguides

Abstract: This paper describes the observation of thermo‐optic and photorefractive effects in an integrated optics spectrum analyzer. The thermo‐optic effect arises because of the dissipation of rf power as heat at the interdigital transducer and at the tuning inductor. The results also indicate that a photorefractive effect takes place at λ=6328 A and power densities ∼50 W/cm2, but in the presence of acoustic power.

Rayleigh Waves and Reflective Periodic Structures

Abstract: While the interdigital transducer is the most important periodic structure for Rayleigh waves, it labours under limitations. To perform its function it must consist of continuous metal strips connected together in a certain configuration. Periodic reflective array structures suffer no such limitations. A rich variety of structures can be conceived and many have been investigated. Examples of periodic arrays are shown in Fig. 1 which may consist of dielectric or metal films or of grooves.

Ultrasonic diffraction grating using an interdigital transducer operating at a liquid-solid interface

Abstract: An ultrasonic optical modulator using an interdigital transducer operating at a liquid–solid boundary is described. The fundamental characteristics of the optical modulator are given for a combination of a He–Ne 0.63‐μm laser and water as an acousto‐optic material. The modulator consists of a piezoelectric ceramic plate with interdigital electrodes. The diffraction pattern can be varied by changing the voltage or the frequency of the electrical signal applied to the transducer. By using the voltage dependence of the first‐order diffraction peak, we demonstrate optical modulation.

Integrated optical techniques for acousto-optic receivers

Abstract: This chapter is concerned primarily with the use of integrated optical techniques in acousto-optic receivers. More specifically, we consider devices in which a light beam is confined in a waveguide deposited on the surface of a suitable planar substrate (typically a piece of single-crystal lithium niobate) and interacts with a surface acoustic wave (SAW) launched by a specially designed interdigital electrode structure.

Sub-micron camera for interdigital transducer fabrication

Abstract: Describes the structure and operation of a submicron resolution camera system for fabricating high frequency interdigital electrode transducers (IDTs) A high resolution, 10× reduction lens is central to the system which produces IDTs by direct optical projection lithography The camera resolution was determined experimentally to be approximately 075 μm The system was subsequently used to fabricate a modified chirp transducer with linewidths ranging from 1 μm to 24 μm

Method for forming electrode of surface acoustic wave device

Abstract: PURPOSE:To improve the yield and to reduce the dispersion of characteristics by forming the ratio of an electrode finger width to an electrode finger interval to a prescribed value and widening the electrode finger width in forming an interdigital transducer electrode. CONSTITUTION:A resist film 3' is constituted so as to obtain the ratio S/L of the electrode finger width L and the electrode finger interval S as nearly 0.8-0.2 and exposed and developed. In this case, the electrode finger pitch is taken as a wavelength lambda of a prescribed resonance frequency. Since the electrode finger width L is wide in this case, it is prevented easily that the electrode finger 2' is too small, and also the generation of side etch caused for low frequency region is prevented and further, pattern break or the like caused for high frequency region is prevented easily. Thus, the interdigital transducer (IDT) electrode with good yield and less dispersion in characteristics is obtained.

Elastic surface wave resonator

Abstract: PURPOSE:To reduce the increase in a floating capacitance by grounding substantially an electrode finger of an interdigital electrode to a surface acoustic wave reflector. CONSTITUTION:A comb line electrode 23 having the electrode finger 2301 nearest to the reflectors 24, 25 is grounded. Even if an electric field is produced between the reflectors 24, 25 in the electrically floating state, since a comb line electrode 23 is at a ground potential, the capacitors C1, C2 are short-circuited by a lead 31 and capacitors C3, C4 are short-circuited by a lead 32. Thus, the electrode capacitance of an interdigital transducer (IDT) has a value C0 depending on the total length of the cross electrode finger so as to reduce the electric coupling between the IDT and the reflectors thereby decreasing the floating capacitance. The increase in the substantial insertion loss is prevented and it is prevented to narrow the variable range of an oscillating frequency section when the resonator is used as an oscillating element.