- Email: [email protected]
The crystal resonator—a digital transducer
as high as 50dB. Data a r e p r e s e n t e d i l l u s t r a ting the s h e a r velocity as a function of onedimensional s t r e s s in p o l y m e t h y l m e t h a c r y late. (1839)
of 10-31bf/in 2 out of a full-scale range of 1041bf/in 2. By suitable conversions, both these sensors yield a direct digital read-out.
(1844)
was 7.8 × 10-2. R i s shown that one can connect l i ne a r p a i r s of surface e l e c t r o d e s in an appropriate binary code to obtain high efficiency and l a r g e bandwidth t r a n s d u c e r s .
(1848) Transducer output indicator Carlsteas, R. H. US Patent 3,445, 840 (20 M a y 1969) (Filed 1 April 1965) A n A - D converter operates on the non-linear output of a transducer to provide a direct indication of the physical quantity or condition actuating the transducer. Digital repetition=rate sensors actuate preset count and time base logic circuits for simulating the break points of a piece-wise approximation of the transducer characteristic curve. This eliminates the calculations involving the characteristic curve of the transducer, which are usually required to convert from the units of the electrical signal obtained as output to the actual physical units being measured. (1840) High frequency acoustic sig nal generator Cleveland Technical Center Inc French Patent 1,578, 219 (14 August 1969), (Applied for 5 July 1968), (In USA 7 July 1967) A nozzle p r o j e c t s a g a s - j e t such that the a i r space at the end of a cavity can be adjusted. The ends of the nozzle and the element forming the cavity have the shape of a truncated cone. A tube and controling valve project a c u r r e n t of gas against that from the nozzle so as to l o d u l a t e the u l t r a s o n i c signal. (1841)
Measurement of the temperature dependence of the velocity of sound in s m a l l solid specimens Gills, M. B., Mlkhailov, I. G., Shutllov, V. A. Soviet Physics--Acoustics, Vol 15, No I (July-September 1969) pp 25-28 T w o new modifications of pulsed electric interferometers are described for measurement of the temperatures coefficient of the velocity of sound in plates. The results are presented from measurements for selected materials (fused quartz, aluminium, and niobium). (184~) An investigation into the p e r f o r m a n c e of nickel alloy m a g n e t o s t r i c t i v e t r a n s d u c e r s p r e p a r e d for c o m m e r c i a l use Grange, A., Brown, B. Applied Acoustics, Vol 2, No 2 (April 1969) pp 111-120 The vibration c h a r a c t e r i s t i c s of a number of c o m m e r c i a l l y p r e p a r e d N i - C o - C r alloy m a g n e t o s t r i c t i v e t r a n s d u c e r s have been measur ed. The behaviour of a single t r a n s ducer coupled to a s t a i n l e s s s t e e l probe, resonant at 13kHz, h as been examined under unloaded conditions. F u r t h e r e x p e r i m e n t s with 3 t r a n s d u c e r s attached to the probe a r e described. The suitability of the existing method of mounting the s y s t e m at the nodal point of the probe has been investigated and r e s u l t s indicate that some improvement in probe output should be p ossible by the use of a flexible mounting at the dodal point of the probe. F u r t h e r e x p e r i m e n t s c a r r i e d out under load conditions show that it i s difficult to know a c c u r a t e l y the resonant frequency of the s y s t e m a s response i s quite fiat.
(1843)
The crystal resonator--a digital t r a n s d u c e r Hammond, P. L., Benjaminson, A. IEEE Spectrum, Vol 6, No 4 (April 1969) pp 53-58 Two s e n s o r s a r e described--the quartz t h e r m o m e t e r and the quartz p r e s s u r e t r a n s d u c e r . The quartz t h e r m o m e t e r o perates at 28MHz and p e r t u r b a t i o n s of frequency have been elim inated in the range --80°C to +250~C. The m a j o r engineering problem in the d e v e l o p ment of the quartz t h e r m o m e t e r was h y s t e r e sis. The quartz p r e s s u r e t r a n s d u c e r o p e r a t e s at b'MHz, fifth overtone, and h a s a s e n s i t i v i t y
Ultrasonic detector IBM French Patent 1,579, 312 (22 August 1969), (Applied for 3 September 1969), (In USA 23 October 1967) This device is for m e a s u r i n g the t hi c kne s s of a moving tape. There a r e t hre e emitting and three r e c e i v i n g ul t ra s oni c t r a n s d u c e r s , one e m i t t e r and one r e c e i v e r give r e f e r e n c e s i g n a l s to a f i l t e r e d a mpl i fi e r output while the detected c a r r i e r s i gna l s from the tape come from a differential amplifier. The phase difference in the s i gna l s i s given from the variation in path length of the emitted signal with r e s p e c t to the reference. (1845) M H z frequency range measured with D I - 2 U device Ivaklmenko, A. T. Measurement Techniques, N o 9 (September 1968) pp 1235-1238 This paper extends the work of one of the authors, to considering the possibility of increasing the frequency range of the D 1 - 2 U from 30cm to 150cm. A description of m e a s u r e m e n t method and equipment used is followed by an account of m e a s u r e m e n t l i m i t s and s y s t e m e r r o r s . Tables show a l t e r n a t i o n s for different power l e v e l s and e r r o r s in alternation m e a s u r e m e n t in the 200-1000MHz range. (1846) On the adequacy of equivalent c l r c u R s for plezomagnetic t r a n s d u c e r s Jagodzinski, Z . Acoustica, Vol 21, No 5 (1969) pp 283-28'/ The dual f o r m s of equivalent c i r c u i t s for piezomagnetic t r a n s d u c e r s a r e d i s c u s s e d and compared. The conclusion i s that the e l e c t r o m e c h a n i c a l pe rforma nc e of the t r a n s ducer i s truly r e p r e s e n t e d only by the c i r c u i t in which the mechanical a r m i s r e p r e s e n t e d by a p a r a l l e l e l e c t r i c a l circuit, with the driving inductance a r m in s e r i e s . The r e v e r s e dual circuit, in which the mechanical a r m i s r e p r e s e n t e d by a s e r i e s c i r c u i t with p a r a l l e l driving inductance, l a y have the same impedance modulus function but the frequencies of mechanical and e l e c t r o m e c h a n i c a l r e s o n a n c e s a r e inverted on the f r e quency scale. Therefore t hi s form of equivalent c i r c u i t cannot be used in the design of ultrasonic equipment. The conclusion i s verified by exp e ri me nt s . (184'/) Excitation and detection of surface elastic waves In piezoelectric crystals Joshi, S. G., and White, R. M. JASA, Vol 46, No 1, Part 1 (July 1969) pp 1'/2'/ The amplitude of the surface elastic wave produced by applying an alternating voltage to an interdigital arrangement of electrodes on the surface of a piezoelectric m e d i u m is determined. The electric field produced by the surface electrodes is calculated assuming piezoelectric coupling of the material can be neglected. This electric field acts as the forcing term for the inhologeneous elastic equation, which is then solved to obtain the amplitude of the surface-wave generated by the transducer. A reciprocal relationship between the excitation and detection problems is used to obtain the power extracted from the surface-wave by an interdigital arrangelent of surface electrodes. Measurements m a d e on single crystals of quartz and cadm i u m sulphide are found to be in good agreement with theoretical predictions. The m a x i m u m value of the product (efficiency × fractional bandwidth) for a surface-wave transducer is calculated. For an interdigital surface-wave transducer on the basal plane of CdS, the m a x i m u m value of this product
Pulsed excitation of transducers Kanevskii, I. N. Soviet Physics--Acoustics, Vol 15, No 1 (July-September 1969) pp50-53 Dependence of signal amplitude of plezoelectric transducers on duration of a rectangular-driving video pulse is investigated theoretically and experimentally. It is shown that as the duration of the pulse is varied the transducer-signal amplitude has a series of alternating maxima, where at sufficiently high frequencies the minima can go to zero for low-damping transducers. The results of the study are applicable to the pulsed excitation of any vibrational systems described by a second-order differential equation.
(lS49) P r e c i s i o n method for m e a s u r i n ~ the velocity of ultrasound in a liquid at 0. 7-30MW-. Kononenko, V. S. and Yakovlev, V. F. Soviet Physics--Acoustics,Vol 15, No i (JulySeptember 1969) pp65-68 A precision method based on electrical interference of the n-th order echo signal investigated for measuring the velocity of ultrasound in a liquid. The use of the n-th echo signal permits very high accuracy in the interference-alignment process. The error of absolute measurements of the velocity of ultrasound was 0.006%; the experimental scatter was half that value. The method enables one to measure the velocity dispersion correct to an error of 0.002-0. 003°/°.
(1850) 1 0 0 M H z Surface acoustoelectrlc amplifier exhthit~l~g stable terminal gain with dc drift field Lakin, K. M. and Collins, J. H. Proc I E E E (April 1969) p '/40 In the experiments described, 1 0 0 M H z acoustic surface (Rayleigh) waves on Y-cut, Z-propagating lithium niobate were amplified using a spatially adjacent m e d i u m of bulk silicon, subjected to a pulsed drift field. Using C. W. signals and d.c. drift power at approximately 7W, a 6dB stable terminal gain at 9.8us delay was achieved. Net electronic gain was 100-- 1200MHz. A n e w method of Rayleigh wave transduction by feeding the R.F. signal in series with a drift field is also described. The principle is that Rayleigh waves are generated by surface carrier waves, provided the velocity of carriers is greater than the phase velocity of Rayleigh waves. (1851) C h a r a c t e r of pseudo s u r f a c e waves ¢m anisotroptc c r y s t a l s Lira, T. C., Farnell, G. W. JASA, Vol 45, No 4 (April 1969) pp 845-851 When the free surface i s anisotropic, a mode of e l a s t i c s urfa c e -w a ve propagation can a r i s e that has many of the p r o p e r t i e s of a n o r m a l surface wave but has a phase velocity higher than that of the t r a n s v e r s e bulk waves in the corresponding direction. The pseudo surface wave i s a coupled mode involving t e r m s decaying rapidly beneath the free surface and a t e r m r e p r e s e n t i n g a bulk wave radiating into the solid. For many choices of c r y s t a l and plane of propagation, the contribution of the bulk t e r m over a range of d i r e c tions i s sufficiently s m a l l that the energy of the wave i s e s s e n t i a l l y concentrated within a few wavelengths of the free surface as with the norma l e l a s t i c surface waves. Moreover, in c e rt a i n specific directions, the bulk t e r m d i s a p p e a r s completely and the ps e udo- s u r f ace wave has all the p r o p e r t i e s of a normal s urfa c e wave. The method of computation of the c h a r a c t e r i s t i c s of the pseudo surface waves i s outlined he re and typical r e s u l t s of velocity, ULTRASONICS J~uary
1970
67
of 10-31bf/in 2 out of a full-scale range of 1041bf/in 2. By suitable conversions, both these sensors yield a direct digital read-out.
(1844)
was 7.8 × 10-2. R i s shown that one can connect l i ne a r p a i r s of surface e l e c t r o d e s in an appropriate binary code to obtain high efficiency and l a r g e bandwidth t r a n s d u c e r s .
(1848) Transducer output indicator Carlsteas, R. H. US Patent 3,445, 840 (20 M a y 1969) (Filed 1 April 1965) A n A - D converter operates on the non-linear output of a transducer to provide a direct indication of the physical quantity or condition actuating the transducer. Digital repetition=rate sensors actuate preset count and time base logic circuits for simulating the break points of a piece-wise approximation of the transducer characteristic curve. This eliminates the calculations involving the characteristic curve of the transducer, which are usually required to convert from the units of the electrical signal obtained as output to the actual physical units being measured. (1840) High frequency acoustic sig nal generator Cleveland Technical Center Inc French Patent 1,578, 219 (14 August 1969), (Applied for 5 July 1968), (In USA 7 July 1967) A nozzle p r o j e c t s a g a s - j e t such that the a i r space at the end of a cavity can be adjusted. The ends of the nozzle and the element forming the cavity have the shape of a truncated cone. A tube and controling valve project a c u r r e n t of gas against that from the nozzle so as to l o d u l a t e the u l t r a s o n i c signal. (1841)
Measurement of the temperature dependence of the velocity of sound in s m a l l solid specimens Gills, M. B., Mlkhailov, I. G., Shutllov, V. A. Soviet Physics--Acoustics, Vol 15, No I (July-September 1969) pp 25-28 T w o new modifications of pulsed electric interferometers are described for measurement of the temperatures coefficient of the velocity of sound in plates. The results are presented from measurements for selected materials (fused quartz, aluminium, and niobium). (184~) An investigation into the p e r f o r m a n c e of nickel alloy m a g n e t o s t r i c t i v e t r a n s d u c e r s p r e p a r e d for c o m m e r c i a l use Grange, A., Brown, B. Applied Acoustics, Vol 2, No 2 (April 1969) pp 111-120 The vibration c h a r a c t e r i s t i c s of a number of c o m m e r c i a l l y p r e p a r e d N i - C o - C r alloy m a g n e t o s t r i c t i v e t r a n s d u c e r s have been measur ed. The behaviour of a single t r a n s ducer coupled to a s t a i n l e s s s t e e l probe, resonant at 13kHz, h as been examined under unloaded conditions. F u r t h e r e x p e r i m e n t s with 3 t r a n s d u c e r s attached to the probe a r e described. The suitability of the existing method of mounting the s y s t e m at the nodal point of the probe has been investigated and r e s u l t s indicate that some improvement in probe output should be p ossible by the use of a flexible mounting at the dodal point of the probe. F u r t h e r e x p e r i m e n t s c a r r i e d out under load conditions show that it i s difficult to know a c c u r a t e l y the resonant frequency of the s y s t e m a s response i s quite fiat.
(1843)
The crystal resonator--a digital t r a n s d u c e r Hammond, P. L., Benjaminson, A. IEEE Spectrum, Vol 6, No 4 (April 1969) pp 53-58 Two s e n s o r s a r e described--the quartz t h e r m o m e t e r and the quartz p r e s s u r e t r a n s d u c e r . The quartz t h e r m o m e t e r o perates at 28MHz and p e r t u r b a t i o n s of frequency have been elim inated in the range --80°C to +250~C. The m a j o r engineering problem in the d e v e l o p ment of the quartz t h e r m o m e t e r was h y s t e r e sis. The quartz p r e s s u r e t r a n s d u c e r o p e r a t e s at b'MHz, fifth overtone, and h a s a s e n s i t i v i t y
Ultrasonic detector IBM French Patent 1,579, 312 (22 August 1969), (Applied for 3 September 1969), (In USA 23 October 1967) This device is for m e a s u r i n g the t hi c kne s s of a moving tape. There a r e t hre e emitting and three r e c e i v i n g ul t ra s oni c t r a n s d u c e r s , one e m i t t e r and one r e c e i v e r give r e f e r e n c e s i g n a l s to a f i l t e r e d a mpl i fi e r output while the detected c a r r i e r s i gna l s from the tape come from a differential amplifier. The phase difference in the s i gna l s i s given from the variation in path length of the emitted signal with r e s p e c t to the reference. (1845) M H z frequency range measured with D I - 2 U device Ivaklmenko, A. T. Measurement Techniques, N o 9 (September 1968) pp 1235-1238 This paper extends the work of one of the authors, to considering the possibility of increasing the frequency range of the D 1 - 2 U from 30cm to 150cm. A description of m e a s u r e m e n t method and equipment used is followed by an account of m e a s u r e m e n t l i m i t s and s y s t e m e r r o r s . Tables show a l t e r n a t i o n s for different power l e v e l s and e r r o r s in alternation m e a s u r e m e n t in the 200-1000MHz range. (1846) On the adequacy of equivalent c l r c u R s for plezomagnetic t r a n s d u c e r s Jagodzinski, Z . Acoustica, Vol 21, No 5 (1969) pp 283-28'/ The dual f o r m s of equivalent c i r c u i t s for piezomagnetic t r a n s d u c e r s a r e d i s c u s s e d and compared. The conclusion i s that the e l e c t r o m e c h a n i c a l pe rforma nc e of the t r a n s ducer i s truly r e p r e s e n t e d only by the c i r c u i t in which the mechanical a r m i s r e p r e s e n t e d by a p a r a l l e l e l e c t r i c a l circuit, with the driving inductance a r m in s e r i e s . The r e v e r s e dual circuit, in which the mechanical a r m i s r e p r e s e n t e d by a s e r i e s c i r c u i t with p a r a l l e l driving inductance, l a y have the same impedance modulus function but the frequencies of mechanical and e l e c t r o m e c h a n i c a l r e s o n a n c e s a r e inverted on the f r e quency scale. Therefore t hi s form of equivalent c i r c u i t cannot be used in the design of ultrasonic equipment. The conclusion i s verified by exp e ri me nt s . (184'/) Excitation and detection of surface elastic waves In piezoelectric crystals Joshi, S. G., and White, R. M. JASA, Vol 46, No 1, Part 1 (July 1969) pp 1'/2'/ The amplitude of the surface elastic wave produced by applying an alternating voltage to an interdigital arrangement of electrodes on the surface of a piezoelectric m e d i u m is determined. The electric field produced by the surface electrodes is calculated assuming piezoelectric coupling of the material can be neglected. This electric field acts as the forcing term for the inhologeneous elastic equation, which is then solved to obtain the amplitude of the surface-wave generated by the transducer. A reciprocal relationship between the excitation and detection problems is used to obtain the power extracted from the surface-wave by an interdigital arrangelent of surface electrodes. Measurements m a d e on single crystals of quartz and cadm i u m sulphide are found to be in good agreement with theoretical predictions. The m a x i m u m value of the product (efficiency × fractional bandwidth) for a surface-wave transducer is calculated. For an interdigital surface-wave transducer on the basal plane of CdS, the m a x i m u m value of this product
Pulsed excitation of transducers Kanevskii, I. N. Soviet Physics--Acoustics, Vol 15, No 1 (July-September 1969) pp50-53 Dependence of signal amplitude of plezoelectric transducers on duration of a rectangular-driving video pulse is investigated theoretically and experimentally. It is shown that as the duration of the pulse is varied the transducer-signal amplitude has a series of alternating maxima, where at sufficiently high frequencies the minima can go to zero for low-damping transducers. The results of the study are applicable to the pulsed excitation of any vibrational systems described by a second-order differential equation.
(lS49) P r e c i s i o n method for m e a s u r i n ~ the velocity of ultrasound in a liquid at 0. 7-30MW-. Kononenko, V. S. and Yakovlev, V. F. Soviet Physics--Acoustics,Vol 15, No i (JulySeptember 1969) pp65-68 A precision method based on electrical interference of the n-th order echo signal investigated for measuring the velocity of ultrasound in a liquid. The use of the n-th echo signal permits very high accuracy in the interference-alignment process. The error of absolute measurements of the velocity of ultrasound was 0.006%; the experimental scatter was half that value. The method enables one to measure the velocity dispersion correct to an error of 0.002-0. 003°/°.
(1850) 1 0 0 M H z Surface acoustoelectrlc amplifier exhthit~l~g stable terminal gain with dc drift field Lakin, K. M. and Collins, J. H. Proc I E E E (April 1969) p '/40 In the experiments described, 1 0 0 M H z acoustic surface (Rayleigh) waves on Y-cut, Z-propagating lithium niobate were amplified using a spatially adjacent m e d i u m of bulk silicon, subjected to a pulsed drift field. Using C. W. signals and d.c. drift power at approximately 7W, a 6dB stable terminal gain at 9.8us delay was achieved. Net electronic gain was 100-- 1200MHz. A n e w method of Rayleigh wave transduction by feeding the R.F. signal in series with a drift field is also described. The principle is that Rayleigh waves are generated by surface carrier waves, provided the velocity of carriers is greater than the phase velocity of Rayleigh waves. (1851) C h a r a c t e r of pseudo s u r f a c e waves ¢m anisotroptc c r y s t a l s Lira, T. C., Farnell, G. W. JASA, Vol 45, No 4 (April 1969) pp 845-851 When the free surface i s anisotropic, a mode of e l a s t i c s urfa c e -w a ve propagation can a r i s e that has many of the p r o p e r t i e s of a n o r m a l surface wave but has a phase velocity higher than that of the t r a n s v e r s e bulk waves in the corresponding direction. The pseudo surface wave i s a coupled mode involving t e r m s decaying rapidly beneath the free surface and a t e r m r e p r e s e n t i n g a bulk wave radiating into the solid. For many choices of c r y s t a l and plane of propagation, the contribution of the bulk t e r m over a range of d i r e c tions i s sufficiently s m a l l that the energy of the wave i s e s s e n t i a l l y concentrated within a few wavelengths of the free surface as with the norma l e l a s t i c surface waves. Moreover, in c e rt a i n specific directions, the bulk t e r m d i s a p p e a r s completely and the ps e udo- s u r f ace wave has all the p r o p e r t i e s of a normal s urfa c e wave. The method of computation of the c h a r a c t e r i s t i c s of the pseudo surface waves i s outlined he re and typical r e s u l t s of velocity, ULTRASONICS J~uary
1970
67