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The concept of an optical profiler based on optical resonance was proposed, highlighting the initial requirements for mode number estimation. We proposed a method for estimating the longitudinal mode number of a laser propagating in an external cavity diode laser with high accuracy, utilizing dual-periodic diffraction gratings. These gratings were fabricated using interference lithography. To estimate the mode number, the wavelengths of two different modes are compared. Therefore, the greater the difference between the wavelengths, the higher the accuracy of the mode number determination. While the mode number difference was approximately 35 when using a conventional diffraction grating, this could be increased by a factor of 20 to around 700 using the dual-periodic grating. The relative accuracy achieved was 1.4 × 10−5. [ABSTRACT FROM AUTHOR]

An investigation is carried out through experiments and numerical calculations for the improvement of the resolution of measuring the pitch deviation of a diffraction scale grating with the diffracted beams. Since the changes in angles of diffraction of the diffracted beams detected by an optical head are utilized to evaluate the pitch deviation in the method, the sensitivity of the optical head directly affects the resolution for measurement of the pitch deviation. Meanwhile, in the previous studies, the resolution of a laser-autocollimation unit in the optical head for the detection of the change in the angle of diffraction of a diffracted beam has been limited to approximately 0.1 arc-second; this has been a bottleneck in increasing the resolution for measurement of the pitch deviation. In this paper, an investigation using a prototype optical head is first conducted in preliminary experiments to clarify the cause of the degradation of the resolution for measurement of the pitch deviation. Numerical calculations are also carried out to confirm the influence of the multiple longitudinal modes (MLM) of a laser beam, which is suggested as the main cause of the degradation of resolution in the results of preliminary experiments. Based on the results of experiments and numerical calculations, an attempt is made to employ a laser beam having a single longitudinal mode (SLM) in the optical head. The pitch deviation of a scale grating with a nominal pitch of 4 μm is measured by a prototype optical head with an SLM laser to verify the improvement of the resolution for measurement of the pitch deviation.

The concept of an optical profiler based on optical resonance was proposed, highlighting the initial requirements for mode number estimation. We proposed a method for estimating the longitudinal mode number of a laser propagating in an external cavity diode laser with high accuracy, utilizing dual-periodic diffraction gratings. These gratings were fabricated using interference lithography. To estimate the mode number, the wavelengths of two different modes are compared. Therefore, the greater the difference between the wavelengths, the higher the accuracy of the mode number determination. While the mode number difference was approximately 35 when using a conventional diffraction grating, this could be increased by a factor of 20 to around 700 using the dual-periodic grating. The relative accuracy achieved was 1.4 × 10−5.

Ultrasonic attenuation measurements were conducted on cross-ply and quasi-isotropic lay-ups of eight types of carbon-fiber reinforced composites (CFRPs) using through-transmission methods with diffraction correction. Attenuation values were substantially higher than those of unidirectional composites and other structural materials. Wave modes, fiber distributions, matrix resins, and consolidation methods affected total attenuation. Transverse mode, quasi-isotropic lay-up, and polyimide and thermoplastic resins generally produced higher attenuation. No clear trends from the fiber distribution were revealed, indicating that it is not feasible presently to predict the attenuation of various lay-ups from the unidirectional values. That is, direct attenuation tests for different laminate lay-ups are needed. This work expanded the existing attenuation database by properly determining the attenuation coefficients of two additional layup types of CFRP laminates. Results showed the merit of ultrasonic attenuation measurements for quality control and structural health monitoring applications. A crucial benefit of the through-transmission methods is that they enable the prediction of Lamb wave attenuation in combination with software like Disperse (ver. 2.0.20a, Imperial College, London, UK, 2013). [ABSTRACT FROM AUTHOR]

This paper presents an application of Legendre polynomial approach to solve the wave propagation in a piezoelectric ZnO planar resonator subjected to stress-free boundary conditions and excited using two thin electrodes connected to an electrical source. The method is able to take into account the boundary conditions, the presence of electrical source and the different dissimilarities of the physical properties. Resonance frequencies of longitudinal modes are calculated in case of an open and short-circuit brunch. Dispersion characteristics are also calculated such as mechanical displacement and stress profiles for different resonance frequencies. The electromechanical coupling coefficient is also calculated. [ABSTRACT FROM AUTHOR]

In an asymmetric Au cubic trimer, influence of the rotation angle (θ) and side length (w) on both plasmonic coupling features and corresponding enhancement factor of hyper-Raman scattering (HRS) process have been investigated comprehensively under the illumination of a longitudinally polarized light. The finite-difference time-domain (FDTD) electrodynamic simulation tool has been employed to calculate the optical cross-section and associated nearfield intensity of the irradiated coupled resonators. As θ increases, the polarization state that dominates the coupling phenomenon is gradually switched from facing sides into facing edges which results in (1) a dramatic change in the spectral response of the trimer and (2) a significant improvement in the nearfield intensity that is directly related to the improvement of HRS signal. Breaking size symmetry of the cubic trimer provides a novel approach to reach the desired spectral response that permits such trimer to be used as an active substrate for HRS procedures. After optimizing both the orientation angle and size of the interacting plasmonic characters forming of the trimer, the enhancement factor of HRS process can reach a value never reported before as high as 1 × 1021. [ABSTRACT FROM AUTHOR]

Effective plasmonic heterotrimers of different geometry have been proposed as an active substrate to substantially enhance the scattered signal of hyper‐Raman scattering process. The three‐particle systems are constructed independently from asymmetric nanoparticles of spherical, cylindrical, and spheroidal shapes. The interacting metallic characters in each one of the three trimers are arranged collinearly in a J‐aggregate configuration and illuminated by a longitudinally polarized light. The finite‐difference time‐domain electrodynamic simulation tool is employed to simulate optical cross‐section and nearfield intensity associated with the excited plasmonic bands. The extinction profile of each one of the three trimers exhibits the excitation of two plasmonic modes. The first is a superradiant mode, which resulted from the in‐phase coupling between the dipole moments induced in each one of the three plasmonic elements. The second mode excited at a shorter wavelength, which is a combination between bright and dark modes (Fano interference). The resonance wavelength of the former mode matches the incident one; meanwhile, the resonance energy of the Fano profile is equivalent to the second‐order Stokes condition. From the values of the highly enhanced nearfield associated with the observation of these modes, the enhancement factor of the hyper‐Raman scattering process is calculated. The simulation results highlight the influence of the selected particle's geometry on both the quality of plasmonic coupling and calculated enhancement factor. The maximum value of the enhancement factor can reach as high as 3.83 × 1017 when the heterotrimer is constructed from spheroids. For nanoparticles of spherical shape, the calculated value of the factor is comparable to the maximum limit; meanwhile, the rod shape demonstrates the minimum limit of the enhancement factor. [ABSTRACT FROM AUTHOR]

In this paper, we experimentally investigated the mode configuration of an excited-state quantum dot laser (ESQDL) under concave mirror optical feedback, and the influences of the feedback strength on the mode characteristics were analyzed. The results showed that after introducing concave mirror optical feedback, some longitudinal modes of the excited-state (ES) existing in a free-running ESQDL could be suppressed. When the feedback strength increased to a certain extent, the ground-state (GS) emission occurred and co-existed with the ES emission. By further increasing the feedback strength, all the longitudinal modes of the ES emission were suppressed, and only the longitudinal modes of the GS emission could be observed. As a result, the emission-state switching from the ES to GS emission was realized. When the ESQDL was biased at a larger current, the feedback strength required to achieve emission-state switching was stronger. [ABSTRACT FROM AUTHOR]

The current study aims at comparing the impact of both the interparticle separation (g) and the longitudinal shift (h) on the plasmonic coupling features in a homodimer composed from two symmetric nanorods arranged in a side-to-side (SS) configuration. To achieve this, a Finite-Difference Time-Domain (FDTD) numerical tool is employed to calculate the optical properties of the dimer system as a function of both g and h under the illumination of both longitudinal and transverse lights. Despite the calculated spectral response of the transverse mode (TM) exhibiting very weak dependency on either g or h, the longitudinal mode (LM) demonstrates very interesting and distinguished optical characteristics in terms of the two structural parameters (g and h). When the value of g increases, the plasmonic coupling is significantly diminished and therefore both the resonance wavelength and the associated nearfield intensity of the observed LM are redshifted exponentially with g. As the two interacting rods are shifted away from each other by increasing h, the polarization state that dominates the plasmonic coupling is gradually switched from the facing sides pattern into the facing edges model and therefore both the charge density and the nearfield intensity of the LM are significantly enhanced. Surprisingly, depending on the relative value of h to the rod's length, as h increases, a redshift followed by a blueshift in both the resonance wavelength and nearfield intensity is observed in the excited LM. The type of the plasmon shift is mainly controlled by the in-phase/out-of-phase arrangement between the induced multipoles and the dipoles. By maintaining a constant value of g, the introduced non-alignment condition sheds the light on an innovative method to precisely control and gradually alters the spectral response of dimer systems to reach the desired optical properties for specific nanoplasmonic-based applications. [ABSTRACT FROM AUTHOR]

Ultrasonic attenuation measurements were conducted on cross-ply and quasi-isotropic lay-ups of eight types of carbon-fiber reinforced composites (CFRPs) using through-transmission methods with diffraction correction. Attenuation values were substantially higher than those of unidirectional composites and other structural materials. Wave modes, fiber distributions, matrix resins, and consolidation methods affected total attenuation. Transverse mode, quasi-isotropic lay-up, and polyimide and thermoplastic resins generally produced higher attenuation. No clear trends from the fiber distribution were revealed, indicating that it is not feasible presently to predict the attenuation of various lay-ups from the unidirectional values. That is, direct attenuation tests for different laminate lay-ups are needed. This work expanded the existing attenuation database by properly determining the attenuation coefficients of two additional layup types of CFRP laminates. Results showed the merit of ultrasonic attenuation measurements for quality control and structural health monitoring applications. A crucial benefit of the through-transmission methods is that they enable the prediction of Lamb wave attenuation in combination with software like Disperse (ver. 2.0.20a, Imperial College, London, UK, 2013).

A unique combination between structural parameters of collinearly arranged spherical particles is proposed as an effective plasmonic substrate for ultrahigh enhancement in hyper-Raman scattering signals. The suggested spherical trimer systems are mainly composed from two identical nanoparticle separated by a third alike shape resonator of different size. All the interacting plasmonic element are made from gold, arranged in 1D array and illuminated by a longitudinally polarized light. The optical properties, spatial distribution of nearfields and the surface charge densities were calculated numerically by FDTD tool. The enhancement factor of the hyper-Raman scattering, and the associated Raman shift were calculated theoretically from the optical response of the trimer. The extinction spectra of the heterotrimers demonstrate the excitation of two plasmonic modes, the first coupled band excited at a longer wavelength and is attributed to the in-phase coupling between the dipole moments induced in each of the three spherical resonators, the other hybrid mode observed in the shorter wavelength region and is resulted from the coupling between the dark mode excited in the intermediate particle and the bright band monitored in the bordered particles. The nearfields associated with the excitation of the two plasmonic modes are strongly localized and highly enhanced at the same intercoupling regions (hot spots) which optically match the excitation wavelength and the second-order stock condition. Through careful selecting of the relative size of the coupled nanoparticles and their coupling separation, the enhancement factor of hyper-Raman scattering signal can reach as high as 1Â Ă—Â 1013. [ABSTRACT FROM AUTHOR]

Featured Application: This paper presents the development of a longitudinal mode dynamic model via experiments of insect-like tailless flapping-wing micro air vehicles (FWMAVs). In this paper, model parameter identification results are presented for a longitudinal mode dynamic model of an insect-like tailless flapping-wing micro air vehicle (FWMAV) using angle and angular rate data from onboard sensors only. A gray box model approach with indirect method was utilized with adaptive Gauss–Newton, Levenberg–Marquardt, and gradient search identification methods. Regular and low-frequency reference commands were mainly used for identification since they gave higher fit percentages than irregular and high-frequency reference commands. Dynamic parameters obtained using three identification methods with two different datasets were similar to each other, indicating that the obtained dynamic model was sufficiently reliable. Most of the identified dynamic model parameters had similar values to the computationally obtained ones, except stability derivatives for pitching moment with forward velocity and pitching rate variations. Differences were mainly due to certain neglected body, nonlinear dynamics, and the shift of the center of gravity. Fit percentage of the identified dynamic model (~49%) was more than two-fold higher than that of the computationally obtained one (~22%). Frequency domain analysis showed that the identified model was much different from that of the computationally obtained one in the frequency range of 0.3 rad/s to 5 rad/s, which affected transient responses. Both dynamic models showed that the phase margin was very low, and that it should be increased by a feedback controller to have a robustly stable system. The stable dominant pole of the identified model had a higher magnitude which resulted in faster responses. The identified dynamic model exhibited much closer responses to experimental flight data in pitching motion than the computationally obtained dynamic model, demonstrating that the identified dynamic model could be used for the design of more effective pitch angle-stabilizing controllers. [ABSTRACT FROM AUTHOR]

The paper presents the design and fabrication of lateral-field-excited (LFE) resonators based on 42° Y-cut single-crystal LiTaO3 (LT) on silicon dioxide (SiO2). A simple coplanar top electrode is defined to excite the bulk acoustic wave modes in the suspended LT/SiO2 structure, and the fabrication process that only involves two lithography steps is more simplified compared to that of commercial film bulk acoustic wave resonators. For a model structure consisting of LT(670 nm)/SiO2 (1500 nm) thin film, two types of acoustic modes are both piezoelectrically active in the LT film: the first one is the thickness-shear mode with a resonance frequency of 2.46 GHz, an electromechanical coupling ( $k_{eff}^{2}$ ) of 1.4%, a high quality factor ( ${Q}$ ) of 1690, and the second one corresponds to longitudinal mode with a resonance frequency of 4.39 GHz, ${k} _{eff}^{2}$ of 1.2%, a high ${Q}$ of 1590, which is among the highest reported for piezoelectric MEMS resonators operating at this frequency range. The excellent performance would enable application scenarios including high-resolution sensors, low-phase-noise oscillators, and low-loss, high selectivity filters in the sub-6 GHz range for the fifth-generation (5G) wireless communication.

In this paper, we experimentally investigated the mode configuration of an excited-state quantum dot laser (ESQDL) under concave mirror optical feedback, and the influences of the feedback strength on the mode characteristics were analyzed. The results showed that after introducing concave mirror optical feedback, some longitudinal modes of the excited-state (ES) existing in a free-running ESQDL could be suppressed. When the feedback strength increased to a certain extent, the ground-state (GS) emission occurred and co-existed with the ES emission. By further increasing the feedback strength, all the longitudinal modes of the ES emission were suppressed, and only the longitudinal modes of the GS emission could be observed. As a result, the emission-state switching from the ES to GS emission was realized. When the ESQDL was biased at a larger current, the feedback strength required to achieve emission-state switching was stronger.

The existing yoke magnetizers can be used for large diameter bridge cable detection, but cannot provide the optimal bias magnetic field due to the repulsion of the polarities arranged in the circumferential direction, which reduces the energy conversion efficiency of the magnetostrictive longitudinal mode guided wave transducer. A magnetostrictive longitudinal mode guided wave transducer with the ring permanent biased magnet is provided to improve energy conversion efficiency for large diameter bridge cables. Firstly, a ring magnetizer for the axial magnetization is proposed, which inspired by the structure of the yoke magnetizer and the adjustable bias magnetic field generated by the solenoid coil. Then, the specific transducer with the ring magnetizers is designed for PES(C) 7–127 cable. Based on the magnetostrictive coupling coefficient curves and magnetization curve of the cable steel wire, the finite element models verify that the magnetization effect of the ring magnetizer is better than the yoke magnetizer for PES(C) 7–127 cables. Furthermore, the structural parameters of the ring magnetizers are optimized based on magnetization strength and magnetization uniformity. Finally, the improved efficiency of the transducer is verified by experiments. The energy conversion efficiency of the transducer is increased by 43.65% at the transmitting side, 4.76% at the receiving side, 48.41% at the both sides. Besides, the weight of the ring magnetizers is 19.85% lower than the yoke magnetizers. [ABSTRACT FROM AUTHOR]

In this paper, model parameter identification results are presented for a longitudinal mode dynamic model of an insect-like tailless flapping-wing micro air vehicle (FWMAV) using angle and angular rate data from onboard sensors only. A gray box model approach with indirect method was utilized with adaptive Gauss–Newton, Levenberg–Marquardt, and gradient search identification methods. Regular and low-frequency reference commands were mainly used for identification since they gave higher fit percentages than irregular and high-frequency reference commands. Dynamic parameters obtained using three identification methods with two different datasets were similar to each other, indicating that the obtained dynamic model was sufficiently reliable. Most of the identified dynamic model parameters had similar values to the computationally obtained ones, except stability derivatives for pitching moment with forward velocity and pitching rate variations. Differences were mainly due to certain neglected body, nonlinear dynamics, and the shift of the center of gravity. Fit percentage of the identified dynamic model (~49%) was more than two-fold higher than that of the computationally obtained one (~22%). Frequency domain analysis showed that the identified model was much different from that of the computationally obtained one in the frequency range of 0.3 rad/s to 5 rad/s, which affected transient responses. Both dynamic models showed that the phase margin was very low, and that it should be increased by a feedback controller to have a robustly stable system. The stable dominant pole of the identified model had a higher magnitude which resulted in faster responses. The identified dynamic model exhibited much closer responses to experimental flight data in pitching motion than the computationally obtained dynamic model, demonstrating that the identified dynamic model could be used for the design of more effective pitch angle-stabilizing controllers.

Purpose: To compare and report the intra- and postoperative outcomes of phacoemulsification between longitudinal (LPKE) and torsional (TPKE) mode, using active fluidics along with the intrepid balanced tip. Methods: This single center prospective randomized comparative study comprised a total 108 consecutive eyes of 108 patients having senile cataract subdivided into nuclear opalescence (NO) grades II–IV according to the lens opacities classification system III (LOCS III). Cataracts of each grade were randomly assigned to two groups LPKE (n = 54) and TPKE (n = 54) mode, who were operated on by the same surgeon using same machine (Centurion® Alcon Laboratories, Inc., USA) having features of both active fluidics and intrepid balanced tip. Pre-, intra-, and postoperative evaluations were done independently by a different author, who was masked to the surgical procedures. Patients were evaluated on the postoperative days (PODs) 1, 7, 15, and 28. Intraoperative outcome measures were cumulative dissipated energy (CDE) and ultrasound time (UST). Postoperative outcome measures were endothelial cell loss (ECL), central corneal thickness (CCT), and best-corrected visual acuity (BCVA). Results: Age, gender, and NO-grade distribution among two modes were comparable (P > 0.05). Difference of CDE and UST between modes were found to be significant (P < 0.001) in favor of TPKE with all NO-grades. TPKE mode performs better than LPKE mode with regard to ECL, CCT-change, and BCVA-change, although the differences were found to be insignificant (P > 0.05). Conclusion: When using active fluidics along with the intrepid balanced tip, TPKE mode appeared to be a more efficient mode of PKE with reduced mean UST and CDE across all NO-grades, as compared to LPKE mode. However, ECL, CCT-change, and BCVA-change were seemed to be comparable between the two modes.

To realize a single-longitudinal-mode laser diode (LD) with high speed direct-modulation, a coupled cavity DFB-LD with two phase-shifts is proposed. From simulated results, it is expected that the resonance frequency of 71.3 GHz and the 3-dB down bandwidth of 95.9 GHz are obtained when the injected current is 3.075 times the threshold current. The resonance frequency for a main-mode is enhanced by an interaction between the main-mode and sub-mode. This interaction is called photon–photon resonance. The proposed coupled cavity DFB-LD is composed of two regions which are connected in series. Both regions have phase-shifted gratings. The phase-shift of the first region is − π; the phase-shift of the second region is − 0.9π. A phase-shift is not introduced at the interface of the two regions. The corrugation pitch of the second region is shorter than that of the first region by 1.6 nm; the grating coupling coefficient is 40 cm−1; each region length is 300 μm. These parameters are modest to fabricate DFB-LDs. [ABSTRACT FROM AUTHOR]

A laser experiment based on Nd;YAG crystal was designed. By using cavity mirrors with special coatings, the transmission loss at each line was strictly controlled. Finally, a single and unconventional 1 123 nm line was obtained. The relationship between the average output power and energy distribution on cross-section of the 1 123 nm laser and the pump level and cavity length was also studied. With a pump power of 125 W and a cavity length of 310 mm, the average output power of the 1 123 nm laser is 11. 12 W, and the beam quality factors are 4.9 ± 0. 1 and 4. 6 ± 0. 1. The results show that higher pumping levels favor an increase in output power, but are accompanied by poorer beam quality, while larger cavity lengths result in improved beam quality. [ABSTRACT FROM AUTHOR]

The mode evolution of an InGaN blue laser diode with operating current and diode temperature was investigated. The spectra of a 445-nm InGaN blue laser diode with operating currents and diode temperatures was recorded using an ultrahigh resolution spectrometer and a scanning Fabry-Perot interferometer. The blue laser diode can deliver a mW-level single frequency beam with about 20 MHz linewidth at nearly above the lasing threshold. And the temperature-dependent wavelength drift was estimated as 0.31 nm for single longitudinal mode operation region. The spectra showed the number of the longitudinal modes increased with raising operating current. Analysis of the mode evolution of a blue laser diode with operating current and diode temperature is important when how to choose the laser diode for specific applications. [ABSTRACT FROM AUTHOR]

Coplanar electrodes are used with the c-axis-oriented piezoelectric film to form the pure longitudinal mode and the pure shear mode solidly mounted resonators (SMRs). Aluminum and molybdenum are used as electrode materials to achieve different excitation pure shear mode and pure longitudinal mode. There is no need to make a bottom electrode or etch the piezoelectric layer, which simplifies the manufacturing and makes the structure stable. Furthermore, the cycle time of the process is significantly reduced. However, the control of the thickness of the Bragg reflectors, roughness control, and electrode photolithography are all challenging aspects of SMR manufacturing. In this study, ZnO piezoelectric film, which has a good electromechanical coupling factor and low transmission loss, was used as the c-axis-oriented piezoelectric film. An RF magnetron sputtering system was used to sputter a seed layer to encourage the growth of the zinc-oxide piezoelectric film and improve the c-axis orientation. The pure longitudinal mode and pure shear mode resonance signals were excited using the room temperature positive axis method. The quality factor and electromechanical coupling coefficient of the pure shear mode were 398% and 4.43%, respectively. The quality factor and electromechanical coupling coefficient of the pure longitudinal mode were 171% and 3.83%, respectively. Stability and feature recognition were accomplished in the pure longitudinal mode and the pure shear mode via a simplified and accelerated manufacturing process using electrodes with the same specifications. [ABSTRACT FROM AUTHOR]

We consider the four-dimensional topologically massive electrodynamics in which a gauge field interacts with rank two antisymmetric tensor field through a topological interaction. The photon becomes massive by eating the rank two tensor field, which is dual to the Higgs mechanism. We explicitly demonstrate the nature of the mechanism by performing a canonical analysis of the theory and discuss various aspects of it. [ABSTRACT FROM AUTHOR]

In order to build a motion system with high resolution, fast response, and long travel range in a probe station, a linear ultrasonic motor was investigated as an alternative to the electromagnetic counterpart in a servo system. This work focused on a longitudinal composite-mode linear ultrasonic motor for the motion servo system in a probe station. The motor was designed based on the required specifications. A finite element model was built to analyze the dynamic response of the stator. The influence of the structural parameters on the dynamic performances, i.e., sensitivity parameters, was calculated to analyze the stability of the structure. Based on these analytical works, a prototype of the stator was developed and mode testing was conducted. The experimental results showed that the proposed design was able to achieve respectable performance: Despite the dual-mode design, the frequency difference between the two working modes was minimized to 608 Hz; and the prototype could operate stably under 55.4 kHz, providing a 0.5 N load with 980 mm/s speed.

Purpose: To compare and report the intra- and postoperative outcomes of phacoemulsification between longitudinal (LPKE) and torsional (TPKE) mode, using active fluidics along with the intrepid balanced tip.Methods: This single center prospective randomized comparative study comprised a total 108 consecutive eyes of 108 patients having senile cataract subdivided into nuclear opalescence (NO) grades II-IV according to the lens opacities classification system III (LOCS III). Cataracts of each grade were randomly assigned to two groups LPKE (n = 54) and TPKE (n = 54) mode, who were operated on by the same surgeon using same machine (Centurion® Alcon Laboratories, Inc., USA) having features of both active fluidics and intrepid balanced tip. Pre-, intra-, and postoperative evaluations were done independently by a different author, who was masked to the surgical procedures. Patients were evaluated on the postoperative days (PODs) 1, 7, 15, and 28. Intraoperative outcome measures were cumulative dissipated energy (CDE) and ultrasound time (UST). Postoperative outcome measures were endothelial cell loss (ECL), central corneal thickness (CCT), and best-corrected visual acuity (BCVA).Results: Age, gender, and NO-grade distribution among two modes were comparable (P > 0.05). Difference of CDE and UST between modes were found to be significant (P < 0.001) in favor of TPKE with all NO-grades. TPKE mode performs better than LPKE mode with regard to ECL, CCT-change, and BCVA-change, although the differences were found to be insignificant (P > 0.05).Conclusion: When using active fluidics along with the intrepid balanced tip, TPKE mode appeared to be a more efficient mode of PKE with reduced mean UST and CDE across all NO-grades, as compared to LPKE mode. However, ECL, CCT-change, and BCVA-change were seemed to be comparable between the two modes. [ABSTRACT FROM AUTHOR]

Summary: Pipe risers partially covered by a wall are difficult to test because the concrete causes large attenuation and mode conversion. Both reasons make it difficult to analyze the signal. This paper reports the design of an axial magnetized magnetostrictive patch transducer (AM‐MPT) for efficient transduction of longitudinal guided wave, which can be used to detect defects in concrete‐covered pipe risers. First, the paper started with a theoretical background about the influence of length‐to‐width ratio of the magnetized rectangular patch on the demagnetizing factors and the magnetic field intensity of the patch. Second, the simulation and experimental results proved that the length‐to‐width ratio of the magnetized iron cobalt patch has a great influence on its magnetic field intensity and signal amplitude of the AM‐MPT. Comparison experiments proved that the static magnetic field of AM‐MPT provided by an iron cobalt patch led to larger signal amplitudes than those provided by magnets. Third, the attenuation of L(0,2) in concrete‐covered pipe riser were studied using the AM‐MPT experimentally, which were according with disperse simulation results basically. And the experimental results proved that AM‐MPT was more suitable to be applied in concrete‐covered pipe risers testing than original MPT. Finally, the AM‐MPT was applied in a defect identification of concrete‐covered pipe riser sample. The experimental results for the AM‐MPT and the piezoelectric transducer showed that the AM‐MPT can potentially be applied in pipe riser defect identification. [ABSTRACT FROM AUTHOR]