Review of Scientific Instruments最新文献

Accurate quantification of Young's modulus in biological tissues enhances clinical accuracy in disease diagnosis, therapy, and prevention. Nevertheless, real-time, intraoperative measurement of Young's modulus in organs remains technically challenging. We propose a novel in situ tissue elasticity assessment method based on the principles of the rebound process, where a magnetized probe is used to impact the target tissue, and Young's modulus is calculated based on how quickly the probe rebounds. The proposed method was validated through a theoretical mechanical model and simulation. The measurement accuracy was verified by replicated measurements across different specimens. A portable handheld device was then developed and deployed for clinical feasibility validation in live animal models. Results demonstrate that the proposed method delivers accurate and reliable measurements. The proposed system offers a novel solution for Young's modulus measurement, which can be used for intraoperative conditions such as lesion assessment during hepatectomy and breast-conserving surgery.

Optical lattices formed by interfering laser beams are widely used to trap and manipulate atoms for quantum simulation, metrology, and computation. To stabilize optical lattices in experiments, it is usually challenging to implement delicate phase-locking systems with complicated optics and electronics to reduce the relative phase fluctuation of multiple laser beams. Here, we report a phase-locking-free scheme to implement an optical lattice by passing a single laser beam through a prism with n-fold symmetric facets and large apex angles. The scheme ensures a stable optical lattice since the interference occurs among different deflected parts of a single laser beam. Various lattice configurations, including a triangular lattice and a quasi-crystalline lattice with tenfold symmetry, are demonstrated. In both cases, stability measurements show a change of lattice constant and a drift of lattice position of less than 1.14% and 1.61% relative to the lattice constant.

A high-resolution spectroscopic system was installed on the Tokamak à Configuration Variable (TCV), whose toroidal lines-of-sight (LOS) cross the divertor region. This system simultaneously measures the Doppler broadening and Doppler shift of several spectral transitions to infer their associated ion temperatures (Ti) and the toroidal component of their flow velocities (Vi). Herein, TCV's Tangential Divertor Spectroscopy System (TDSS) is described, along with its data analysis procedure and the first simultaneous measurements of temperature and flow velocity of C2+, He+, and N+ ions. The TDSS can be configured with a range of LOS that can be tailored to different divertor magnetic configurations. To obtain high sensitivity and accuracy in the kinetic ion parameters, each LOS is complemented by a tangentially opposed LOS to achieve a velocity sensitivity of 2.5 km/s/pixel that implicitly annuls any spectroscopic first-order drifts. A spectral resolution of 0.2 Å allows for reliable temperature determination down to ∼1 eV for He ions and ∼3 eV for the heavier C and N ions. These abilities, together with TCV's plasma shaping and positioning flexibility, were used to obtain the poloidal distributions of Ti and Vi for several impurity ions across the divertor. These measurements, together with the TS measurements of Te and ne, can be used to study the convective vs conductive partitions of energy transport across the scrape-off-layer plasma, which is crucial to the physics of energy transport in the divertor.

In the present study, a practical method is proposed and validated for the simultaneous measurement of local flow velocity and temperature in liquid metals under magnetic fields. The method leverages the Seebeck effect to measure temperature and the electromotive force induced by the fluid's motion in a magnetic field to determine velocity. Theoretical analysis and experimental validation confirm the method's accuracy, with temperature deviations within 0.15 K and velocity measurements deviating less than 5%. The study introduces a combined potential method for measuring the Seebeck coefficient of liquid metals, which eliminates errors associated with temperature gradient measurements. Experiments demonstrate that the thermomagnetic effect has a negligible impact on potential measurements under the investigated conditions. This key finding validates a direct signal processing pathway, allowing for the precise determination of velocity by simply eliminating the now-quantified thermoelectric effects from the total measured signal. The findings highlight the method's potential for real-time flow monitoring in high-temperature, opaque fluids, offering significant advancements over traditional measurement techniques.

Maintaining the highest quality and output of photon science in the VUV-, EUV-, soft-, and tender-x-ray energy ranges requires high-quality blazed profile gratings. Currently, their availability is critical due to technological challenges and limited manufacturing resources. In this work, we show the developed method for manufacturing blazed gratings relevant for synchrotron-based science by means of electron-beam lithography (EBL). We investigate different parameters influencing the optical performance of blazed profile gratings and develop a robust process for the manufacturing of high-quality blazed gratings using polymethyl methacrylate as a high resolution positive tone resist and ion beam etching. Finally, we demonstrate excellent agreement in efficiency between the produced EBL grating and the theoretical prediction.

In this work, we stabilize a 1556.2 nm fiber laser to the 5S1/2 → 5D5/2 two-photon transition in 87Rb in a carefully designed compact physics package. A commercial fiber frequency comb divides the optical frequency into 200 MHz microwave output, which demonstrates a fractional frequency stability of 2.2 × 10-13 at τ = 1 s and 8.1 × 10-15 at τ = 4000 s, without linear drift removal. We analyze the systematic effect on the short-term and long-term stabilities in detail. The short-term and long-term stabilities are limited by shot noise and ac Stark shift, respectively. The rubidium two-photon optical clock is a promising candidate for the next-generation space-borne atomic clock.

The growing applications of pulse power technology demand higher precision in pulse waveforms. The LC-Marx circuit, a promising topology, offers advantages, such as fast rise time and high energy density, but suffers from a fundamental limitation: an inherent oscillatory output that prevents the generation of stable flattop pulses. This study addresses this long-standing challenge by introducing a novel synergistic method that integrates multi-frequency resonant superposition with a precision active drive delay compensation strategy. While the principle of Fourier synthesis is well-understood, our primary innovation lies in its successful practical implementation within a multi-stage resonant LC-Marx architecture. We demonstrate that active timing control is the critical enabling technique for compensating for non-ideal component tolerances, transforming the native oscillating decay pulse into a high-fidelity quasi-square waveform. Through theoretical analysis, circuit simulation, and experimental validation, we demonstrate that actively synchronizing the third harmonic's zero-crossing point is critical for waveform shaping. Experimental results show a dramatic improvement in pulse top ripple from over 20% to less than 5%, successfully demonstrating the generation of an approximate square wave. This work expands the applicability of compact LC-Marx generators for advanced pulsed power applications requiring high-fidelity waveforms, such as medical electroporation and semiconductor processing.

A multi-slit nozzle valve, hereafter referred to as the "Synthesizer," with five independent plena was designed, manufactured, and characterized to be used as a gas target for laser-plasma interaction experiments. The reported approach allows one to control the density profile over a wide range of density modulations. To illustrate the flexibility of the multi-slit valve, we present the cases of two different lengths slit nozzles. The 3D gas flow simulations predict a density distribution similar to the measured results, giving the option for future computerized designs of gas load, according to the user's desire. Interestingly, one specific gas load configuration indicates a potential for laser guiding of relevance for laser wakefield acceleration.

A direct current-alternating current (DC-AC) separated photodiode detector has been developed and optimized for the signal characteristics of photothermal heterodyne imaging (PHI). The detector features a large photosensitive area (diameter = 5 mm), a flat frequency response, and a single-photodiode design. The gains of the DC and AC signal channels can be independently configured, for example, a gain of 103 for the DC signal and 105 for the AC signal. The cutoff frequency is set to 1.6 kHz, and the -3 dB bandwidth of transimpedance amplifier reaches about 5.8 MHz. This detector is easy to operate, highly resistant to external noise, and meets the imaging requirements of PHI experiments.

In response to the current issues of high cost, low accuracy, and inability to protect the original battery quality in electrolyte concentration measurement methods, a concentration prediction method based on RF coaxial probe and Levenberg-Marquardt Backpropagation neural network is proposed. First, a neural network prediction system for electrolyte concentration based on a coaxial probe is constructed. Then, it is compared with the Backpropagation (BP) neural networks optimized by the Bayesian regularized training method and BP neural networks optimized by the quantitative conjugate gradient method. The results show that this method has higher prediction accuracy. Taking zinc trifluoromethanesulfonate [Zn(CF3SO3)2] electrolyte as an example, a series of concentration measurement experiments are carried out using an RF coaxial probe to verify the method's feasibility. The experimental results show that the RF coaxial probe neural network concentration prediction method can effectively measure the electrolyte concentration, with a maximum relative error of only 4.42% and a maximum absolute error of 4.94%. These data indicate that the proposed prediction method has high accuracy and reliability for measuring water-based electrolyte concentration and can predict the electrolyte concentration in real-time.