Axial Range Research Articles

Chromatic confocal displacement measurement using a double-sided phase diffractive lens

A chromatic confocal displacement measurement (CCDM) system using a double-sided phase diffractive lens (DPDL) is demonstrated. The DPDL is designed to produce a strong dispersion, minimize the optical structure and reduce the difficulty of fabrication and assembly, in addition to reducing the weight and size of the probe of the CCDM. A CCDM experimental system was set up based on the DPDL, and the results of the measurement experiments show that the axial measurement range of the CCDM system reaches 9.463 mm in the working wavelength range (500-700 nm), the relative error is less than 0.022% and the axial resolution near the designed focal length is better than 0.5 µm.

Long-Axial-Range Double-Helix Point Spread Functions for 3D Volumetric Super-Resolution Imaging.

Single-molecule localization microscopy (SMLM) is a powerful tool for observing structures beyond the diffraction limit of light. Combining SMLM with engineered point spread functions (PSFs) enables 3D imaging over an extended axial range, as has been demonstrated for super-resolution imaging of various cellular structures. However, super-resolving structures in 3D in thick samples, such as whole mammalian cells, remains challenging as it typically requires acquisition and postprocessing stitching of multiple slices to cover the entire sample volume or more complex analysis of the data. Here, we demonstrate how the imaging and analysis workflows can be simplified by 3D single-molecule super-resolution imaging with long-axial-range double-helix (DH)-PSFs. First, we experimentally benchmark the localization precisions of short- and long-axial-range DH-PSFs at different signal-to-background ratios by imaging fluorescent beads. The performance of the DH-PSFs in terms of achievable resolution and imaging speed was then quantified for 3D single-molecule super-resolution imaging of mammalian cells by DNA-PAINT imaging of nuclear lamina protein lamin B1 in U-2 OS cells. Furthermore, we demonstrate how the use of a deep-learning-based algorithm allows the localization of dense emitters, drastically improving the achievable imaging speed and resolution. Our data demonstrate that using long-axial-range DH-PSFs offers stitching-free, 3D super-resolution imaging of whole mammalian cells, simplifying the experimental and analysis procedures for obtaining volumetric nanoscale structural information.

High coupling efficiency with large axial direction coupling adjustment range in water-jet guided laser

In the traditional water-jet guided laser (WJGL) processing system, convex lens is used to focus Gaussian laser beam, where the waist and divergence angle are constrained. The focal depth is small, and there are problems such as divergence angle and aberration, which results in the difficult coupling adjustment because the adjustment range of laser coupling to water-jet fiber is limited to the Rayleigh range. In this study, non-diffraction laser (NDL) is generated by an axicon, which has the characteristics of small central spot and large non-diffraction range (NDR). The axial random coupling is realized in the NDR, and the problem of axial coupling between the focused laser and the water-jet generated by nozzle micro-hole is solved. Besides, this paper presents a novel technique to generate NDL by the combination of concave axicon (CCA) and convex axicon (CVA), which solves the small cone angle of the single CVA and the non-modulation defect of the corresponding optical and mechanical structure, and extends the starting point of the NDR to improve the coupling utilization rate of the NDR and the flexibility of the system. The focusing and coupling transmission characteristics of convex lens and axicons mode in WJGL are compared and analyzed. The generated NDL in the NDR at the axial reference coordinate point position of 50 mm and 70 mm is successfully coupled into the water-jet fiber. After the coupling transmission of 20 mm, the coupling efficiency, the morphology of the transmitted spot and the peak power density were basically the same, and the coupling efficiency of the central spot was about 81 %. However, the output spot peak power density and coupling efficiency decrease sharply when the axial coupling deviation exceeds 5 mm adopting convex lens. In contrast, the NDL can achieve a random coupling with high axial coupling tolerance in NDR. The research provides a solution for efficient adjustment and transmission of laser coupling into water-jet in highly stable WJGL.

A thermo-mechanical coupling load model for high-frequency piezoelectric ultrasonic transducer

The ultrasonic micromachining systems significantly improve machining efficiency and quality, which is increasingly being applied in the manufacturing of microstructures and micro parts. However, the mechanical and thermal loads of the high-frequency piezoelectric ultrasonic transducer (HPUT) of ultrasonic micromachining systems have serious interference with the precise control of resonance frequency tracking, which further causes uncontrollable processing quality and precision. To improve the controllability of resonance frequency tracking, a thermo-mechanical coupling load model for HPUTs is proposed to establish the relationship between the resonance frequency and thermo-mechanical coupling load by introducing the force load constants and thermal load constants into the 6-terminal network electromechanical equivalent circuit. The experimental results show that the proposed thermo-mechanical coupling load model can accurately predict the trend of the resonance frequency when the thermo-mechanical coupling load is under the axial force range of 0–10 N and temperature range of 35-60℃.

Speckle Characteristic Based Auto-focusing Approach for Diffuse Object in Digital Holography

Multi-wavelength digital holography extends the axial measurement range to the order of several tens of microns or more and makes the inspection of optical-rough objects and objects with steep slopes possible. As the optical-rough surface would superimpose speckle field on hologram, the existing focus evaluation criteria frequently fail in indicating correct reconstruction distance. This paper proposes a focus evaluation algorithm for focus detection of diffused surfaces. The average size of the speckle is used as the index and the average size of speckle is evaluated through morphological image processing. Two roughness specimens and a gear tooth are used as test pieces to validate the feasibility of the proposed method. Compared with the existing image focus evaluation method, the proposed morphological average size of speckle approach shows good robustness and sensitivity to various kinds of diffusing surface of mechanical parts.

Coherent linking between confocal amplitude image and confocal phase image in dual-comb microscopy

We propose a method for integrating confocal amplitude and phase images obtained through dual-comb microscopy (DCM). DCM combines the benefits of confocal laser microscopy and quantitative phase microscopy, offering high axial resolution and scan-less imaging. By leveraging the coherence between confocal amplitude and phase images within the same DCM system, we accurately determine the number of phase wrapping iterations, thereby eliminating ambiguity in phase wrapping. We demonstrate this approach using samples with micrometer-range optical thickness and nanometer-scale surface roughness. The results demonstrate an expanded axial range, spanning from micrometers to millimeters, while maintaining nanometer-level axial resolution. This integrated DCM imaging technique enables the simultaneous acquisition of confocal amplitude image and absolute phase image, thus enhancing its potential for wide-axial-dynamic-range imaging across various applications.

Long-Range Three-Dimensional Tracking of Nanoparticles Using Interferometric Scattering Microscopy.

Tracking nanoparticle movement is highly desirable in many scientific areas, and various imaging methods have been employed to achieve this goal. Interferometric scattering (iSCAT) microscopy has been particularly successful in combining very high spatial and temporal resolution for tracking small nanoparticles in all three dimensions. However, previous works have been limited to an axial range of only a few hundred nanometers. Here, we present a robust and efficient measurement and analysis strategy for three-dimensional tracking of nanoparticles at high speed and with nanometer precision. After discussing the principle of our approach using synthetic data, we showcase the performance of the method by tracking gold nanoparticles with diameters ranging from 10 to 80 nm in water, demonstrating an axial tracking range from 4 μm for the smallest particles up to over 30 μm for the larger ones. We point out the limitations and robustness of our system across various noise levels and discuss its promise for applications in cell biology and material science, where the three-dimensional motion of nanoparticles in complex media is of interest.

Numerical Study on Pressure Fluctuation in Electric Coolant Pump

Abstract Adjusting the flow rate of an electronic coolant pump (ECP) over a wide range can cause significant internal pressure fluctuations, leading to vibration and noise. This study uses numerical simulation to compare pressure fluctuations at the backflow orifice and within the impeller of an ECP at various flow rates. The backflow creates periodic disturbances in the impeller inlet region. As the flow rate increases, the axial influence range of the backflow on the impeller inlet decreases, reducing the amplitude of pressure fluctuations by up to 7.9%. The characteristic frequencies of pressure fluctuations at the backflow orifice include the blade passing frequency and its first harmonic. Within the impeller, the pressure fluctuation amplitude increases with both flow direction and flow rate, with characteristic frequencies encompassing the rotational frequency, BPF, and its first harmonic. At low flow rates, the overall variation of pressure fluctuations inside the impeller shows an opposite trend compared to design and high flow rates. The impact of the rotational frequency on pressure fluctuations inside the impeller is significantly smaller at the design flow rate than at other flow rates. This study offers insights that can help optimize ECP design and enhance their operational performance.

Self-interference digital holography with computational aberration correction

Self-interference digital holography (SIDH) enables 3D imaging of incoherently emitting objects over a large axial range using only three 2D images. Our previous research demonstrated that point-like sources emitting as few as 4,200 photons can be reconstructed over a 10 µm axial range. Combining SIDH with single-molecule localization microscopy (SMLM) has the potential to achieve 3D super-resolution imaging across a large axial range without mechanical refocusing of the sample. However, optical aberrations affect the localization performance of SIDH and must be corrected, especially for large-volume 3D imaging. In this paper, we propose a fast, guide-star-free computational aberration correction method for SIDH. Our method can correct optical aberrations in low signal light conditions over the entire imaging axial range without any additional hardware. We use a sensorless-AO method in a virtual pupil plane to optimize the wavefront based on a frequency-space metric. Using this method, we demonstrate an improvement in both the Strehl ratio up to ∼0.98 and the SIDH localization precision to near the ideal case.

Feasibility of a deep-inspiration breath-hold [18F]AlF-NOTA-LM3 PET/CT imaging on upper-abdominal lesions in NET patients: in comparison with respiratory-gated PET/CT

PurposesTo explore the clinical feasibility and efficacy of a deep inspiration breath-hold (BH) PET/CT using [18F]AlF-NOTA-LM3 on upper abdominal lesions in patients with neuroendocrine tumors (NETs).MethodsTwenty-three patients underwent a free-breath (FB) whole-body PET/CT, including a 10 min/bed scan for the upper abdomen with a vital signal monitoring for respiratory gating (RG) followed by a 20-second BH PET/CT covering the same axial range. For the upper abdomen bed, the following PET series was reconstructed: a 2-min FB PET; RG PET (6 bins); a 20-second and 15-second BH PET (BH_15 and BH_20). Semi-quantitative analysis was performed to compare liver SUVmean, lesion SUVmax, MTV, its percentage difference and target-to-background ratio (TBR) between both BH PET and RG PET images. Subgroup analysis considered lesion location, MTV and SUVmax. A 5-point Likert scale was used to perform visual analysis and any missed or additional lesions were identified compared with RG PET.ResultsQuantitative analysis on overall lesions (n = 78) revealed higher SUVmax and TBR, and smaller MTV for both BH PET compared to FB and RG PET, with lesion location-specific variations. Neither significant difference was observed in all metrics between RG and FB PET in larger lesions, nor in MTV in lower-uptake lesions. However, both BH PET significantly enhanced these measurements. In the visual analysis, both BH PET showed noninferior performance to RG PET, and were evaluated clinically acceptable. Additional and missed lesions were observed in FB and both BH PET compared with RG PET, but didn’t alter the clinical management. The BH_15 PET showed comparable performance to BH_20 PET in any comparison.ConclusionThe BH PET/CT using [18F]AlF-NOTA-LM3 is effective in detecting upper abdominal lesions, offering more accurate quantitative measurements. Using a novel PET/CT scanner, a 15-second BH PET can provide comparable and superior performance to RG PET, indicating potential feasibility in clinical routines.

Mixing Of A Starting Turbulent Jet In Homogeneous And Isotropic Turbulence

The mixing of a starting turbulent jet, injected with an injection velocity of U = 18.8 m/s from a tube with a diameter of D = 4mm (Reynolds number Re = 4800, characteristic time scale t* = D/U = 0.21 ms at the nozzle exit), is experimentally investigated in the presence of homogenous and isotropic turbulence (HIT) using Planar Laser-induced Fluorescence (PLIF). The root-mean-square (RMS) velocity of the ambient HIT is 0.38 and 0.63 m/s, corresponding to turbulent Reynolds numbers of Reλ = 190 and 250, respectively. Spatial distributions of mixture fraction and scalar dissipate rate (SDR) were measured within an axial range of y = 0 – 10 D and at different times after the start of injection (ASIs) up to 21.4 t*. Ambient HIT did not alter the location or size of the leading vortex ring in the initial formation stage. However, it was able to enhance the entrainment of ambient fluids in this stage and deform/transport both the leading and the trailing vortex rings at later stages, despite that the ASIs examined were only comparable to its Kolmogorov timescale. Ambient HIT also introduced a significant increase to the fluctuations of the jet penetrations length but only a marginal reduction (less than 10%) to the averaged jet penetration speed. PDFs of the ensemble averaged mixture fraction within the whole jet region showed increased probability of low mixture fraction values – and therefore indicating enhanced entrainment and mixing – in the presence of ambient HIT. Ensemble averaged distributions of the SDR showed no significant alterations by the ambient HIT in the initial formation stage of the leading vortex ring. At later stages, while the high SDRs in the leading vortex ring remained concentrated in a layer along the edge of the vortex ring for Reλ = 0, it became increasingly uniformly distributed with a lower maximum value as the ambient HIT increased. Similar, but less significant, impact of the ambient HIT on the SDR fields was observed in the trailing vortex rings, while no noticeable impact was found in the shear layer close to the nozzle exit.

Dual-wavelength spiral interferometry.

Spiral interferometry acquires the topography of the sample and determines the elevation or depression of the sample structure by a single measurement. The method has advantages in simple measurements and stable optical setup due to the coaxial interferometer. However, the measurable axial range was limited by the wavelength of the light. Here, we demonstrate dual-wavelength spiral interferometry without a significant modification to the original setup of the spiral interferometry. The retrieved phase profile using a synthesized wavelength of 3.33 µm enlarges the measurable axial range with a magnification factor of 6.2 compared with that measured by the light at 532 nm.

Axial de-scanning using remote focusing in the detection arm of light-sheet microscopy

Rapid, high-resolution volumetric imaging without moving heavy objectives or disturbing delicate samples remains challenging. Pupil-matched remote focusing offers a promising solution for high NA systems, but the fluorescence signal’s incoherent and unpolarized nature complicates its application. Thus, remote focusing is mainly used in the illumination arm with polarized laser light to improve optical coupling. Here, we introduce a novel optical design that can de-scan the axial focus movement in the detection arm of a microscope. Our method splits the fluorescence signal into S and P-polarized light, lets them pass through the remote focusing module separately, and combines them with the camera. This allows us to use only one focusing element to perform aberration-free, multi-color, volumetric imaging without (a) compromising the fluorescent signal and (b) needing to perform sample/detection-objective translation. We demonstrate the capabilities of this scheme by acquiring fast dual-color 4D (3D space + time) image stacks with an axial range of 70 μm and camera-limited acquisition speed. Owing to its general nature, we believe this technique will find its application in many other microscopy techniques that currently use an adjustable Z-stage to carry out volumetric imaging, such as confocal, 2-photon, and light sheet variants.

Directly measured strain patterns of the anterior talofibular and calcaneofibular ligaments after isolated ATFL repair in a combined ATFL and CFL injury: A cadaver study

BackgroundEven though 20% of chronic lateral ankle instability results from a combined anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) injury, only the ATFL is sutured using arthroscopic ligament repair techniques. Although some biomechanical and clinical studies have proved that isolated ATFL repair yields excellent results, previous biomechanical studies were performed using systems that only allow indirect estimations. The purpose of this study was to clarify strain patterns by directly measuring repaired ATFL and CFL strain patterns on cadaveric models that underwent isolated ATFL repair of a combined ATFL and CFL injury. MethodsThe miniaturization ligament performance probe (MLPP) system was used for directly measuring the strain patterns to insert the strain gauges into the mid-substance of normal and repaired ATFL and CFL fibers in five cadaveric specimens to allow measurement of strain patterns in the axial and three-dimensional motion of the ankle. ResultsThe normal and repaired ATFL showed similar strain patterns in axial and three-dimensional motions. During the axial range of motion of the ankle, the repaired CFL showed a strain pattern almost similar to that of normal CFL, but the strain increased as the plantar flexion or dorsiflexion angle increased to the maximum value of 100 at 30° plantarflexion or strain values of 17–55/100 at 15°dorsiflexion. During three-dimensional motion, the repaired CFL was under the maximum value of 100 during dorsiflexion-inversion and exhibited less strain (7–38/100) during plantar flexion-eversion. ConclusionThe repaired CFL did not show a strain pattern that was completely consistent with a normal strain pattern; however, it did have some degree of tension similar to a normal strain pattern, even though it was not directly repaired.

Off-Axis Co-Optical Path Large-Range Line Scanning Chromatic Confocal Sensor

This article proposes a line scanning chromatic confocal sensor to solve the problem of limited chromatic confocal measurement due to the small measurement range and low measurement efficiency in the industrial inspection process. To obtain an extensive dispersion range, the advantages of a simple single-axis structure are combined with the advantages of a large luminous flux of a biaxial structure. Considering large-scale measurement, our sensor uses off-axis rays to limit the illumination path and imaging path to the same optical path structure. At the same time, the field of view is expanded, and a symmetrical structure is adopted to provide a compact optical path and improve space utilization. The simulation and physical system test results shows that the sensor scanning line length is 12.5 mm, and the axial measurement range in the 450 nm to 750 nm band is better than 20 mm. The axial resolution of the detector is ±1 µm combined with the subpixel centroid extraction data processing method, and the maximum allowable tilt angle for specular reflection samples is ±7°. The thicknesses of transparent standard flat glass and the wet collagen membrane are measured. The maximum average error is 1.3 µm, and the relative error is within 0.7%. The constructed sensor is of great significance for rapidly measuring the three-dimensional profile, flatness, and thickness in the fields of transparent biological samples, optics, micromechanics, and semiconductors.

C-Slot Circular Polarized Antenna for Hybrid Energy Harvesting and Wireless Sensing

This paper presents a new hybrid energy harvesting on electromagnetic solar for wireless energy harvesting of ambient from sensors of low-power devices. The axial ratio (AR) requirements produce Left-Hand Circular Polarization (LHCP) and Right-Hand Circular Polarization (RHCP) and simultaneously produce a 90-degree phase difference during energy harvesting, adopting a new design in designing a dual-feed broadband circular polarized (CP) antenna. To get the frequency band 2.3–2.4 GHz, we propose a C-Slot antenna with a circular patch dual feed. To estimate the diversity of the phase and magnitude output of the feed configuration under AR value, we used a 50 Ohm feed network output of the characteristic analysis for a dual feed CP antenna. An Axial ratio frequency range of less than 3 dB is achieved using polarization analysis with different branch channel couplers. To produce a DC output voltage, a high-frequency rectifier circuit embedded with a thin-film solar cell on the antenna is then connected to two T-junction power divider rectifiers, resulting in a high-efficiency design. A complete system-level analysis will include multiple signal classification methods of powered ambient RF energy using a wireless energy harvesting array that proposes a compact structure and demonstrates optimal configuration. Reliable operation in typical indoor environments indicates a self-contained sensor Node. Therefore, it has significant implications for powering small electronics and wireless sensor applications independently of the IoT Network or real implementation telecommunications industry.

DL-EDOF: Novel Multi-Focus Image Data Set and Deep Learning-Based Approach for More Accurate and Specimen-Free Extended Depth of Focus.

Depth of focus (DOF) is defined as the axial range in which the specimen stage moves without losing focus while the imaging apparatus remains stable. It may not be possible to capture an image that includes the entire specimen in focus due to the narrow DOF in microscopic systems. Extended depth of focus (EDOF) is used to overcome this limitation in microscopic systems. Although the researchers have developed so many EDOF microscope approaches, this research field still has some crucial shortcomings such as high computational costs, complexity and execution time, requiring additional equipment, low precise characterization of curves, and edges in images, varying performance depending on the specimen and microscope, using only gray levels of input images to acquire the pixel's focus values. In order to minimize these shortcomings and comprehensively analyze the performance of EDOF approaches, a novel multi-focus image data set is generated, and a deep learning-based EDOF microscope approach is proposed in this study. When compared with the state-of-art EDOF approaches, our study provides various crucial contributions such as the first EDOF approach based on unsupervised deep learning, providing more accurate and specimen-free EDOF, generating a novel multi-focus image data, not requiring any pre- or post-processing technique and acquiring the pixel's focus degrees using deep features. In order to evaluate the effectiveness of the suggested approach, 20 different EDOF approaches are applied to a multi-focus image data set containing 9 image collections (4 synthetic and 5 microscope image collections) in total. Performance analysis metrics with and without requiring a reference image are preferred to identify which EDOF microscope approach can extract more essential details from the multi-focus images for the synthetic and microscope image collections, which are Root Mean Square Error (RMSE), Peak Signal Noise Ratio (PSNR), Universal Quality Index (UQI), Correlation Coefficient (CC), Perception-based Image Quality Evaluator (PIQE), Blind/Referenceless Image Spatial Quality Evaluator (BRISQUE), Extension of Universal Quality Index for N Images (UQIN), and Naturalness Image Quality Evaluator (NIQE). Objective and subjective analysis of this study demonstrates that unsupervised deep learning model is more efficient to transmit crucial details from multi-focus images. Moreover, the suggested EDOF microscope approach with highest PSNR, UQI, CC, UQIN and lowest RMSE, PIQE, BRISQUE, NIQE produces higher performance than the state-of-art approaches.

Research on the influence of heat release from cement hydration on the mechanical properties of casing

In order to study the influence of cement hydration heat release on the mechanical properties of casing, this paper calculates the wellbore temperature and pressure field based on the mathematical model of steady-state heat conduction of casing-cement ring-formation rock, establishes a mathematical model for the mechanical evaluation of cement hydration heat release and casing interaction, and performs finite element calculation and experimental simulation of the effect of cement hydration heat release on casing loss, and the results show that the results show: Along the axial direction of the wellbore, the maximum stress on the entire cement ring occurs in the lower position of the cement ring, and the maximum deformation on the casing occurs in the middle position. The axial stress variation range of the middle part of the casing is 50MPa, and the strain is 0.12%; The axial stress variation range of the outer ring is 235MPa, and the strain is 0.09%; The circumferential stress of the middle part varies from 500MPa to 0.255%. It is found that the stress and strain in the middle part of cement sheath are large, and yield is prone to occur. Under the action of cement hydration heat release, the long-axis elliptical deformation of (7.15∼31.8) mm occurs in the casing, that is, a large ovality is produced, which weakens the collapse strength of the casing. Two repeated tests showed that under the cement hydration heat release condition at the casing loss position, the temperature change of 60°C caused the increase of axial force of casing column and the increase of annular air pressure, which caused the non-uniform deformation of casing under the composite load of external extrusion and compression axial force.

Axial Range Expansion Method for Multi-Differential Confocal Three-Dimensional Imaging

Axial Range Expansion Method for Multi-Differential Confocal Three-Dimensional Imaging

Dual-wavelength Fourier ptychographic microscopy for topographic measurement.

Topographic measurements of micro- or nanostructures are essential in cutting-edge scientific disciplines such as optical communications, metrology, and structural biology. Despite the advances in surface metrology, measuring micron-scale steps with wide field of view (FOV) and high-resolution remains difficult. This study demonstrates a dual-wavelength Fourier ptychographic microscopy for high-resolution topographic measurement across a wide FOV using an aperture scanning structure. This structure enables the capture of a three-dimensional (3D) sample's scattered field with two different wavelength lasers, thus allowing the axial measurement range growing from nano- to micro-scale with enhanced lateral resolution. To suppress the unavoidable noises and artifacts caused by temporal coherence, system vibration, etc., a total variation (TV) regularization algorithm is introduced for phase retrieval. A blazed grating with micron-scale steps is used as the sample to validate the performance of our method. The agreement between the high-resolution reconstructed topography with our method and that with atomic force microscopy verified the effectiveness. Meanwhile, numerical simulations suggest that the method has the potential to characterize samples with high aspect-ratio steps.