- 标题
- 摘要
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- 实验方案
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Resolution-enhanced imaging using interferenceless coded aperture correlation holography with sparse point response
摘要： interferenceless coded aperture correlation holography (i-coAcH) is a non-scanning, motionless, incoherent digital holography technique. in this study we use a special type of i-coAcH in which its point spread hologram (pSH) is ensemble of sparse dots. With this pSH an imaging resolution beyond the classic diffraction limit is demonstrated. This resolution improvement is achieved due to the position of the coded aperture between the object and the lens-based imaging system. the coded aperture scatters part of the light, that otherwise is blocked by the system aperture, into the optical system, and by doing that, extends the effective numerical aperture of the system. The use of sparse PSH increases the signal-to-noise ratio of the entire imaging system. A lateral resolution enhancement by a factor of about 1.6 was noted in the case of I-COACH compared to direct imaging.
关键词： resolution enhancement,signal-to-noise ratio,interferenceless coded aperture correlation holography,incoherent digital holography,sparse point response
更新于2025-09-23 15:19:57
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Microfluidic shear rheology and wall-slip of viscoelastic fluids using holography-based flow kinematics
摘要： In this study, we report microfluidic shear rheology and wall-slip using the 3D-resolved flow kinematics obtained from digital holography microscopy (DHM). We computationally reconstruct the recorded holograms to visualize the tracer imbued flow volume in linear microchannels, followed by the implementation of particle tracking velocimetry (PTV) to quantitate spatially resolved velocity fields in 3D. In order to select optimal parameters for DHM-PTV characterization of viscoelastic fluids, we studied the effect of the hologram recording distance, seeding density, and particle size. Using the optimal parameters, we show quantitative characterization of the shear rheology from the velocity fields without any a priori assumptions of wall boundary conditions or constitutive equation. The viscosity vs shear rate data for Newtonian and polyethylene oxide (PEO) solutions could be measured in the range of ≈0.05 to 20 000 s?1 with just three input pressures using sample volumes as low as 20 μl. These data from holographic shear rheometry were found to be in good agreement with computational fluid dynamics simulations and macrorheometry. With respect to the wall-slip, we find that highly viscoelastic PEO solutions can show slip lengths in the order of few microns. Finally, we discuss holographic visualization of particle migration in microfluidic flows, which can limit flow field access, whereas at the same time provide a fingerprint of the suspending fluid rheology.
关键词： viscoelastic fluids,particle tracking velocimetry,wall-slip,digital holography microscopy,microfluidic shear rheology
更新于2025-09-23 15:19:57
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Application of Infrared Digital Holography for Characterization of Inhomogeneities and Voluminous Defects of Single Crystals on the Example of ZnGeP2
摘要： In this work, the method of IR digital holography intended for detection of volumetric defects in ZnGeP2 single crystals has been tested. The holographic method is veri?ed by a comparison of the results obtained with the data obtained by other methods. The spatial resolution of the experimental setup is ~15–20 μm. The volumetric defects of the ZnGeP2 crystal structure (in samples with thickness up to 50 mm) such as growth striations, dislocation chain, and inclusions of the second phase (Zn3P2) shaped as needles up to ~100 μm long and ~10 μm wide have been visualized by the method of IR digital holography.
关键词： digital holography,single crystals,inhomogeneities,ZnGeP2,voluminous defects
更新于2025-09-23 15:19:57
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Optical Fiber Applications || Optical Fibers Profiling Using Interferometric and Digital Holographic Methods
摘要： Optical fibers are extensively used in modern technology such as sensing, short-distance and long-distance telecommunications. This motivated many researchers to present different methods in order to characterize optical fibers and determine their refractive index profiles. In addition, variation of refractive index profiles of optical fibers suffering mechanical stresses or other external effects reflects good information about the internal structure of these fibers and how they are responding to these external effects. Optical interferometry and digital holography methods are accurate and effective tools used to achieve this task. In this chapter, we illustrate the application of different types of optical interference on conventional, polarizing maintaining and thick optical fibers. Also, we illustrate some mathematical interpretations (and recently automatic analyzing of interference patterns) that have been used to reconstruct the accurate refractive index profiles of optical fibers. Some experimental interferograms and refractive index profiles are demonstrated as well.
关键词： optical interferometry,refractive index profile,digital holography,optical fiber,interferogram analyses
更新于2025-09-23 15:19:57
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Digital holography for non-invasive quantitative imaging of two-dimensional materials
摘要： Digital holography has found applications in many walks of life, from medicine to metrology, due to its ability to measure complex fields. Here, we use the power of digital holography to quantitatively image two-dimensional Transition Metal Dichalcogenides (TMDs) such as MoS2 and WS2 placed on a SiO2/Si substrate and determine their complex refractive indices or layer thicknesses. By considering the different refractive indices of the TMDs as they are thinned down from bulk to monolayers and by holographically capturing both the amplitude and the phase of reflected light, single atomic layers of TMDs, about 0.7 nm thick, can be resolved. Using holography, we also predict the number of layers contained within a thick TMD flake, which shows agreement with results obtained using Atomic Force Microscopy (AFM). A Bland–Altman analysis was performed to compare our experimental results with the standard AFM measurements, yielding a limit of agreement <5 nm for samples with thicknesses ranging from 15 to 60 nm. Our technique is non-contact, non-invasive, does not require scanning, and produces a field of view of a few hundred micrometers by a few hundred micrometers in a single capture. To further our study, we also perform simulations to demonstrate how the thickness of the SiO2 layer and the laser wavelength are critical in optimizing the amplitude and phase response of a two-dimensional material. These simulations can be used as a roadmap to determine the ideal wavelength and SiO2 layer thickness that should be used to accurately determine the refractive index or thickness of any given sample.
关键词： digital holography,Atomic Force Microscopy,layer thicknesses,Bland–Altman analysis,Transition Metal Dichalcogenides,two-dimensional materials,complex refractive indices
更新于2025-09-23 15:19:57
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Deep Learning for Computational Mode Decomposition in Optical Fibers
摘要： Multimode ?bers are regarded as the key technology for the steady increase in data rates in optical communication. However, light propagation in multimode ?bers is complex and can lead to distortions in the transmission of information. Therefore, strategies to control the propagation of light should be developed. These strategies include the measurement of the amplitude and phase of the light ?eld after propagation through the ?ber. This is usually done with holographic approaches. In this paper, we discuss the use of a deep neural network to determine the amplitude and phase information from simple intensity-only camera images. A new type of training was developed, which is much more robust and precise than conventional training data designs. We show that the performance of the deep neural network is comparable to digital holography, but requires signi?cantly smaller efforts. The fast characterization of multimode ?bers is particularly suitable for high-performance applications like cyberphysical systems in the internet of things.
关键词： mode decomposition,deep learning,few-mode ?ber,digital holography
更新于2025-09-19 17:13:59
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[Institution of Engineering and Technology 20th Italian National Conference on Photonic Technologies (Fotonica 2018) - Lecce, Italy (23-25 May 2018)] 20th Italian National Conference on Photonic Technologies (Fotonica 2018) - Polarization digital holography for birefringence characterization of sperm cells
摘要： Birefringence in sperm heads depends on a very compact and organized structural normality. Additionally, when the acrosome reaction happens, due to a reorganization of the proteins, the birefringence occurs only in the post-acrosomal region. Thus, the polarization state of the semen is an interesting method to characterize their healthy state and to select reacted sperm cells. In this paper, a characterization of the birefringence pattern of sperm head by polarized digital holography microscopy is presented as a label free technique.
关键词： Digital holography,Sperm selection,Digital morphology,Sperm texture,Birefringence
更新于2025-09-16 10:30:52
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Reflection in-line and off-axis hybrid digital holography
摘要： We propose an in-line and off-axis hybrid holographic method for imaging reflective objects. The in-line and off-axis digital holograms are recorded by a Michelson interferometer. The approximate phase of object wave is obtained by spectral filtering approach from the off-axis hologram, and it is used as an initial input in an iterative procedure for retrieving the complex field of the object from the in-line hologram. In this way, the output of the iterative procedure can produce higher quality amplitude and phase images compared to only in-line or off-axis digital holography. The performance of this method has been demonstrated by acquiring the amplitude and phase images of a resolution target and a microelectronic chip.
关键词： Reflective object,Phase retrieval,Spectral filtering,Digital holography
更新于2025-09-16 10:30:52
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[IEEE 2018 17th Workshop on Information Optics (WIO) - Québec, QC, Canada (2018.7.16-2018.7.19)] 2018 17th Workshop on Information Optics (WIO) - Grating-assisted spatial phase-shifting incoherent digital holography with compressive sensing for noise reduction
摘要： We have proposed grating-assisted spatial phase-shifting incoherent digital holography for capturing holograms of dynamically moving objects. With our method, four individual self-reference holograms of a spatially incoherent light are simultaneously created on an image sensor. Thus, it is possible to detect complex amplitude distribution from a single captured image by using a phase-shifting technique. In the present study, we aim to improve the quality of reconstructed images in our method by introducing compressive sensing. To validate the effectiveness of compressive sensing in our method, a 3D image was reconstructed from detected complex amplitude distribution by enforcing the sparsity constraint on the total variation of a signal. As a result, the introduction of compressive sensing can effectively reduce noise and out-of-focus artifacts in our method.
关键词： phase-shifting interferometer,3D imaging,diffractive optical element,compressive sensing,digital holography
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - In Flow Manipulation and Characterization of Cancer Cells by Coherent Computational Microscopy
摘要： Liquid biopsy has shown remarkably promising in oncology for the early diagnosis of cancer through the detection of circulating biomarkers such as circulating tumor cells (CTCs). Recent evidences suggest that CTCs represent effective prognostic and predictive biomarkers to monitor/predict therapy efficacy in breast, colon and prostate cancers [1,2]. However, the frequency of CTCs in blood is approximately 1 to 10 cells per 10 mL of blood, which is as challenging as looking for a needle in a haystack. In microfluidics, Digital Holography (DH) has been shown to be a promising technique to characterize CTCs with the aim to detect them inside a heterogeneous liquid sample. DH is label-free, real-time and gives access to the complex amplitude of the object [3-6]. Thus, any classification approach based on the holographic signature can exploit a reach information content to take a decision. Moreover, the flexible refocusing capability of DH imaging allows to inspect an entire liquid volume with a single capture. This enables the high-throughput inspection of blood and other bodily fluids rapidly flowing inside microfluidic channels. In DH, the sample is probed from one single direction and the phase delay introduced by the sample in through transmission acts as a contrast agent. Hence, the optical thickness measurable by DH imaging is an integral information, i.e. the sum of all the contributions experienced by the coherent light during its passage through the sample. In order to decouple the refractive index from the physical thickness and to resolve its distribution along the optical axis, tomography exploits multiple recordings, probing the sample from different angles and combining the corresponding phase-contrast maps [7,8]. Various schemes have been proposed to minimize the number of sampling angles and to make the recording stage faster in order to match the requirements and time constraints imposed by real biological problems. Here we show the recent advances of in-flow holographic tomography, which exploits a controlled induced rotation of the sample inside the microfluidic channel to probe it from different view angles with no mechanical rotation of the source beam [8,9]. We introduce an effective algorithm to recover from the recorded phase maps the set of angles required as input of the optical projection tomography algorithm [7-9]. We show the application of holographic flow tomography to the characterization of different cancer cells [10], namely breast cancer cells, ovarian cancer cells and neuroblastoma. We also discuss different possibilities of Lab-on-a-Chip design and flow engineering that allow us to induce controlled rotations while maintaining the high-throughput nature of DH microscopy [9,11,12]. In the next future, the large amount of data obtainable by this approach will be used to train a neural network devoted to classify CTCs, distinguishing them from the other components of a blood stream.
关键词： liquid biopsy,cancer cells,microfluidics,circulating tumor cells,holographic tomography,Lab-on-a-Chip,digital holography
更新于2025-09-16 10:30:52