- 标题
- 摘要
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- 实验方案
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Electrochemical and surface deformation studies on electrodeposited nanostructured Bi2Te3 thin films
摘要： In this article, we have used double exposure digital holographic interferometry (DEDHI) technique for surface deformation study and hologram recording during synthesis of the Bi2Te3 thin films by electrodeposition method. The synthesized Bi2Te3 thin films were characterized structural, morphological, electrochemical, wettability and surface deformation study. Further the holograms are recorded during the electrodeposition process by varying the concentration of electrolyte. From the recorded fringes the stress, deposited mass and thickness have been calculated. It is observed that the fringe width, mass of deposited thin films, and stress to substrate changes with the concentration of electrolyte. The DEDHI technique is found more reliable for thickness measurement in electrodeposition process. The EIS study confirms that the deposited material is highly conducting.
关键词： Bi2Te3,EIS,Holography,DEDHI,Electrochemical properties,Electrodeposition
更新于2025-11-14 15:16:37
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Three-dimensional holographic imaging using data collected over cylindrical apertures
摘要： The previously proposed near-field holographic imaging algorithms are based on the data collected over rectangular apertures. In this letter, we propose an approach for three-dimensional near-field holographic imaging with data collected over cylindrical apertures. Circular deconvolution is employed to deal with the periodicity of the functions along the azimuthal direction.
关键词： holography,microwave imaging,non-destructive testing
更新于2025-09-23 15:23:52
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An optical asymmetric encryption scheme with biometric keys
摘要： In this paper, an asymmetric cryptosystem for optical image encryption using biometric keys is proposed based on the phase retrieval algorithm and the phase-truncated Fourier transforms (PTFT) scheme which addresses the issue of key distribution with enhanced security in the optical encryption process. In the proposed system, the encryption keys include optically generated biometric keys and the random phase mask keys of the PTFT scheme, while the decryption keys are kept as the private key in terms of the binary key and the generated phase-only mask of the PTFT scheme. If a person is authorized to retrieve the biometric keys by providing the fingerprint hologram and reconstruction parameters at the receiver stage, then the proposed system satisfies the criteria of asymmetric cryptography with information authentication approach. The biometric key features, by using the digital holography are kept secure and is utilized in both the encryption and decryption operations so that the authenticity of the ciphertext by using the biometric keys can be verified during the decryption process. Numerical simulations are carried out to test the effectiveness and validity of the proposed system.
关键词： Authentication,Fingerprint biometric key,Asymmetric cryptosystem,Digital holography,Optical encryption and decryption
更新于2025-09-23 15:23:52
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Hyperspectral holographic microscopy of bio-objects based on a modified Linnik interferometer
摘要： We present a modified Linnik microinterferometer that can register image-plane hyperspectral holograms in reflection of various microobjects in incoherent light. A voice coil was integrated into the reference arm of the interferometer to enable mirror displacement. A set of interferograms is registered in each pixel of a high-speed CMOS camera. Post processing yields spectrally resolved image-plane holograms of the object. Quantitative phase images of red blood cells are obtained for each spectral component σ = 1/λ.
关键词： microscopy,Linnik interferometer,holography,white light interferometry,Fourier transform microspectroscopy
更新于2025-09-23 15:23:52
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Speckle-free common-path quantitative phase imaging with high temporal phase stability using a partially spatially coherent multi-spectral light source
摘要： Quantitative phase imaging (QPI) has been an important technique for the determination of various biophysical parameters, such as the refractive index and morphology of biological cells and tissues. The technique has been implemented using off-axis and common path digital holographic microscopy (DHM). Off-axis DHM, though being ideal for QPI, offers lower temporal phase stability compared to common path techniques. Common path DHM offers a higher temporal phase stability but, being a coherent imaging technique, suffers from speckle artefacts and spurious interference fringes due to the high coherence of the light source. Both artefacts not only degrade the image quality, but also affect the phase measurement results. In this paper, we report the implementation of common path QPI set-up using a partially spatially coherent multi-spectral light source. The spatial coherence of the red and green color lasers is reduced by using a rotating diffuser. Also, a speckle free QPI was implemented using common path Fresnel biprism interferometer. A Fresnel biprism is used in the self-referencing mode, thus offering the advantage of no optical power loss in addition to high temporal stability and the least speckle artefacts. Furthermore, it is very easy to implement, as the system completely replaces the need for spatial filtering at the source end as well as for the reference beam generation. The experiments have been carried out on industrial and biological samples to prove the effect.
关键词： phase measurement,Fresnel biprism interferometer,digital holography,coherence
更新于2025-09-23 15:23:52
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Holographic colour prints for enhanced optical security by combined phase and amplitude control
摘要： Conventional optical security devices provide authentication by manipulating a specific property of light to produce a distinctive optical signature. For instance, microscopic colour prints modulate the amplitude, whereas holograms typically modulate the phase of light. However, their relatively simple structure and behaviour is easily imitated. We designed a pixel that overlays a structural colour element onto a phase plate to control both the phase and amplitude of light, and arrayed these pixels into monolithic prints that exhibit complex behaviour. Our fabricated prints appear as colour images under white light, while projecting up to three different holograms under red, green, or blue laser illumination. These holographic colour prints are readily verified but challenging to emulate, and can provide enhanced security in anti-counterfeiting applications. As the prints encode information only in the surface relief of a single polymeric material, nanoscale 3D printing of customised masters may enable their mass-manufacture by nanoimprint lithography.
关键词： holography,colour prints,anti-counterfeiting,optical security,phase and amplitude control
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - Hangzhou (2018.8.13-2018.8.17)] 2018 IEEE International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO) - Optimization of Phase Noise in Digital Holographic Microscopy
摘要： A phase noise optimizing method was proposed in this paper to improve the imaging quality of digital microscopic holography (DHM). In this method, bidimensional empirical mode decomposition (BEMD) was utilized to decompose the digital hologram. According to the principle of decomposition, the characteristics of first order intrinsic mode function (IMF1) are close to the gray value of ideal interference fringes. Therefore, after using BEMD method the digital hologram was optimized with enhanced interference fringes, from which phase image with reduced noise can be retrieved. The validity of the proposed method on noise reduction was verified by experimental results on a nano-step.
关键词： digital holography,phase,bidimensional empirical mode decomposition,noise
更新于2025-09-23 15:22:29
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Evolution of volatile cloud in pulverized coal combustion with high-speed digital inline holographic visualization
摘要： The coal devolatilization plays a significant role in the combustion of pulverized coal particles. The evolution of volatile cloud during devolatilization of pulverized coal particles (105–125 μm) is studied in a high-temperature flat-flame burner by combining high-speed photography with high-speed digital inline holography (DIH). By the high-speed holographic visualization, the evolution of volatile cloud of pulverized coal from volatile release to soot aggregation generation can be divided into four stages. Effects of coal type on volatile cloud evolution are investigated using three different coals, i.e., Shanxi bituminous coal, Ximeng lignite and Yinni lignite. The results show that both the Shanxi bituminous coal and Ximeng lignite produce soot aggregation during devolatilization, which is rarely observed for Yinni lignite. Moreover, Shanxi bituminous coal has a higher potential in soot cluster formation for its higher coal rank than Ximeng lignite. The high-speed reconstructed image sequences are analyzed to measure the velocity slip between the parent particle and volatile cloud. Compared with Shanxi bituminous coal, Ximeng lignite exhibits a larger slip velocity. This work also demonstrates that high-speed DIH has the powerful capacity of directly observing the evolution of volatile cloud, and helps to gain a deep understanding of pulverized coal combustion.
关键词： Volatile cloud,Coal combustion,High-speed digital inline holography,Soot aggregation,High-speed photography
更新于2025-09-23 15:22:29
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Simultaneous Generation of Complex Structured Curve Beam
摘要： At present, people are using holographic technologies to shape complex optical beams for both fundamental research and practical applications. However, most of the reported works are focusing on the generation of a single beam pattern based on the computer-generated hologram (CGH). In this paper, we present a method for simultaneously shaping the multiple beam lattice where the intensity and phase of each individual beam can be prescribed along an arbitrary geometric curve. The CGH that is responsible for each individual beam is calculated by using the holographic beam shaping technique, afterwards all the CGHs are multiplexed and encoded into one phase-only hologram by adding respective linear phase grating such that different curves are appeared in different positions of the focal regions. We experimentally prove that the simultaneous generation of multiple beams can be readily achieved. The generated beams are especially useful for applications such as multitasking micro-machining and optical trapping.
关键词： computer holography,beam shaping,spatial light modulation
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Krakow (2018.10.16-2018.10.18)] 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Noise-filtering method for large-scale holographic 3D display
摘要： In a digital holographic display, it is not desirable to observe the conjugate image and zeroth-order diffracted light in the reconstructed image. To remove noise, various methods have been proposed to limit the noise bandwidth in the Fraunhofer region using optics. In general, a 4-F relay optic-based noise-filtering system is used in these noise-filtering methods. However, in the case of a holographic display configuration, where a conventional 4-F relay optics-based noise-filtering optical system is applied, the optical performance at a critical level is required because the diffraction angle and display area become larger. Here, we propose parallel noise filtering as a new method to remove the optical noise in a holographic display. The proposed parallel noise-filtering method can be achieved by applying a new noise-filtering optical system based on 2-F relay optics. The proposed technique significantly reduces the burden on the holographic display optics configuration and dramatically reduces the optical path to enable a holographic display with a commercially available form factor.
关键词： Noise filtering,Holography,3D display
更新于2025-09-23 15:22:29