
Zhengjun LiuHarbin Institute of Technology | HIT · School of Physics
Zhengjun Liu
Ph.D
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254
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Introduction
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August 2007 - present
Publications
Publications (254)
Lens-free on-chip microscopy (LFOCM) is a high-throughput computational imaging technique that enables high-resolution, label-free imaging without requiring complex optical systems. However, LFOCM encounters significant challenges in achieving high-resolution reconstructions due to noise accumulation. We propose a high-fidelity LFOCM method that in...
We introduce what we believe is a novel approach for wavefront reconstruction by a laterally moving lens, in conjunction with amplitude-phase retrieval. Compared to axial multiple-image phase retrieval methods, the proposed lateral methodology exhibits superiority of accuracy. To minimize the effect of position error of lens, we have also developed...
We introduce a kind of radially polarized partially coherent beam with a prescribed sinh-Gauss non-uniform correlation structure, named a radially polarized sinh-Gauss non-uniformly correlated (RPSNC) beam. Utilizing the ordinary Huygens–Fresnel principle, we derive the analytical formulas for the spectral intensity and the spectral degree of polar...
Structured illumination microscopy (SIM) is a widely applied fluorescence super-resolution imaging technique. It can also serve as high-throughput imaging in coherent imaging systems. However, coherent SIM requires additional qualitative/quantitative phase imaging methods to acquire phase information. This paper proposes a structured illumination m...
Coherent diffraction imaging (CDI) is a lens-free imaging paradigm that avoids the diffraction limit caused by lens chromatic aberration. However, due to the ill-posed problem of phase retrieval, experiments often require the collection of multiple diffraction patterns for image reconstruction, which limits its application in dynamic imaging scenar...
In fine-grained sentiment analysis, a burgeoning and exceptionally challenging subtask is Aspect Sentiment Triplets Extraction (ASTE). This task aims to extract aspect terms, and opinion terms, and determine their corresponding sentiment polarity from a given sentence. Most previous research has focused primarily on creating novel tagging schemes t...
SAR-to-optical (S2O) translation is able to covert SAR into optical images, which help the interpreter to extract information efficiently. In the absence of strictly matched datasets, it is difficult for existing methods to complete training on unpaired data with a minimum amount of data. By employing the recent Schrödinger bridge-based transformat...
Quantitative phase imaging (QPI) has emerged as a practical technique for acquiring structural information from phase objects. Digital holography can realize phase detection, but it is limited by a spatial bandwidth product or affected by the overlap of conjugate images. The phase retrieval algorithm serves as an effective tool for QPI dealing with...
In the realm of natural language processing (NLP), aspect-based sentiment analysis plays apivotal role. Recently, there has been a growing emphasis on techniques leveraging GraphConvolutional Neural Network (GCN). However, there are several challenges associated withcurrent approaches: (1) Due to the inherent transitivity of CGN, training inevitabl...
Traditional encryption algorithms like DES suffer from the issue of key length (128 bits to 256 bits) and the inconvenience of memorization. Users typically store keys in a file or device, or even directly on a computer hard drive, releasing the key through a relatively easy-to-remember passphrase. Addressing these issues, this paper proposes a nov...
As a multimodal form of hate speech on social media, hateful memes are more aggressive and
cryptic threats to the real life of humans. Automatic detection of hateful memes is crucial, but the images and texts in most memes are only weakly consistent or even irrelevant. Although existing works have achieved the initial goal of detecting hateful mem...
As a multimodal form of hate speech on social media, hateful memes are more aggressive and cryptic threats to the real life of humans. Automatic detection of hateful memes is crucial, but the images and texts in most memes are only weakly consistent or even irrelevant. Although existing works have achieved the initial goal of detecting hateful meme...
A monochromatic coherent light field can be represented by a two-dimensional complex amplitude, and the amplitude part of the complex amplitude is defined as the phase of the light field.
Prior to the introduction of the theory of Compressive Sensing (CS), traditional signal acquisition relied upon the Nyquist theorem.
In this chapter, fluorescence imaging and microscopy are introduced in detail. It is the fundamental mechanisms, different imaging modalities and complex techniques facing the frontiers of biological and medical research. A comprehensive overview of fluorescence imaging and microscopy is given, including advanced techniques as well. From understand...
Babkock proposed the use of a wavefront sensor to detect wavefront aberration information and then utilize deformable optical elements to generate controllable optical phase shifts for compensating wavefront aberrations, giving rise to the fundamental concept of adaptive optics. Leighton developed a first-order active optical system for compensatin...
Computed tomography (CT) imaging is a non-invasive diagnostic technique and is widely used for severe diseases in the field of medical imaging. X-ray beam, γ-ray, ultrasonic and other signals, are employed to detect the cross-sectional scanning of a certain part of the human body with high sensitivity. CT has the characteristics of fast scanning ti...
While traditional imaging methods utilize light reflected or scattered from an object for imaging, where light from the object plane is transmitted to the detector plane and the CCD receives the light field information for direct imaging, ghost imaging is a technique that uses optical correlation for imaging.
Polarization imaging is a technique that involves capturing and analyzing the polarization properties of light to obtain additional information about a scene or an object.
The progression of human society has always been intertwined with scientific exploration. Visual information, as the most intuitive and explicit form of data, has become one of humanity's primary ways of acquiring information. Nevertheless, human visual capabilities have always been limited. To overcome this, people have combined specific optical p...
Ordinary lenses cannot reflect, refract or focus X-rays, so coded aperture imaging arises at the historic moment. Modulation masks can change the distribution of beam in imaging systems. This chapter introduces the theoretical basis of coded aperture imaging technology and the basic structure of the computational imaging models. Then the method of...
Computational holography combines traditional optical imaging with computational techniques, which can improve the capabilities of a camera, and reduce the cost and size of camera elements. In this chapter, the theoretical basis and application of the computer generated holography is introduced. First, principles and reconstruction algorithms of di...
Autofocus technology is a crucial technique in computational optical imaging. The clarity evaluation function (CEF) serves as the criterion for autofocus, making it the core of the autofocus algorithm. In this paper, we propose a CEF based on amplitude differences of fractional Fourier transform (ADFrFT). ADFrFT extracts information from the fracti...
Speckle-correlation optical scattering imaging (SCOSI) has shown the potential for non-invasive biomedical diagnostic applications, which directly utilizes the scattering patterns to reconstruct the deep and non-line-of-sight objects. However, the course of the translation of this technique to preclinical biomedical imaging applications has been po...
Ultrasound coupling is one of the critical challenges for traditional photoacoustic (or optoacoustic) microscopy (PAM) techniques transferred to the clinical examination of chronic wounds and open tissues. A promising alternative potential solution for breaking the limitation of ultrasound coupling in PAM is photoacoustic remote sensing (PARS), whi...
Traditional single-pixel imaging (SPI) encounters challenges such as high sampling redundancy and poor imaging quality, constraining its widespread application. Despite a range of orthogonal modulation modes have been employed in structured illumination to enhance imaging performance, some encoding issues still persist in information sampling, impe...
We report a new computational imaging methodology for complex optical field based on a single-frame diffraction intensity pattern acquisition with a simplified aperture and an extremely low-cost industrial machine vision camera. The current design of the apertures for the recovery of complex optical field was suffering from specific coding associat...
In this paper, we present an optical video encryption system based on an improved 3D Arnold model in Gyrator domains. For the sake of convenience, we present a concept of four-dimensional image model for video data. After converting satellite video data into a four-dimensional image model, a module movement scrambling algorithm is designed to addre...
Hao Shen Xiangru Liu Qi Cui- [...]
Wei Liu
Photoacoustic microscope (PAM) with a low-optical NA suffers from a limited view along the optical axis, due to the coherent cancellation of acoustic pressure waves after being excited with a smoothly focused beam. Using larger-NA (NA > 0.3) objectives can readily overcome the limited-view problem, while the consequences are the shallow working dis...
Annular-illumination quantitative phase imaging based on Kramers–Kronig relations (AIKK) achieves a large space-bandwidth-time product. The reconstruction algorithm is non-iteration, parameter-free, and object-independent constitutionally. Based on the observation and analyticity of intensity spectrum characteristics and symmetry in spatial and fre...
A dual-color watermarking algorithm using elliptical monogenic wavelet transform and singular value decomposition is proposed. Firstly, the original host image and two color watermark images are decomposed into RGB components. Arnold transform is employed to scramble the RGB components of the second watermark image. Secondly, those RGB components o...
In multi‐distance coherent diffraction imaging (MDCDI), the task of distance calculation for multi‐diffraction images is cumbersome. The information features are hard‐to‐extract and the region of interest extraction algorithms are difficult to be adopted. A universal salient feature region selection algorithm by using the area with the highest dens...
A novel optical image encryption is proposed based on multiplexing of the random phase encoding with shift and rotation operations in domains of two transforms, extended fractional Fourier transform (eFrFT) and Fresnel transform. The original image is subjected to eFrFT with the action of the random phase mask. The mask is shifted and rotated to en...
For most optical encryption mechanisms, craft precision of phase modulation components is finite, restricting information efficient sharing and compatibility with processing. We demonstrate an alternative method with strong practicability in which a random phase is modulated by multiplexed sensing without optical elements, releasing the constraints...
Two remote sensing image encryption algorithms based on the randomness of audio channel sequences are proposed and their robustness is verified by many attack experiments. The first encryption algorithm uses the randomness of audio to encrypt image pixels in RMD. Compared with traditional image encryption algorithms, this algorithm has high randomn...
A secondary particle filter (SPF) inversion method for geostationary space object characteristics based on ground photometric data is presented. The method combines the estimation results of the standard particle filter (PF) algorithm and the resampling algorithm of the particle generation process. SPF first generates N particles according to the s...
In this paper, a novel secure image signal transmission scheme was proposed in wireless systems, in which the poly-polarization filtering and the orthogonal matrix (PPF-OM) were combined to protect the image signal and eliminate the polarization dependent loss (PDL) at the same time, which was caused by the non-ideal wireless channel. This scheme d...
In this chapter, the methods of image encryption and decryption based on optical transformation are introduced. The extended fractional Fourier transform is constructed by designing an eccentric lens group, and is used in the image encryption system. By using the Fresnel diffraction model, an iterative phase recovery algorithm is constructed, and a...
In this chapter, the methods of image encryption and decryption based on optical transformation are introduced. The extended fractional Fourier transform is constructed by designing an eccentric lens group, and is used in the image encryption system. By using the Fresnel diffraction model, an iterative phase recovery algorithm is constructed, and a...
Ptychography is a lens-free imaging method which can outstrip the resolution limitations of optical apparatuses, even so the algorithm automatically totes background noise during the imaging process. In order to rehabilitate a more exquisite image, an adaptive iterative guided filtering method is designed. The guided filter is incorporated into the...
In the present methods of multiple intensity measurements, the recorded different intensity patterns are supposed to have the identical quality and the contribution of different images to the result is the same. However, intensity patterns are of different quality, since the raw patterns are affected by environment noise and focusing distance in th...
Speckle correlation techniques based on the memory effect can recover objects from multiple scattered light without the information of the scattering media. The existing methods, however, are limited by the inherent angular width of the memory effect, and the retrieval algorithms frequently converge to erroneous solutions. In this paper, we propose...
This paper presents an image fusion network based on a special residual network and attention mechanism. Compared with the traditional fusion network, the image fusion network has the advantages of an end-to-end network and integrates the feature extraction advantages of the attention mechanism residual network. It overcomes the shortcomings of the...
Recent experiment reveals that the dielectric response to the bias electric field has obvious dependence on the frequency, which is mainly manifested in strong field-enhanced effect and weak field-enhanced effect, and reveals the novel mechanism behind this behavior. We find that the strong field-enhanced effect is caused by electromechanical coupl...
We introduce a kind of radially polarized partially coherent (RPPC) beam with a prescribed non-uniform correlation function, called a radially polarized cosine non-uniformly correlated (RPCNUC) beam. Based on the extended Huygens–Fresnel principle, we study the propagation properties in free space and in a turbulent atmosphere. Unlike RPPC beams wi...
Auto-focusing is an essential task for lensfree holographic microscopy, where the optimal focal plane needs to be determined from refocused Z-stack data. In this work, we propose a new auto-focusing criterion, nuclear norm of gradient (NoG), to enhance the accuracy of distance estimation for lensfree imaging. The NoG metric is composed of three par...
A novel optical image encryption is proposed based on multiplexing of the random phase encoding after shift and rotation operations in domains of extended fractional Fourier transform (eFrFT) and Fresnel transform. The original image is subjected to eFrFT with the action of the random phase mask. The mask is shifted and rotated. The image obtained...
The distance errors in coherent diffraction imaging degrade reconstructed images. In this paper, a fast auto-positioning algorithm based on subdivision search is proposed to calculate the position of each image. The search scheme can obtain diffraction distances quickly and accurately. For the same range and search accuracy, the calculation speed o...
A novel optical signature and authentication cryptosystem is proposed by applying triangular association encryption algorithm (TAEA) and 3D Arnold transform in Gyrator domains. Firstly, a triangular association encryption algorithm (TAEA) is designed, which makes it possible to turn the diffusion of pixel values within bands into the diffusion with...
Focusing objects accurately over short time scales is an essential and nontrivial task for a variety of microscopy applications. In this Letter, an autofocusing algorithm using pixel difference with the Tanimoto coefficient (PDTC) is described to predict the focus. Our method can robustly distinguish differences in clarity among datasets. The gener...
Recent experiments have revealed that the order of the electro-optic (EO) effect depends on the frequency of electric field in paraelectric nanodisordered KTa1-xNb x O3 (KTN) crystal. Through the dielectric frequency spectrum under the bias electric field, enormous linear and quadratic EO effects were discovered at the resonance frequencies, which...
For lensless diffraction imaging, it is a challenging dilemma to achieve a large field of view (FOV) and high resolution with a small amount of data at the same time. Ptychography can reconstruct the high-resolution image and illumination light simultaneously. But the illumination is limited to a small size by a probe in typical ptychography. For l...
We present a compact optical encryption scheme by using a continuous-random-motion blurring model in an optical imaging system. Image encryption is performed by additive motion blur effects with continuous and random shifts of a camera. Real-time random phase modulation can be achieved without the use of random phase mask. Storage of the key is mor...
Annular-illumination quantitative phase imaging based on space-domain Kramers–Kronig relations (AIKK) is a newly developed technique that is object-independent and non-iterative reconstructed inherently. Only capturing four low-resolution images, the AIKK system gains a resolution enhancement of nearly twofold. Under matching constraints between th...
We propose a novel single-plane phase retrieval method to realize high-quality sample reconstruction for lensfree on-chip microscopy. In our method, complex wavefield reconstruction is modeled as a quadratic minimization problem, where total variation and joint denoising regularization are designed to keep a balance of artifact removal and resoluti...
An optical color image cryptosystem is presented by using bit-level modified integer nonlinear coupled chaos model in Fresnel diffraction domains. Firstly, a bit-level modified integer nonlinear coupled chaos model (INCCM) controlled by linear feedback shift register (LFSR) is designed. Subsequently, a framework of LFSR controlling image encryption...
Recent experiments have revealed an unusual electro-optic (EO) effect in relaxor KTa1-xNbxO3 (KTN) crystals. Our study reveals that the frequency dependence of EO effect is discrete, which can be attributed to multiscale polar nanoregions (PNRs). Traditionally, the EO effect of relaxor KTN is typically attributed to the relaxation of PNR subject to...