Aiming at some common problems of the current dual-wavelength multi-step phase-shifting interferometric imaging method, a dual-wavelength generalized phase-shifting interferometric imaging method is proposed in this work. In this method, the phase shift can be any value within (0, ), which need not be a special value or a known value, and the introduced phase shift of two wavelengths is independent of each other. By calculating the difference between each two phase-shifted interferograms and the Hilbert transform values, the introduced phase shift can be calculated, and then the wrapped phase distribution at a single wavelength can be calculated, and finally the continuous phase under the synthetic wavelength can be obtained. Then through a series of simulation, the effectiveness and feasibility of this method are confirmed. Finally, it is concluded that proposed method can not only quickly process open straight stripes, but also process closed circular stripes, and have very high accuracy and excellent phase recovery effect.
Tongue diagnosis is a way of aiding the diagnosis and identification of pathological conditions by observing tongue images in Chinese medicine diagnosis. The application of photo chromatography to diagnosis allows for the accurate and comprehensive extraction of tongue features. The main characteristic parameter of tongue diagnosis is color information, so this paper proposes a diagnostic method based on the proportion of the primary color of the tongue and the H-component to assist in the analysis. The method treats the tongue color and moss color as a whole, extracts the pixels and proportions of each tongue color and selects the primary color, uses a threshold method to distinguish between healthy and diseased tongue images based on the primary color proportion, and then uses a gray-scale histogram and H-component histogram to extract each feature parameter to achieve sub-classification of the diseased images. The experimental results show that the method is feasible, more stable and accurate than traditional methods, and can improve the diagnostic efficiency.
Digital holographic microscopy (DHM) is an efficient optical measurement and imaging technology with the advantages of non- invasion, non-damage, high sensitivity and high resolution. However, its resolution is still limited by the diffraction limit of the system. The structured light illumination microscopy (SIM) is a good super resolution imaging technology, which obtains high frequency information of objects by changing the lighting mode to achieve improved imaging resolution. In order to discuss the factors that affect structured light phase imaging, we first simulated the entire imaging process of a structured light digital holography system using Matlab software, and then systematically analyzed the effects of four factors, structured light spatial frequency, loading direction, modulation level, and noise level, on the imaging situation, and reached corresponding conclusions. The above research results can provide a reference for the study of structured light phase imaging methods.
As an important parameter for evaluating optical devices, chromatic aberration is an enduring research hotspot in optics. The traditional bulk lens relies on the polished surface profile on the transparent optical material to achieve the required gradual phase change. Compared with the traditional lens, the metalens can achieve the effect of focusing the beam with a more suitable small size standard. In this paper, the geometric phase method is used to realize the phase shift required by the surface of the achromatic metalens through the unique design of the nano-unit column array. In order to be applied to the optical path of multi-wavelength phase microscopy imaging, the metalens designed in this paper effectively eliminates chromatic aberration in the visible light band from 500 nm to 595 nm and improves the imaging resolution. It also satisfy the needs of modern optical devices for ultra-light, ultra-thin and easy portability, and can be used in a variety of optical instruments, aerospace and military fields.
Phase extraction is a key step in phase imaging. The accuracy and speed of phase recovery directly affect the quality and efficiency of phase imaging. In this paper, a statistical average method for phase retrieval is proposed by combining the two-step phase-shifting interference with the characteristics of diffractive phase field. The main operations of this method are subtraction and statistical average. The simulation results of a sphere show the feasibility and high accuracy of the method. And the simulation results of a red blood cell and a white blood cell discuss the application of this method in biological imaging.
Quantitative phase imaging technology has become an important technology for imaging phase objects such as cells in virtue of the advantages of non-destructive, non-invasive and high accuracy. More importantly, the phase of a cell is closely related to its internal structure and component. In this paper, according to the morphological and optical characteristics of typical leukocytes, the approximate models of different kinds of cells were firstly established to obtain the corresponding phases. Then, digital image edge operators such as gradient, gradient module and Laplace were used to detect the phase maps. Subsequently with the phase detection images of the cell, its feature information, such as the morphology and the refractive index change can be analyzed. Simulation results suggested that the edge operators are sensitive to the morphology, the interface of each medium and component of the cell. Therefore, the edge detection method of phase image can be used for cell’s classification recognition and preliminary determination of internal structure
Digital phase microscopy has made great progress in the study of morphology and dynamics of biological cells, especially the homogeneous cells. For the heterogeneous nucleated cells with relatively complex internal structures, there are still few methods of phase unwrapping suitable for observation and measurement. In this paper, a method is proposed to identify the substructure of cells only with their wrapped phases. According to the structural features of real nucleated cells, their similar models are established firstly, and then their wrapped phases are obtained in Cartesian coordinates and polar coordinates. Based on the relationship between the parameters of the two coordinate systems, the pattern recognition and image processing techniques are used to analyze the parcel phase of the single-core and multi-core, regular and irregular kernels, and the central and boundary kernel models. Then, the texture shape distribution, the texture overlap condition, the opening and closing state of the equal phase line, the peak number and the peak position are selected as reference features, and these reference features are combined and optimized as the judgment condition for identifying the nuclear structure model, and the wrapped phase in polar coordinates is screened and identified, which effectively distinguishes three typical types of nuclear cell models. It provides a new, unpacked method for the classification and identification the substructures of the nucleated cells.
Dual-wavelength digital holographic microscopy technique has many important applications in the imaging of biological cells. It has some significant advantages, such as the large measurement range and no phase unwrapping procedures. However, the multi-steps image is required in synchronous interference microscopy, it is not suitable to perform real-time dynamic imaging of samples. In this paper, in order to meet the research and clinical application of dynamic imaging of living cells, a phase recovery algorithm is proposed in dual-wavelength interference and one-step microscopic imaging. This algorithm is on the basis of the principle of the digital holographic off-axis synchronous microscopy image. In this algorithm, only by means of Fourier transform, filtering, frequency-shifting operations, inverse Fourier transform to the dual-wavelength off-axis microscopic interferogram, the continuous phase of the sample can be calculated. Simulation result of the lymphocyte shows that this method is feasible, and the error analysis suggests that it has good accuracy. This approach is free of phase unwrapping, and has no the calculation of the phase shift and no the multi-step imaging. It can recover the phase distribution only from one dual-wavelength interferogram. So it has a high potential application for the technology development, and can be applied to accurate dynamic imaging of biological cells and tissues.
Dual-wavelength interferometry is one of the most effective technique in optical metrology and phase imaging by virtue of its unique advantages. In this paper, a fast derivative method for phase extraction is proposed to improve the imaging efficiency in simultaneous dual-wavelength interferometry. In this algorithm, only three off-axis wavelength-multiplexed phase-shifted interferograms are required. And only by calculating the difference between the first interferogram and other interferogram and calculating its first-order derivative, the wrapped phase of each single-wavelength can be obtained. Subsequently, the continuous phase at a synthetic wavelength can be determined freeing from the complex unwrapping procedure. Moreover, the thickness can also be obtained from the phase. Simulation results show that this method is effective and demonstrate its performance of faster computing speed and high accuracy.
To evaluate the efficacy and safety of photothermal with dinitrophenyl hapten (DNP) for patients with malignant melanoma (MM), Patients with pathology confirmed stage III or IV MM were enrolled. Seventy-two patients were randomized into two groups, DNP alone group (n=36) and DNP plus photothermal therapy group (n=36). The results showed that the patients in the combination treatment group had longer median progression-free survival time (19.0m vs. 12.0m, p=0.007). No severe adverse events were observed in both groups. Thus, the combination of photothermal therapy and DNP maybe a new therapeutic strategy for patients with advanced MM.
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