Infrared meibography is a technique for imaging meibomian glands that are located in the rim of the eyelids. An automated methodology for analysing these images was proposed to assess meibomian glands structure and he...
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This paper presents an optical method and system for contactless measurement of the mass flow rate of melts by digital cameras. The proposed method is based on reconstruction of melt stream geometry and flow velocity ...
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This paper presents an optical method and system for contactless measurement of the mass flow rate of melts by digital cameras. The proposed method is based on reconstruction of melt stream geometry and flow velocity calculation by cross correlation, and is very cost-effective due its modest hardware requirements. Using a laboratory test rig with a small inductive melting pot and reference mass flow rate measurement by weighing, the proposed method was demonstrated to have an excellent dynamic response (0.1 s order of magnitude) while producing deviations from the reference of about 5% in the steady-state flow regime. Similar results were obtained in an industrial stone wool production line for two repeated measurements. Our method was tested in a wide range of melt flow rates (0.05-1.2 kg/s) and did not require very fast cameras (120 frames per second would be sufficient for most industrial applications). (C) 2018 Optical Society of America
To design a stable laser vision seam-tracking system, an advanced weld imageprocessing algorithm based on Siamese networks is investigated and proposed to resist the interference of arc and spatter in the welding pro...
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To design a stable laser vision seam-tracking system, an advanced weld imageprocessing algorithm based on Siamese networks is investigated and proposed to resist the interference of arc and spatter in the welding process. This specially designed neural network, combined with powerful feature expression capabilities of deep learning, takes two welding images with different sizes as inputs and generates a target confidence map in a single forward pass by using the cross-correlation algorithm. To prevent the error accumulation and model drift, an online update strategy via local cosine similarity is developed. The use of metal inert-gas welding can realize real-time and precious tracking under the condition that the strong arc continuously shields the welding seam feature points. (C) 2018 Optical Society of America.
In this paper, we present a model that analyzes the influence of the temperature on the modulation transfer function (MTF) of an infrared membrane diffraction optical system. Based on the physical imaging mechanism of...
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In this paper, we present a model that analyzes the influence of the temperature on the modulation transfer function (MTF) of an infrared membrane diffraction optical system. Based on the physical imaging mechanism of diffractive optical systems, the imaging characteristics of the diffraction optical system are characterized by using diffraction efficiency. Then we establish the corresponding calculation model and MTF analysis model based on scalar diffraction theory. In particular, considering the material properties of flexible membrane optical elements and thermal environment effect, the Zernike polynomials are used to establish the thickness distribution model of the membrane diffractive optical components combined with the finite element analysis. After that, we modify the MTF calculation model of diffraction optical system and accordingly propose the model of the infrared membrane diffraction optical system. Finally, we present some experimental results for a 2-m infrared membrane diffraction optical system. The results show that when the temperature is -40 degrees C and wavelength band is 80 nm at the center field of view, the diffraction efficiency is reduced to 81%, and MTF at 751 p/mm is reduced to 0.12. And when the temperature is -40 degrees C at edge field of view, the efficiency at center wavelength is reduced to 71%, and MTF at 751 p/mm is reduced to 0.02. The established model and method can be used to estimate the imaging performance of a space infrared membrane diffractive telescope and provide theoretical guidance for the processing algorithm and imaging system design. (C) 2018 Optical Society of America
As a key component in optical microscopy imaging systems, autofocus technology has a significant effect on imaging quality. In this paper, an optical microscopy autofocus method that includes a wavelet denoising algor...
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As a key component in optical microscopy imaging systems, autofocus technology has a significant effect on imaging quality. In this paper, an optical microscopy autofocus method that includes a wavelet denoising algorithm based on a power threshold function and a Brenner image quality evaluation algorithm is presented. Experimental results show that the power threshold function wavelet denoising algorithm, which can be adopted to obtain more realistic optical images, is superior to the traditional soft, hard, hyperbolic, and exponential threshold functions in terms of peak signal-to-noise ratio, signal-to-noise ratio, mean squared error, and histogram indicators;moreover, compared to the Roberts, sum modulus difference (SMD), and energy gradient functions, the Brenner image quality evaluation algorithm can be used to quickly and accurately lock onto the focal plane. By integrating and applying these two core algorithms in the autofocus image acquisition system of a microscope, the image sharpness and focusing quality are greatly improved, which benefits the further evaluation of images. (C) 2018 Optical Society of America
Interferometric particle imaging enables particle size estimation in a wide range [from 10 mu m to a few millimeters] depending on the optical system design. With a multi-view optical system, it is possible to extract...
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Interferometric particle imaging enables particle size estimation in a wide range [from 10 mu m to a few millimeters] depending on the optical system design. With a multi-view optical system, it is possible to extract more information about the 3D morphology of the particle. In this study, multi-view interferometric out-of-focus imaging of ice particles is performed in a backward-scattering configuration. It is used to estimate ice particle volume and thus to reduce uncertainty concerning particle size estimation. It is further used to better analyze the presence of nearby particles whose images overlap. (C) 2018 Optical Society of America
The commercialization of EnChroma glasses has generated great expectations for people to be able to see new colors or even correct color vision deficiency (CVD). We evaluate the effectiveness of these glasses using tw...
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The commercialization of EnChroma glasses has generated great expectations for people to be able to see new colors or even correct color vision deficiency (CVD). We evaluate the effectiveness of these glasses using two complementary strategies for the first time. The first consists of using the three classical types of tests - recognition, arrangement and discrimination - with and without glasses, with a high number of individuals. In the second, we use the spectral transmittance of the glasses to simulate the appearance of stimuli in a set of scenes for normal observers and observers with CVD. The results show that the glasses introduce a variation of the perceived color, but neither improve results in the diagnosis tests nor allow the observers with CVD to have a more normal color vision. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
To match the virtual image and actual environment in an augmented reality (AR) system, it is necessary to complete the task of three-dimensional (3D) tracking registration. This paper proposes a new method for 3D trac...
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To match the virtual image and actual environment in an augmented reality (AR) system, it is necessary to complete the task of three-dimensional (3D) tracking registration. This paper proposes a new method for 3D tracking registration. Previous methods extract feature points in images to realize tracking registration. In this paper, the objects are extracted from the deep convolution neural network in the scene, and the camera pose is estimated by establishing the constraint relation of the objects. Then, 3D tracking and registration of the virtual object are realized. We design an improved single-shot multibox detector semantic segmentation network to identify and segment the scene and extract the pixel classification results of the objects in the scene. The effect of classification with this method is better. The depth of the extracted object is estimated based on the data from the left and right cameras, and the 2D image is converted into a 3D point cloud. A camera pose estimation method, combined with multiobjective information, is proposed. The camera transformation matrix is directly estimated by establishing a mathematical model. This method avoids the effect on the accuracy of the camera pose estimation when the feature points are not sufficient. Moreover, by assigning different weights to the point clouds of different objects, errors caused by the model can be reduced. The experimental results showed that the 3D registration method proposed in this paper is less than 2.5 pixels in the application scene of an augmented reality head-up display. This method had a better effect compared with that of existing methods and also improved driving safety. (C) 2018 Optical Society of America
A novel time-multiplexed multi-view three-dimensional (3D) display has been implemented using a projector array to provide the image source and an angular steering-screen module to generate multiple high density horiz...
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A novel time-multiplexed multi-view three-dimensional (3D) display has been implemented using a projector array to provide the image source and an angular steering-screen module to generate multiple high density horizontal views. The liquid crystal (LC)-based steering screen was specially developed to deflect light beams over a small range and operate in synchronism with the projector array with the use of a customized FPGA driver. The prototype produces vivid color 3D scenes with smooth parallax to multiple viewers. The experimental results verify the proposed multi-projection time-multiplexed multi-view 3D display method that uses a steering screen to produce dense views. Displaying both static and dynamic 3D contents is achieved in our implemented 36-view 3D display prototype. The results of crosstalk measurements are given and analyzed to evaluate the display performance. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
In this paper, we propose a new super-resolution imaging technique based on fluorescence blinking (SRFB). Contrary to structured illumination microscopy (SIM), SRFB considers the time-varying fluorescence distribution...
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In this paper, we propose a new super-resolution imaging technique based on fluorescence blinking (SRFB). Contrary to structured illumination microscopy (SIM), SRFB considers the time-varying fluorescence distribution under a suitable density as the varying illuminated speckle pattern, and therefore, external speckle patterns or diffusers are not required. With several images recorded at different times, a super-resolution image can be obtained through an iterative algorithm modified from Fourier ptychography. Recorded image sequences in a microscopy imaging experiment based on photo switching or fluorescence blinking effects, such as STORM and SOFI, can be handled with SRFB and used to recover a super-resolution image. The simulation and experimental results confirm that the SRFB scheme can surpass the diffraction limit by a factor greater than two. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
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