Invited paper-Super-resolution imaging technology
2017, 46(11): 1103001.
doi: 10.3788/IRLA201746.1103001
Photoacoustic imaging (PAI) or optoacoustic imaging, the modern application of an ancient physical discovery to biomedical imaging, is without doubt one of the most exciting imaging technologies that has drawn increasing attention from biomedical specialists. In PAI, the rich contrast of optical excitation is seamlessly combined with the high spatial resolution and large penetration depth of ultrasonic detection to produce clear images of optically scattering biological tissues. As a complementary imaging modality that surpasses the territory of traditional microscopic optical imaging, PAI has been explored for numerous biomedical studies, and hence enthusiastically embraced by researchers around the globe who have attested to its unique imaging capabilities, namely the deep penetration and functional sensitivity. Not surprisingly, as the market clearly sees the promise, the commercial production of PAI systems has grown apace with the technological advancements and clinical applications. The adoption of commercial PAI in research and clinical settings has however seen difficulties, majorly due to costs, regulatory blocks, and competition with mainstream technologies. Here, from a practical standpoint, a wide range of commercial PAI systems currently available in the market were introduced, their advantages and disadvantages were analyzed, and the design considerations for targeted applications were emphasized. The key technological, logistical, and clinical issues were also discussed that need to be solved to accelerate the technology translations. By doing so, it is hoped that a clearer picture of the future commercialization of PAI for clinicians, researchers, and industrial entrepreneurs will be presented.
2017, 46(11): 1103002.
doi: 10.3788/IRLA201746.1103002
Cell is the basic unit and functional unit of living body. The study of the internal structure and function of living cells is one of the foundations of mastering the essence of life. Therefore, the realtime observation of living cells is of great significance for the development of life sciences. Conventional optical microscopy is limited by the diffraction limits and can not observe the details of biological structures below 200 nm. In the past 20 years, with the rapid development of super-diffraction limit optical theory, technology, devices and fluorescent probes, super-resolution microscopy has become an important method for life science research. However, most super-resolution microscopic methods or measurements take a long time, or are likely to cause photobleaching/phototoxicity, and are severely limited in living cell studies. In this paper, based on the study of fast super-resolution microscopy, the photoactivated localization microscopy and stochastic optical reconstruction microscopy were introduced based on single molecule localization microscopy. The stimulated emission depletion microscopy based on fluorescence non-linear saturated light conversion and structured illumination microscopy based on structured light illumination was also introduced. Besides, the development and application of cell imaging were explored. Finally, an outlook of the future development trend of super-resolution microscopy in living cell imaging was provided.
2017, 46(11): 1103003.
doi: 10.3788/IRLA201746.1103003
A scanning near-field optical microscope (SNOM) based on an apertureless optical probe was presented. The probe had a V shape hollow on its top and coated with metal film. Illumination near-field light (NFL) will emit from the apex of probe when far-field light (FFL) is focused on the hollow. There is a phase difference between collected NFL and FFL, which relates to the distance between probe and sample. The collected FFL can be eliminated using a Glan-Taylor analyzer according to the phase difference. The experimental results show the phase difference of this system is 57. The spatial resolution of SNCOM is less than 12 nm.
2017, 46(11): 1103004.
doi: 10.3788/IRLA201746.1103004
A method of full-field micro strain measurement using digital image correlation was proposed to evaluate the risk of printed circuit board assembly failure induced by stress. It outperformed traditional testing methods based on experiment in terms of full-field strain measurement and location of strain concentration. Experimental method based on three-dimensional digital image correlation and stress loading strategy was designed. The risk of circuit board assembly failure was evaluated by the obtained full-field distributions of principle strain and history curves of strain on selected local areas. High repeatability of the presented method, which was better than 100 , was exhibited by the experiments, allowing the obtainment of the circuit board assembly full-field micro strain distribution. Moreover, areas where strain exceeds rated value can be localized easily and exhibited intuitively. The presented method provides important measured data which can be used to improve the circuit board assembly design, reduce the risk of circuit board assembly failure, and protect the safety of electronic components.
2017, 46(11): 1103005.
doi: 10.3788/IRLA201746.1103005
A method, which can extract the particle size information with a resolution beyond /NA, was proposed. This was achieved by applying Fourier ptychographic(FP) ideas to the present problem. In a typical FP imaging platform, a 2D LED array was used as light sources for angle-varied illuminations, a series of low-resolution images were taken by a full sequential scan of the array of LEDs, and the data were then combined to produce a high-resolution image. Here, the particle size information was extracted by turning on each single LED on a circle, whose radius was chosen according to an expression for the resolution limit. The simulated results show that the proposed method can reduce the total number of images without loss of reliability in the results, and the total number of images can be further reduced by optimizing the aperture overlapping rate.
2017, 46(11): 1103006.
doi: 10.3788/IRLA201746.1103006
Through the analysis of confocal microscope in the imaging process caused by the position, such as optical hardware deviation converge and pinhole position deviation occurring in image distortion phenomenon, a position correction function into interpolation algorithm was proposed for nonlinear distortion image correction and rehabilitation. The convolution neural network based on machine learning technology was applied to improve the quality of image position correction after degradation when training a single image. The five layers of convolution and down sampling to join pooling layer were employed to reduce the order of magnitude in network parameters. The results show that the pooling layer can improve the operation speed significantly and improve the sharpness of the image.
2017, 46(11): 1103007.
doi: 10.3788/IRLA201746.1103007
A real time integral imaging pickup system was proposed using a binocular stereo camera. In the proposed system, the conventional camera array was replaced by the binocular stereo camera for three-dimensional (3D) scene pickup, which made the system simpler. In the system, left view and right view images were first captured by the binocular stereo camera, and the high-resolution depth map was calculated in the graphics processing unit. Then, the depth map and color texture image were used to generate the parallax images of new perspectives in parallax, and pixel mapping algorithm was adopted to obtain the high-resolution elemental image array for the real-time integral imaging display. In the experiment, the resolution of the calculated depth map was 4.25 times more than the depth map acquired by Microsoft Kinect2, the real-time pickup and display for 3D scene can be achieved in case the resolution of elemental image array was 1 920 pixel1 080 pixel, and sub-images was 99. The experiment results demonstrate the effectiveness of the proposed system.
2017, 46(11): 1103008.
doi: 10.3788/IRLA201746.1103008
A batch of super-resolution fluorescence microscopy technologies have been invented to overcome the diffraction limit of traditional optical microscopy. It thereby greatly enhances the capacity of sub-cellular structure investigation. Among these super-resolution microscopy, Stochastic Optical Reconstruction Microscopy (STORM) based on single molecule localization has attracted more and more attention by researchers due to its straightforward principle, simple operation mode as well as super-high resolution. First, the basic principle of single molecule localization was introduced, the design of the light path of STORM was discussed, and the principles of 2D-STORM and 3D-STORM were provided. Then, the development of multi-color imaging as well as correlative STORM and electron microscopy were discussed. Finally, some recent typical researches depending on STORM were presented.
