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Technology developments and biomedical applications of polarization-sensitive optical coherence tomography
Zhenyang DING,Chia-Pin LIANG,Yu CHEN
Front. Optoelectron.. 2015, 8 (2): 128-140.
https://doi.org/10.1007/s12200-015-0475-1
Polarization-sensitive optical coherence tomography (PS-OCT) enables depth-resolved mapping of sample polarization information, such as phase-retardation and optical axis orientation, which is particularly useful when the nano-scale organization of tissue that are difficult to be observed in the intensity images of a regular optical coherence tomography (OCT). In this review, we survey two types of methods and systems of PS-OCT. The first type is PS-OCT with single input polarization state, which contain bulk optics or polarization maintaining fiber (PMF) based systems and single-mode fiber (SMF) based systems. The second type is PS-OCT with two different input polarization states, which contain SMF based systems and PMF based systems, through either time, frequency, or depth multiplexing. In addition, representative biomedical applications using PS-OCT, such as retinal imaging, skin cancer detection, and brain mapping, are demonstrated.
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Resolution and contrast enhancements of optical microscope based on point spread function engineering
Yue FANG, Cuifang KUANG, Ye MA, Yifan WANG, Xu LIU
Front. Optoelectron.. 2015, 8 (2): 152-162.
https://doi.org/10.1007/s12200-015-0479-x
Point spread function (PSF) engineering-based methods to enhance resolution and contrast of optical microscopes have experienced great achievements in the last decades. These techniques include: stimulated emission depletion (STED), time-gated STED (g-STED), ground-state depletion microscopy (GSD), difference confocal microscopy, fluorescence emission difference microscopy (FED), switching laser mode (SLAM), virtual adaptable aperture system (VAAS), etc. Each affords unique strengths in resolution, contrast, speed and expenses. We explored how PSF engineering generally could be used to break the diffraction limitation, and concluded that the common target of PSF engineering-based methods is to get a sharper PSF. According to their common or distinctive principles to reshape the PSF, we divided all these methods into three categories, nonlinear PSF engineering, linear PSF engineering, and linear-based nonlinear PSF engineering and expounded these methods in classification. Nonlinear effect and linear subtraction is the core techniques described in this paper from the perspective of PSF reconstruction. By comparison, we emphasized each method’s strengths, weaknesses and biologic applications. In the end, we promote an expectation of prospective developing trend for PSF engineering.
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Fourier domain optical coherence tomography with ultralong depth range
Zhihua DING,Yi SHEN,Wen BAO,Peng LI
Front. Optoelectron.. 2015, 8 (2): 163-169.
https://doi.org/10.1007/s12200-015-0463-5
The depth ranges of typical implementations of Fourier domain optical coherence tomography (FDOCT), including spectral domain OCT (SDOCT) and swept source OCT (SSOCT), are limited to several millimeters. To extend the depth range of current OCT systems, two novel systems with ultralong depth range were developed in this study. One is the orthogonal dispersive SDOCT (OD-SDOCT), and the other is the recirculated swept source (R-SS) interferometer/OCT. No compromise between depth range and depth resolution is required in both systems. The developed OD-SDOCT system realized the longest depth range (over 100 mm) ever achieved by SDOCT, which is ready to be modified for depth-encoded parallel imaging on multiple sites. The developed R-SS interferometer achieved submicron precision within a depth range of 30 mm, holding potential in real-time contact-free on-axis metrology of complex optical systems.
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Vascular distribution imaging of dorsal skin window chamber in mouse with spectral domain optical coherence tomography
Jian GAO,Xiao PENG,Peng LI,Zhihua DING,Junle QU,Hanben NIU
Front. Optoelectron.. 2015, 8 (2): 170-176.
https://doi.org/10.1007/s12200-015-0480-4
Doppler optical coherence tomography or optical Doppler tomography (ODT) has been demonstrated to spatially localize flow velocity mapping as well as to obtain images of microstructure of samples simultaneously. In recent decades, spectral domain Doppler optical coherence tomography (OCT) has been applied to observe three-dimensional (3D) vascular distribution. In this study, we developed a spectral domain optical coherence tomography system (SD-OCT) using super luminescent diode (SLD) as light source. The center wavelength of SLD is 835 nm with a 45-nm bandwidth. Theoretically, the transverse resolution, axial resolution and penetration depth of this SD-OCT system are 6.13 μm, 6.84 μm and 3.62 mm, respectively. By imaging mouse model with dorsal skin window chamber, we obtained a series of real-time OCT images and reconstructed 3D images of the specific area inside the dorsal skin window chamber by Amira. As a result, we can obtain the clear and complex distribution images of blood vessels of mouse model.
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Fluorescence microendoscopy imaging based on GRIN lenses with one- and two-photon excitation modes
Wei YAN,Xiao PENG,Danying LIN,Qi WANG,Jian GAO,Teng LUO,Jie ZHOU,Tong YE,Junle QU,Hanben NIU
Front. Optoelectron.. 2015, 8 (2): 177-182.
https://doi.org/10.1007/s12200-015-0503-1
With the rapid development of life sciences, there is an increasing demand for intravital fluorescence imaging of small animals. However, large dimensions and limited working distances of objective lenses in traditional fluorescence microscopes have limited their imaging applications mostly to superficial tissues. To overcome these disadvantages, researchers have developed the graded-index (GRIN) probes with small diameters for imaging internal organs of small animals in a minimally invasive fashion. However, dynamic imaging based on GRIN lens has not been studied extensively. Here, this paper presented a fluorescence endoscopic imaging system based on GRIN lenses using one-photon and two-photon excitation. GRIN lenses with 1.15 mm diameter and 7.65 mm length were used in the system. The images were acquired by a compact laser scanning imaging system with a resonant galvo-mirror system to scan the laser beam and a photomultiplier tube (PMT) to detect fluorescence signals. Experimental results showed that this system using two-photon excitation could implement dynamic fluorescence microendoscopic imaging and monitor the movement of blood flow beneath the skin in anesthetized mice while producing images with higher contrast and signal to noise ratio (SNR) than those using one photon excitation. It would be a useful tool for studying biological processes of small animals or plants in vivo.
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Diagnostics of bronchopulmonary diseases through Mahalanobis distance-based absorption spectral analysis of exhaled air
A. A. BULANOVA,E. B. BUKREEVA,Yu. V. KISTENEV,O. Yu. NIKIFOROVA
Front. Optoelectron.. 2015, 8 (2): 183-186.
https://doi.org/10.1007/s12200-015-0498-7
Accurate diagnosis of different bronchopulmonary diseases is important in clinical practice. This study involved 20 healthy volunteers and 77 patients with bronchopulmonary diseases, including chronic obstructive pulmonary disease (COPD), bronchial asthma, pulmonary tuberculosis, and community-acquired pneumonia. The absorption spectrum of exhaled air samples was recorded on an intra-cavity photo-acoustic gas analyzer (ILPA-1, Special Technologies, Ltd., Russia) with photo-acoustic detectors and CO2 laser with a tuning range from 9.2 to 10.8 μm. In conclusion, analysis of the Mahalanobis distance-based absorption spectral profiles of breath air from bronchopulmonary patients and healthy volunteers allows the formulation of a preliminary diagnosis.
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Optimised synthesis of close packed ZnO cloth and its applications in Li-ion batteries and dye-sensitized solar cells
Yue QIAN,Rong LIU,Xiujuan JIN,Bin LIU,Xianfu WANG,Jin XU,Zhuoran WANG,Gui CHEN,Junfeng CHAO
Front. Optoelectron.. 2015, 8 (2): 220-228.
https://doi.org/10.1007/s12200-015-0490-2
Close packed ZnO nanoparticles on carbon cloth were synthesized by repeating a facile hydrothermal route in this study. After characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), the obtained ZnO cloth was further studied for the applications in lithium (Li)-ion batteries (LIBs) and dye-sensitized solar cells (DSSCs). When ZnO cloth annealed at 400°C for 2 h were used as anodes of LIBs, it exhibited high capacity of 600 mAh/g and outstanding cycling capability without significant fading after 130 cycles. Moreover, it was also found that our electrodes displayed good stabilities under various humidity and temperature. Furthermore, the obtained composites were calcined at higher temperature (800°C) to remove carbon and white pure ZnO cloth was formed. We transferred the as-formed ZnO cloth to?fluorine-doped tin oxide (FTO) substrate to make DSSCs, exhibiting an improved efficiency of around 0.38% assisted by TiCl4 treatment.
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