2020

• Record 385 of
  
  Title:Optimization of polishing wheel and investigation of its tool influence function
  
  Author(s):Yao, YongSheng(1,2); Ma, Zhen(1); Dinga, JiaoTeng(1,2); Wu, XiaoGe(1); Li, QiXin(1,2); Chen, QinFang(1); Fan, XueWu(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11568  Issue:   DOI: 10.1117/12.2579896  Published: 2020  
  Abstract:In this paper, a new type of wheel polishing tool is designed. Through the bevel gear structure, only one motor is used to realize the revolution and rotation of the polishing wheel, which makes the structure simple, small inertia, and stable operation. Traditional polishing wheels have a three-layer structure: Internal rigid hub, middle flexible rubber, and external polishing pad. It is found through experiments that the hardness of rubber has a greater influence on the tool influence function (TIF). Therefore, by optimizing the hardness of the rubber, we obtained a TIF very close to the Gaussian shape, which is conducive to the rapid convergence of the surface error. Finally, the effects of polishing wheel speed, polishing pressure and polishing time on the TIF, as well as the stability of the TIF, are studied through experiments. Experiments show that: (1) There is no linear relationship between the removal efficiency of the polishing wheel, the polishing wheel speed, and the polishing pressure, but as the parameter increases, the increase in the removal efficiency slows down; (2) There is a good linear relationship between the removal amount of the polishing wheel and time; (3) The TIF is very stable, and the stability of the TIF reaches 98%. © 2020 SPIE. All rights reserved.
  Accession Number: 20204909580455
• Record 386 of
  
  Title:High-resolution shape from focus based on line scan imaging
  
  Author(s):Ling, Xi(1,2); Zhang, Pengchang(1); Zhang, Zhaoyang(3); Gao, Ruixue(1,2)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11567  Issue:   DOI: 10.1117/12.2579988  Published: 2020  
  Abstract:The surfaces of many ancient relics as murals and oil paintings we can see today appear three-dimensional features to some extent, which poses a challenging problem for line scan imaging to capture the features on these objects. With this goal in mind, a line scan camera-based shape from focus (SFF) method is proposed for obtaining three-dimensional information in planar cultural heritages with three-dimensional features. First, line scan imaging is employed to obtain high-resolution image sequence of objects. Next, spatial frequency (SF) is used to evaluate the focus quality of a specific local area of each image in the image sequence to find out the position of the best focused image. Through analyzing the relationship between this position and the relative movement distance of the camera-object, the three-dimensional shape of the object can be roughly estimated. Then, a fitting method was utilized to refine the local details of the three- dimensional shape of the object. An experimental setup is established to restore the three-dimensional shape of the test sample using the proposed SFF algorithm. Root mean square error (RMSE) was used as the evaluation criteria, and the result demonstrated the effectiveness of the proposed method, which shows the high precision three-dimensional shape recovery and also gains the benefits of high resolution and uniform point cloud distribution. Finally, the factors affecting the results of 3D reconstruction was discussed in detail, which may guide the selection of parameters in practice. © 2020 SPIE.
  Accession Number: 20205009602524
• Record 387 of
  
  Title:Reconstruction of compressed video via non-convex minimization
  
  Author(s):Ji, Chao(1); Tian, Jinshou(2,3); Sheng, Liang(4); He, Kai(2,5); Xin, Liwei(1,2); Yan, Xin(2); Xue, Yanhua(2); Zhang, Minrui(2); Chen, Ping(1,2); Wang, Xing(2)
  Source: AIP Advances  Volume: 10  Issue: 11  DOI: 10.1063/5.0022860  Published: November 1, 2020  
  Abstract:This paper studies the sparsity prior to compressed video reconstruction algorithms. An effective non-convex 3DTPV regularization (0 © 2020 Author(s).
  Accession Number: 20204709502978
• Record 388 of
  
  Title:Optical design of space debris detection system with wide field of view
  
  Author(s):Zhang, Gengyao(1,2); Fan, Xuewu(1); Ma, Zixuan(1,2); Qin, Guang(1,2)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11570  Issue:   DOI: 10.1117/12.2574684  Published: 2020  
  Abstract:At present, the frequency of human space activities continues to increase, resulting in more and more space debris, which poses a great threat to the working satellite. The collision of debris and satellites may cause abnormal operation of the satellite or even complete damage. Based on the 3u cubic satellite platform, this paper has designed a miniaturized visible light detection system with a full field of view of 12° (9°×7°). the wavelength band of the system is 450 ~ 800nm, the pixel size of the detector is 5μm, the entrance pupil diameter is 60mm, the system focal length is 150mm, the detection system is composed of 8 lenses. Using optical design software to evaluate the image quality of the optical system, the results show that the diffusion spots in each field of view are approximately circular, the maximum RMS radius is less than 7.4 μm, and the energy distribution in each field of view is more than 80% within 3 × 3 pixels, field curvature, distortion all meet the requirements of the detection system. Finally, the tolerance analysis results show that the design has good imaging quality and meets the system performance requirements and machining requirements. The visible light detection system has a large field of view, light weight, low processing cost and high energy concentration. and can meet the demand for space debris detection in Earth orbit. © 2020 SPIE. All rights reserved.
  Accession Number: 20204909580495
• Record 389 of
  
  Title:High-power tunable sub-nm narrowband near-diffraction-limited superfluorescent fiber source based on a single-lens spectral filter
  
  Author(s):Gao, Wei(1,2,3); Fan, Wenhui(1,3,4); Zhang, Yanpeng(2); Ju, Pei(1,3); Zhao, Baoyin(1); Wu, Peng(1,3); Li, Gang(1,3); Gao, Qi(1,3); Li, Zhe(1,3)
  Source: Optics Communications  Volume: 463  Issue:   DOI: 10.1016/j.optcom.2020.125359  Published: 15 May 2020  
  Abstract:We propose a method for a high-power tunable sub-nm narrowband near-diffraction-limited superfluorescent fiber source (SFS) based on a single-lens spectral filter (SLSF), which is composed of a grating monochromator and a movable space-fiber coupler. The center wavelength of the SLSF is set to 1063 nm with a full width at half-maximum (FWHM) linewidth of less than 0.08 nm. By utilizing the SLSF and a broadband amplified SFS, a tunable sub-nm narrowband SFS seed source is obtained, and the central wavelength of the sub-nm narrowband SFS seed source can be easily tuned from 1052.4 nm to 1072.8 nm by adjusting the SLSF. After a three-stage amplifier system, the output power of this sub-nm narrowband SFS is boosted to 230W with the FWHM range from 0.10 nm to 0.12 nm. The beam quality factors (M2) of the full power sub-nm narrowband SFS at 1060.1 nm is 1.20. The proposed tunable sub-nm SFS has advantages of high spectral resolution, simple configuration, which may have potential applications in the industrial production and scientific research. © 2020 Elsevier B.V.
  Accession Number: 20200508111068
• Record 390 of
  
  Title:Graphene Fabrication by Using Femtosecond Pulsed Laser and Its Application on Passively Q-Switched Solid-State Laser as Saturable Absorber
  
  Author(s):Li, Guangying(1); Zhang, Guodong(1); Lou, Rui(1); Wang, Yishan(1); Xie, Xiaoping(1); Wang, Jiang(2); Wang, Yonggang(2); Cheng, Guanghua(3)
  Source: IEEE Photonics Journal  Volume: 12  Issue: 2  DOI: 10.1109/JPHOT.2020.2966217  Published: April 2020  
  Abstract:Here we report on the exfoliation of graphene by using femtosecond pulsed laser with the highly oriented pyrolytic graphite (HOPG) immersed in water. The size of the graphene flakes was demonstrated to be well regulated by controlling the peak-power density of the femtosecond laser irradiation on the HOPG. The transmission electron microscopy (TEM) and Raman spectroscopy were used to identify the morphology and crystalline phase of the graphene. As an application, the few-layers-graphene absorber with a modulation depth of 0.5% was used in a passive Q-switched Nd: YVO4 laser. A Q-switched nanosecond pulse train with the maximum pulse energy of 262.35 nJ and the narrowest pulse duration of 131.6 ns was obtained. © 2009-2012 IEEE.
  Accession Number: 20201308352370
• Record 391 of
  
  Title:Polarization grating based on diffraction phase microscopy for quantitative phase imaging of paramecia
  
  Author(s):Zhang, Meiling(1); Ma, Ying(1); Wang, Yu(1); Wen, Kai(1); Zheng, Juanjuan(1,2); Liu, Lixin(1); Gao, Peng(1)
  Source: Optics Express  Volume: 28  Issue: 20  DOI: 10.1364/OE.404289  Published: September 28, 2020  
  Abstract:This study presents a polarization grating based diffraction phase microscopy (PGDPM) and its application in bio-imaging. Compared with traditional diffraction phase microscopy (DPM) of which the fringe contrast is sample-dependent, the fringe contrast of PG-DPM is adjustable by changing the polarization of the illumination beam. Moreover, PG-DPM has been applied to real-time phase imaging of live paramecia for the first time. The study reveals that paramecium has self-helical forward motion characteristics, or more specifically, 77% clockwise and 23% anti-clockwise rotation when moving forward. We can envisage that PG-DPM will be applied to many different fields. © 2020 OSA - The Optical Society. All rights reserved.
  Accession Number: 20204109337108
• Record 392 of
  
  Title:Compact, High-Performance All-Polarization-Maintaining Er: Fiber Frequency Comb with Single Fiber Actuator
  
  Author(s):Cai, Yajun(1); Zhang, Ting(2); Pan, Ran(3); Hu, Xiaohong(1); Ye, Feng(2); Zhang, Wei(1); Zhao, Wei(2); Wang, Yishan(1)
  Source: IEEE Photonics Journal  Volume: 12  Issue: 4  DOI: 10.1109/JPHOT.2020.3010558  Published: August 2020  
  Abstract:The large volume and weak environmental adaptability of fiber optical frequency combs (OFCs) have become the main obstacles for their applications in various fields. To address these issues, in this study, we present a compact, low-cost f-to-2f interferometer and fiber actuator with a large tuning range and a high control bandwidth for a 200-MHz OFC that is based on a 1.5-μm all-polarization-maintaining fiber mode-locked laser. By employing customized fiber-coupled gradient index lenses, our f-to-2f interferometer is encapsulated in a miniature tube with a diameter of only 4 mm and a length of 40 mm, which substantially reduces the optical section size of the frequency comb as compared to conventional devices. The carrier envelope offset beat with a signal-to-noise ratio of 40 dB is detected in a resolution bandwidth of 360 kHz. In addition, a laboratory-made piezoelectric transducer-driven mechanical actuator for repetition rate regulation exhibited a large tuning range of 106 kHz (corresponding to an effective temperature drift of 53 °C) and a high control bandwidth of approximately 1 kHz. This resulted in a robust repetition rate locking with an Allan deviation of 330 μHz at a gate time of 1 s and a residual integrated timing jitter of 418 fs [3 Hz to 1 MHz] when referenced to a hydrogen maser. Along with reducing the size and improving the environmental adaptability of the OFC, our design can also decrease the power consumption of the system significantly. Our findings provide a new direction to the development of OFCs for various applications. © 2009-2012 IEEE.
  Accession Number: 20203609138390
• Record 393 of
  
  Title:High-power erbium-doped fiber laser with a carbon nanotubes-doped sol-gel glass mode-locker
  
  Author(s):Chen, Zhendong(1); Wang, Yonggang(1); Lv, Ruidong(1); Liu, Sicong(1); Wang, Jiang(1); Wang, Yishan(2)
  Source: Optical Fiber Technology  Volume: 58  Issue:   DOI: 10.1016/j.yofte.2020.102189  Published: September 2020  
  Abstract:Generally, broadband absorbers has much non-saturable loss and low laser damage threshold, which limits the average output power of the fiber lasers mode locked by broadband absorbers. Exceptions are the absorbers in evanescent wave mode locking, in which way only weak laser passes through the absorber section. However, evanescent wave mode locking method needs to change the original structure of the fiber. Most of the commercial fiber-lasers adopt face-to-face passive mode-locking. Therefore, it is important to increase the damage threshold of the broadband absorbers. In this study, for the first time, a single-walled carbon nanotube (SWNT)-doped sol-gel glass composite absorber is fabricated using a low-temperature sol-gel method. The main component of the sol-gel glass is compact amorphous inorganic silicon-dioxide, which has high laser-damage threshold. The SWNT-doped sol-gel glass is integrated into the erbium-doped fiber (EDF) laser and mode-locking occurs at 1559 nm. The shortest pulse duration is 456 fs, and the maximum average output power is 110.65 mW. Compared to most EDF lasers based on broadband absorbers, the average output power is one of the highest values. The results indicate that encapsulating absorber in the inorganic sol-gel matrix is a promising method for fabricating high power ultrafast fiber laser type absorbers. © 2020 Elsevier Inc.
  Accession Number: 20203008969808
• Record 394 of
  
  Title:High power, tunable, ultra-narrowband Yb-doped superfluorescent fiber source operating at wavelength less than 1055 nm with 20 nm tuning range
  
  Author(s):Ju, Pei(1,2); Fan, Wenhui(1,2,3); Zhao, Baoyin(1); Gao, Wei(1,2,4); Zhang, Tongyi(1,2); Li, Gang(1,2); Gao, Qi(1,2); Li, Zhe(1,2)
  Source: Infrared Physics and Technology  Volume: 111  Issue:   DOI: 10.1016/j.infrared.2020.103530  Published: December 2020  
  Abstract:Tunable, narrowband superfluorescent fiber sources (SFSs) are significantly important for spectral combination. Here, we propose a high power, tunable, ultra-narrowband Yb-doped SFS operating at wavelength less than 1055 nm with 20 nm tuning range. The system is composed of a broadband SFS, a home-mode space-to-fiber tunable spectral filter, and a three-stage amplifier chain. In order to achieve three typical characteristics, namely, operating in the shorter wavelength region (SWR) with wide spectrum, tunable and narrowband, and high-power output, the performance of the system is investigated and optimized based on the rate equations with temperature, grating monochromator and the coupling theory of Gaussian beam between fibers. Theoretical investigation indicates that a broadband SFS operating in the SWR with wide spectrum can be achieved by controlling temperature within a certain range. Moreover, by optimizing space-to-fiber tunable spectral filter, the tunable, ultra-narrowband SFS with linewidth of 0.088 nm can be obtained. In addition, the seed laser with signal to noise ratio (SNR) of more than 30 dB and the appropriate length of active fiber can gain better amplification performance from the main amplifier. Based on these optimized parameters, a high power, tunable, ultra-narrowband Yb-doped SFS has been built experimentally. The output power of narrowband SFS operating in tunable range from 1035 nm to 1055 nm exceeds 300 W with M2 factor of 1.47, and the measured full width at half maximum and SNR of which are less than 0.1 nm and beyond 30 dB, respectively. This work extends the spectral region and capacity of narrowband SFSs, and will be useful for further power scaling of spectral beam combination. © 2020 Elsevier B.V.
  Accession Number: 20204209358173
• Record 395 of
  
  Title:Fast structured illumination three-dimensional color microscopic imaging method based on Hilbert-transform
  
  Author(s):Qian, Jia(1,2); Dang, Shi-Pei(1,2); Zhou, Xing(1); Dan, Dan(1); Wang, Zhao-Jun(3); Zhao, Tian-Yu(1,2); Liang, Yan-Sheng(3); Yao, Bao-Li(1,2); Lei, Ming(2,3)
  Source: Wuli Xuebao/Acta Physica Sinica  Volume: 69  Issue: 12  DOI: 10.7498/aps.69.20200352  Published: June 20, 2020  
  Abstract:As a wide-field microscopy, structured illumination microscopy (SIM) enables super-resolution and three-dimensional (3D) imaging. It has recently received lots of attention due to the advantages of high spatial resolution, short image recording time, and less photobleaching and phototoxicity. The SIM has found numerous important applications in time-lapse imaging of living tissues and cellular structures in the field of biomedical science. Color information is an important physical quantity describing the characteristics of living creatures and reflects the differences in its microstructure and optical property to some extent. Although HSV (hue, saturation, value) color space based structured illumination full-color 3D optical sectioning technique can recover the full color information on the surface of the samples without color distortion. However, for each optical sectioning, three raw images with fixed phase shift are required to calculate the sectioning images by the rootmean square (RMS) algorithm. This will dramatically increase the data acquisition time and data storage space, especially for a large-scaled sample that needs image stitching strategy. The image processing progress operated in HSV color space need to run the RMS algorithm three times in each channel of HSV space for every section, and transform the images between RGB (red-green-blue) space and HSV space twice. This will absolutely extend the data processing time and put forward higher requirements for computer hardware and software for data storage and processing. To this end, in this paper, a fast 3D color optical sectioning SIM algorithm based on Hilbert-transform is proposed. The Hilbert-transform has proved to be a powerful tool in digital signal and image processing and has successfully applied to the SIM. Here, only two raw images with structured illumination are needed to reconstruct a full-color optical sectioned image for each slice. This fast 3D color sectioning method has the advantage of insensitivity to phase-shift error and has better adaptability to noise, high quality color sectioning images can be obtained under the phase-shift error or noise disturbed environment. The image acquisition data are reduced by 1/3 and the color optical sectioning reconstruction time is saved by about 28%, this new method effectively improves the efficiency and speed for 3D color imaging and will bring a wider application range for SIM. © 2020 Chinese Physical Society.
  Accession Number: 20203108997131
• Record 396 of
  
  Title:Research Progress of Atomic Layer Deposited Micro-channel Plate
  
  Author(s):Guo, Junjiang(1,2,3); Zhu, Xiangping(1,2); Xu, Yantao(1,2); Cao, Weiwei(1,2,3); Zou, Yongxing(1); Lu, Min(1); Peng, Bo(1); Si, Jinhai(3); Guo, Haitao(1)
  Source: Cailiao Daobao/Materials Reports  Volume: 34  Issue: 2  DOI: 10.11896/cldb.18110031  Published: February 10, 2020  
  Abstract:The micro-channel plate (MCP) is the core device for electronic multiplication and signal amplification in the fields of optical communication and optoelectronic technology, and the performance improvement research of MCP is mainly focused on increasing gain, extending service life and reducing dark count. Currently, the commonly used commercial MCPs are still prepared based on the traditional lead silicate glass via hydrogen reduction process. Although its gain, lifetime and dark count can reach 103, 0.3 C/cm2, 0.25 events/(s•cm2), respectively, optimized by four generations of glass components and preparation process, the glass composition and complicated preparation process limit its further enhancement in performance, e.g. lower ion feedback and background noise, and higher gain. In view of this, researchers have proposed and perfected a new solution over the past decade: adopting atomic layer deposition (ALD) techno-logy to deposit functional layers, including the conductive layers and secondary electron emission layers onto the surface of borosilicate glass substrates. Thereby, an MCP with conduction and electron multiplication capability is obtained. This novel ALD-MCP can effectively avoid the restriction of substrate glass on its performance optimization, realize the independent design of the substrate glass and the functional layer's materials, and significantly improve the comprehensive performance of the MCP. Through continuous attempts, the ALD functional layers exhibiting much superior performance to that of traditional MCP have been developed. The prevailing deposition materials for conductive layer are Al2O3/ZnO, Al2O3/W or Al2O3/Mo, and for the secondary electron emission layers are MgO or Al2O3, with the products' gain elevated to 104, dark count reduced to 0.078 events/(s•cm2), and lifetime prolonged to 7 C/cm2. However, its stability still requires further improvement. In addition, deeper investigations are needed to improve deposition efficiency, and to optimize and regulate the performance of functional layers. This paper provides a systematic summary over the worldwide research status of ALD-MCP from the perspectives of functional layer composition and product performance. Moreover, it also gives a critical discussion involving the problems in current research and a prospective outlook for future development trends. © 2020, Materials Review Magazine. All right reserved.
  Accession Number: 20201208313072