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APPLICATIONS-CENTERED RESEARCH IN OPTICS

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Early Posting

Accepted papers to appear in an upcoming issue

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January


Gas Filling Dynamics of a Hollow-Core Photonic Bandgap Fiber for Non-Vacuum Conditions

  • Rosalind Wynne and Banafsheh Barabadi
  • received 10/13/2014; accepted 01/22/2015; posted 01/22/2015; Doc. ID 224432
  • [full text: PDF (795) KB)]
  • Abstract: This paper introduces an analytical model for the pressure-driven delivery of gas mixtures consisting of multiple components of gases with varied viscosity to hollow-core photonic crystal fiber (PCF). PCFs have been used for all-fiber spectroscopy configurations for gases like methane and acetylene that are relevant to the development of all-fiber chemical sensors. The unique structure of these fibers permits the formation of a gas cell with micron scaled volumes to promote strong interaction with the guided optical field supported by increase interaction lengths and low optical losses. The influence of the effective viscosity of the delivered gas is significant to the fiber filling process and is emphasized in this discussion. Unlike previous work, this investigation is not limited to closed-loop configurations with low gas-flows, single-gas delivery systems or vacuum conditions. The findings of this study are relevant to applications employing spectroscopy principles including manufacturing process monitoring for integrated fibers possessing metal-oxide junctions and PCF based evanescent-field Raman spectroscopy applications. The experimental results agree with the predictions for the case of hydrodynamic flow under non-vacuum conditions. The dynamics of the gas delivery to the perforated optical fiber were predicted and demonstrated for a 0.365m fiber length with a 12.5 micron core. This core region was occupied by a preliminary gas, which affected the filling rates. The effective viscosities for the pure gas (acetylene) produced filling rates of 6 s (at 10 psi) and 11 s (at 5 psi). However, mixed gases (acetylene balance carbon dioxide) presented a viscosity dependent delay of 0.3 s and 0.5 s, respectively.

Keywords (OCIS):

  • (060.2280) Fiber optics and optical communications : Fiber design and fabrication
  • (060.2370) Fiber optics and optical communications : Fiber optics sensors
  • (060.4005) Fiber optics and optical communications : Microstructured fibers
  • (060.5295) Fiber optics and optical communications : Photonic crystal fibers

High power Ho:YAG laser wing-pumped by a Tm:fiber laser at 1933 nm

  • Zhao Ting, Fei Wang, and Deyuan SHEN
  • received 10/30/2014; accepted 01/22/2015; posted 01/22/2015; Doc. ID 226007
  • [full text: PDF (398) KB)]
  • Abstract: We report on the high-power and efficient operation of a Ho:YAG laser wing-band pumped by a Tm:fiber laser at 1933 nm. Using an output coupler of 10% transmission, a maximum continuous-wave (CW) output power of 24.2 W at 2124 nm was generated under 42.6 W of absorbed pump power, corresponding to a slope efficiency with respect to absorbed pump power of 57.6%. Operating wavelength of the Ho:YAG laser centered at 2092 or 2124 nm depending on the different resonator design. Prospects for further improvement in laser performances with this wing-pump configuration are discussed.

Keywords (OCIS):

  • (140.3460) Lasers and laser optics : Lasers
  • (140.3510) Lasers and laser optics : Lasers, fiber
  • (160.5690) Materials : Rare-earth-doped materials

Grating surface plasmon resonance sensor: angular sensitivity; metal oxidization effect of Al-based device in optimal structure

  • Changhong Chen, Xiaoliang Sun, and Xuewen Shu
  • received 10/06/2014; accepted 01/21/2015; posted 01/22/2015; Doc. ID 224396
  • [full text: PDF (1153) KB)]
  • Abstract: Here we present wavelength (λ)-independent ultimate and maximum angular sensitivity of grating surface plasmon resonance sensor as long as the grating of metal having much higher permittivity than analyte (na^2). For 1.32≤na≤1.36, the maximum angular sensitivity reaches 493.7 (535.9) °/RIU by the single (double)-dip method. The real Al-based sensor in optimal structure for high figure of merit exhibits the higher sensitivity but narrower reflection dip when working at longer wavelength, and the real sensitivity increases from 292.5 (344.5) to 338.0 (396.3) °/RIU at respective λ=0.85 and 1.55 μm before the metal oxidation. After the oxidization, the sensitivity is degraded by ≤3.2% (2.8%), and detection error of δna≤1.3e-3 (1.1e-3) is introduced to the sensor working at near-infrared wavelengths of interest.

Keywords (OCIS):

  • (240.6680) Optics at surfaces : Surface plasmons
  • (280.4788) Remote sensing and sensors : Optical sensing and sensors
  • (050.6624) Diffraction and gratings : Subwavelength structures

Photon counting imaging and phase mask multiplexing for multiple images authentication and digital hologram security

  • Naveen Nishchal, Sudheesh Rajput, and Dhirendra Kumar
  • received 10/20/2014; accepted 01/21/2015; posted 01/22/2015; Doc. ID 225303
  • [full text: PDF (900) KB)]
  • Abstract: We propose an image encryption system based on phase mask multiplexing and photon counting imaging (PCI) technique for multiple image authentications and digital hologram security. Multiple images to be authenticated are converted into phase-only images using phase retrieval algorithm in fractional Fourier transform domain. The multiple phase-only images are multiplexed into a single phase-only mask and it is further encrypted into a complex valued function. The photon limited image is generated by applying the PCI technique to complex valued function. For decryption, the photon limited decrypted images are obtained after applying the appropriate keys. The photon limited decrypted image contains sufficient information for verification because this image has sparse representation. To verify the photon limited decrypted image, the optical correlation filters can be used. The proposed system has also been used for hologram security. For hologram security, the system provides multiple layers of security by hiding multiple encrypted images. The computer simulation results have been presented. The authentication scheme has been tested for securing three-dimensional information through experimentally recorded Fresnel digital hologram.

Keywords (OCIS):

  • (070.0070) Fourier optics and signal processing : Fourier optics and signal processing
  • (100.0100) Image processing : Image processing
  • (100.2000) Image processing : Digital image processing
  • (100.4550) Image processing : Correlators
  • (090.1995) Holography : Digital holography
  • (070.2575) Fourier optics and signal processing : Fractional Fourier transforms

A hybrid method for multiple viewpoint projection hologram

  • Guanglin Yang, Haiyan Xie, and xiaochuan wang
  • received 10/08/2014; accepted 01/21/2015; posted 01/22/2015; Doc. ID 224468
  • [full text: PDF (1114) KB)]
  • Abstract: A hybrid method for Multiple Viewpoint Projection (MVP) holography using Semi-global Matching (SGM) and Virtual View Generation (VVG) is proposed to synthesize a hologram effectively. The Stereo Correspondence using SGM method performs much better matching than local methods, and is almost as accurate as global matching methods. The VVG based on the disparity images can generate the virtual viewpoint images. The method can conquer the tremendous information of the generated projection images, which improve the process speed and reduce the redundant information of the image acquisition process. The method of generating virtual projection images is adopted to avoid applying the camera (or lens) array and the depth camera so that the image acquisition system complex structure of MVP holography is simplified. The image inpainting method is applied to optimize the virtual projection images, and improve the synthesis speed and reconstruction image quality. And it is possible to acquire and real-time display 3D objects outside the laboratory. In order to challenge the tremendous information of hologram, several experimental schemes are performed. Experimental results have verified our method validity.

Keywords (OCIS):

  • (090.1760) Holography : Computer holography
  • (090.4220) Holography : Multiplex holography
  • (100.3010) Image processing : Image reconstruction techniques
  • (090.1995) Holography : Digital holography

Membrane based Deformable Mirror: Intrinsic aberrations and alignment issues

  • Raja Bayanna Ankala, Shibu Mathew, S. Chatterjee, P Venkatakrishnan, and Rohan Louis
  • received 10/09/2014; accepted 01/21/2015; posted 01/22/2015; Doc. ID 224683
  • [full text: PDF (1600) KB)]
  • Abstract: A Deformable Mirror (DM) is an important component of an Adaptive Optics system. It is known that an on-axis spherical/parabolic optical component, placed at an angle to the incident beam introduces defocus as well as astigmatism in the image plane. Although the former can be compensated by changing the focal plane position, the latter cannot be removed by mere optical re-alignment. Since the DM is to be used to compensate a turbulence-induced curvature term in addition to other aberrations, it is necessary to determine the aberrations induced by such (curved DM surface) an optical element when placed at an angle (other than 0º) of incidence in the optical path. To this effect, we estimate to a first order, the aberrations introduced by a DM as a function of the incidence angle and deformation of the DM surface. We record images using a simple setup in which the incident beam is reflected by a 37 channel Micro Machined Deformable Mirror for various angles of incidence. It is observed that astigmatism is a dominant aberration which was determined by measuring the difference between the tangential and sagital focal planes. We justify our results on the basis of theoretical simulations and discuss the feasibility of using such a system for adaptive optics considering a trade-off between wavefront correction and astigmatism due to deformation.

Keywords (OCIS):

  • (080.1010) Geometric optics : Aberrations (global)
  • (120.4630) Instrumentation, measurement, and metrology : Optical inspection
  • (120.4640) Instrumentation, measurement, and metrology : Optical instruments
  • (220.1000) Optical design and fabrication : Aberration compensation
  • (220.1140) Optical design and fabrication : Alignment
  • (110.1080) Imaging systems : Active or adaptive optics

Research on rapid fabrication technique for nanometer-precision aspherical surfaces

  • Wenlin Liao, Yifan Dai, Nie Xuqing, Xuhui Xie, and Ci Song
  • received 11/20/2014; accepted 01/21/2015; posted 01/22/2015; Doc. ID 228230
  • [full text: PDF (2837) KB)]
  • Abstract: High-precision aspherical optics are widely used in modern optical systems with the ability of providing high image quality, but aspherical surface is more challenging to fabricate for its more complex shape compared with other surfaces. Ion beam figuring provides a highly deterministic technology for the ultra-precision fabrication of aspherical surfaces, where the convergent efficiency and the final accuracy, however, are strongly dependent on the original surface state. The topography and distribution of the surface errors generated during the pre-processing should be taken into account. Consequently, we propose a combined technique that includes magnetorheological finishing, smoothing polishing and Ion beam figuring. This technique can effectively control different surface errors during polishing process, and then rapidly realize the nanometer-precision fabrication. Comparative figuring experiments are performed on a parabolic surface, and the original surfaces before ion beam figuring are pre-processed by manual polishing and our combined technique, respectively. The results indicate that abundant high-slope and middle-to-high frequency surface errors exist on the surface after the conventional polishing, and this surface state limits the final fabrication accuracy. Nevertheless, smooth surface is prepared by our combined technique and a nanometer-precision aspherical surface is rapidly obtained, which demonstrates the feasibility of our proposed method.

Keywords (OCIS):

  • (220.1250) Optical design and fabrication : Aspherics
  • (220.4610) Optical design and fabrication : Optical fabrication
  • (220.5450) Optical design and fabrication : Polishing

Compressive sensing based robust multispectral double-image encryption

  • Byung-Geun Lee, Byoungho Kim, Inbarasan Muniraj, Guo Situ, and Nitin Rawat
  • received 12/03/2014; accepted 01/21/2015; posted 01/22/2015; Doc. ID 228884
  • [full text: PDF (4067) KB)]
  • Abstract: We demonstrate a multispectral double-image based cryptosystem that exploits only a tiny number of random white-noise samples for proper decryption. Primarily, one of the two down-sampled images is converted into the phase function after being shuffled by Arnold transform (AT), while the other image is modulated as an amplitude-based image after AT. Consecutively, a full double-image encryption can be achieved by employing classical double random phase encryption (DRPE) technique in the fractional Fourier transform domain (FrFT) with corresponding fractional orders. In this study, the encrypted complex data is randomly sampled via compressive sensing (CS) framework by which only 25% of the sparse white noise samples are being reserved to realize decryption with zero or small errors. As a consequent, together with correct phase keys, fractional orders and proper inverse AT operators, lp minimization must been utilized to decrypt the original information. Thus, in addition to the perfect image reconstruction, the proposed cryptosystem provides an additional layer of security to the conventional DRPE system. Both the mathematical and numerical simulations were carried out to verify the feasibility as well as the robustness of the proposed system. The simulation results are presented in order to demonstrate the effectiveness of the proposed system. To the best of our knowledge, this is the first report on integrating CS with encrypted complex samples for information security.

Keywords (OCIS):

  • (040.1520) Detectors : CCD, charge-coupled device
  • (040.1880) Detectors : Detection
  • (070.0070) Fourier optics and signal processing : Fourier optics and signal processing
  • (090.2880) Holography : Holographic interferometry
  • (070.2575) Fourier optics and signal processing : Fractional Fourier transforms
  • (070.6120) Fourier optics and signal processing : Spatial light modulators

Using the Doppler shift induced by a galvanometric mirrors scanning to reach the shot noise limit with the laser optical feedback imaging (LOFI) setup

  • Olivier Jacquin, Eric Lacot, Hugues Guillet de Chatellus, and olivier HUGON
  • received 10/16/2014; accepted 01/20/2015; posted 01/22/2015; Doc. ID 225080
  • [full text: PDF (1031) KB)]
  • Abstract: We propose a new method to remove the contribution of parasitic reflections in the images of laser optical feedback imaging technique. The LOFI technique is an ultrasensitive imaging technique very interesting for imaging objects through a scattering medium. However, the LOFI sensitivity can be dramatically limited by parasitic optical feedback occurring in the experimental setup. In previous papers, we have already proposed methods to filter a parasitic optical feedback but they are not well suited to metric working distances. This is why we propose a new method using a Doppler frequency shift induced by the moving mirror which allows to scan the object to image. This Doppler frequency shift allows to distinguish the photons reflected by the target and the parasitic photons reflected by the optical components in the experimental setup. In this paper, we demonstrate theoretically and experimentally the possibility to filter the parasitic reflection in LOFI images by using this Doppler frequency shift. With this method, the signal to noise ratio is significantly improved (by a factor 15) and we obtain a shot noise limited image through a scattering medium of an object at 3 meters from the detector.

Keywords (OCIS):

  • (110.0110) Imaging systems : Imaging systems
  • (110.0113) Imaging systems : Imaging through turbid media
  • (110.3175) Imaging systems : Interferometric imaging

Effect of hot electron blast force on ultrafast laser ablation of nickel thin film

  • Yong Gan, Yonggang Shen, Wanjun Qi, Yaogen Shen, and Zhen Chen
  • received 10/22/2014; accepted 01/20/2015; posted 01/22/2015; Doc. ID 225142
  • [full text: PDF (819) KB)]
  • Abstract: The hot electron blast effect on the femtosecond laser-induced response of a nickel nanofilm is numerically studied by a coupled continuum-atomistic method. It is found that the hot electron blast force significantly affects the laser-induced stress waves in the nickel film, whereas the lattice temperature is much less influenced by the blast force. The simulation results for the laser ablation of the nickel film reveal that the neglect of hot electron blast effect could significantly underestimate the ablation depth and overpredict the ablation threshold. It is also shown that the blast force effect on the photomechanical ablation of nickel film becomes less significant with the increasing laser fluence.

Keywords (OCIS):

  • (140.3390) Lasers and laser optics : Laser materials processing
  • (140.3440) Lasers and laser optics : Laser-induced breakdown
  • (140.7090) Lasers and laser optics : Ultrafast lasers
  • (160.3900) Materials : Metals

Angular sensitivities for color filters incorporating different metallic gratings

  • Yan Ye, Yun Zhou, Linsen Chen, Donglin Pu, and haoshu Zhu
  • received 11/10/2014; accepted 01/20/2015; posted 01/22/2015; Doc. ID 226045
  • [full text: PDF (666) KB)]
  • Abstract: Angular sensitivities for color filters incorporating three typical metalized resonant gratings are discussed by rigorous coupled wave analysis. The transmissions at normal incidence for three color filters have the same resonant wavelengths although they demonstrate different transmission characteristics. To figure out the physical originations of these resonant wavelengths, their amplitude distributions of the electric field are analyzed. For different resonant wavelengths of the same structure, the less different the origination is, the wider the angular tolerance will be, which is verified by the transmissions intensities in band diagram and the transmission spectra at different incident angles.

Keywords (OCIS):

  • (050.0050) Diffraction and gratings : Diffraction and gratings
  • (090.0090) Holography : Holography
  • (230.0230) Optical devices : Optical devices

(LC2014) 3D Graphical Physically-Based Simulator of Rainbows together with the Background Scene

  • moon jung
  • received 09/30/2014; accepted 01/20/2015; posted 01/22/2015; Doc. ID 216951
  • [full text: PDF (7804) KB)]
  • Abstract: This paper presents a single scattering 3D graphics simulator of rainbows that includes the thick- ness of the rain shaft and the background scenery. The simulator is devised so that we can find a good configuration of the sun, the viewers, and the volume of water drops in a complicated geomet- ric setting. The background scene geometry and light re ecting properties are modelled using 3D graphics tools. The simulator makes both the light re ected from the background surface and the light scattered by water drops contribute to the final image, by taking the depth to the background surface into account. The simulator generates an image of rainbow by using the radiative transfer equation (RTE). We use ray optics to compute the average scattering cross section and the average phase function of particles which are the main parameters of the RTE. Depending on the density distribution of the water drops, the rainbow is perceived to be translucent, and the background scene is seen through the rainbow. We simulate other eects of the variation of the water drop density and the location of the viewer, e.g. the visibility of the secondary rainbow, the brightness of the sky around the rainbow, the close-up view of the rainbow, and the full circle rainbow. We explain these eects partly by computing the luminance contrasts of the primary and secondary bows against their local backgrounds.

Keywords (OCIS):

  • (010.1290) Atmospheric and oceanic optics : Atmospheric optics
  • (010.7295) Atmospheric and oceanic optics : Visibility and imaging
  • (010.1690) Atmospheric and oceanic optics : Color
  • (010.5620) Atmospheric and oceanic optics : Radiative transfer

Integral imaging system optical design with aberrations consideration

  • ayat karimzadeh
  • received 10/06/2014; accepted 01/20/2015; posted 01/22/2015; Doc. ID 224050
  • [full text: PDF (710) KB)]
  • Abstract: Integral imaging is a technique for displaying three-dimensional (3D) images using microlens arrays. This paper discusses optical design of integral imaging system with aberration consideration. All previously reported systems analyzed and designed only with using paraxial optics relations The paper describes simulation and optimization of an integral imaging system using geometrical optics methods, and OSLO optical design software. Designed system contains three microlens arrays with spherical surfaces.

Keywords (OCIS):

  • (110.6880) Imaging systems : Three-dimensional image acquisition
  • (220.1010) Optical design and fabrication : Aberrations (global)
  • (220.2740) Optical design and fabrication : Geometric optical design

Ballistic Imaging of Diesel Sprays Using a Picosecond Laser: Characterization and Demonstration

  • Jason Porter, Sean Duran, and Terry Parker
  • received 10/16/2014; accepted 01/20/2015; posted 01/22/2015; Doc. ID 224224
  • [full text: PDF (2014) KB)]
  • Abstract: Ballistic imaging using a 15 picosecond pulse laser in high-injection-pressure diesel sprays is reported. An optical Kerr effect shutter, constructed from a CS2 liquid cell and activated by a 15 picosecond pulse at 1064 nm, produces effective 532 nm imaging pulses between 7 and 15 picoseconds. The performance of the imaging system is characterized using an Air Force target positioned before an optical cell filled with polystyrene spheres in a water suspension. The impact of spatial filtering, temporal filtering, and scattering path length on image resolution are reported. The technique is demonstrated by imaging the near-orifice region of methyl oleate and methyl butyrate sprays injected using a high-pressure single-hole fuel injector with direct comparison against simultaneous orthogonal shadowgraphy.

Keywords (OCIS):

  • (000.2170) General : Equipment and techniques
  • (100.2960) Image processing : Image analysis
  • (110.0110) Imaging systems : Imaging systems
  • (110.0113) Imaging systems : Imaging through turbid media

Identification of atomic lines and molecular bands of benzene and carbon disulfide liquids by using LIBS

  • seyyed jabbar mousavi, Marziye Hemati Farsani, Nareh Asadoorian, Seyyed Mohammad Reza Darbany, Mahmoud Soltanalkotabi, and Abdollah Eslami Majd
  • received 10/08/2014; accepted 01/20/2015; posted 01/22/2015; Doc. ID 224274
  • [full text: PDF (1271) KB)]
  • Abstract: Plasma emission of liquid benzene (C6H6) and carbon disulfide (CS2) have been studied by using LIBS technique in air. Atomic lines of carbon, hydrogen, sulfur, nitrogen and oxygen and molecular emissions of CN and C2 have been identified. The formation mechanism of C2 and CN molecules has been discussed. Combustion process and more mole fraction of hydrogen in benzene have caused decreasing atomic lines intensity of oxygen and increasing atomic lines intensity of hydrogen with respect to the carbon disulfide and air. Also more intense CN molecular bands and weak nitrogen atomic lines in C6H6 spectrum than CS2 have been observed. In addition, molecular emissions of C2 have not been observed in CS2 spectrum. The electron temperature and the vibrational temperature have been calculated from the atomic lines and molecular bands intensity, respectively. Finally, the validity of the Local Thermodynamic Equilibrium (LTE) assumption in this experiment has been shown.

Keywords (OCIS):

  • (300.6210) Spectroscopy : Spectroscopy, atomic
  • (300.6390) Spectroscopy : Spectroscopy, molecular
  • (300.6365) Spectroscopy : Spectroscopy, laser induced breakdown

Reflection and transmission calculations in a multilayer structure with coherent, incoherent and partially coherent interference, using the transmission line method

  • Nikolaos Stathopoulos, Stelios Savaidis, Athanasios Botsialas, Zisis Ioannidis, Dimitra Georgiadou, Maria Vasilopoulou, and Gerasimos Pagiatakis
  • received 11/11/2014; accepted 01/20/2015; posted 01/20/2015; Doc. ID 226745
  • [full text: PDF (858) KB)]
  • Abstract: A generalized transmission line method (TLM) that provides reflection and transmission calculations for a multilayer dielectric structure with coherent, partial coherent and incoherent layers is presented. The method is deployed on two different application fields. The first application of the method concerns the thickness measurement of the individual layers of an organic light emitting diode (OLED). By using a fitting approach between experimental spectral reflectance measurements and the corresponding TLM calculations, it is shown that the thickness of the films can be estimated. The second application of the TLM concerns the calculation of the external quantum efficiency of an organic photovoltaic (OPV) with partially coherent rough interfaces between the layers. Numerical results regarding the short circuit photocurrent for different layer thicknesses and rough interfaces are provided and the performance impact of the rough interface is discussed in detail.

Keywords (OCIS):

  • (030.5770) Coherence and statistical optics : Roughness
  • (040.5350) Detectors : Photovoltaic
  • (230.3670) Optical devices : Light-emitting diodes
  • (230.4170) Optical devices : Multilayers
  • (240.0310) Optics at surfaces : Thin films
  • (240.5770) Optics at surfaces : Roughness

Non-uniform grid target tessellation method for the design of lens group with rectangular uniform illumination

  • Zhenjie Liu and Feihong Yu
  • received 10/10/2014; accepted 01/19/2015; posted 01/20/2015; Doc. ID 223346
  • [full text: PDF (1318) KB)]
  • Abstract: A non-uniform grid target tessellation method is proposed for designing a lens group with rectangular uniform illumination, a small screen incident angle and high collection efficiency. A collimation lens is first designed to collimate the source rays preliminarily. Secondly, the source collected solid angle is tessellated so that each source ray encompasses the same flux. Thirdly, the source rays are traced to the first surface of lens2. Finally, the non-uniform grid target tessellation iteration is applied to find the integration constraint mapping. The free-form surface constructed with this method can exactly refract the rays to their corresponding target location, and the rectangular uniform illumination is accomplished. To verify the effectiveness of the proposed method, a design example is presented with a rectangular figuration and a high uniformity, the incident angle is smaller than and the collection efficiency reaches 96% with Lambertian point source.

Keywords (OCIS):

  • (220.3620) Optical design and fabrication : Lens system design
  • (220.2945) Optical design and fabrication : Illumination design
  • (080.4298) Geometric optics : Nonimaging optics

Blind spectral deconvolution with Wavelet regularization for Poisson noise

  • Liu Hai, Zhang Tianxu, and Yan Luxin
  • received 10/20/2014; accepted 01/19/2015; posted 01/20/2015; Doc. ID 225257
  • [full text: PDF (463) KB)]
  • Abstract: In this work, we introduce a blind deconvolution approach with Wavelet regularization for the Raman spectrum and total variation (TV) regularization for instrument function. The proposed algorithm can effectively suppress the Poisson noise as well as preserve the spectral structure information. Moreover, the split Bregman method is adopted to solve the proposed model. The comparative results on the simulated and measured Raman spectra show that the Wavelet-based method outperforms the conventional methods. The deconvolution Raman spectrum is more convenient for extracting the spectral feature and interpreting the unknown chemical mixtures.

Keywords (OCIS):

  • (100.3190) Image processing : Inverse problems
  • (170.5660) Medical optics and biotechnology : Raman spectroscopy
  • (300.6320) Spectroscopy : Spectroscopy, high-resolution
  • (060.3510) Fiber optics and optical communications : Lasers, fiber

Aerosol optical properties and precipitable water vapor column in the atmosphere of Bergen, Norway.

  • Dennis Muyimbwa, Jakob Stamnes, Øyvind Frette, Borge Hamre, Yi-Chun Chen, and TADDEO SSENYONGA
  • received 10/27/2014; accepted 01/19/2015; posted 01/20/2015; Doc. ID 225644
  • [full text: PDF (569) KB)]
  • Abstract: Direct solar radiances at a ground-based station in Bergen, Norway have been measured and analyzed for the period between February, 2012 and April, 2014. The spectral aerosol optical thickness and precipitable water vapor column retrieved from these measurements were found to have a seasonal variation with highest values in summer and lowest values in winter. The highest value of the monthly median aerosol optical thickness at 440 nm of about 0.16 was measured in July and the lowest of about 0.04 was measured in December. The highest value of the monthly median precipitable water vapor column of about 2.0 cm was measured in July and the lowest of about 0.4 cm was measured in December. Angstrom exponents were derived and used to deduce aerosol particle size distributions. Coarse-mode aerosol particles were found to dominate most of the time during the measurement period, but fine-mode aerosol particles were found to dominate during the winter seasons. The derived Angstrom exponent values suggested that aerosols containing sea-salt could have been dominating at this station during the measurement period.

Keywords (OCIS):

  • (010.1100) Atmospheric and oceanic optics : Aerosol detection
  • (010.1110) Atmospheric and oceanic optics : Aerosols
  • (010.1290) Atmospheric and oceanic optics : Atmospheric optics
  • (120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
  • (120.0280) Instrumentation, measurement, and metrology : Remote sensing and sensors

Performance analysis of a car to car visible light communication system

  • Pengfei Luo, Zabih Ghassemlooy, Hoa Le Minh, Edward Bentley, Andrew Burton, and Xuan Tang
  • received 11/11/2014; accepted 01/19/2015; posted 01/20/2015; Doc. ID 226435
  • [full text: PDF (1575) KB)]
  • Abstract: This paper presents the analytical performance analysis of the car-to-car visible light communications system under different communication geometries. A market-weighted headlamp beam pattern model, measured dirt effects on light distribution and the road surface reflection model are employed. We consider both the line-of-sight and non-line-of-sight links, and outline the relationship between the communication range and the system bit error rate (BER) performance. Results show that the wet road surface can help to increase the received optical power and improve the BER performance after a certain distance, and the communications coverage range can reach up to 20 m at a data rate of 2 Mbps when a photodetector is mounted on the car at a height of 0.2-0.4 m above road surface.

Keywords (OCIS):

  • (060.4510) Fiber optics and optical communications : Optical communications
  • (120.4820) Instrumentation, measurement, and metrology : Optical systems

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