Accepted papers to appear in an upcoming issue
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Real time monitoring of ruling grating resolution by digital wave-front
- received 08/28/2014; accepted 11/26/2014; posted 11/26/2014; Doc. ID 221808
- [full text: PDF (490) KB)]
- Abstract: In order to solve the problem that the grating quality can’t be monitored directly in real time, we provided a method based on Rayleigh criterion, with our designing optical measurement structure to measure yaw and position errors of grating ruling machine feeding system. Gratings are ruled with or without errors correction by the real-time monitoring system respectively. It shows that the resolution got without errors correction is reduced from 99.97％ to 87.47％, while the resolution got with errors correction is stable, remaining 99.99％~ 97.21％. The experimental result turns out that the grating quality can be guaranteed by monitoring grating resolution in real time.
- (050.1950) Diffraction and gratings : Diffraction gratings
- (120.5050) Instrumentation, measurement, and metrology : Phase measurement
- (220.4830) Optical design and fabrication : Systems design
- (350.5730) Other areas of optics : Resolution
A measurement method for optical retardation based on phase difference effect of laser feedback fringes
- received 09/15/2014; accepted 11/26/2014; posted 11/26/2014; Doc. ID 222930
- [full text: PDF (1154) KB)]
- Abstract: We present a measurement method for optical phase retardation, which utilizes a phase-difference phenomenon of the feedback fringes in orthogonally-polarized directions of a laser with anisotropic weak feedback. This phase difference is dominated by the measured retardation. Measurement principle is given based on the three-mirror cavity model, and experiments are conducted with quartz wave plates. A measurement range from 0° to 180° is achieved, the uncertainty is theoretically better than 0.5° and the measurement precision can be improved further. This method is suitable for online application and has better anti-disturbance ability than the previous method based on laser feedback.
- (120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
- (140.0140) Lasers and laser optics : Lasers and laser optics
- (260.1440) Physical optics : Birefringence
A novel temporal compensation method of pulse-distortion in saturated laser amplifiers
- received 10/08/2014; accepted 11/26/2014; posted 11/26/2014; Doc. ID 224511
- [full text: PDF (766) KB)]
- Abstract: We provide a tunable temporal shaping method of laser pulse to compensate pulse-distortion in saturated laser amplifiers. The solutions of our computer programs, which express pulse-distortion because of saturation effects in pulse laser amplifiers, determine the optimum input pulse-shape required to produce a top-hat target pulse-shape at the output of the saturated laser amplifier. With the tuning ability of the method provided here, the top-hat target pulse-shape can be maintained at different output characteristic energies relative to the saturation energy of the amplifier. Moreover, the relation is experimentally verified using a solid-state laser amplifier chain. The method will prove useful in applications of high energy laser amplifier systems that require a top-hat pulse-shape to be efficient, such as the pump laser pulse of optical parametric chirped pulse amplification (OPCPA).
- (140.3280) Lasers and laser optics : Laser amplifiers
- (140.3540) Lasers and laser optics : Lasers, Q-switched
Packaged microsphere-taper coupling system with high Q factor
- received 10/14/2014; accepted 11/26/2014; posted 11/26/2014; Doc. ID 224998
- [full text: PDF (2542) KB)]
- Abstract: A novel packaged microsphere-taper coupling system which consists of a glass tube and two glass plates is proposed and demonstrated in this paper. We analyze the impact of the microsphere distortion on the resonant spectrum and it is observed that a very high quality factor (Q) up to 1.08 × 108 can be achieved by optimizing the microsphere position and orientation relative to the fiber taper. The Q maintenance and stable spectrum are realized by placing the packaged structure in a sealed organic glass box. What’s more, to verify the practicability of the sealed device, thermal sensing experiments are carried out, which indicates the excellent convenience of the device with a resolution of 1.12 ×10-4 The portability and robustness of the packaged structure make it strikingly attractive and potential in practical microcavity sensors and lasers.
- (140.4780) Lasers and laser optics : Optical resonators
- (140.3948) Lasers and laser optics : Microcavity devices
- (280.4788) Remote sensing and sensors : Optical sensing and sensors
Analytic known-plaintext attack to phase-shifting interferometry-based cryptosystem
- received 10/09/2014; accepted 11/25/2014; posted 11/26/2014; Doc. ID 224710
- [full text: PDF (1032) KB)]
- Abstract: We demonstrate a new analytic approach to known-plaintext attack on optical cryptosystem based on phase-shifting interferometry technique (PSI). With the proposed analytic attack method, an opponent can access the exact decryption keys and obtain the perfect attack results. This demonstration, as far as our best knowledge, shows that the optical cryptosystem based on PSI technique is vulnerable to known-plaintext attack for the first time.
- (090.1995) Holography : Digital holography
- (100.4998) Image processing : Pattern recognition, optical security and encryption
Numerical and theoretical analysis on the absorption properties of metasurface based terahertz absorber with different thicknesses
- received 09/23/2014; accepted 11/25/2014; posted 11/26/2014; Doc. ID 223634
- [full text: PDF (1272) KB)]
- Abstract: In this paper, we numerically and theoretically discuss the novel absorption properties of a conventional metasurface based terahertz (THz) electromagnetic absorber with different dielectric thicknesses. Two absorption modes are presented in the considered frequency band due to the increased dielectric thickness, and both modes can achieve the near-unity absorptions when the dielectric layer are reached to additional nλd/2 (n=1, 2) thicknesses. The surface currents between the metasurface resonators and ground plane are not associated any longer, different from the conventional thin absorbers. Moreover, the electromagnetic (EM) wave energies are completely absorbed by the metasurface resonators and the main function of ground plane is to reflect the incident EM waves back to the resonators. The discussed novel absorption properties are analyzed and explained by classical electromagnetic theory and interference theory after numerical demonstrations. These findings can broaden the potential applications of the metasurface based absorbers in THz area for different requirements.
- (230.5750) Optical devices : Resonators
- (310.1620) Thin films : Interference coatings
- (160.3918) Materials : Metamaterials
- (310.6628) Thin films : Subwavelength structures, nanostructures
- (310.6805) Thin films : Theory and design
Accurate projector calibration based on a new point-to-point mapping relationship between the camera and projector images
- received 07/16/2014; accepted 11/25/2014; posted 11/26/2014; Doc. ID 216979
- [full text: PDF (1196) KB)]
- Abstract: The mapping relationship between the charge-coupled device (CCD) of camera and the digital micro-mirror device (DMD) of projector, together with the algorithm to estimate parameters of projector, determines the accuracy of projector calibration. In this paper, a new method is presented to achieve sub-pixel level mapping between the camera and projector images. Instead of directly mapping the circle centers from the CCD to the DMD which is pixel precision based, a set of pixels on the circle edge are extracted on the CCD and mapped onto the DMD. The locations of the circle centers are extracted on the DMD by the least-square fitting technique, thus achieving sub-pixel precision. Compared to existing approaches based on directly mapping of the circle centers on the camera image to the projector image, the proposed method is characterized by higher accuracy in the mapping the points and thus the projector calibration. Experimental results are presented to show the effectiveness of proposed method in the improvement of the accuracy of projector calibration.
- (040.1520) Detectors : CCD, charge-coupled device
- (050.5080) Diffraction and gratings : Phase shift
- (120.4820) Instrumentation, measurement, and metrology : Optical systems
- (150.1488) Machine vision : Calibration
- (110.5086) Imaging systems : Phase unwrapping
Novel Optical Layout of Autostereoscopic Display That Simultaneously Reproduces Two Views Each with Full-Screen Resolution
- received 10/20/2014; accepted 11/24/2014; posted 11/26/2014; Doc. ID 225331
- [full text: PDF (6336) KB)]
- Abstract: Traditional 60 Hz autostereoscopic displays with static amplitude parallax barriers have a half of full-screen resolution in each of two displayed views of three-dimensional (3D) scene. The known 120 Hz autostereoscopic displays with dynamic amplitude parallax barriers have full-screen resolution but are characterized by essential light intensity losses and crosstalk in each of displayed views. The recently proposed autostereoscopic displays with simultaneous reproducing two image elements in each display pixel and with a polarization parallax barrier has full-screen resolution. But existing optical layout of these displays does not provide optimum operating conditions for the polarization parallax barrier creating a tendency to degrade the contrast and color characteristics. This paper presents a novel optical layout characterized by the reversed order of the arrangement of optical components autostereoscopic display in compare with the existing optical layout. In the novel optical layout the pointed problems are absent due to providing optimum operating conditions for all the optical components while preserving the full functionality of the autostereoscopic display. Experimental results are presented to confirm the obtaining good contrast and color characteristics in the novel optical layout.
- (100.6890) Image processing : Three-dimensional image processing
- (110.0110) Imaging systems : Imaging systems
Design method for a thin uniform direct backlight using a diffuser plate with a pattern on the surface and optical films
- received 08/25/2014; accepted 11/23/2014; posted 11/25/2014; Doc. ID 220083
- [full text: PDF (1036) KB)]
- Abstract: We researched a design method for improving uniformity of a thin direct backlight by using a diffuser plate (DP) with a pattern on the surface. It was found that the transmittance angle distribution (TAD) of the DP indicated the performance for uniformity and was an essential physical quantity for a backlight optical system with the DP. We clarified the relationship between the design parameters of the DP (the pattern and the mean free path of a ray in the DP) and the TAD of the DP by a simulation based on Mie theory and the experiments. The direct backlight, in which the distance between the DP and the lamps was less than 5 mm, was demonstrated. The illuminance uniformity of the DP was improved to 0.98 by the DP with a pattern that makes the TAD nearly constant distribution. Furthermore, the optical films on the DP were optimized, and the illuminance uniformity of the backlight achieved 0.99.
- (120.2040) Instrumentation, measurement, and metrology : Displays
- (230.1980) Optical devices : Diffusers
- (230.3720) Optical devices : Liquid-crystal devices
Comprehensive study on the light shielding potential of thermotropic layers in respect of the development of new materials
- received 09/12/2014; accepted 11/23/2014; posted 11/25/2014; Doc. ID 221966
- [full text: PDF (5495) KB)]
- Abstract: In recent years thermotropic overheating protection glazings have been in the focus of both solar thermal collector technology and architecture. A thermotropic glazing changes its light transmittance from highly transparent to light diffusing upon reaching a certain threshold temperature autonomously and reversibly. In thermotropic systems with fixed domains (TSFD) the scattering domains are embedded in a polymer matrix, which exhibit a sudden change of the refractive index upon reaching a threshold temperature. The aim of the present study was to comprehensively investigate the light shielding characteristics and potential of TSFD materials by applying simulation of light scattering in particle filled layers. In random walk simulations a variety of parameters were varied systematically and the effect on the light transmission behavior of TSFD was studied. The calculation steps of the simulation process are shown in detail. The simulations demonstrate that there is great potential for the production of functional materials with high overheating protection efficiency.
- (230.4170) Optical devices : Multilayers
- (290.4020) Scattering : Mie theory
- (290.5850) Scattering : Scattering, particles
- (350.6050) Other areas of optics : Solar energy
Optical constants of Cu, Ag, and Au revisited
- received 10/08/2014; accepted 11/23/2014; posted 11/26/2014; Doc. ID 223717
- [full text: PDF (420) KB)]
- Abstract: We have determined the optical constants in the energy range 0.1-6 eV for bulk Cu, Ag, and Au using Kramers-Kronig analysis of previously unpublished reflectance data. The results are compared to those commonly used from the literature.
- (160.4760) Materials : Optical properties
- (240.6680) Optics at surfaces : Surface plasmons
- (300.1030) Spectroscopy : Absorption
- (310.6860) Thin films : Thin films, optical properties
- (350.4238) Other areas of optics : Nanophotonics and photonic crystals
- (250.5403) Optoelectronics : Plasmonics
(DH3D2014)Resolution enhancement of spectrum normalization in synthetic aperture digital holographic microscopy
- received 09/02/2014; accepted 11/23/2014; posted 11/24/2014; Doc. ID 222117
- [full text: PDF (11969) KB)]
- Abstract: This study describes the overlapping of spatial frequency bands for synthetic aperture in digital holography, using spectrum normalization to effectively enhance the spatial resolutions of image reconstruction. Synthesized spectrum swelling induced by excessive frequency overlaps can be normalized through the inverse apodization of an adjustable window function, which is similar to the effects of suppressing low-frequency expansion and strengthening high-frequency components of the reconstructed images. The results indicated that using the normalized spectrum synthesis that requires only a few frequency bands effectively enhances the spatial resolution and phase sensitivity of reconstructed images in digital holographic microscopy.
- (100.6640) Image processing : Superresolution
- (220.1230) Optical design and fabrication : Apodization
- (090.1995) Holography : Digital holography
Mechanisms for the millisecond laser-induced functional damage to silicon charge-coupled imaging sensors
- received 09/05/2014; accepted 11/21/2014; posted 11/24/2014; Doc. ID 222488
- [full text: PDF (4114) KB)]
- Abstract: A three-dimension model is established to simulate the process of millisecond Nd:YAG laser irradiate the CCD, basic on its array and multilayer structure. The transient temperature and thermal stress field of the CCD were obtained by using the finite element method. The temperature dependences of material parameters are taken into account in the calculation. The results indicate that the coupled interaction of the heat damage and thermal stress damage is the main reason for the millisecond laser damage CCD. The softening of PMMA microlens or rupture of silica microlens reduces the fill factor of CCD. The plastic-deformation of the silicon substrate increases a great deal of dark current. The peeled of Al-shield introduces the leakage current. Most importantly, the melting through of Al-shield layer and the fracture of silica insulting layer is the two critical factors for the functional damage to CCD. Meanwhile, the influences of the material and fill factor of the microlens were also considered. The results show that the plastic damage of silicon substrate is more dramatic than the PMMA microlens CCD. And the damage threshold decreases along with the increasing fill factor.
- (000.4430) General : Numerical approximation and analysis
- (040.1520) Detectors : CCD, charge-coupled device
- (140.3330) Lasers and laser optics : Laser damage
- (140.6810) Lasers and laser optics : Thermal effects
The design of optical systems for LED road luminaires
- received 09/16/2014; accepted 11/21/2014; posted 11/24/2014; Doc. ID 223067
- [full text: PDF (4504) KB)]
- Abstract: The introduction of light emitting diodes for lighting necessitated a completely new quality in the construction of luminaires. Different production technology required new methods and designing tools. It has also challenged designers with new problems to solve. The design process from concept to implementation of the LED luminaire is shown in the example of road lighting. The methods and procedures used by the designer are described. Also the technological problems influencing the quality of lighting implemented are addressed.
- (080.3620) Geometric optics : Lens system design
- (220.0220) Optical design and fabrication : Optical design and fabrication
- (220.3620) Optical design and fabrication : Lens system design
- (080.1753) Geometric optics : Computation methods
Electromagnetically induced grating in the microwave driven four level atomic systems
- received 09/11/2014; accepted 11/21/2014; posted 11/21/2014; Doc. ID 222677
- [full text: PDF (974) KB)]
- Abstract: A new scheme to investigate an electromagnetically induced grating in a N-type configuration in the presence of a strong standing coupling field, additional coherent fields and microwave driven field is presented. By considering Coherent Population Trapping (CPT) condition in a four level microwave driven N-type atomic system, a novel nonlinear optical storage is obtained via linear absorption vanishing and giant Kerr nonlinearity during light propagation. It is revealed that nonlinear properties in this atomic medium are maximum in the CPT condition, and these nonlinear properties could be affected and modulated by means of microwave driven field. In this condition, high phase modulated diffraction efficiency is attained. The diffraction pattern is sensitive to variables of the phase and amplitude of microwave field, consequently one can control the efficiency of different orders of grating more conveniently. The first-order diffraction efficiency of the grating about 45% can be obtained via choosing optimum values for phase and amplitude of microwave field. It is shown that the phase and modulation grating could be controlled effectively by atom-field radiation parameters such as interaction length L of atomic sample and applied filed detunings. It is noticed that a novel fast communication device could be obtained at the zero absorption point and on the superluminal light level.
- (050.0050) Diffraction and gratings : Diffraction and gratings
- (050.1940) Diffraction and gratings : Diffraction
- (050.1950) Diffraction and gratings : Diffraction gratings
- (190.0190) Nonlinear optics : Nonlinear optics
- (190.4400) Nonlinear optics : Nonlinear optics, materials
- (190.2055) Nonlinear optics : Dynamic gratings
Three-dimensional (3D) facial recognition using passive LWIR polarimetric imaging
- received 10/07/2014; accepted 11/21/2014; posted 11/21/2014; Doc. ID 224226
- [full text: PDF (1226) KB)]
- Abstract: We use a polarimetric camera to record the Stokes parameters and the degree-of-linear polarization of long-wavelength infrared (LWIR) radiation emitted by human faces. These Stokes images are combined with Fresnel relations to extract a surface normal. The surface normal is integrated to yield a three-dimensional facial image. One major difficulty of this technique is that the normal vectors determined from the polarizations are not unique. We overcome this problem by introducing an additional boundary condition on the subject. The major sources of error in producing inversions is noise in the images caused by scattering of the background signal and the ambiguity in determining the surface normals from the Fresnel coefficients.
- (110.6820) Imaging systems : Thermal imaging
- (110.6880) Imaging systems : Three-dimensional image acquisition
- (260.5430) Physical optics : Polarization
Secure Chaotic Transmission of ECG Signals with Acousto- Optic Modulation under Profiled Beam Propagation
- received 09/25/2014; accepted 11/20/2014; posted 11/20/2014; Doc. ID 223854
- [full text: PDF (595) KB)]
- Abstract: Electrocardiography (ECG) signals are used for both medical purposes and for identifying individuals. It is often necessary to encrypt this highly sensitive information before it is transmitted over any channel. A closed-loop acousto-optic hybrid device, acting as a chaotic modulator, is applied to ECG signals to achieve this encryption. Recently, improved modeling of this approach using profiled optical beams has shown it to be very sensitive to key parameters that characterize the encryption and decryption process, showing its potential for secure transmission of analog and digital signals. Here, the encryption and decryption is demonstrated for ECG signals, both analog and digital versions, illustrating strong encryption without significant distortion. Performance analysis pertinent to both analog and digital transmission of the ECG waveform is also carried out using output signal-to-noise (SNR), signal-to-distortion (SDR) and bit-error-rate (BER) measures relative to the key parameters and presence of channel noise in the system.
- (060.4080) Fiber optics and optical communications : Modulation
- (140.1540) Lasers and laser optics : Chaos
- (170.1065) Medical optics and biotechnology : Acousto-optics
- (060.4785) Fiber optics and optical communications : Optical security and encryption
Spectral shaping of all-fiber torsional acousto-optic tunable filter
- received 10/13/2014; accepted 11/20/2014; posted 11/20/2014; Doc. ID 224946
- [full text: PDF (679) KB)]
- Abstract: Spectral shaping of an all-fiber torsional acousto-optic (AO) tunable filter is studied. The technique is based on the axial modulation of AO coupling strength along a highly birefringent optical fiber, which is achieved by tailoring outer diameter of the fiber along its propagation axis. Two kinds of filter spectral shaping schemes – Gaussian apodization and the matched filtering with triple resonance peaks – are proposed and numerically investigated under the realistic experimental conditions: the 50-cm-long AO interaction length of the fiber and the half of original fiber diameter as the minimum thickness of tailored fiber section. The results show that the highest peak of sidelobe spectra in filter transmission is suppressed from 11.64% to 0.54% via Gaussian modulation of the AO coupling coefficient (κ). Matched filtering with triple resonance peaks operating with a single radio-frequency signal is also achieved by cosine modulation of κ, of which modulation period determines the spectral distance between two satellite peaks located in both wings of the main resonance peak. The splitting of two satellite peaks in the filter spectra reaches 48.2 nm while the modulation period varies from 7.7 to 50 cm. The overall peak power of two satellite resonances is calculated to 22% of the main resonance power. The results confirm the validity and practicality of our approach, and predict a robust and stable operation of the designed all-fiber torsional AO filters.
- (060.2310) Fiber optics and optical communications : Fiber optics
- (230.1040) Optical devices : Acousto-optical devices
Spectral measurement of birefringence using particle swarm optimization analysis
- received 07/14/2014; accepted 11/20/2014; posted 11/21/2014; Doc. ID 216918
- [full text: PDF (1720) KB)]
- Abstract: The measurement of the birefringence is useful for examination both technical and biological objects. One of the main problems is, that the polarization state of light in birefringent media changes periodically. Without knowledge of the period number, birefringence cannot be determined reliably. We propose to analyze spectrum of light in order to determine the birefringence. We use a Particle Swarm Optimization algorithm for automatic processing spectra of light transmitted through birefringent material for two orthogonal states of polarization. We have tested described algorithm on a liquid crystal cell with varying effective birefringence. The proposed method can be used for measurement of birefringence without knowing number of retardation period or approximate value of measurement result. It makes it useful for automatic measurements, when hundreds or thousands of spectra need to be analyzed.
- (120.5410) Instrumentation, measurement, and metrology : Polarimetry
- (160.3710) Materials : Liquid crystals
Two Dimensional Quantitative Measurements of Methyl Radicals in Methane/Air Flame
- received 09/09/2014; accepted 11/19/2014; posted 11/20/2014; Doc. ID 222709
- [full text: PDF (976) KB)]
- Abstract: Two-dimensional (2D) quantitative measurements of methyl (CH3) radicals in a methane/air Hencken flame at atmospheric pressure are performed using coherent microwave Rayleigh scattering (Radar) from Resonance Enhanced Multi-Photon Ionization (REMPI) technique. 2D scanning and subsequent quantification are employed for Radar REMPI. The 2D quantitative results were used to verify the numerical calculations. The Rayleigh-integral effect was involved in the calculation due to the real experimental configuration. A 25% error existed between the experimental results and numerical calculation while the overall concentration distributions between experiment and modeling of single flamelet have fairly good agreement with each other.
- (300.6350) Spectroscopy : Spectroscopy, ionization
- (300.6360) Spectroscopy : Spectroscopy, laser