Accepted papers to appear in an upcoming issue
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Wedge-plate Shear for Focus-shifting Testing in Single-shot Laser System
- received 12/06/2012; accepted 05/15/2013; posted 05/15/2013; Doc. ID 180084
- [full text: PDF (763) KB)]
- Abstract: A Wedge-plate shear shifting system (WPSS) with adjustable accuracy and measuring range is proposed for measuring the focus-shifting caused by thermal distortion in a single-shot laser system. Two Beam Splitter Groups (BSG) are used in this method to precisely split a single beam into multiple beams with different optical path difference (OPD). The focus-shifting is determined by position change of the minimum spot on detector. This method is convenience, economic, specia1ly it solves the problem of catching focus-shifting in ultra-short time.
- (120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
- (120.4570) Instrumentation, measurement, and metrology : Optical design of instruments
(HM) A Graphene Based Tunable Terahertz and Infrared Band-Pass Filter
- received 02/27/2013; accepted 05/15/2013; posted 05/15/2013; Doc. ID 186068
- [full text: PDF (789) KB)]
- Abstract: This paper presents a sheet of graphene as a simple band-pass filter in terahertz and infrared frequencies. Central frequency and quality factor of this band-pass filter can be tuned by changing the physical parameters such as substrate thickness, gate voltage, temperature, and conductivity of the graphene. Effects of these parameters on surface plasmon polariton waves and filter specifications are numerically depicted
- (310.6860) Thin films : Thin films, optical properties
- (250.5403) Optoelectronics : Plasmonics
High efficiency Nd:LuVO4 quasi-three-level 916 nm laser under polarized pumping
- received 03/21/2013; accepted 05/15/2013; posted 05/17/2013; Doc. ID 187564
- [full text: PDF (586) KB)]
- Abstract: An efficient laser diode pumped Nd:LuVO4 916 nm laser by using the polarized pumping is reported. The maximum continuous-wave output power of 4.75 W is achieved at the incident pump power of 27.8 W, with an optical-to-optical efficiency of ~17.1% and a slope efficiency of ~29.5%. The slope efficiency is up to 45.4% with respect to the absorbed pump power and nearly 1.7 times higher than the previous results ever reported under the 808 nm diode laser pumping. The beam quality is measured to be M2~2.3 at the output power of 4.75 W. © 2013 Optical Society of America
- (140.0140) Lasers and laser optics : Lasers and laser optics
- (140.3480) Lasers and laser optics : Lasers, diode-pumped
- (140.3530) Lasers and laser optics : Lasers, neodymium
- (140.3580) Lasers and laser optics : Lasers, solid-state
Coherent Optical Сorrelator Based on Combined Halftone and Position Modulation of Light Phase
- received 04/04/2013; accepted 05/15/2013; posted 05/17/2013; Doc. ID 188145
- [full text: PDF (654) KB)]
- Abstract: Usually only a halftone (grayscale) modulation of light is used to present the processed and reference signals in the input plane of analog coherent optical (ACO) correlators, based on spatial integrating the product of two (processed and reference) signals. The halftone modulation requires two transparencies to record two signals separately as the desired product of two spatial signals is obtained by sequential location of two spatial halftone records along the light path. Such optical layout leads to the need for precision mutual alignment of two separate signal recordings. This paper presents a one-stage ACO correlation method based on combined halftone and position modulation of light phase which is produced by joint phase recording two signals on a single transparency. The joint phase recording provides the high optical efficiency of informational light modulation, automatically supports the spatial coincidence of corresponding elements of both recorded signals and providing the same spatial scale for both recordings. The suggested method can also be used for introducing phase weight functions in the schemes of space-time ACO processing of wave signals.
- (070.0070) Fourier optics and signal processing : Fourier optics and signal processing
- (070.1170) Fourier optics and signal processing : Analog optical signal processing
- (070.4550) Fourier optics and signal processing : Correlators
Simplified model for light scattering from granular materials of different moist.
- received 01/23/2013; accepted 05/14/2013; posted 05/15/2013; Doc. ID 183757
- [full text: PDF (599) KB)]
- Abstract: Reflection measurements have been performed on dry and moistened sand grains and glass spheres respectively. By looking at the reflection distribution in the plane of incidence a simple model for determining the water content has been proposed. The model is a combination of two sheared cosine-functions and it consists of only two parameters. One parameter controls whether the reflection is mainly in the forward or backward direction. The former is true when the water content is high and the latter when the material is dry. The other parameter gives an idea of the homogeneity of the material.
- (280.0280) Remote sensing and sensors : Remote sensing and sensors
- (290.1990) Scattering : Diffusion
- (290.4210) Scattering : Multiple scattering
- (290.5820) Scattering : Scattering measurements
Size effect on the optical limiting in suspensions of detonation nanodiamond clusters
- received 02/26/2013; accepted 05/14/2013; posted 05/14/2013; Doc. ID 185608
- [full text: PDF (2466) KB)]
- Abstract: We report on the optical limiting in stable aqueous suspensions of detonation nanodiamond clusters with average size of 50, 110 and 320 nm. The nanosecond Z - scan experiments at wavelength of 532 nm revealed that the larger the cluster size, the better the optical limiting performance and the higher the ray stability of the nanodiamond suspension. Our analysis showed that the nonlinear scattering and the nonlinear absorption are the dominant mechanisms of optical limiting in aqueous nanodiamond suspensions.
- (190.4400) Nonlinear optics : Nonlinear optics, materials
- (160.4236) Materials : Nanomaterials
Compact Flattop Laser Beam Shaper Using Vectorial Vortex
- received 03/18/2013; accepted 05/14/2013; posted 05/15/2013; Doc. ID 187243
- [full text: PDF (845) KB)]
- Abstract: In this paper, we demonstrate a compact flattop beam shaper to realize two-dimensional flattop focus through generating second order Full Poincaré beam. Liquid crystal material is used in the device as the voltage-dependent birefringent material to provide appropriate phase retardation modulation. The beam shaper is fabricated and tested. Experimental results show that high quality flattop profiles can be obtained with steep edge roll-off. The tolerance of different input beam sizes of the beam shaper is also verified in the experimental demonstration.
- (050.1960) Diffraction and gratings : Diffraction theory
- (140.3300) Lasers and laser optics : Laser beam shaping
- (160.3710) Materials : Liquid crystals
- (230.6120) Optical devices : Spatial light modulators
- (260.5430) Physical optics : Polarization
Active and passive SWIR and NIR imaging for horizontal and slant paths close to ground
- received 02/04/2013; accepted 05/14/2013; posted 05/16/2013; Doc. ID 184765
- [full text: PDF (4334) KB)]
- Abstract: This paper investigates active and passive SWIR imaging for slant paths close to ground. The main sensor, a gated SWIR camera was collecting both passive and active images along a 2 km long path over an airfield and also from our roof top laboratory looking over open fields. For some investigations we also used a gated system working in the NIR region and thermal as well as color CCD cameras. The sensor was elevated by a lift in steps from 1.6-13.5 meters or placed in a roof top laboratory 13 m above ground.Targets were resolution charts and human targets. The turbulence was measured along the path with anemometers and scintillometers. The image performance was evaluated by measurement of the image blur and also by performing observer perception tests. The results reveal a strong dependence on the sensor height especially during daytime
- (280.3420) Remote sensing and sensors : Laser sensors
- (110.0115) Imaging systems : Imaging through turbulent media
12345678910111213141516171819202122232425262728293031Interference-based multiple-image encryption with silhouette removal by position multiplexing
- received 04/02/2013; accepted 05/13/2013; posted 05/13/2013; Doc. ID 188134
- [full text: PDF (3974) KB)]
- Abstract: 12345678910111213141516171819202122232425262728293031An approach to multiple-image optical encryption based on encryption and verification method based on interference and position multiplexing is proposed. In the encryption process, multiple images are analytically hidden into three phase only masks (POMs). The encryption algorithm for this new method is quite simple and does not need iterative encoding. For decryption, both the digital method and optical method could be employed. Also, we analyze the multiplexing capacity through the correlation coefficient. In addition, the silhouette problem that exists in previous interference-based encryption method with two POMs can be eliminated during the generation procedure of POMs based on the interference principle. Simulation results are presented to verify the validity of the proposed approach.
- (070.0070) Fourier optics and signal processing : Fourier optics and signal processing
- (100.1160) Image processing : Analog optical image processing
Controlling the transverse localization of THz waves in an InSb based disordered waveguide array using temperature
- received 02/19/2013; accepted 05/12/2013; posted 05/15/2013; Doc. ID 185499
- [full text: PDF (613) KB)]
- Abstract: We propose that the transverse localization in semiconductor based disordered waveguide array can be made controllable in the terahertz regime by changing the ambient temperature. The standard scalar Helmholtz equation is used to describe terahertz wave propagation through the waveguide array. It is first assumed that the waveguides are fabricated from InSb semiconductor, while the spacing between them is composed of a dielectric. The disorder is introduced in the system by random refractive index of the spacing medium. Our results demonstrate that the transverse width of the output intensity increases with increasing the temperature. This effect is attributed to the temperature-dependent electric permittivity of the used semiconductor. Then, the waveguides are composed of a dielectric and the spacing between them filled with InSb semiconductor. For this case, to introduce disorder, we assumed that the refractive index of the waveguides is randomized. It is found that the output intensity becomes more localized with increasing temperature. However, further increasing the temperature leads to the delocalization of output intensity. The effect of spacing between adjacent waveguides on the threshold degree of disorder has also investigated.
- (260.3160) Physical optics : Interference
- (070.7345) Fourier optics and signal processing : Wave propagation
Design and Development of a injection-molded demultiplexer for optical communication systems in the visible range
- received 03/06/2013; accepted 05/11/2013; posted 05/14/2013; Doc. ID 186107
- [full text: PDF (1649) KB)]
- Abstract: Optical simulation software based on the ray tracing method offers easy and fast results in imaging optics. This method can also be applied in other fields of light propagation. For short distance communications polymer optical fibers (POFs) are gradually gaining importance. This kind of fiber offers a larger core diameter, e.g. step index POF features a core diameter of 980 µm. Consequently, POFs have a large number of modes (>3 million modes) in the visible range and ray tracing could be used to simulate the propagation of light. This simulation method is not only applicable for the fiber itself but also for the key components of a complete POF network, e.g. couplers or other key-elements of the transmission line. In this paper a demultiplexer designed and developed by means of ray tracing is presented. Compared to the classical optical design, requirements for optimal design differ particularly with regard to minimize the insertion loss. The basis of the presented key element is a wavelength division multiplex device using a Rowland spectrometer set-up. In this approach the input fiber carries multiple wavelengths, which will be divided into multiple output fibers that transmit only one wavelength. To adapt the basic set-up to POF, the guidance of light in this element has to be changed fundamentally. Here, a monolithic approach is presented with a blazed grating using an aspheric mirror to minimize most of the aberrations. In the simulations the POF is represented by an area light source, while the grating is analyzed for different orders and the highest possible efficiency. In general, the element should be designed in a way that it can be produced with a mass production technology like injection molding in order to offer a reasonable price less than 10 EUR. However, designing the elements with regard to injection molding leads to some inherent challenges. The microstructure of an optical grating and the thick-walled 3D molded parts both result in high demands on the injection molding process. This also requires a complex machining of the molding tool. Therefore, different experiments are done to optimize the process parameter, find the best molding material, and find a suitable machining method for the molding tool. The paper will describe the development of the demultiplexer by means of ray tracing simulations step by step. Also the process steps and the realized solutions for the injection molding are described.
- (060.2330) Fiber optics and optical communications : Fiber optics communications
- (060.4230) Fiber optics and optical communications : Multiplexing
- (060.4510) Fiber optics and optical communications : Optical communications
- (220.4830) Optical design and fabrication : Systems design
- (230.1950) Optical devices : Diffraction gratings
Study of reference waves in single-exposure generalized phase-shifting digital holography
- received 03/05/2013; accepted 05/11/2013; posted 05/15/2013; Doc. ID 186446
- [full text: PDF (3394) KB)]
- Abstract: The appropriate reference wave in single-exposure phase-shifting digital holography using a random-complex-amplitude encoded reference wave is experimentally investigated.Although the reference wave is generalized, the quality of reconstructed images depends on it.Furthermore, when the reference wave satisfies a certain condition, reconstructed images can not be obtained in this method.After the certain condition is presented, the appropriate condition is studied using a speckle property.Experimental results are given to investigate relations between the quality of reconstructed images and the sizes of speckles of the reference waves.The results proves that the appropriate reference wave exists in this method.
- (030.6140) Coherence and statistical optics : Speckle
- (050.5080) Diffraction and gratings : Phase shift
- (090.1995) Holography : Digital holography
- (110.7348) Imaging systems : Wavefront encoding
Sensitivity improvement of Micro-grating accelerometer based on differential detection method
- received 04/03/2013; accepted 05/11/2013; posted 05/16/2013; Doc. ID 188209
- [full text: PDF (2538) KB)]
- Abstract: A differential detection method (DTM) with utility-type and ease of realization for micro-grating accelerometer is reported so as to reduce the common-mode noise and improve the sensitivity of micro-grating accelerometer. The theoretical model is established based on scalar diffraction theory for differential detection. According to the simulation and analysis of the DTM, the theoretical result shows that the sensitivity of the micro-grating accelerometer can be improved at least twice. Based on the analysis, the detection circuit is designed with proper parameters and devices for the hand-held experimental prototype, which is realized with our micro-grating acceleration sensor (MGAS) fabricated by inductively coupled plasma (ICP), lift-off, and anodic bonding of glass/silicon, etc. The experiment of the prototype is conducted with the turntable. Compared with the single-order detection method whose sensitivities are 6.797V/g (0th order, 1g = 9.8 m/s²) and 7.767V/g (1st order), the result of differential detection method shows that the sensitivity of the micro-grating accelerometer is 18.61V/g with an improvement for over two times. And the overall signal-to-noise ratio (SNR) improvement is 6.47dB with the input of 0.86g.
- (120.1880) Instrumentation, measurement, and metrology : Detection
- (120.3180) Instrumentation, measurement, and metrology : Interferometry
- (230.1950) Optical devices : Diffraction gratings
- (280.4788) Remote sensing and sensors : Optical sensing and sensors
12345678910111213141516171819202122232425262728293031Uniform Illumination Design by Configuration of LEDs and Optimization of LED Lens for Large-scale Color Mixing Applications
- received 03/20/2013; accepted 05/11/2013; posted 05/13/2013; Doc. ID 187470
- [full text: PDF (1457) KB)]
- Abstract: 12345678910111213141516171819202122232425262728293031In many applications, the emitting light from LEDs with different colors need to be mixed together on a large scale plane and this illumination mode is usually generated with a diffuser. Abandoning the traditional method, we proposed a LED color mixing method which can produce both high color uniformity and irradiance uniformity pattern. This method is composed of two main aspects: arrangement of irradiance array and design of LED lens. With the method, an independent rectangular irradiance distribution is generated by each lens unit, and the large scale color uniform illumination is obtained by arraying the irradiance distribution. A 3×3 array of LED module units consisting of 36 LED lens units with 4 different colors are designed, and a desired result with high color uniformity is obtained.
- (220.3630) Optical design and fabrication : Lenses
- (230.3670) Optical devices : Light-emitting diodes
- (220.2945) Optical design and fabrication : Illumination design
- (220.4298) Optical design and fabrication : Nonimaging optics
12345678910111213141516171819202122232425262728293031Improved Algorithm for Multiwavelength Single-Shot Interferometric Surface Profiling: Speeding Up the Multiwavelength-Integrated Local Model Fitting Method by Local Information Sharing
- received 02/12/2013; accepted 05/11/2013; posted 05/13/2013; Doc. ID 185134
- [full text: PDF (6155) KB)]
- Abstract: 12345678910111213141516171819202122232425262728293031The local model fitting (LMF) methodis a single-shot interferometric surface profiling algorithmthat possesses non-destructive, fast, accurate, and robust measurement capabilities.To extend the measurement range of LMF,extensions based on multiwavelength light sources such asthe multiwavelength-matched LMF (MM-LMF) method andthe multiwavelength-integrated LMF (MI-LMF) method were proposed recently.MM-LMF is computationally efficient but it tends to suffer from phase unwrapping errors,whereas MI-LMF tends to be accurate but it is computationally expensive.In this paper, we improve the computational efficiency of MI-LMFby combining it with MM-LMF via local information sharing.Through actual experiments, we demonstrate that the proposed methodis approximately 10 times faster than the original MI-LMF method,with measurement accuracy kept comparable.
- (240.0240) Optics at surfaces : Optics at surfaces
- (240.6700) Optics at surfaces : Surfaces
Fast Calculation Method of Complex Space Target's Optical Cross Section
- received 03/11/2013; accepted 05/10/2013; posted 05/15/2013; Doc. ID 186591
- [full text: PDF (865) KB)]
- Abstract: This paper utilizes the Optical Cross Section (OCS) to characterize the optical scattering characteristics of space target under the conditions of sun lighting. First, we derive the mathematical expression of OCS according to the theory of radiometric, and deduce the analytical OCS expressions of the Lambert cylinder and sphere. Then we put forward the fast calculation method of complex space target’s OCS based on the visual computing method by utilizing OpenGL and target 3ds model. Through the OCS simulation of Lambert bodies, we verify the accuracy and computational speed of the algorithm, and the results show that the absolute error is less than 0.01m2, and the spending time is less than 0.05s. At last we select the material BRDF model parameters in the visible bands for three actual complex target models and calculate their respective OCS curves.
- (290.1350) Scattering : Backscattering
- (350.5610) Other areas of optics : Radiation
- (290.1483) Scattering : BSDF, BRDF, and BTDF
12345678910111213141516171819202122232425262728293031High spatial resolution zonal wavefront reconstruction with improved initial value determination scheme for lateral shearing interferometry
- received 01/11/2013; accepted 05/09/2013; posted 05/10/2013; Doc. ID 183336
- [full text: PDF (3327) KB)]
- Abstract: 12345678910111213141516171819202122232425262728293031An improved high spatial resolution zonal method is proposed for wavefront reconstruction in lateral shearing interferometry. The main advance of the proposed method is that the initial values are determined by modal reconstruction, the determined initial values are more accurate than that determined by linear interpolation as that used in previous high spatial resolution zonal method. The validity of the proposed method is investigated through comparison with the previous high spatial resolution zonal method by some numerical experiments. The simulation results show that the reconstruction of the proposed method is more accurate and more stable to the shear ratios. Furthermore, a comprehensive property comparison is performed among the proposed method, the previous high spatial resolution zonal method, and the modal method.
- (120.3940) Instrumentation, measurement, and metrology : Metrology
- (120.5050) Instrumentation, measurement, and metrology : Phase measurement
12345678910111213141516171819202122232425262728293031Sensitive Detection of CO2 Implementing Tuneable Thulium-doped ‘All-fibre’ Laser
- received 01/16/2013; accepted 05/09/2013; posted 05/10/2013; Doc. ID 183659
- [full text: PDF (926) KB)]
- Abstract: 12345678910111213141516171819202122232425262728293031In this paper a compact, yet sensitive gas detection system based on a modulated, tuneable Thulium-doped fibre laser in the 2 µm wavelength region is reported. The laser operating wavelength range centred at a wavelength of 1.995 µm has been selected to access the R(50) transition ( ) of CO2 based on its line-strength and achieving isolation from interfering high-temperature water absorption features. The laser line-width and tuning range are optimized accordingly. The modulation of the fibre laser, through pump source modulation, and ‘locking’ detection mechanism has been utilized to eliminate laser intensity noise and therefore to obtain a compact gas sensor with high sensitivity. The absorption spectrum, as well as the line-strength and the concentration level of CO2, have been monitored through absorption spectroscopy techniques. The measured minimum detectable concentration of CO2 obtained using the system shows that it is quite capable of detecting trace gas in the ppm level. The stable laser performance achieved in the sensor system illustrates its potential for the development of practical, compact yet sensitive fibre laser based gas sensor systems.
- (060.4080) Fiber optics and optical communications : Modulation
- (140.3600) Lasers and laser optics : Lasers, tunable
- (010.1030) Atmospheric and oceanic optics : Absorption
- (060.3510) Fiber optics and optical communications : Lasers, fiber
12345678910111213141516171819202122232425262728293031Plasma-Debris Sputter Resistant X-ray Mirror
- received 02/11/2013; accepted 05/08/2013; posted 05/09/2013; Doc. ID 185142
- [full text: PDF (3235) KB)]
- Abstract: 12345678910111213141516171819202122232425262728293031A diamond-like carbon (DLC) mirror, used as a grazing incident mirror in a plasma X-ray source, exhibits a high resistance to plasma debris sputtering. Good mirror reflectivity at a wavelength of 13.5 nm was confirmed using synchrotron radiation at the NewSUBARU facility. The erosion rate due to plasma debris sputtered at the incident debris angle of 20° was measured using a laser-produced Xe plasma source developed by the authors. The results indicate that the DLC film has a 5- and 15-fold higher sputtering resistance compared to films made of the traditional mirror materials Ru and Au, respectively. Because the DLC mirror retains a high sputtering resistance to Sn ions, it may be effective in Sn plasma source applications. We conclude that a grazing incident X-ray mirror coated with DLC can be of use as a plasma debris sputtering resistant mirror.
- (340.7470) X-ray optics : X-ray mirrors
- (340.7480) X-ray optics : X-rays, soft x-rays, extreme ultraviolet (EUV)
- (350.1820) Other areas of optics : Damage
- (350.5400) Other areas of optics : Plasmas
12345678910111213141516171819202122232425262728293031Effects of surface roughness on optical properties andsensitivity of fiber-optic evanescent wave sensors
- received 03/01/2013; accepted 05/08/2013; posted 05/09/2013; Doc. ID 186153
- [full text: PDF (2339) KB)]
- Abstract: 12345678910111213141516171819202122232425262728293031The effects of surface roughness on the light transmission properties and sensitivity of fiber-optic evanescent wave sensors are investigated. A simple method of increasing the sensitivity based on the surface roughness (pit depth δ and diameter ∆) and incident angle Ui of light rays on the fiber input end is proposed. We discovered that as 2δ/∆ increases, the transmitted light intensity decreases, but the sensitivity initially increases and then decreases. In sensors containing fibers of various roughnesses, the sensitivity to glucose solutions reached -11.7 mW/riu at 2δ/∆ = 0.32 and increased further to -15.3 mW/riu with proper adjustment of Ui.
- (060.0060) Fiber optics and optical communications : Fiber optics and optical communications
- (080.0080) Geometric optics : Geometric optics
- (220.0220) Optical design and fabrication : Optical design and fabrication
- (240.0240) Optics at surfaces : Optics at surfaces
- (280.4788) Remote sensing and sensors : Optical sensing and sensors