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Full-Text Articles in Physics

Role Of Diffusive, Photovoltaic, And Thermal Effects In Beam Fanning In Linbo3, Jaw-Jueh Liu, Partha P. Banerjee, Q. W. Song Apr 2016

Role Of Diffusive, Photovoltaic, And Thermal Effects In Beam Fanning In Linbo3, Jaw-Jueh Liu, Partha P. Banerjee, Q. W. Song

Partha Banerjee

We analyze the steady-state (Gaussian) beam fanning in LiNbO3 from the nonlinearly coupled Kukhtarev equations by including both diffusive and photovoltaic effects and by adding the thermal effect in the calculation. There is good agreement between theory and experiment. The results show a symmetric beam-fanning pattern whose size depends on the beam waist and the power. Possible applications of our results in nondestructive testing of material parameters and optical limiting are discussed.


Simulation Of Two-Dimensional Nonlinear Envelope Pulse Dynamics By A Two-Step Spatiotemporal Angular Spectrum Method, H. K. Sim, Adrianus Korpel, Karl E. Lonngren, Partha P. Banerjee Apr 2016

Simulation Of Two-Dimensional Nonlinear Envelope Pulse Dynamics By A Two-Step Spatiotemporal Angular Spectrum Method, H. K. Sim, Adrianus Korpel, Karl E. Lonngren, Partha P. Banerjee

Partha Banerjee

We present an extension of our previous nonlinear beam-simulation method to the propagation and interaction of pulse envelopes. The extra time dimension is applied in the context of a dispersive nonlinear medium that is described by a Klein–Gordon equation with an added cubically nonlinear, self-focusing term. Pulse propagation in this medium is modeled as the evolution of a spatiotemporal spectrum—i.e., the frequency-dependent angular spectrum of the pulse envelope—traversing a sequence of self-induced, thin, weak phase filters. Preliminary simulation experiments show agreement with known behavior in the absence of nonlinearity, confirm the existence of an (apparently unstable ...


Theoretical And Experimental Studies Of Propagation Of Beams Through A Finite Sample Of A Cubically Nonlinear Material, Partha P. Banerjee, Raj M. Misra, M. Maghraoui Apr 2016

Theoretical And Experimental Studies Of Propagation Of Beams Through A Finite Sample Of A Cubically Nonlinear Material, Partha P. Banerjee, Raj M. Misra, M. Maghraoui

Partha Banerjee

Propagation of an externally focused or defocused Gaussian beam in a cubically nonlinear material is studied analytically and experimentally. The theoretical analysis is applied to determine the sign and magnitude of n2 for a material by means of a single-beam experiment with a finite nonlinear sample within which propagational diffraction cannot be neglected. Experimental results for a solution of chlorophyll in ethanol are reported. Based on available theory, an average n2 can be defined for a nonlinearity of thermal origin, and this value is found to be in good agreement with experimental results. Finally, the theoretical analysis and ...


On A Simple Derivation Of The Fresnel Diffraction Formula And A Transfer Function Approach To Wave Propagation, Partha P. Banerjee, Ting-Chung Poon Apr 2016

On A Simple Derivation Of The Fresnel Diffraction Formula And A Transfer Function Approach To Wave Propagation, Partha P. Banerjee, Ting-Chung Poon

Partha Banerjee

The Fresnel diffraction formula is straightforwardly obtained by solving a partial differential equation (PDE) for envelope propagation using Fourier transform techniques. The PDE, in turn, can be derived from the dispersion relation of a linear medium by employing a simple operator formalism. The transfer function and impulse response of propagation follows as a spin‐off and is used to solve illustrative problems. Huygens’ principle is visualized as a consequence of the convolution property of linear systems.


Notch Spatial Filtering With An Acousto-Optic Modulator, Partha P. Banerjee, Dongqing Cao, Ting-Chung Poon Apr 2016

Notch Spatial Filtering With An Acousto-Optic Modulator, Partha P. Banerjee, Dongqing Cao, Ting-Chung Poon

Partha Banerjee

The role of acousto-optic (AO) modulators in programmable real-time image processing has recently been demonstrated. For fully investigating the image-processing capabilities of the AO modulator, general techniques to derive spatial transfer functions are needed for a variety of physical situations. We develop a technique to determine the spatial transfer functions numerically for various cases of beam incidence on an AO modulator. Normal incidence and incidence at twice the Bragg angle are investigated as examples for which double-sided and single-sided notch spatial filtering, respectively, are achieved. The observed spatial-filtering characteristics are reconciled with simple intuitive physical arguments.


Nonlinear Transverse Effects In Second-Harmonic Generation, Pawel Pliszka, Partha P. Banerjee Apr 2016

Nonlinear Transverse Effects In Second-Harmonic Generation, Pawel Pliszka, Partha P. Banerjee

Partha Banerjee

We study a three-dimensional model of interaction of fundamental-frequency and second-harmonic beams in a quadratically nonlinear medium. Numerical simulations of the three-dimensional propagation problem in the presence of diffraction and anisotropy are performed under the paraxial approximation. The role of the transverse effects in various regimes is investigated. We demonstrate the effect of phase modulation and an induced nonlinear focusing during the interaction of the fundamental frequency with the generated second harmonic.


Multiwave Coupling In A High-Gain Photorefractive Polymer, Kenji Matsushita, Partha P. Banerjee, S. Ozaki, Daisuke Miyazaki Apr 2016

Multiwave Coupling In A High-Gain Photorefractive Polymer, Kenji Matsushita, Partha P. Banerjee, S. Ozaki, Daisuke Miyazaki

Partha Banerjee

The characteristics of a new high-gain photorefractive polymer composite with a PNP chromophore are investigated. Competition between beam fanning and two-wave coupling (TWC) is predicted and verified experimentally. The intensity dependence of TWC gain is studied. Higher diffraction order and forward phase conjugation in a TWC geometry are observed and explained.


Linear And Nonlinear Propagation In Negative Index Materials, Partha P. Banerjee, George Nehmetallah Apr 2016

Linear And Nonlinear Propagation In Negative Index Materials, Partha P. Banerjee, George Nehmetallah

Partha Banerjee

We analyze linear propagation in negative index materials by starting from a dispersion relation and by deriving the underlying partial differential equation. Transfer functions for propagation are derived in temporal and spatial frequency domains for unidirectional baseband and modulated pulse propagation, as well as for beam propagation. Gaussian beam propagation is analyzed and reconciled with the ray transfer matrix approach as applied to propagation in negative index materials. Nonlinear extensions of the linear partial differential equation are made by incorporating quadratic and cubic terms, and baseband and envelope solitary wave solutions are determined. The conditions for envelope solitary wave solutions ...


Application Of Up-Sampling And Resolution Scaling To Fresnel Reconstruction Of Digital Holograms, Logan Williams, George Nehmetallah, Rola Aylo, Partha P. Banerjee Apr 2016

Application Of Up-Sampling And Resolution Scaling To Fresnel Reconstruction Of Digital Holograms, Logan Williams, George Nehmetallah, Rola Aylo, Partha P. Banerjee

Partha Banerjee

Fresnel transform implementation methods using numerical preprocessing techniques are investigated in this paper. First, it is shown that up-sampling dramatically reduces the minimum reconstruction distance requirements and allows maximal signal recovery by eliminating aliasing artifacts which typically occur at distances much less than the Rayleigh range of the object. Second, zero-padding is employed to arbitrarily scale numerical resolution for the purpose of resolution matching multiple holograms, where each hologram is recorded using dissimilar geometric or illumination parameters. Such preprocessing yields numerical resolution scaling at any distance. Both techniques are extensively illustrated using experimental results.


Achieving Enhanced Gain In Photorefractive Polymers By Eliminating Electron Contributions Using Large Bias Fields, C. M. Liebig, S. H. Buller, Partha P. Banerjee, S. A. Basun, Pierre-Alexandre Blanche, J. Thomas, Cory W. Christenson, N. Peyghambarian, Dean R. Evans Apr 2016

Achieving Enhanced Gain In Photorefractive Polymers By Eliminating Electron Contributions Using Large Bias Fields, C. M. Liebig, S. H. Buller, Partha P. Banerjee, S. A. Basun, Pierre-Alexandre Blanche, J. Thomas, Cory W. Christenson, N. Peyghambarian, Dean R. Evans

Partha Banerjee

Photorefractive polymers have been extensively studied for over two decades and have found applications in holographic displays and optical image processing. The complexity of these materials arises from multiple charge contributions, for example, leading to the formation of competing photorefractive gratings. It has been recently shown that in a photorefractive polymer at relatively moderate applied electric fields the primary charge carriers (holes) establish an initial grating, followed by a subsequent competing grating (electrons) resulting in a decreased two-beam coupling and diffraction efficiencies. In this paper, it is shown that with relatively large sustainable bias fields, the two-beam coupling efficiency is ...


3d Visualization Using Pulsed And Cw Digital Holographic Tomography Techniques, George Nehmetallah, Partha P. Banerjee, D. Ferree, R. Kephart, Sarat C. Praharaj Apr 2016

3d Visualization Using Pulsed And Cw Digital Holographic Tomography Techniques, George Nehmetallah, Partha P. Banerjee, D. Ferree, R. Kephart, Sarat C. Praharaj

Partha Banerjee

We outline the use of digital holographic tomography to determine the three-dimensional (3D) shapes of falling and static objects, such as lenslets and water droplets. Reconstruction of digitally recorded inline holograms is performed using multiplicative and Radon transform techniques to reveal the exact 3D shapes of the objects.


Imaging Diffractometer With Holographic Encoding Enhancements For Laser Sensing And Characterization, Joesph Binford, Bradley Duncan, Jack Parker, Elizabeth Beecher, Mark Delong Nov 2015

Imaging Diffractometer With Holographic Encoding Enhancements For Laser Sensing And Characterization, Joesph Binford, Bradley Duncan, Jack Parker, Elizabeth Beecher, Mark Delong

Bradley D. Duncan

What is believed to be a novel holographic optical encoding scheme has been developed to enhance the performance of laser sensors designed for the measurement of wavelength and angular trajectory. A prototype holographic imaging diffractometer has been created to reconstruct holographic cueing patterns superimposed in the focal plane of wide-angle scene imagery. Based on experimental pattern metric measurements at the focal plane, a theoretical model is used to compute the laser source wavelength and its apparent propagation direction within the sensor's field of view. The benefits of incorporating holographic enhancements within an imager-based sensor architecture are discussed.


Optical Sparse Aperture Imaging, Nicholas Miller, Matthew Dierking, Bradley Duncan Nov 2015

Optical Sparse Aperture Imaging, Nicholas Miller, Matthew Dierking, Bradley Duncan

Bradley D. Duncan

The resolution of a conventional diffraction-limited imaging system is proportional to its pupil diameter. A primary goal of sparse aperture imaging is to enhance resolution while minimizing the total light collection area; the latter being desirable, in part, because of the cost of large, monolithic apertures. Performance metrics are defined and used to evaluate several sparse aperture arrays constructed from multiple, identical, circular subapertures. Subaperture piston and∕or tilt effects on image quality are also considered. We selected arrays with compact nonredundant autocorrelations first described by Golay. We vary both the number of subapertures and their relative spacings to arrive ...


Monte Carlo Simulation Of Multiple Photon Scattering In Sugar Maple Tree Canopies, Michael Greiner, Bradley Duncan, Matthew Dierking Nov 2015

Monte Carlo Simulation Of Multiple Photon Scattering In Sugar Maple Tree Canopies, Michael Greiner, Bradley Duncan, Matthew Dierking

Bradley D. Duncan

Detecting objects hidden beneath forest canopies is a difficult task for optical remote sensing systems. Rather than relying upon the existence of gaps between leaves, as other researchers have done, our ultimate goal is to use light scattered by leaves to image through dense foliage. Herein we describe the development of a Monte Carlo model for simulating the scattering of light as it propagates through the leaves of an extended tree canopy. We measured several parameters, including the gap fraction and maximum leaf-area density, of a nearby sugar maple tree grove and applied them to our model. We report the ...


Improving Mid-Frequency Contrast In Sparse Aperture Optical Imaging Systems Based Upon The Golay-9 Array, Andrew Stokes, Bradley Duncan, Matthew Dierking Nov 2015

Improving Mid-Frequency Contrast In Sparse Aperture Optical Imaging Systems Based Upon The Golay-9 Array, Andrew Stokes, Bradley Duncan, Matthew Dierking

Bradley D. Duncan

Sparse aperture imaging systems are capable of producing high resolution images while maintaining an overall light collection area that is small compared to a fully filled aperture yielding the same resolution. This is advantageous for applications where size, volume, weight and/or cost are important considerations. However, conventional sparse aperture systems pay the penalty of reduced contrast at midband spatial frequencies. This paper will focus on increasing the midband contrast of sparse aperture imaging systems based on the Golay-9 array. This is one of a family of two-dimensional arrays we have previously examined due to their compact, non-redundant autocorrelations. The ...


Periodic, Pseudo-Noise Waveforms For Multi-Function Coherent Ladar, Matthew Dierking, Bradley Duncan Nov 2015

Periodic, Pseudo-Noise Waveforms For Multi-Function Coherent Ladar, Matthew Dierking, Bradley Duncan

Bradley D. Duncan

We report the use of periodic, pseudonoise waveforms in a multifunction coherent ladar system. We exploit the Doppler sensitivity of these waveforms, as well as agile processing, to enable diverse ladar functions, including high range resolution imaging, macro-Doppler imaging, synthetic aperture ladar, and range-resolved micro-Doppler imaging. We present analytic expressions and simulations demonstrating the utility of pseudonoise waveforms for each of the ladar modes. We also discuss a laboratory pseudonoise ladar system that was developed to demonstrate range compression and range-resolved micro-Doppler imaging, as well as the phase recovery common to each of the coherent modes.


Holographic Aperture Ladar, Bradley Duncan, Matthew Dierking Nov 2015

Holographic Aperture Ladar, Bradley Duncan, Matthew Dierking

Bradley D. Duncan

Holographic aperture ladar is a variant of synthetic aperture ladar that seeks to increase cross-range scene resolution by synthesizing a large effective aperture through the motion of a smaller receiver and through the subsequent proper phasing and correlation of the detected signals in postprocessing. Unlike in conventional synthetic aperture ladar, however, holographic aperture ladar makes use of a two- dimensional translating sensor array, not simply a translating point detector. Also unlike in conventional synthetic aperture ladar, holographic aperture images will be formed in the two orthogonal cross-range dimensions parallel and perpendicular to the sensor platform’s direction of motion. The ...


Experimental Demonstration Of A Stripmap Holographic Aperture Ladar System, Jason Stafford, Bradley Duncan, Matthew Dierking Nov 2015

Experimental Demonstration Of A Stripmap Holographic Aperture Ladar System, Jason Stafford, Bradley Duncan, Matthew Dierking

Bradley D. Duncan

By synthesizing large effective apertures through the translation of a smaller imaging sensor and the subsequent proper phasing and correlation of detected signals in postprocessing, holographic aperture ladar (HAL) systems seek to increase the resolution of remotely imaged targets. The stripmap HAL process was demonstrated in the laboratory, for the first time to our knowledge. Our results show that the stripmap HAL transformation can precisely account for off-axis transmitter induced phase migrations. This in turn allows multiple pupil plane field segments, sequentially collected across a synthetic aperture, to be coherently mosaiced together. As a direct consequence, we have been able ...


Effects Of Spatial Modes On Ladar Vibration Signature Estimation, Douglas Jameson, Matthew Dierking, Bradley Duncan Nov 2015

Effects Of Spatial Modes On Ladar Vibration Signature Estimation, Douglas Jameson, Matthew Dierking, Bradley Duncan

Bradley D. Duncan

Ladar-based vibrometry has been shown to be a powerful technique in enabling the plant identification of machines. Rather than sensing the geometric shape of a target laser vibrometers sense motions of the target induced by moving parts within the system. Since the target need not be spatially resolved, vibration can be sensed reliably and provide positive identification at ranges beyond the imaging limits of the aperture. However, as the range of observation increases, the diffraction-limited beam size on the target increases as well, and may encompass multiple vibrational modes on the target's surface. As a result, vibration estimates formed ...


Bidirectional Scattering Distribution Functions Of Maple And Cottonwood Leaves, Michael Greiner, Bradley Duncan, Matthew Dierking Nov 2015

Bidirectional Scattering Distribution Functions Of Maple And Cottonwood Leaves, Michael Greiner, Bradley Duncan, Matthew Dierking

Bradley D. Duncan

We present our investigations into the optical scattering properties of both sugar maple (Acer saccarum) and eastern cottonwood (Populus deltoides) leaves in the near-IR wavelength regime. The bidirectional scattering distribution function (BSDF) describes the fractions of light reflected by and transmitted through a leaf for a given set of illumination and observation angles. Experiments were performed to measure the BSDF of each species at a discrete set of illumination and observation angles. We then modeled the BSDFs in such a way that other researchers may interpolate their values for scattering in any direction under illumination at any angle.


Demonstrated Resolution Enhancement Capability Of A Stripmap Holographic Aperture Ladar System, Samuel Venable, Bradley Duncan, Matthew Dierking, David Rabb Nov 2015

Demonstrated Resolution Enhancement Capability Of A Stripmap Holographic Aperture Ladar System, Samuel Venable, Bradley Duncan, Matthew Dierking, David Rabb

Bradley D. Duncan

Holographic aperture ladar (HAL) is a variant of synthetic aperture ladar (SAL). The two processes are related in that they both seek to increase cross-range (i.e., the direction of the receiver translation) image resolution through the synthesis of a large effective aperture. This is in turn achieved via the translation of a receiver aperture and the subsequent coherent phasing and correlation of multiple received signals. However, while SAL imaging incorporates a translating point detector, HAL takes advantage of a two-dimensional translating sensor array. For the research presented in this article, a side-looking stripmap HAL geometry was used to sequentially ...


Saturated Semiconductor Optical Amplifier Phase Modulation For Long Range Laser Radar Applications, Jennifer Carns, Bradley Duncan, Matthew Dierking Nov 2015

Saturated Semiconductor Optical Amplifier Phase Modulation For Long Range Laser Radar Applications, Jennifer Carns, Bradley Duncan, Matthew Dierking

Bradley D. Duncan

We investigate the use of a semiconductor optical amplifier operated in the saturation regime as a phase modulator for long range laser radar applications. The nature of the phase and amplitude modulation resulting from a high peak power Gaussian pulse, and the impact this has on the ideal pulse response of a laser radar system, is explored. We also present results of a proof-of-concept laboratory demonstration using phase-modulated pulses to interrogate a stationary target.


Coupling Efficiencies For General Target Illumination Ladar Systems Incorporating Single Mode Optical Fiber Receivers, Christopher Brewer, Bradley Duncan, Kenneth Barnard, Edward Watson Nov 2015

Coupling Efficiencies For General Target Illumination Ladar Systems Incorporating Single Mode Optical Fiber Receivers, Christopher Brewer, Bradley Duncan, Kenneth Barnard, Edward Watson

Bradley D. Duncan

A rigorous method for modeling received power coupling efficiency (ηF/R) and transmitted power coupling efficiency (ηF/T) in a general-target-illumination ladar system is presented. For our analysis we concentrate on incorporating a single-mode optical fiber into the ladar return signal path. By developing expressions for both ηF/R and ηF/T for a simple, diffuse target, our model allows for varying range, beam size on target, target diameter, and coupling optics. Through numerical analysis ηF/R is shown to increase as the range to target increases and decrease as target diameter increases, and ηF/T is shown to decrease ...


Parametric Extension Of The Classical Exposure Schedule Theory For Angle-Multiplexed Photorefractive Recording Using The Common-Aperture Beam Geometry, Mark Delong, Bradley Duncan, Jack Parker Nov 2015

Parametric Extension Of The Classical Exposure Schedule Theory For Angle-Multiplexed Photorefractive Recording Using The Common-Aperture Beam Geometry, Mark Delong, Bradley Duncan, Jack Parker

Bradley D. Duncan

The gradual reorientations in crystal geometry encountered during angle-multiplexed holographic recording with obliquely incident recording beams can create significant parametric exposure-time and recording-angle dependencies in both grating writing- and erasure-time constants. We present a parametric extension of the classically derived backward-recursion algorithm that compensates for the intermingling effects of recording geometry, writing-beam intensity variations, and unique crystal behavior. We present experimental data for a sequence of 301 holograms recorded with the goal of equal hologram strength and, separately, the same sequence recorded with the goal of equal hologram reconstruction intensity—which are different cases for a steeply incident readout beam.


Space-Bandwidth Product Enhancement Of A Monostatic, Multi-Aperture Infrared Image Upconversion Ladar Receiver Incorporating Periodically Polled Linbo3, Christopher Brewer, Bradley Duncan, Phillip Maciejewski, Sean Kirkpatrick, Edward Watson Nov 2015

Space-Bandwidth Product Enhancement Of A Monostatic, Multi-Aperture Infrared Image Upconversion Ladar Receiver Incorporating Periodically Polled Linbo3, Christopher Brewer, Bradley Duncan, Phillip Maciejewski, Sean Kirkpatrick, Edward Watson

Bradley D. Duncan

We investigate the space-bandwidth product of a ladar system incorporating an upconversion receiver. After illuminating a target with an eye-safe beam, we direct the return into a piece of periodically poled LiNbO3 where it is upconverted into the visible spectrum and detected with a CCD camera. The theoretical and experimental transfer functions are then found. We show that the angular acceptance of the upconversion process severely limits the receiver field of regard for macroscopic coupling optics. This limitation is overcome with a pair of microlens arrays, and a 43% increase in the system’s measured space-bandwidth product is demonstrated.


Real-Time Non-Linear Image Processing Using An Active Optical Scanning Technique, Bradley Duncan, Ting-Chung Poon, Ron Piper Nov 2015

Real-Time Non-Linear Image Processing Using An Active Optical Scanning Technique, Bradley Duncan, Ting-Chung Poon, Ron Piper

Bradley D. Duncan

Real-time non-linear image processing has been achieved using an active optical scanning technique. This paper reports experimental results in edge extraction for both binary and grey-scale transmissive objects. Binary edge extraction is achieved using morphological transformations, while grey-scale edge extraction is achieved using a threshold decomposition technique. Advantages and limitation of both techniques are identified.


Optical-Fiber Preamplifiers For Ladar Detection And Associated Measurements For Improving The Signal-To-Noise Ratio, Michael Salisbury, Paul Mcmanamon, Bradley Duncan Nov 2015

Optical-Fiber Preamplifiers For Ladar Detection And Associated Measurements For Improving The Signal-To-Noise Ratio, Michael Salisbury, Paul Mcmanamon, Bradley Duncan

Bradley D. Duncan

In an effort to increase achievable postdetection signal-tonoise ratios (SNRs) of continuous-wave, 1-gm all-solid-state ladar systems, a prototype rare-earth-doped optical-fiber amplifier has been included in the optical return signal path of both a heterodyne and a directdetection ladar system. We provide numerical predictions for SNR increases according to our previously developed theory. We also detail our experimental efforts and provide the results of SNR measurements for four distinct cases: direct ladar detection with and without a fiber amplifier, and heterodyne ladar detection with and without a fiber amplifier. Experimentally measured increases in SNRs for ladar systems incorporating an optical-fiber amplifier ...


Volume Holographic Memory For Laser Threat Discrimination, Mark Delong, Bradley Duncan, Jack Parker Nov 2015

Volume Holographic Memory For Laser Threat Discrimination, Mark Delong, Bradley Duncan, Jack Parker

Bradley D. Duncan

Using conventional volume-holographic angle multiplexing in an Fe:LiNbO3 crystal, we have developed a compact laser threat discriminator, intended for aircraft integration, that optically detects laser spatial coherence and angle of arrival while simultaneously rejecting incoherent background sources, such as the Sun. The device is intended for a specific type of psychophysical laser attack against U.S. Air Force pilots, namely, third-world-country exploitation of inexpensive and powerful cw Ar-ion or doubled Nd:YAG lasers in the visible spectrum to blind or disorient U.S. pilots. The component does not solve the general tactical laser weapon situation, which includes identifying precision-guided ...


Analysis Of Ladar Range Resolution Enhancement By Sinusoidal Phase Modulation, Leonard Masters, Martin Mark, Bradley Duncan Nov 2015

Analysis Of Ladar Range Resolution Enhancement By Sinusoidal Phase Modulation, Leonard Masters, Martin Mark, Bradley Duncan

Bradley D. Duncan

The ability of a ladar system to resolve two or more separate returns from a combined echo is related to the effective correlation bandwidth of the pulse emitted by the ladar system. Phase modulation of an outgoing pulse introduces additional frequency components, which increases the effective correlation bandwidth of the pulse and thus improves the range resolution of the system. In this paper, we discuss the general theoretical basis for achieving improved range resolution using a modulated waveform and a matched filter receiver. We then demonstrate these concepts by considering the particular case of improved range resolution for a sinusoidally ...


Aberration Production Using A High-Resolution Liquid-Crystal Spatial Light Modulator, Jason Schmidt, Matthew Goda, Bradley Duncan Nov 2015

Aberration Production Using A High-Resolution Liquid-Crystal Spatial Light Modulator, Jason Schmidt, Matthew Goda, Bradley Duncan

Bradley D. Duncan

Phase-only liquid-crystal spatial light modulators provide a powerful means of wavefront control. With high resolution and diffractive (modulo 2𝜋) operation, they can accurately represent large-dynamic-range phase maps. As a result, they provide an excellent means of producing electrically controllable, dynamic, and repeatable aberrations. However, proper calibration is critical to achieving accurate phase maps. Several calibration methods from previous literature were considered. With simplicity and accuracy in mind, we selected one method for each type of necessary calibration. We augmented one of the selected methods with a new step that improves its accuracy. After calibrating our spatial light modulator with our ...