116 papers in 17 sessions   55 session videos Change year:
Browse by:

PULPOS: A multi-purpose adaptive optics test bench for testing advanced wavefront sensing concepts

JF1B.2 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Physics-based model of imaging of biometrics data through atmospheric turbulence

JF1B.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Enhanced Pyramid Wavefront Sensor via End-to-End trained diffractive optical layer

JF1B.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Design and training of a deep neural network for estimating the optical gain in pyramid wavefront sensors

JF1B.6 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

An Open-Source Python library for Digital Holographic Microscopy Imaging

JTh2A.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Enhancement of a spectral resolution through spectral reconstruction in a static modulated Fourier transform spectrometer

JTh2A.10 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Image Phase Alignment Super-Sampling: a computational method for achieving super-resolution in macroscopic imaging

JTh2A.12 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Quantum correlation microscopy localising sub-diffraction emitters in 3D

JTh2A.14 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Label-free Longitudinal Imaging of Cortical Myelin through Intact Mouse Skull Using Computational Conjugate Adaptive Optics

JTh2A.16 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Generation of Double Focal Spots by Focusing Azimuthally Polarized Double Ring Shaped Beam with Annular Classical Axicon

JTh2A.17 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Low-loss Tunable Beam Magnification with a Light-Shaping Diffuser and an Adaptive Lens

JTh2A.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Upgrading Interferometric Focal Length Measurement Techniques with Adaptive Optics

JTh2A.5 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

The Effect of Aberration Correction on Coherent Raman Imaging of Mouse Brain Tissues

JTh2A.6 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Pupil Masking and Rotated Sub-apertures

JTh2A.7 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Improving the precision of semiconductor overlay measurements using dark-field digital holographic microscopy

JTh2A.8 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Invariant Coded Aperture Design for Compressive Imaging

JTh2A.9 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Autonomous Optical Sensor to Study the Evolution of Snow Density in Polar Environment

JTu2A.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Design and Characterization of a Low-Cost Photoacoustic Sensor for NO2 Using Lateral Illumination and Background Suppression

JTu2A.10 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Mid-infrared hydrocarbons characterization using open-path electro-optic dual-comb spectroscopy

JTu2A.11 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Tuning of distance resolution and measurable range of FMCW LiDAR based on frequency mixing

JTu2A.12 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Compact active hyperspectral imager based on tuneable short wave infrared supercontinuum laser

JTu2A.2 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Precise Recognition of Synaptic Weight Modulation Under Ultra-low Light Illumination Using Bilayer Oxide Thin-film Transistors

JTu2A.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Multi-Species Sensing Using CEAS and DNN in Shock Tube Kinetics

JTu2A.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Tunable erbium-doped fiber laser using a MZI based on CHCF

JTu2A.5 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Beam-Angle-Scanning Surface Plasmon Resonance Sensor

JTu2A.6 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Folic Acid-based Detection of Rare Circulating Cancer Cells by Polyaniline Coated U-bent Optical Fiber

JTu2A.7 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Simulation of the optical properties of seedless grapes including Henyey-Greenstein scattering

JTu2A.8 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Calibration of a spectral imager with a widely tunable radiance source

JTu2A.9 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Reconstructing Turbulent Wavefronts from Plenoptic Data Measured by a Plenoptic Wavefront Sensor

JTu5D.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Assessment of adaptive optics corrected optical links availability from integrated turbulence parameters by machine learning

JTu5D.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

GPU Acceleration of Weighted Additive Light Field Displays

JW2A.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Real-Time Pitch Modification of Elastic Cellulose Nanocrystal Films

JW2A.11 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Displacement Laser sensor based on a Mach-Zehnder Interferometer Constructed Via Concatenating Two Optical Fiber Tapers

JW2A.12 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Michelson Interferometry technique for the Dryness measurement of Saturated Steam

JW2A.13 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Real-time monocular 3D sensor using infrared speckle projection and an optimized 3D measurement method based on OpenCL acceleration

JW2A.14 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

A UV-Broadband Cavity-Enhanced spectrometer for the sensitive monitoring of BTEX in ambient air

JW2A.15 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Single Shot Multispectral Multidimensional Computational Imaging Using Quasi-Random Lenses

JW2A.16 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Nanotemplates for humidity sensing layers made by two-photon-polymersation printing

JW2A.17 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Training on System for Opto-Electrical Neural Network

JW2A.18 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

An undercomplete autoencoder for denoising computational 3D sectional images

JW2A.19 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Generation of phase hologram from multiple 3D axially overlapping objects without crosstalk

JW2A.2 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Determination of Hg in Biological Samples of Black Storks by Zeeman Atomic Absorption Spectrometry

JW2A.20 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Flexible two-photon endomicroscope probe with double-cladding antiresonant fiber

JW2A.21 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Granulometry and fractal analysis for the detection of pathological changes in retinal OCT images

JW2A.22 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

3D Time-of-Flight Camera Based Face Mask Recognition Using Facial Contour and Artificial Neural Network

JW2A.23 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Fiber Optic Sensing: Creating Value from Data (Applications in Oil & Gas)

JW2A.24 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Quad-Band Metamaterial Absorber Based on Coplanar Cu Films for Refractive Index Sensing

JW2A.25 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Understanding Imaging Process of a Human Eye – A Report on ISCOSA Sponsored Student Outreach Event

JW2A.26 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Luminescence dynamics in R. subcapitata as a precocious ecotoxicology indicator

JW2A.27 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Pytorch Deep learning Approach for Detection of Breast Cancer by Digital Holographic Method

JW2A.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Numerical investigation on tomography of multiple elements with single tunable laser

JW2A.31 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Measurement of Angular Goos-Hanchen Shift in Subwavelength Gratings near Surface Plasmon Resonance

JW2A.33 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Optical compensation of beveled structures in a geometrical waveguide for near-eye displays by using index matching cover layers

JW2A.34 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

The Effect of the Range of Dipole Interaction Within a DDA-Style Description of the Scattering of Light by Non-Spherical Aerosol and Hydrosol Particles

JW2A.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Magnetic modulation of IR properties of rod-slit complementary spintronic metasurfaces in presence of a molecular vibration

JW2A.44 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Low-Coherence Diode Laser Array Light Source for High-Speed Imaging

JW2A.46 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Study of wavelength dependency on diffraction efficiency of volume holographic gratings based couplers in waveguide displays

JW2A.47 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

DHC sensor for the study of rhythmic processes of autochthonous plankton

JW2A.48 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

High-throughput cell migration sensor based on lensless dark-field digital in-line holographic microscopy

JW2A.49 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Low-Cost Measurement of Water Quality Based on Scattering of Light

JW2A.51 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Aerosol Sauter mean diameter sensing method based on the optical scattering response of the combined particle volume-surface area

JW2A.52 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

A Fiber Tip Refractive Index Sensor Featuring a Dynamic Micromirror

JW2A.53 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Mirror Overlay Imaging System for High Magnification with Large FOV

JW2A.55 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Stress Fields Extraction in Multi-Polarized Photoelasticity Images Using Deep Convolutional Neural Networks

JW2A.6 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Real-time in situ study of adsorption kinetics in PMMA thin films using infrared spectroscopy

JW2A.7 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

A Surface Plasmon Resonance drew Biosensor based on U-Shape Photonic Crystal Fiber

JW2A.8 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

A low-cost and compact device for complex optical filed imaging

JW2A.9 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Deep-learning-enhanced three-dimensional photoacoustic imaging using a linear transducer array

JW5A.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Realization of Motion Parallax through Realistic and Immersive Video Rendering

JW5A.2 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

TEM-based single-shot coherent 3D imaging

JW5A.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Color Video Compression and Encryption with Hybrid Method

JW5A.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Wavefront reconstruction using a damped transpose matrix of the influence function

JW5A.5 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Space-Time DiffuserCam Video Reconstruction using Implicit Neural Representations

JW5B.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Learning-assisted Matrix-Pencil Method for Indirect Time-of-Flight Image Demixing

JW5B.2 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Enhancing fluorescence microscopy performance with Richardson-Lucy based deep learning

JW5B.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

A 1.26-inch 40.7 Mega-Pixel Photon-Counting Quanta Image Sensor with 0.35e- Read Noise and 95dB Single-Exposure Dynamic Range

JW5B.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Mid-infrared Incoherent Three-Dimensional Imaging Using Lucy-Richardson-Rosen Algorithm

JW5B.5 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

3-D Localization of Micromanipulators Using Microscopy for Autonomous Visual Servoing

JW5C.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Digital stitching holographic microscopy for precise tribology measurement

JW5C.2 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

CMSnet: State of the Art Deep Learning Multiscale Reconstruction for Compressive Sensing

JW5C.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Motion Picture Recording of Propagation of a Light Pulse by Digital Light-in-flight Recording by Holography Using a Biological Specimen as a Diffuser

JW5C.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Noise estimation via the optimal truncation variation for multimode fiber single-pixel imaging

JW5C.5 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

KAOS, a multipurpose active optics system for EUV/Soft X-rays

JW5D.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

High spectral and temporal resolution gas phase studies with quantum cascade laser dual-comb spectroscopy

JW5D.2 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Noise Reduction in Optical Coherence Tomography Volumes for Improved 3D Visualization

JW5D.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Comparison of Optical Characterization Methods for Transmission Spectroscopy

JW5D.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Detecting DNA-Ligand Electrostatic Interactions With a FRET-Based Probe

JW5D.5 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Experimental Analysis on the Effect of High Order OAM on the Scintillation of Asymmetric Perfect Vortex Beams

PTh3F.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Impulse Response of OAM Beams Propagating Through Turbid Underwater Environment

PTh3F.2 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Challenges when Partially Training a Machine Learning-Based Optical Communication System in Variable Experimental Conditions

PTh4F.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Predicting Deep Atmospheric Turbulence Using a Deep Echo State Neural Network

PTh4F.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

A Physics-Guided Machine Learning Model for the Prediction of Atmospheric Refraction

PTh4F.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

The earth’s atmosphere works like a spherical lens

PTh4F.5 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Imaging Techniques Through Unfavorable Media

PTh5F.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Optical propagation over water: Wave optics simulation compared to experimental measurements

PTu3D.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Comparison of Turbulence Estimates over Water Derived from a Time-Lapse Imaging Technique and from Numerical Weather Prediction with Observation Data

PTu3D.2 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Outer Length Scales in Nocturnal Stable Boundary Layers

PTu3D.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Turbulence Kinetic Energy dissipation rate estimated from clear air radar data: comparisons of models in light of DataHawk UAV measurements

PTu3D.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Investigation of transmission over the sea using a boundary layer scintillometer

PTu4D.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Comparison between Turbulence Measurements from Anemometry, Optical, and Gradient Techniques

PTu4D.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Collimated Gaussian Beam Size: Near-Field and Far-Field Approximations

PTu4D.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Image-plane scintillation of complex targets in diverse heterogenous turbulent regimes

PTu4D.5 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Propagation studies of ultrafast high intensity pulses in the atmosphere

PTu4D.6 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Automated Classification of Non-Kolmogorov Turbulence Using a Higher-Order Surrogate Function

PTu4D.7 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

The impact of optical turbulence created by Rayleigh Benard convection on vortex structure in beams carrying orbital angular momentum

PW1F.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Phase Screen Generation for Non-Kolmogorov Turbulence

PW1F.2 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Techniques to Quantify Ambient Aerosol Optical Properties from Measurements of Extinction and Scattering

PW1F.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

The Polarization State Effect on the Performance of E-O Imaging Sensors at Atmospheric Degraded Environment

PW3F.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Novel link budget modelling for NLOS submarine optical wireless links

PW3F.2 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Strategies for Correction of Atmospheric and Underwater Effects on Laser Communications Systems

PW3F.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Collimated Gaussian Beam Size: Near-Field and Far-Field Approximations

PW4F.1 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Optimal Beams and Minimizing Scintillation

PW4F.2 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Thermal Effects in Short Laser Pulses: Suppression of Wave Collapse

PW4F.3 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Computation of Optimal Beams in Weak Turbulence

PW4F.4 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Insight to atmospheric turbulence through irradiance measurements

PW4F.5 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF

Efficiently Calculating Extended Isoplanatic Angles Over Horizontal Paths

PW4F.6 Propagation Through and Characterization of Atmospheric and Oceanic Phenomena (pcAOP) 2022 View: PDF