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Journal Article

Statistical optics

TL;DR: Development of this more comprehensive model of the behavior of light draws upon the use of tools traditionally available to the electrical engineer, such as linear system theory and the theory of stochastic processes.
Abstract: Course Description This is an advanced course in which we explore the field of Statistical Optics. Topics covered include such subjects as the statistical properties of natural (thermal) and laser light, spatial and temporal coherence, effects of partial coherence on optical imaging instruments, effects on imaging due to randomly inhomogeneous media, and a statistical treatment of the detection of light. Development of this more comprehensive model of the behavior of light draws upon the use of tools traditionally available to the electrical engineer, such as linear system theory and the theory of stochastic processes.
Citations
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Journal ArticleDOI
TL;DR: An up-to-date survey on FSO communication systems is presented, describing FSO channel models and transmitter/receiver structures and details on information theoretical limits of FSO channels and algorithmic-level system design research activities to approach these limits are provided.
Abstract: Optical wireless communication (OWC) refers to transmission in unguided propagation media through the use of optical carriers, i.e., visible, infrared (IR), and ultraviolet (UV) bands. In this survey, we focus on outdoor terrestrial OWC links which operate in near IR band. These are widely referred to as free space optical (FSO) communication in the literature. FSO systems are used for high rate communication between two fixed points over distances up to several kilometers. In comparison to radio-frequency (RF) counterparts, FSO links have a very high optical bandwidth available, allowing much higher data rates. They are appealing for a wide range of applications such as metropolitan area network (MAN) extension, local area network (LAN)-to-LAN connectivity, fiber back-up, backhaul for wireless cellular networks, disaster recovery, high definition TV and medical image/video transmission, wireless video surveillance/monitoring, and quantum key distribution among others. Despite the major advantages of FSO technology and variety of its application areas, its widespread use has been hampered by its rather disappointing link reliability particularly in long ranges due to atmospheric turbulence-induced fading and sensitivity to weather conditions. In the last five years or so, there has been a surge of interest in FSO research to address these major technical challenges. Several innovative physical layer concepts, originally introduced in the context of RF systems, such as multiple-input multiple-output communication, cooperative diversity, and adaptive transmission have been recently explored for the design of next generation FSO systems. In this paper, we present an up-to-date survey on FSO communication systems. The first part describes FSO channel models and transmitter/receiver structures. In the second part, we provide details on information theoretical limits of FSO channels and algorithmic-level system design research activities to approach these limits. Specific topics include advances in modulation, channel coding, spatial/cooperative diversity techniques, adaptive transmission, and hybrid RF/FSO systems.

1,749 citations

Journal ArticleDOI
TL;DR: Focusing of coherent light through opaque scattering materials by control of the incident wavefront with a brightness up to a factor of 1000 higher than the brightness of the normal diffuse transmission is reported.
Abstract: We report focusing of coherent light through opaque scattering materials by control of the incident wavefront. The multiply scattered light forms a focus with a brightness that is up to a factor of 1000 higher than the brightness of the normal diffuse transmission.

1,624 citations

Journal ArticleDOI
TL;DR: In this paper, the FLASH soft X-ray free-electron laser was used to reconstruct a coherent diffraction pattern from a nano-structured nonperiodic object, before destroying it at 60,000 K.
Abstract: Theory predicts that with an ultrashort and extremely bright coherent X-ray pulse, a single diffraction pattern may be recorded from a large macromolecule, a virus, or a cell before the sample explodes and turns into a plasma. Here we report the first experimental demonstration of this principle using the FLASH soft X-ray free-electron laser. An intense 25 fs, 4 x 10{sup 13} W/cm{sup 2} pulse, containing 10{sup 12} photons at 32 nm wavelength, produced a coherent diffraction pattern from a nano-structured non-periodic object, before destroying it at 60,000 K. A novel X-ray camera assured single photon detection sensitivity by filtering out parasitic scattering and plasma radiation. The reconstructed image, obtained directly from the coherent pattern by phase retrieval through oversampling, shows no measurable damage, and extends to diffraction-limited resolution. A three-dimensional data set may be assembled from such images when copies of a reproducible sample are exposed to the beam one by one.

957 citations


Cites background from "Statistical optics"

  • ...The on-axis path length of the reflected beam from the sample to the CCD was 55 mm, and for 32 nm radiation and objects smaller than 20 μm, this distance is in the far field, where the diffraction pattern is equal to the Fourier transform of the exit wave [27]....

    [...]

  • ...For 32 nm radiation and objects smaller than 20 μm, this distance is in the far field, where the diffraction pattern is equal to the Fourier transform of the exit wave [27]....

    [...]

Journal ArticleDOI
TL;DR: The NASA/NGA Shuttle Radar Topography Mission (SRTM) collected interferometric radar data which has been used by the Jet Propulsion Laboratory to generate a near-global topography data product for latitudes smaller than 60° as mentioned in this paper.
Abstract: The NASA/NGA Shuttle Radar Topography Mission (SRTM) collected interferometric radar data which has been used by the Jet Propulsion Laboratory to generate a near-global topography data product for latitudes smaller than 60°. One of the primary goals of the mission was to produce a data set that was globally consistent and with quantified errors. To achieve this goal, an extensive global ground campaign was conducted by NGA and NASA to collect ground truth that would allow for the global validation of this unique data set. This paper documents the results of this SRTM validation effort using this global data set. The table shown below summarizes our results (all quantities represent 90 percent errors in meters).

906 citations


Cites background from "Statistical optics"

  • ...After correcting each beam for an optimal constant range offset, a linear fit of the range offset versus orbit gives a derived slope is 5.9 4.2 mm/orbit, which indicates very little change over the mission....

    [...]

  • ...For homogeneous statistical processes, it can be shown (Goodman, 1985) that the structure function can be related to the height error correlation function, C( ), by (2) where is the standard deviation of the process (which is constant in space)....

    [...]

Journal ArticleDOI
TL;DR: A small, portable, and robust confocal microscope that is capable of imaging normal and abnormal skin morphology and dynamic processes in vivo, in both laboratory and clinical settings is built.

854 citations


Cites background from "Statistical optics"

  • ...This, then, causes spatial variations in the phase of the detected wavefront which produces speckle across the detector aperture (Goodman, 1985)....

    [...]

  • ...This, then, causes spatial variations in the phase of the detected wavefront which produces speckle across the detector aperture (Goodman, 1985).]...

    [...]

References
More filters
Journal ArticleDOI
TL;DR: An up-to-date survey on FSO communication systems is presented, describing FSO channel models and transmitter/receiver structures and details on information theoretical limits of FSO channels and algorithmic-level system design research activities to approach these limits are provided.
Abstract: Optical wireless communication (OWC) refers to transmission in unguided propagation media through the use of optical carriers, i.e., visible, infrared (IR), and ultraviolet (UV) bands. In this survey, we focus on outdoor terrestrial OWC links which operate in near IR band. These are widely referred to as free space optical (FSO) communication in the literature. FSO systems are used for high rate communication between two fixed points over distances up to several kilometers. In comparison to radio-frequency (RF) counterparts, FSO links have a very high optical bandwidth available, allowing much higher data rates. They are appealing for a wide range of applications such as metropolitan area network (MAN) extension, local area network (LAN)-to-LAN connectivity, fiber back-up, backhaul for wireless cellular networks, disaster recovery, high definition TV and medical image/video transmission, wireless video surveillance/monitoring, and quantum key distribution among others. Despite the major advantages of FSO technology and variety of its application areas, its widespread use has been hampered by its rather disappointing link reliability particularly in long ranges due to atmospheric turbulence-induced fading and sensitivity to weather conditions. In the last five years or so, there has been a surge of interest in FSO research to address these major technical challenges. Several innovative physical layer concepts, originally introduced in the context of RF systems, such as multiple-input multiple-output communication, cooperative diversity, and adaptive transmission have been recently explored for the design of next generation FSO systems. In this paper, we present an up-to-date survey on FSO communication systems. The first part describes FSO channel models and transmitter/receiver structures. In the second part, we provide details on information theoretical limits of FSO channels and algorithmic-level system design research activities to approach these limits. Specific topics include advances in modulation, channel coding, spatial/cooperative diversity techniques, adaptive transmission, and hybrid RF/FSO systems.

1,749 citations

Journal ArticleDOI
TL;DR: Focusing of coherent light through opaque scattering materials by control of the incident wavefront with a brightness up to a factor of 1000 higher than the brightness of the normal diffuse transmission is reported.
Abstract: We report focusing of coherent light through opaque scattering materials by control of the incident wavefront. The multiply scattered light forms a focus with a brightness that is up to a factor of 1000 higher than the brightness of the normal diffuse transmission.

1,624 citations

Journal ArticleDOI
TL;DR: In this paper, the FLASH soft X-ray free-electron laser was used to reconstruct a coherent diffraction pattern from a nano-structured nonperiodic object, before destroying it at 60,000 K.
Abstract: Theory predicts that with an ultrashort and extremely bright coherent X-ray pulse, a single diffraction pattern may be recorded from a large macromolecule, a virus, or a cell before the sample explodes and turns into a plasma. Here we report the first experimental demonstration of this principle using the FLASH soft X-ray free-electron laser. An intense 25 fs, 4 x 10{sup 13} W/cm{sup 2} pulse, containing 10{sup 12} photons at 32 nm wavelength, produced a coherent diffraction pattern from a nano-structured non-periodic object, before destroying it at 60,000 K. A novel X-ray camera assured single photon detection sensitivity by filtering out parasitic scattering and plasma radiation. The reconstructed image, obtained directly from the coherent pattern by phase retrieval through oversampling, shows no measurable damage, and extends to diffraction-limited resolution. A three-dimensional data set may be assembled from such images when copies of a reproducible sample are exposed to the beam one by one.

957 citations

Journal ArticleDOI
TL;DR: The NASA/NGA Shuttle Radar Topography Mission (SRTM) collected interferometric radar data which has been used by the Jet Propulsion Laboratory to generate a near-global topography data product for latitudes smaller than 60° as mentioned in this paper.
Abstract: The NASA/NGA Shuttle Radar Topography Mission (SRTM) collected interferometric radar data which has been used by the Jet Propulsion Laboratory to generate a near-global topography data product for latitudes smaller than 60°. One of the primary goals of the mission was to produce a data set that was globally consistent and with quantified errors. To achieve this goal, an extensive global ground campaign was conducted by NGA and NASA to collect ground truth that would allow for the global validation of this unique data set. This paper documents the results of this SRTM validation effort using this global data set. The table shown below summarizes our results (all quantities represent 90 percent errors in meters).

906 citations

Journal ArticleDOI
TL;DR: A small, portable, and robust confocal microscope that is capable of imaging normal and abnormal skin morphology and dynamic processes in vivo, in both laboratory and clinical settings is built.

854 citations