The ALMA 1st LO Reference system consists of a laser synthesizer, active line length correction, ... more The ALMA 1st LO Reference system consists of a laser synthesizer, active line length correction, photonic distribution, and a photonic receiver. The phase stability and phase drift specifications are very ambitious, and the effort to meet them has led to small evolutions and improvements in the design. This memo gives a general description of the system, and documents its current measured performance levels, as measured in the laboratory.
Different types of massive interacting binaries with Be components are discussed. Due to mass exc... more Different types of massive interacting binaries with Be components are discussed. Due to mass exchange, Be stars in these systems have some peculiar characteristics. Often it is even difficult to find traces of the Be star and/or mass-losing star in the optical region of the spectrum. Using the value of the orbital period as a primary parameter, it is possible to divide all massive interacting binaries into two large groups: short-period or classical Algols and long-period binaries. The last group includes a number of very active mass transfer systems named as W Serpentis. There is also a small group of double systems whose stars do not fill their Roche lobes but have emission lines in the spectrum. Properties of their spectral variability are discussed. Analysis of each group lets us find different behaviours in mass exchange that depend on the size of their Roche lobes.
As defined in the 2007 Decadal Survey's recommended CLARREO mission (Anderson, 2007), observation... more As defined in the 2007 Decadal Survey's recommended CLARREO mission (Anderson, 2007), observations of climate are needed to monitor both the radiative energy (im)balance (short wave in and IR out) and the evolution of the climate state. In addition, detailed observations are needed to constrain key processes at work in the climate system. To determine and improve the realism and predictive skill of climate models, observations must provide these capabilities as independently from the models as possible. This is challenging because satellite observations typically do not contain sufficient information to determine the climate state uniquely and unambiguously (e.g. Rodgers, 2000). One of the great contributions of NWP has been the generation of analyses that in some sense optimally combine the information from observations with model forecasts to estimate the system state. The problem, from a climate standpoint, is that some portion of the model climatology, whose realism needs to be assessed, is imbedded within the analyses.
The ALMA project (Atacama Large Millimeter Array) is a collection of 50 radio telescopes that wil... more The ALMA project (Atacama Large Millimeter Array) is a collection of 50 radio telescopes that will be installed and operated in the high altitude desert of Atacama in northern Chile. The array is phased locked using a microwave reference generated from highly stable phase locked laser signals transmitted over 15km single mode fiber. In this paper we demonstrate the ability of generating and distributing high frequency photonic based microwave reference in a single mode fiber of 14 km to 2 of the ALMA radio telescopes. 81GHz photonic LO reference is generated and transmitted over the single mode fiber to the receivers of the 2 antennas. The paper will also present the method used to measure and dynamically stabilize the phase of the microwave photonics reference transmitted to 2 antennas while simulating antenna motion. The photonic phase correction system will null the unwanted phase in the microwave reference resulted from the motion of the telescope, maintaining coherence between the 2 antennas.
Nanophotonics and Macrophotonics for Space Environments II, 2008
NASA's Phoenix Mars lander employs a suite of instruments to investigate the properties of th... more NASA's Phoenix Mars lander employs a suite of instruments to investigate the properties of the planet's North polar region. A Robotic Arm is used to retrieve subsurface samples for analysis, and a Robotic Arm Camera mounted on the wrist of the arm provides images of the surface and of material in the scoop. The RAC and the Optical Microscope both utilize LEDs, which enable the generation of true color imagery and provide higher illumination levels at lower power levels than the incandescent lamps used on a predecessor instrument. Although red, green and blue LEDs were available when the instruments were being developed, the manufacturers had not tested the devices in all the environments the spacecraft would encounter. This paper details the results of a series of tests conducted to qualify the lamps for the temperature, vibration, and radiation environments they would encounter during the mission.
The version in the Kent Academic Repository may differ from the final published version. Users ar... more The version in the Kent Academic Repository may differ from the final published version. Users are advised to check http://kar.kent.ac.uk for the status of the paper. Users should always cite the published version of record.
This paper reports the design, characterization and implementation of a fiber Bragg grating (FBG)... more This paper reports the design, characterization and implementation of a fiber Bragg grating (FBG) temperature sensor in a power electronic inverter which has a high electromagnetic interference (EMI) radiation. The performance and characteristics of the sensor are investigated by monitoring the tem perature variation of the insulated gate bipolar transistor (IGBT) in photovoltaic (PV) arrays inverter. The thermal expansion of the optical fiber is enhanced by mounting the FBG sensor to a metal sheet. Due to this enhancement, the FBG temperature sensor recorded an improvement in terms of linearity and sensitivity. A comparison is made between the performance of the enhanced FBG sensor and a thermocouple in a high EMI environment, and the results show that the FBG sensor performs better.
The ALMA 1 LO Reference system consists of a laser synthesizer, active line length correction, ph... more The ALMA 1 LO Reference system consists of a laser synthesizer, active line length correction, photonic distribution, and a photonic receiver. The phase stability and phase drift specifications are very ambitious, and the effort to meet them has led to small evolutions and improvements in the design. This memo gives a general description of the system, and documents its current measured performance levels, as measured in the laboratory.
Aluminum nitride (AlN) is a high thermal conductivity ceramic substrate for microelectronics with... more Aluminum nitride (AlN) is a high thermal conductivity ceramic substrate for microelectronics with a better thermal coefficient of expansion match to silicon than traditional oxide substrates. Metallization techniques are needed to increase the ease of use of AlN as a substrate for high power circuits, high frequency devices, and multichip modules. Excimer laser assisted deposition of copper and aluminum addresses
The ALMA project (Atacama Large Millimeter Array) is a collection of 50 radio telescopes that wil... more The ALMA project (Atacama Large Millimeter Array) is a collection of 50 radio telescopes that will be installed and operated in the high altitude desert of Atacama in northern Chile. The array is phased locked using a microwave reference generated from highly stable phase locked laser signals transmitted over 15km single mode fiber. In this paper we demonstrate the ability of generating and distributing high frequency photonic based microwave reference in a single mode fiber of 14 km to 2 of the ALMA radio telescopes. 81GHz photonic LO reference is generated and transmitted over the single mode fiber to the receivers of the 2 antennas. The paper will also present the method used to measure and dynamically stabilize the phase of the microwave photonics reference transmitted to 2 antennas while simulating antenna motion. The photonic phase correction system will null the unwanted phase in the microwave reference resulted from the motion of the telescope, maintaining coherence between the 2 antennas.
NASA's Phoenix Mars lander employs a suite of instruments to investigate the properties of the pl... more NASA's Phoenix Mars lander employs a suite of instruments to investigate the properties of the planet's North polar region. A Robotic Arm is used to retrieve subsurface samples for analysis, and a Robotic Arm Camera mounted on the wrist of the arm provides images of the surface and of material in the scoop. The RAC and the Optical Microscope both utilize LEDs, which enable the generation of true color imagery and provide higher illumination levels at lower power levels than the incandescent lamps used on a predecessor instrument. Although red, green and blue LEDs were available when the instruments were being developed, the manufacturers had not tested the devices in all the environments the spacecraft would encounter. This paper details the results of a series of tests conducted to qualify the lamps for the temperature, vibration, and radiation environments they would encounter during the mission.
To address fundamental climate observing needs, we are building a cm and mm wavelength satellite-... more To address fundamental climate observing needs, we are building a cm and mm wavelength satellite-tosatellite occultation instrument called the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). ATOMMS will profile atmospheric moisture to 1-3%, temperature to ~0.4K and geopotential height to 10m with 200m vertical resolution from near the surface to the mesopause in clear and cloudy air. 1-3% precision ozone and water isotope profiles will extend from the upper troposphere into the mesosphere. Accuracies with averaging will be 10 to 100 times better. We will demonstrate ATOMMS in 2009 using 2 high altitude aircraft.
MRI) program, we will build a prototype instrument and use it to demonstrate a powerful new satel... more MRI) program, we will build a prototype instrument and use it to demonstrate a powerful new satellite-borne atmospheric remote sensing concept called the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). With previous funding from NSF, we have been developing the ATOMMS concept and our analysis shows that such an instrument will improve upon the vertical resolution, precision and absolute accuracy of present satellite observations of atmospheric water vapor, temperature and pressure by an order of magnitude or more in both clear and cloudy weather, capabilities that will fulfill crucial needs for climate change research and policy making. NSF has further indicated that ~$300M could be available to support an ATOMMS satellite mission once we demonstrate broad support in the geoscience research community for the mission.
The Active Temperature Ozone and Moisture Microwave Spectrometer (ATOMMS) is an active aircraft t... more The Active Temperature Ozone and Moisture Microwave Spectrometer (ATOMMS) is an active aircraft to aircraft remote sensing occultation instrument that is designed to accurately measure the vertically resolved profiles of temperature, pressure, density, water and ozone content of the atmosphere. It uses a complimentary set of microwave transmitters and receivers in ~22 GHz and ~183 GHz water bands installed in each aircraft to measure the absorption of water and ozone as a function of altitude. Space constraints prevent the use of two separate antennas for each of these bands, so a single, dual frequency antenna system has been designed to simultaneously transmit and receive these two widely spaced frequency bands. This paper presents a detailed design of a HDPE anti-reflection grooved lens antenna that is illuminated by 2 separate, coaxially mounted feed horns for the two different frequency bands. We present the design, optimization and initial testing of the feed and lens system.
As defined in the 2007 Decadal Survey's recommended CLARREO mission , observations of climate are... more As defined in the 2007 Decadal Survey's recommended CLARREO mission , observations of climate are needed to monitor both the radiative energy (im)balance (short wave in and IR out) and the evolution of the climate state. In addition, detailed observations are needed to constrain key processes at work in the climate system. To determine and improve the realism and predictive skill of climate models, observations must provide these capabilities as independently from the models as possible. This is challenging because satellite observations typically do not contain sufficient information to determine the climate state uniquely and unambiguously (e.g. . One of the great contributions of NWP has been the generation of analyses that in some sense optimally combine the information from observations with model forecasts to estimate the system state. The problem, from a climate standpoint, is that some portion of the model climatology, whose realism needs to be assessed, is imbedded within the analyses.
The temporal drift due to the polarization noise in an ultralow temporal drift photonic phase ref... more The temporal drift due to the polarization noise in an ultralow temporal drift photonic phase reference distribution system is analyzed. The temporal drift is shown to be associated with the polarization changes, the differential group delay of the subsequent parts, and, the state of polarization dispersion of the photonic local oscillator signal. Such temporal drift cannot be corrected by line length correction schemes. As an example, polarization changes from a fiber stretcher are presented, discussed, and identified as one of the major contributors to the system temporal drift. A numerical model is developed. The magnitude and statistical distribution (based on random coupling) of the temporal drift excited by the polarization change of the fiber stretcher are investigated. Experimental work demonstrates that reduction in the polarization change successfully reduces the temporal drift, as predicted by the theory and simulation.
The temporal drift due to the polarization noise in an ultralow temporal drift photonic phase ref... more The temporal drift due to the polarization noise in an ultralow temporal drift photonic phase reference distribution system is analyzed. The temporal drift is shown to be associated with the polarization changes, the differential group delay of the subsequent parts, and, the state of polarization dispersion of the photonic local oscillator signal. Such temporal drift cannot be corrected by line length correction schemes. As an example, polarization changes from a fiber stretcher are presented, discussed, and identified as one of the major contributors to the system temporal drift. A numerical model is developed. The magnitude and statistical distribution (based on random coupling) of the temporal drift excited by the polarization change of the fiber stretcher are investigated. Experimental work demonstrates that reduction in the polarization change successfully reduces the temporal drift, as predicted by the theory and simulation.
The ALMA 1st LO Reference system consists of a laser synthesizer, active line length correction, ... more The ALMA 1st LO Reference system consists of a laser synthesizer, active line length correction, photonic distribution, and a photonic receiver. The phase stability and phase drift specifications are very ambitious, and the effort to meet them has led to small evolutions and improvements in the design. This memo gives a general description of the system, and documents its current measured performance levels, as measured in the laboratory.
Different types of massive interacting binaries with Be components are discussed. Due to mass exc... more Different types of massive interacting binaries with Be components are discussed. Due to mass exchange, Be stars in these systems have some peculiar characteristics. Often it is even difficult to find traces of the Be star and/or mass-losing star in the optical region of the spectrum. Using the value of the orbital period as a primary parameter, it is possible to divide all massive interacting binaries into two large groups: short-period or classical Algols and long-period binaries. The last group includes a number of very active mass transfer systems named as W Serpentis. There is also a small group of double systems whose stars do not fill their Roche lobes but have emission lines in the spectrum. Properties of their spectral variability are discussed. Analysis of each group lets us find different behaviours in mass exchange that depend on the size of their Roche lobes.
As defined in the 2007 Decadal Survey's recommended CLARREO mission (Anderson, 2007), observation... more As defined in the 2007 Decadal Survey's recommended CLARREO mission (Anderson, 2007), observations of climate are needed to monitor both the radiative energy (im)balance (short wave in and IR out) and the evolution of the climate state. In addition, detailed observations are needed to constrain key processes at work in the climate system. To determine and improve the realism and predictive skill of climate models, observations must provide these capabilities as independently from the models as possible. This is challenging because satellite observations typically do not contain sufficient information to determine the climate state uniquely and unambiguously (e.g. Rodgers, 2000). One of the great contributions of NWP has been the generation of analyses that in some sense optimally combine the information from observations with model forecasts to estimate the system state. The problem, from a climate standpoint, is that some portion of the model climatology, whose realism needs to be assessed, is imbedded within the analyses.
The ALMA project (Atacama Large Millimeter Array) is a collection of 50 radio telescopes that wil... more The ALMA project (Atacama Large Millimeter Array) is a collection of 50 radio telescopes that will be installed and operated in the high altitude desert of Atacama in northern Chile. The array is phased locked using a microwave reference generated from highly stable phase locked laser signals transmitted over 15km single mode fiber. In this paper we demonstrate the ability of generating and distributing high frequency photonic based microwave reference in a single mode fiber of 14 km to 2 of the ALMA radio telescopes. 81GHz photonic LO reference is generated and transmitted over the single mode fiber to the receivers of the 2 antennas. The paper will also present the method used to measure and dynamically stabilize the phase of the microwave photonics reference transmitted to 2 antennas while simulating antenna motion. The photonic phase correction system will null the unwanted phase in the microwave reference resulted from the motion of the telescope, maintaining coherence between the 2 antennas.
Nanophotonics and Macrophotonics for Space Environments II, 2008
NASA's Phoenix Mars lander employs a suite of instruments to investigate the properties of th... more NASA's Phoenix Mars lander employs a suite of instruments to investigate the properties of the planet's North polar region. A Robotic Arm is used to retrieve subsurface samples for analysis, and a Robotic Arm Camera mounted on the wrist of the arm provides images of the surface and of material in the scoop. The RAC and the Optical Microscope both utilize LEDs, which enable the generation of true color imagery and provide higher illumination levels at lower power levels than the incandescent lamps used on a predecessor instrument. Although red, green and blue LEDs were available when the instruments were being developed, the manufacturers had not tested the devices in all the environments the spacecraft would encounter. This paper details the results of a series of tests conducted to qualify the lamps for the temperature, vibration, and radiation environments they would encounter during the mission.
The version in the Kent Academic Repository may differ from the final published version. Users ar... more The version in the Kent Academic Repository may differ from the final published version. Users are advised to check http://kar.kent.ac.uk for the status of the paper. Users should always cite the published version of record.
This paper reports the design, characterization and implementation of a fiber Bragg grating (FBG)... more This paper reports the design, characterization and implementation of a fiber Bragg grating (FBG) temperature sensor in a power electronic inverter which has a high electromagnetic interference (EMI) radiation. The performance and characteristics of the sensor are investigated by monitoring the tem perature variation of the insulated gate bipolar transistor (IGBT) in photovoltaic (PV) arrays inverter. The thermal expansion of the optical fiber is enhanced by mounting the FBG sensor to a metal sheet. Due to this enhancement, the FBG temperature sensor recorded an improvement in terms of linearity and sensitivity. A comparison is made between the performance of the enhanced FBG sensor and a thermocouple in a high EMI environment, and the results show that the FBG sensor performs better.
The ALMA 1 LO Reference system consists of a laser synthesizer, active line length correction, ph... more The ALMA 1 LO Reference system consists of a laser synthesizer, active line length correction, photonic distribution, and a photonic receiver. The phase stability and phase drift specifications are very ambitious, and the effort to meet them has led to small evolutions and improvements in the design. This memo gives a general description of the system, and documents its current measured performance levels, as measured in the laboratory.
Aluminum nitride (AlN) is a high thermal conductivity ceramic substrate for microelectronics with... more Aluminum nitride (AlN) is a high thermal conductivity ceramic substrate for microelectronics with a better thermal coefficient of expansion match to silicon than traditional oxide substrates. Metallization techniques are needed to increase the ease of use of AlN as a substrate for high power circuits, high frequency devices, and multichip modules. Excimer laser assisted deposition of copper and aluminum addresses
The ALMA project (Atacama Large Millimeter Array) is a collection of 50 radio telescopes that wil... more The ALMA project (Atacama Large Millimeter Array) is a collection of 50 radio telescopes that will be installed and operated in the high altitude desert of Atacama in northern Chile. The array is phased locked using a microwave reference generated from highly stable phase locked laser signals transmitted over 15km single mode fiber. In this paper we demonstrate the ability of generating and distributing high frequency photonic based microwave reference in a single mode fiber of 14 km to 2 of the ALMA radio telescopes. 81GHz photonic LO reference is generated and transmitted over the single mode fiber to the receivers of the 2 antennas. The paper will also present the method used to measure and dynamically stabilize the phase of the microwave photonics reference transmitted to 2 antennas while simulating antenna motion. The photonic phase correction system will null the unwanted phase in the microwave reference resulted from the motion of the telescope, maintaining coherence between the 2 antennas.
NASA's Phoenix Mars lander employs a suite of instruments to investigate the properties of the pl... more NASA's Phoenix Mars lander employs a suite of instruments to investigate the properties of the planet's North polar region. A Robotic Arm is used to retrieve subsurface samples for analysis, and a Robotic Arm Camera mounted on the wrist of the arm provides images of the surface and of material in the scoop. The RAC and the Optical Microscope both utilize LEDs, which enable the generation of true color imagery and provide higher illumination levels at lower power levels than the incandescent lamps used on a predecessor instrument. Although red, green and blue LEDs were available when the instruments were being developed, the manufacturers had not tested the devices in all the environments the spacecraft would encounter. This paper details the results of a series of tests conducted to qualify the lamps for the temperature, vibration, and radiation environments they would encounter during the mission.
To address fundamental climate observing needs, we are building a cm and mm wavelength satellite-... more To address fundamental climate observing needs, we are building a cm and mm wavelength satellite-tosatellite occultation instrument called the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). ATOMMS will profile atmospheric moisture to 1-3%, temperature to ~0.4K and geopotential height to 10m with 200m vertical resolution from near the surface to the mesopause in clear and cloudy air. 1-3% precision ozone and water isotope profiles will extend from the upper troposphere into the mesosphere. Accuracies with averaging will be 10 to 100 times better. We will demonstrate ATOMMS in 2009 using 2 high altitude aircraft.
MRI) program, we will build a prototype instrument and use it to demonstrate a powerful new satel... more MRI) program, we will build a prototype instrument and use it to demonstrate a powerful new satellite-borne atmospheric remote sensing concept called the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). With previous funding from NSF, we have been developing the ATOMMS concept and our analysis shows that such an instrument will improve upon the vertical resolution, precision and absolute accuracy of present satellite observations of atmospheric water vapor, temperature and pressure by an order of magnitude or more in both clear and cloudy weather, capabilities that will fulfill crucial needs for climate change research and policy making. NSF has further indicated that ~$300M could be available to support an ATOMMS satellite mission once we demonstrate broad support in the geoscience research community for the mission.
The Active Temperature Ozone and Moisture Microwave Spectrometer (ATOMMS) is an active aircraft t... more The Active Temperature Ozone and Moisture Microwave Spectrometer (ATOMMS) is an active aircraft to aircraft remote sensing occultation instrument that is designed to accurately measure the vertically resolved profiles of temperature, pressure, density, water and ozone content of the atmosphere. It uses a complimentary set of microwave transmitters and receivers in ~22 GHz and ~183 GHz water bands installed in each aircraft to measure the absorption of water and ozone as a function of altitude. Space constraints prevent the use of two separate antennas for each of these bands, so a single, dual frequency antenna system has been designed to simultaneously transmit and receive these two widely spaced frequency bands. This paper presents a detailed design of a HDPE anti-reflection grooved lens antenna that is illuminated by 2 separate, coaxially mounted feed horns for the two different frequency bands. We present the design, optimization and initial testing of the feed and lens system.
As defined in the 2007 Decadal Survey's recommended CLARREO mission , observations of climate are... more As defined in the 2007 Decadal Survey's recommended CLARREO mission , observations of climate are needed to monitor both the radiative energy (im)balance (short wave in and IR out) and the evolution of the climate state. In addition, detailed observations are needed to constrain key processes at work in the climate system. To determine and improve the realism and predictive skill of climate models, observations must provide these capabilities as independently from the models as possible. This is challenging because satellite observations typically do not contain sufficient information to determine the climate state uniquely and unambiguously (e.g. . One of the great contributions of NWP has been the generation of analyses that in some sense optimally combine the information from observations with model forecasts to estimate the system state. The problem, from a climate standpoint, is that some portion of the model climatology, whose realism needs to be assessed, is imbedded within the analyses.
The temporal drift due to the polarization noise in an ultralow temporal drift photonic phase ref... more The temporal drift due to the polarization noise in an ultralow temporal drift photonic phase reference distribution system is analyzed. The temporal drift is shown to be associated with the polarization changes, the differential group delay of the subsequent parts, and, the state of polarization dispersion of the photonic local oscillator signal. Such temporal drift cannot be corrected by line length correction schemes. As an example, polarization changes from a fiber stretcher are presented, discussed, and identified as one of the major contributors to the system temporal drift. A numerical model is developed. The magnitude and statistical distribution (based on random coupling) of the temporal drift excited by the polarization change of the fiber stretcher are investigated. Experimental work demonstrates that reduction in the polarization change successfully reduces the temporal drift, as predicted by the theory and simulation.
The temporal drift due to the polarization noise in an ultralow temporal drift photonic phase ref... more The temporal drift due to the polarization noise in an ultralow temporal drift photonic phase reference distribution system is analyzed. The temporal drift is shown to be associated with the polarization changes, the differential group delay of the subsequent parts, and, the state of polarization dispersion of the photonic local oscillator signal. Such temporal drift cannot be corrected by line length correction schemes. As an example, polarization changes from a fiber stretcher are presented, discussed, and identified as one of the major contributors to the system temporal drift. A numerical model is developed. The magnitude and statistical distribution (based on random coupling) of the temporal drift excited by the polarization change of the fiber stretcher are investigated. Experimental work demonstrates that reduction in the polarization change successfully reduces the temporal drift, as predicted by the theory and simulation.
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Papers by Sarmad Albanna