Melanie Ott - Academia.edu (original) (raw)

Papers by Melanie Ott

SPIE Photonics West, Feb 1, 2020

Planetary Defense and Space Environment Applications, 2016

In June 2005, the NESC received a multi-faceted request to determine the long term reliability of... more In June 2005, the NESC received a multi-faceted request to determine the long term reliability of fiber optic termini on the ISS that exhibited flaws not manufactured to best workmanship practices. There was a lack of data related to fiber optic workmanship as it affects the long term reliability of optical fiber assemblies in a harsh environment. A fiber optic defect analysis was requested which would find and/or create various types of chips, spalls, scratches, etc., that were identified by the ISS personnel. Once the defects and causes were identified the next step would be to perform long term reliability testing of similar assemblies with similar defects. The goal of the defect analysis would be for the defects to be observed and documented for deterioration of fiber optic performance. Though this report mostly discusses what has been determined as evidence of poor manufacturing processes, it also concludes the majority of the damage could have been avoided with a rigorous proc...

For over thirty years NASA has had success with space flight missions that utilize optical fiber

Goddard Space Flight Center is conducting a search for space flight worthy fiber optic cable asse... more Goddard Space Flight Center is conducting a search for space flight worthy fiber optic cable assemblies that will benefit all projects at all of the NASA centers. This paper is number two in a series of papers being issued as a result of this task to define and qualify space grade fiber optic cable assemblies. Though to qualify and use a fiber optic cable in space requires treatment of the cable assembly as a system, it is very important to understand the design and behavior of its parts. This paper addresses that need, providing information on cable components shrinkage testing and radiation testing results from recent experiments at Goddard Space Flight Center. This work is an extension of the "lessons learned" reported in the first paper of this series entitled "Fiber Optic Cable Assemblies for Space Flight: Issues and Remedies," published and presented at the AIAA World Congress in Anaheim CA, on October 15, 1997.

This slide presentation reviews the process for implementation and qualification of space flight ... more This slide presentation reviews the process for implementation and qualification of space flight photonic components. It discusses the causes for most common anomalies for the space flight components, design compatibility, a specific failure analysis of optical fiber that occurred in a cable in 1999-2000, and another ExPCA connector anomaly involving pins that broke off. It reviews issues around material selection, quality processes and documentation, and current projects that the Photonics group is involved in. The importance of good documentation is stressed.

For over thirty years NASA has had success with space flight missions that utilize optical fiber

Fiber optic cables are widely used in modern systems that must provide stable operation during ex... more Fiber optic cables are widely used in modern systems that must provide stable operation during exposure to changing environmental conditions. For example, a fiber optic cable on a satellite may have to reliably function over a temperature range of -50°C up to 125°C. While the system requirements for a particular application will dictate the exact method by which the fibers should be prepared, this work will examine multiple ruggedized fibers prepared in different fashions and subjected to thermal qualification testing. The data show that if properly conditioned the fiber cables can provide stable operation, but if done incorrectly, they will have large fluctuations in transmission.

Over the past ten years, NASA has studied the effects of harsh environments on optical fiber asse... more Over the past ten years, NASA has studied the effects of harsh environments on optical fiber assemblies for communication systems, lidar systems, and science missions. The culmination of this has resulted in recent technologies that are unique and tailored to meeting difficult requirements under challenging performance constraints. This presentation will focus on the past mission applications of optical fiber assemblies, including: qualification information, lessons learned, and new technological advances that will enable the road ahead.

In general, high temperature testing is used to determine LED and laser diode lifetimes, even tho... more In general, high temperature testing is used to determine LED and laser diode lifetimes, even though laser diode failure mechanisms are more sensitive to increases in current density. As a measured parameter of degradation, the current density is of great significance when searching for failure modes in a laser diode. Raising the current density however, is not really indicative of lifetime since it is more likely a situation to be avoided than one that simulates normal lifetime degradation. The reliability of semiconductor sources is very dependent on the degradation modes. This report intends to summarize some of the degradation modes and capabilities of typical LEDs and laser diodes currently used in many communication and sensing systems.

2009 35th European Conference on Optical Communication, 2009

The Photonics Group at the United States NASA Goddard Space Flight Center has been supporting the... more The Photonics Group at the United States NASA Goddard Space Flight Center has been supporting the design, development, manufacturing and integration of the optical fiber subsystem on the Express Logistics Carrier for the ISS. Some lessons learned are presented.

The Global Ecosystem Dynamics Investigation (GEDI) instrument was designed, built, and tested in-... more The Global Ecosystem Dynamics Investigation (GEDI) instrument was designed, built, and tested in-house at NASA’s Goddard Space Flight Center and launched to the International Space Station (ISS) on December 5, 2018. GEDI is a multibeam waveform LiDAR (light detection and ranging) designed to measure the Earth’s global tree height and canopy density using 8 laser beam ground tracks separated by roughly 600 meters. Given the ground coverage required and the 2 year mission duration, a unique optical design solution was developed. GEDI generates 8 ground sampling tracks from 3 transmitter systems viewed by a single receiver telescope, all while maximizing system optical efficiency and transmitter to receiver boresight alignment margin. The GEDI optical design, key optical components, and system level integration and testing are presented here. GEDI began 2 years of science operations in March 2019 and so far, it is meeting all of its key optical performance requirements and is returning...

Presented here is a summary of information concerning the usage of fiber lasers in a space flight... more Presented here is a summary of information concerning the usage of fiber lasers in a space flight environment. The scientific needs of NASA are addressed in reference to laser systems and applications and how fiber lasers fit those needs are summarized. The technology is explained briefly with focus on harsh environment reliability of the components that are used in typical fiber laser systems towards the goal of assessing the technology for space flight missions.

Optical fiber modulators are of great interest to space flight projects for communications and LI... more Optical fiber modulators are of great interest to space flight projects for communications and LIDAR applications. Due to the harsh environments and long duration for most missions, space flight applications have a unique set of demands for photonics parts. This study focuses on the reliability of commercially available optical fiber modulators for space flight environments. General failures modes covered by the Telecordia standards are discussed as well as mitigation techniques for ground based systems. The failure modes that are beyond the mitigation of the Telecordia standards are included as well along with long term reliability and space flight environmental considerations towards the eventual implementation of these devices in space flight instrumentation. A survey of commercial devices was conducted and a single device was chosen based on the failure mode investigation and taking into account the general requirements of typical space flight components. The details for testing...

SPIE Photonics West, Feb 1, 2020

Planetary Defense and Space Environment Applications, 2016

In June 2005, the NESC received a multi-faceted request to determine the long term reliability of... more In June 2005, the NESC received a multi-faceted request to determine the long term reliability of fiber optic termini on the ISS that exhibited flaws not manufactured to best workmanship practices. There was a lack of data related to fiber optic workmanship as it affects the long term reliability of optical fiber assemblies in a harsh environment. A fiber optic defect analysis was requested which would find and/or create various types of chips, spalls, scratches, etc., that were identified by the ISS personnel. Once the defects and causes were identified the next step would be to perform long term reliability testing of similar assemblies with similar defects. The goal of the defect analysis would be for the defects to be observed and documented for deterioration of fiber optic performance. Though this report mostly discusses what has been determined as evidence of poor manufacturing processes, it also concludes the majority of the damage could have been avoided with a rigorous proc...

For over thirty years NASA has had success with space flight missions that utilize optical fiber

Goddard Space Flight Center is conducting a search for space flight worthy fiber optic cable asse... more Goddard Space Flight Center is conducting a search for space flight worthy fiber optic cable assemblies that will benefit all projects at all of the NASA centers. This paper is number two in a series of papers being issued as a result of this task to define and qualify space grade fiber optic cable assemblies. Though to qualify and use a fiber optic cable in space requires treatment of the cable assembly as a system, it is very important to understand the design and behavior of its parts. This paper addresses that need, providing information on cable components shrinkage testing and radiation testing results from recent experiments at Goddard Space Flight Center. This work is an extension of the "lessons learned" reported in the first paper of this series entitled "Fiber Optic Cable Assemblies for Space Flight: Issues and Remedies," published and presented at the AIAA World Congress in Anaheim CA, on October 15, 1997.

This slide presentation reviews the process for implementation and qualification of space flight ... more This slide presentation reviews the process for implementation and qualification of space flight photonic components. It discusses the causes for most common anomalies for the space flight components, design compatibility, a specific failure analysis of optical fiber that occurred in a cable in 1999-2000, and another ExPCA connector anomaly involving pins that broke off. It reviews issues around material selection, quality processes and documentation, and current projects that the Photonics group is involved in. The importance of good documentation is stressed.

For over thirty years NASA has had success with space flight missions that utilize optical fiber

Fiber optic cables are widely used in modern systems that must provide stable operation during ex... more Fiber optic cables are widely used in modern systems that must provide stable operation during exposure to changing environmental conditions. For example, a fiber optic cable on a satellite may have to reliably function over a temperature range of -50°C up to 125°C. While the system requirements for a particular application will dictate the exact method by which the fibers should be prepared, this work will examine multiple ruggedized fibers prepared in different fashions and subjected to thermal qualification testing. The data show that if properly conditioned the fiber cables can provide stable operation, but if done incorrectly, they will have large fluctuations in transmission.

Over the past ten years, NASA has studied the effects of harsh environments on optical fiber asse... more Over the past ten years, NASA has studied the effects of harsh environments on optical fiber assemblies for communication systems, lidar systems, and science missions. The culmination of this has resulted in recent technologies that are unique and tailored to meeting difficult requirements under challenging performance constraints. This presentation will focus on the past mission applications of optical fiber assemblies, including: qualification information, lessons learned, and new technological advances that will enable the road ahead.

In general, high temperature testing is used to determine LED and laser diode lifetimes, even tho... more In general, high temperature testing is used to determine LED and laser diode lifetimes, even though laser diode failure mechanisms are more sensitive to increases in current density. As a measured parameter of degradation, the current density is of great significance when searching for failure modes in a laser diode. Raising the current density however, is not really indicative of lifetime since it is more likely a situation to be avoided than one that simulates normal lifetime degradation. The reliability of semiconductor sources is very dependent on the degradation modes. This report intends to summarize some of the degradation modes and capabilities of typical LEDs and laser diodes currently used in many communication and sensing systems.

2009 35th European Conference on Optical Communication, 2009

The Photonics Group at the United States NASA Goddard Space Flight Center has been supporting the... more The Photonics Group at the United States NASA Goddard Space Flight Center has been supporting the design, development, manufacturing and integration of the optical fiber subsystem on the Express Logistics Carrier for the ISS. Some lessons learned are presented.

The Global Ecosystem Dynamics Investigation (GEDI) instrument was designed, built, and tested in-... more The Global Ecosystem Dynamics Investigation (GEDI) instrument was designed, built, and tested in-house at NASA’s Goddard Space Flight Center and launched to the International Space Station (ISS) on December 5, 2018. GEDI is a multibeam waveform LiDAR (light detection and ranging) designed to measure the Earth’s global tree height and canopy density using 8 laser beam ground tracks separated by roughly 600 meters. Given the ground coverage required and the 2 year mission duration, a unique optical design solution was developed. GEDI generates 8 ground sampling tracks from 3 transmitter systems viewed by a single receiver telescope, all while maximizing system optical efficiency and transmitter to receiver boresight alignment margin. The GEDI optical design, key optical components, and system level integration and testing are presented here. GEDI began 2 years of science operations in March 2019 and so far, it is meeting all of its key optical performance requirements and is returning...

Presented here is a summary of information concerning the usage of fiber lasers in a space flight... more Presented here is a summary of information concerning the usage of fiber lasers in a space flight environment. The scientific needs of NASA are addressed in reference to laser systems and applications and how fiber lasers fit those needs are summarized. The technology is explained briefly with focus on harsh environment reliability of the components that are used in typical fiber laser systems towards the goal of assessing the technology for space flight missions.

Optical fiber modulators are of great interest to space flight projects for communications and LI... more Optical fiber modulators are of great interest to space flight projects for communications and LIDAR applications. Due to the harsh environments and long duration for most missions, space flight applications have a unique set of demands for photonics parts. This study focuses on the reliability of commercially available optical fiber modulators for space flight environments. General failures modes covered by the Telecordia standards are discussed as well as mitigation techniques for ground based systems. The failure modes that are beyond the mitigation of the Telecordia standards are included as well along with long term reliability and space flight environmental considerations towards the eventual implementation of these devices in space flight instrumentation. A survey of commercial devices was conducted and a single device was chosen based on the failure mode investigation and taking into account the general requirements of typical space flight components. The details for testing...