Mr. Frank V. LaRocca Profile

Frank V. LaRocca

Electro-Optical Engineer at MEI Technologies Inc

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Publications (10)

Proceedings Article | 21 November 2017 Open Access

The optical fiber array bundle assemblies for the NASA lunar reconnaissance orbiter; evaluation lessons learned for flight implementation from the NASA electronic parts and packaging program

Melanie Ott, Robert Switzer, Richard Chuska, Frank LaRocca, William Thomes, Lance Day, Shawn MacMurphy

Proceedings Volume 10566, 1056618 (2017) https://doi.org/10.1117/12.2308221

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Proceedings Article | 20 November 2017 Open Access

Development and qualification of a fiber optic cable for Martian environments

C. Lindensmith, W. T. Roberts, M. Meacham, M. Ott, F. LaRocca, W. J. Thomes

Proceedings Volume 10565, 1056519 (2017) https://doi.org/10.1117/12.2309109

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Proceedings Article | 20 November 2017 Open Access

Multi-mode optical fibers for connecting space-based spectrometers

W. T. Roberts, C. Lindenmisth, S. Bender, E. Miller, E. Motts, M. Ott, F. LaRocca, J. Thomes

Proceedings Volume 10565, 105651A (2017) https://doi.org/10.1117/12.2309137

KEYWORDS: Spectrometers, Optical fibers, Cladding, Astronomical imaging, Laser induced breakdown spectroscopy, Raman spectroscopy, Head, Light scattering, Silica, Plasma

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Laser spectral analysis systems are increasingly being considered for in situ analysis of the atomic and molecular composition of selected rock and soil samples on other planets [1][2][3]. Both Laser Induced Breakdown Spectroscopy (LIBS) and Raman spectroscopy are used to identify the constituents of soil and rock samples in situ. LIBS instruments use a high peak-power laser to ablate a minute area of the surface of a sample. The resulting plasma is observed with an optical head, which collects the emitted light for analysis by one or more spectrometers. By identifying the ion emission lines observed in the plasma, the constituent elements and their abundance can be deduced. In Raman spectroscopy, laser photons incident on the sample surface are scattered and experience a Raman shift, exchanging small amounts of energy with the molecules scattering the light. By observing the spectrum of the scattered light, it is possible to determine the molecular composition of the sample.

For both types of instruments, there are advantages to physically separating the light collecting optics from the spectroscopy optics. The light collection system will often have articulating or rotating elements to facilitate the interrogation of multiple samples with minimum expenditure of energy and motion. As such, the optical head is often placed on a boom or an appendage allowing it to be pointed in different directions or easily positioned in different locations. By contrast, the spectrometry portion of the instrument is often well-served by placing it in a more static location. The detectors often operate more consistently in a thermally-controlled environment. Placing them deep within the spacecraft structure also provides some shielding from ionizing radiation, extending the instrument’s useful life. Finally, the spectrometry portion of the instrument often contains significant mass, such that keeping it off of the moving portion of the platform, allowing that portion to be significantly smaller, less massive and less robust.

Large core multi-mode optical fibers are often used to accommodate the optical connection of the two separated portions of such instrumentation. In some cases, significant throughput efficiency improvement can be realized by judiciously orienting the strands of multi-fiber cable, close-bunching them to accommodate a tight focus of the optical system on the optical side of the connection, and splaying them out linearly along a spectrometer slit on the other end.

For such instrumentation to work effectively in identifying elements and molecules, and especially to produce accurate quantitative results, the spectral throughput of the optical fiber connection must be consistent over varying temperatures, over the range of motion of the optical head (and it’s implied optical cable stresses), and over angle-aperture invariant of the total system. While the first two of these conditions have been demonstrated[4], spectral observations of the latter present a cause for concern, and may have an impact on future design of fiber-connected LIBS and Raman spectroscopy instruments. In short, we have observed that the shape of the spectral efficiency curve of a large multi-mode core optical fiber changes as a function of input angle.

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Proceedings Article | 3 September 2008 Paper

Vibration performance comparison study on current fiber optic connector technologies

William Thomes, Frank LaRocca, Robert Switzer, Melanie Ott, Richard Chuska, Shawn Macmurphy

Proceedings Volume 7070, 70700A (2008) https://doi.org/10.1117/12.796644

KEYWORDS: Connectors, Shape memory alloys, Fiber optics, Polishing, Metals, Optical fiber cables, Fiber optics tests, Step index fibers, Ceramics, Inspection

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Proceedings Article | 3 September 2008 Paper

Fiber optic cable thermal preparation to ensure stable operation

William Thomes, Richard Chuska, Melanie Ott, Frank LaRocca, Robert Switzer, Shawn Macmurphy

Proceedings Volume 7070, 70700B (2008) https://doi.org/10.1117/12.796977

KEYWORDS: Optical fiber cables, Connectors, Single mode fibers, Temperature metrology, Manufacturing, Coating, Sensors, Transmittance, Fiber coatings, Polymers

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Proceedings Article | 3 September 2008 Paper

Applications of optical fiber assemblies in harsh environments: the journey past, present, and future

Melanie Ott, Frank LaRocca, William Joe Thomes, Robert Switzer, Richard Chuska, Shawn Macmurphy

Proceedings Volume 7070, 707009 (2008) https://doi.org/10.1117/12.797021

KEYWORDS: Optical fibers, Connectors, Optical fabrication, Ranging, Telecommunications, Fiber lasers, Optics manufacturing, Space telescopes, Mercury, Fiber optics

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Proceedings Article | 26 August 2008 Paper

Development, qualification, and integration of the optical fiber array assemblies for the Lunar Reconnaissance Orbiter

Melanie Ott, Robert Switzer, Richard Chuska, Frank LaRocca, William Joe Thomes, Shawn MacMurphy

Proceedings Volume 7095, 70950P (2008) https://doi.org/10.1117/12.797216

KEYWORDS: Ranging, Optical fibers, Fiber lasers, Optical fabrication, Optical arrays, Connectors, Fiber optics, Antennas, Space telescopes, Telescopes

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Proceedings Article | 26 September 2007 Paper

Investigation of hermetically sealed commercial LiNbO₃ optical modulator for use in laser/LIDAR space-flight applications

William Thomes, Frank LaRocca, Melanie Ott, Xiaodan Linda Jin, Richard Chuska, Shawn MacMurphy, Tracee Jamison

Proceedings Volume 6713, 67130T (2007) https://doi.org/10.1117/12.732525

KEYWORDS: Modulators, Waveguides, Gamma radiation, Optical modulators, Commercial off the shelf technology, Fiber lasers, Crystals, Imaging systems, Optical components, Photodiodes

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Proceedings Article | 26 September 2007 Paper

Space flight qualification on a novel five-fiber array assembly for the lunar orbiter laser altimeter (LOLA) at NASA Goddard Space Flight Center

Xiaodan Linda Jin, Melanie Ott, Frank LaRocca, Richard Chuska, Steve Schmidt, Adam Matuszeski, Shawn Macmurphy, William Thomes, Robert Switzer

Proceedings Volume 6713, 67130S (2007) https://doi.org/10.1117/12.734021

KEYWORDS: Connectors, Phase modulation, Diamond, Signal attenuation, Manufacturing, Sensors, Optical fabrication, Gamma radiation, Lamps, Optical fibers

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Proceedings Article | 26 September 2007 Paper

Requirements validation testing on the 7 optical fiber array connector/cable assemblies for the Lunar Reconnaissance Orbiter (LRO)

Melanie Ott, Xiaodan Linda Jin, Frank LaRocca, Adam Matuszeski, Richard Chuska, Shawn MacMurphy

Proceedings Volume 6713, 67130Q (2007) https://doi.org/10.1117/12.733965

KEYWORDS: Optical fabrication, Optical fibers, Ranging, Connectors, Phase modulation, Data modeling, Diamond, Optical arrays, Lawrencium, Space telescopes

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Showing 5 of 10 publications

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