Ms. Diana Maestas Profile

Diana Maestas

at Air Force Research Lab

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Publications (4)

Proceedings Article | 12 March 2024 Presentation

Microscopic-physics model for interface-roughness scattering and nonlinear electron transport in superlattice

Danhong Huang, Po-Hsin Shih, Godfrey Gumbs, Thi-Nga Do, Christian Morath, Tanya Maestas

Proceedings Volume PC12880, PC1288003 (2024) https://doi.org/10.1117/12.2690859

KEYWORDS: Scattering, Superlattices, Electron transport

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Proceedings Article | 3 October 2023 Presentation + Paper

Event-based camera refractory period characterization and initial clock drift evaluation

Peter McMahon-Crabtree, Lucas Kulesza, Brian McReynolds, Daniel O'Keefe, Anirvin Puttur, Diana Maestas, Christian Morath, Matthew McHarg

Proceedings Volume 12693, 126930V (2023) https://doi.org/10.1117/12.2672301

KEYWORDS: Cameras, Clocks, Sensors, Commercial off the shelf technology, Integrating spheres, Light sources, Monte Carlo methods, Light emitting diodes, Modulation, Visualization

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Event-based camera (EBC) technology provides high-dynamic range operation and shows promise for efficient capture of spatio-temporal information, producing a sparse data stream and enabling consideration of nontraditional data processing solutions (e.g., new algorithms, neuromorphic processors, etc.). Given the fundamental difference in camera architecture, the EBC response and noise behavior differ considerably compared to standard CCD/CMOS framing sensors. These differences necessitate the development of new characterization techniques and sensor models to evaluate hardware performance and elucidate the trade-space between the two camera architectures. Laboratory characterization techniques reported previously include noise level as a function of static scene light level (background activity) and contrast responses referred to as S-curves. Here we present further progress on development of basic characterization methods and test capabilities for commercial-off-the-shelf (COTS) visible EBCs, with a focus on measurement of pixel deadtime (refractory period) including results for the 4th-generation sensor from Prophesee and Sony. Refractory period is empirically determined from analysis of the interspike intervals (ISIs), and results visualized using log-histograms of the minimum per-pixel ISI values for a subset of pixels activated by a controlled dynamic scene. Our tests of the Prophesee gen4 EVKv2 yield refractory period estimates ranging from 6.1 msec to 6.8 μsec going from the slowest (20) to fastest (100) settings of the relevant bias parameter, bias_refr. We also introduce and demonstrate the concept of pixel bandwidth measurement from data captured while viewing a static scene – based on recording data at a range of refractory period setting and then analyzing noise-event statistics. Finally, we present initial results for estimating and correcting EBC clock drift using a GPS PPS signal to generate special timing events in the event-list data streams generated by the DAVIS346 and DVXplorer EBCs from iniVation.

Proceedings Article | 30 September 2022 Presentation + Paper

Automated characterization techniques and testbeds for event-based cameras

Peter McMahon-Crabtree, Wellesley Pereira, Robert Crow, Richard Preston, Lucas Kulesza, Ryan Crowell, Christian Morath, Diana Maestas, Zachry Theis, Patricia Sablan

Proceedings Volume 12233, 122330B (2022) https://doi.org/10.1117/12.2634166

KEYWORDS: Sensors, Cameras, Reliability, Gamma radiation, Aerospace engineering, Optical testing, Ionizing radiation effects

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Event-based camera (EBC) technology shows promise for efficient capture of spatio-temporal information, producing a sparse data stream and enabling consideration of nontraditional data processing solutions (e.g., new algorithms, neuromorphic processors). Given the fundamental difference in camera architecture, the EBC response and noise behavior differ considerably compared to standard CCD/CMOS framing sensors. These differences necessitate development of new characterization techniques to quantify performance and assess if the EBC technology produces benefits relative to traditional imaging sensors. Here we present progress on development of basic sensor performance modeling and test capabilities for commercial-off-the-shelf visible EBCs. Laboratory characterization techniques include noise level as a function of static scene light level (termed background activity) and EBC temporal contrast response to dynamic signals. Initial environmental tests of the Prophesee PPS3MVCD event-based sensor found several addressable areas of concern but identified no showstoppers that would prevent use of this device in a high-reliability aerospace application. Two independent radiation tolerance test efforts, one for the PPS3MVCD and another for the iniVation DAVIS346 EBC (both based on 180 nm CMOS technology), indicate functional issues for total ionizing dose (TID) of greater than 30 krad(Si), and show background activity increasing with TID. However, no significant change in contrast response was observed. One DAVIS346 exhibited functional failure following final gamma radiation dose from 20 krad(Si) to 50 krad(Si), and the readout saturated during doses dominated by negative-polarity events (by a factor of 10 or greater). A second DAVIS346 locked-up during proton dose but recovered normal operation following a brief rest period and power cycling. DAVIS346 pixels include both change detection (DVS) and standard grayscale frames (APS) functionalities – driven by a single photodiode; results show a 70% increase in dark current and 23% increase in dark event noise after proton exposure to 20 krad(Si). As new versions of EBC technology are developed for infrared wavelengths, we anticipate these characterization techniques will be largely translatable to IR EBCs.

Proceedings Article | 30 May 2019 Paper

Comparing II-VI and III-V infrared detectors for space applications

Elizabeth Steenbergen, Christian Morath, Diana Maestas, Geoffrey Jenkins, Julie Logan

Proceedings Volume 11002, 110021B (2019) https://doi.org/10.1117/12.2519250

KEYWORDS: Quantum efficiency, Mercury cadmium telluride, Infrared detectors, Sensors, Photodiodes, Diffusion, Photodetectors

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