Mr. Ronald J. Hardgrove Profile

Ronald J. Hardgrove

Electro-optics Flight Chief at United States Air Force

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Publications (1)

Proceedings Article | 1 November 2024 Presentation + Paper

Spectral-spatial ground targets for measurement of airborne electro-optical imaging system performance

Robert Sundberg, James Grassi, Michael Kogan, Cory Garms, Paul Corlies, Neil Goldstein, Bridget Tannian, Megan Stark, Marsha Fox, Timothy Perkins, Ronald Hardgrove, Karapet Gyurjyan, Steven Santaniello, Todd Christensen, Vu Hoang

Proceedings Volume 13200, 132000U (2024) https://doi.org/10.1117/12.3030794

KEYWORDS: Modulation transfer functions, Cameras, Temperature metrology, Sensors, Tunable filters, Imaging systems, Long wavelength infrared, Diffusers, Design, Reflectivity

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Targets located on the Precision Impact Range Area (PIRA) of Edwards AFB are used to evaluate imaging systems’ sensitivity and spatial resolution to ensure they meet specified requirements. Spectral Sciences, Inc., is developing a field-ready electro-optical sensor calibration/test system for airborne instruments from the visible through longwave infrared. This spectral region is particularly challenging because of the contributions from both solar and thermal fluxes. The system is composed of spectral-spatial ground targets and atmospheric characterization instruments. The design challenges for a new ground target installation applicable over short to long ranges and a broad optical spectrum include: 1) development of an innovative spectral-spatial, high contrast, high uniformity, knife edge target for determination of the spatial characteristics of the imaging system under test, such as the Modulation Transfer Function (MTF) and Relative Edge Response (RER), Noise Equivalent Temperature Difference (NETD), linearity and more; 2) development and implementation of a suite of auxiliary instruments to quantify the atmospheric effects, such as line-of-sight (LOS) turbulence, surface temperatures, humidity, and visibility; 3) development of targets with stable, quantifiable spectral response that can be used for evaluation for the spectral characteristics of multi- or hyperspectral imaging systems; and 4) engineering the target set for simplified long-term maintenance and durability. In this paper we report on the development of a prototype 2m by 2m thermally controlled knife edge target. The target is composed of four 1m by 1m panels each of which has independent temperature control and face surface materials which can be exchanged with other panel faces to produce patterns or spectral features. The full prototype system can be rotated and tipped to maximize the surface area apparent to a sensor system under test. The paper includes initial field measurements of the target array using visible, MWIR and LWIR imaging systems.

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