Image quality, meteorological optical range, and fog particulate number evaluation using the Sandia National Laboratories fog chamber

Abstract

Abstract. The evaluation of optical system performance in fog conditions typically requires field testing. This can be challenging due to the unpredictable nature of fog generation and the temporal and spatial nonuniformity of the phenomenon itself. We describe the Sandia National Laboratories fog chamber, a new test facility that enables the repeatable generation of fog within a 55 m × 3 m × 3 m (L × W × H) environment, and demonstrate the fog chamber through a series of optical tests. These tests are performed to evaluate system image quality, determine meteorological optical range (MOR), and measure the number of particles in the atmosphere. Relationships between typical optical quality metrics, MOR values, and total number of fog particles are described using the data obtained from the fog chamber and repeated over a series of three tests. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Measuring resolution degradation of long-wavelength infrared imagery in fog

“…The facility was an enclosed 3 m × 3 m × 55 m chamber. This capability was demonstrated in previous studies that show resolution degradation caused by fog in visible imaging systems 23 and how polarized light was transmitted in fog. 26 Sandia's fog facility generates an aerosol by spraying a salt water solution through 80 spray nozzles distributed along the length of the chamber.…”

“…The resolution loss caused by scattering in aerosols and fog has been well-studied for visible light. 1,6,7,13,[15][16][17][18][19][20][21][22][23] Some of the studies determined the effect of image blurring was negligible. 13,21,22 However, other studies demonstrated that image blurring significantly decreased image quality.…”

“…13,21,22 However, other studies demonstrated that image blurring significantly decreased image quality. 7,[17][18][19][20]23 Sadot et al 24 showed that scattering from aerosols significantly affected LWIR image quality in clear conditions. The previous measurements [10][11][12]14 of LWIR imaging performance through fog did not account for the resolution degradation cause by blurring.…”

Event-based sensing for the detection of modulated signals in degraded visual environments

“…Previous work has been performed to understand and improve the limits of detection for framing cameras in atmospheric aerosols 2,3,5,[7][8][9][10][11][12][13][14][15][16][17][18] . We compare our results to 𝜇 𝑠 values presented in the framing sensor literature for the detection and resolution of stationary objects within this DVE (i.e., fog).…”

“…Below, we provide some high-level background relevant to the discussions contained within the manuscript. We would like to specifically draw attention to the fact that at present we are comparing our current work and analysis to previous work performed in this space using framing cameras 2,3,5,[7][8][9][10][11][12][13][14][15][16][17][18] . These framing datasets were collected in a variety of different DVEs, some experimentally generated and others naturally occurring.…”