Comparison of a physics-based BIL simulator with experiments

Abstract

Laser Gated Imaging is a unique camera technology. It provides long-range night vision in complete darkness as well as in degraded weather conditions, such as rain, fog and haze. Burst illumination laser (BIL) imaging combines an active laser illumination with time gating (or range gating) camera. For these reasons, BIL imaging has become increasingly important in Defense and security applications. In an associated paper [01], we present a model (PIAF) developed to evaluate the relevant physical phenomena (scintillation, speckle…) impacting on the BIL imaging. This paper presents preliminary experimental results and comparisons with PIAF simulations.

Modeling of an active burst illumination imaging system: comparison between experimental and modelled 3D scene

“…An experimental validation of propagation models was done and results were presented in an associated paper [12]. This section illustrates one result of the global validation that we have performed.…”

“…A final random number allows us to choose a single couple of values. Speckle BRDF BDD Speckle BDD Speckle Speckle Speckle A A A A , , , , , ⋅ = φ φ (12) An EM approach can't be generalized to the entire plane surface of the target. Even if our simplified approach considers coherent effects as a radiometric balance, two simple cases are also adopted: rough surfaces where we consider lambertian surfaces with random phases or surfaces cancelling coherent effects (phase is set to zero), mirror surfaces with phase conservation.…”

“…Then, we adapt the Siphos data base by rotation of the scatter plot until the averaged phase φ Speckle, avg obtained with Siphos code is equivalent to the averaged phase φ BRDF, avg . Next step consists in normalizing couples of amplitudes and phases as describe in relation (12). A final random number allows us to choose a single couple of values.…”

Simulation of a laser range-gated SWIR imaging system in weak turbulence conditions

“…Since the expressions for turbulence blur, (7), and angle-of-arrival variance, (9), are both well established, this effort should focus on verification of the methods used to simulate anisoplanatic turbulence blur and turbulence distortion. The latter could be verified using a split-step Fourier-transform algorithm in which point sources are propagated from the target and imaged by the camera 21 . However, it is recognized that the classical method for generating phase screens does not accurately duplicate large-scale phase perturbations such as tilt that are responsible for distortions.…”

Mosaic active imaging: direct physical modelling and image reconstruction

“…The end-to-end model presented here is based on a initial work on the flash laser imaging system published in [1]. It includes all the physical components: the laser, the deflection laser, the target, the outbound and inbound atmospheric paths and the camera.…”