Risley prism scan-based approach to standoff trace explosive detection

Craig R Schwarze,Scott Newbry,Elizabeth Schundler,Robert Vaillancourt,Ryan Benedict-Gill

doi:10.1117/1.oe.53.2.021110

Craig R Schwarze, Scott Newbry + Show 3 more

Open Access

https://doi.org/10.1117/1.oe.53.2.021110

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Abstract

A number of optical techniques are available to perform active standoff trace explosive detection. Integrating a laser scanner provides the ability to detect explosives over a wide area as well as to assess the full extent of a threat. Risley prism laser-beam steering systems provide a robust alternative to conventional scanner solutions and are ideal for portable and mobile systems due to their compact size, low power, large field-of-view, and fast scan speed. The design of a long-wave infrared Risley prism-scanned diffuse reflectance spectroscopy system along with data obtained from a prototype system is presented for both simulant and live explosive materials.

Highlights

The detection and identification of explosive materials are important issues in modern society
Optical techniques operating in the longwave infrared (LWIR) provide an effective solution owing to the availability of a rich level of vibrational spectroscopic information that can distinctly and uniquely describe the materials comprising the explosive compounds
For a given amount of laser power and system throughput, the maximum standoff range is limited by the system noise equivalent power (NEP), which can be no better than the detector NEP for a cooled system operating in the Downloaded From: https://www.spiedigitallibrary.org/journals/Optical-Engineering on 01 Mar 2022 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use

Summary

Introduction

The detection and identification of explosive materials are important issues in modern society. In order to be effective, standoff explosive detection systems need to be able to provide coverage over a reasonable lateral spatial extent such as the doorway of a building entrance, the side of a car at a checkpoint, or the ground in front of a vehicle in transit, which can be accomplished through the use of a laser-pointing device. Fast steering mirrors can provide the necessary response time and aperture, but they are generally limited to fields of view on the order of a few degrees. A Risley Prism Scanner (RPS) can provide a modest clear aperture, large FOR, and fast response time and scan speeds in a small package requiring low-operating power. Schwarze et al.: Risley prism scan-based approach to standoff trace explosive detection trinitramine (RDX), and pentaerythritol tetranitrate (PETN), and the results are presented.

System Layout and Requirements

Risley Prism Scanner Assembly

Collection Optics

Prototype DRS System

Findings

System Test Using Simulants and Explosives