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Multi-spectral Tunable Detection (MultiTuDe) Lens for Rapid In-situ Forensic Analysis

NCJ Number
300665
Date Published
December 2020
Length
19 pages
Author(s)
Milind Mahajan; Dong-Feng Gu; Bryce Murray; Weiya Zhang; John Mansell
Agencies
NIJ
Grant Number(s)
2018-75-CX-0042
Annotation

This is the Final Report of a project with the goal of developing a low-cost multispectral imaging system that retains the advantages of the traditional liquid crystal tunable filter (LCTF) hardware.

Abstract

The researchers on this project (Teledyne Scientific and Imaging) previously demonstrated the feasibility of enabling an integrated multispectral imaging triage/survey tool capable of nearly real time enhancement of target signatures of forensic interest by collecting and analyzing various wave lengths and polarization channels, using passive or active illumination and powerful backend processing algorithms. The feasibility of the concept was demonstrated through brass-board camera implementation and off-line image processing. A traditional birefringent filter design (Lyot filter) was optimized by novel materials and engineering to achieve improved transmission and fast speed. This electro-optically (EO) tunable bandpass filter, along with a specially designed commercial off-the-shelf multispectral lens and a monochrome camera as the imaging hardware. Although the project demonstrated a fast EO tuned multispectral imaging system, the complexity and the cost of both filter and lens was an impediment to potential transition to an affordable product. The current project was an effort to enable an inherently low-cost multispectral imaging system while retaining the advantages of the traditional liquid crystal tunable filter (LCTF) hardware. The current project developed an unconventional and innovative reflective lens design that uses a tunable cholesteric liquid crystal (ChLC) cell as a narrowband EO tuned reflector, the critical spectral control element. The novel characteristics of the design are emphasized in this report. All the primary project goals were met. It integrated, tested, and demonstrated the Multi-spectral Tunable Detection (MultiTuDe) Lens. 14 figures and 28 references

Date Created: April 12, 2021