Etched liquid-crystal Fabry-Perot tunable optical filters can provide high-enough spectral resolution for background discrimination and rapid tuning in atmospheric sensing.

Hyperspectral imaging has proven its efficiency for target detection applications but the acquisition mode and the data rate are major issues when dealing with real-time detection applications. It can be useful to use snapshot spectral imagers able to acquire all the spectral channels simultaneously on a single image sensor. Such snapshot spectral imagers suffer from the lack of spectral resolution. It is then mandatory to carefully select the spectral content of the acquired image with respect to the proposed application. We present a novel approach of hyperspectral band selection for target detection which maximizes the contrast between the background and the target by proper optimization of positions and linewidths of a limited number of filters. Based on a set of tunable band-pass filters such as Fabry-Perot filters, the device should be able to adapt itself to the current scene and the target looked for. Simulations based on real hyperspectral images show that such snapshot imagers could compete well against hyperspectral imagers in terms of detection efficiency while allowing snapshot acquisition, and real-time detection.

background

Segmented tunable filters advance multispectral imaging

Adaptive band selection snapshot multispectral imaging in the VIS/NIR domain

Hyperspectral imaging has proven its efficiency for target detection applications but the acquisition mode and the data
rate are major issues when dealing with real-time detection applications. It can be useful to use snapshot spectral imagers
able to acquire all the spectral channels simultaneously on a single image sensor. Such snapshot spectral imagers suffer
from the lack of spectral resolution. It is then mandatory to carefully select the spectral content of the acquired image
with respect to the proposed application. We present a novel approach of hyperspectral band selection for target
detection which maximizes the contrast between the background and the target by proper optimization of positions and
linewidths of a limited number of filters. Based on a set of tunable band-pass filters such as Fabry-Perot filters, the
device should be able to adapt itself to the current scene and the target looked for. Simulations based on real
hyperspectral images show that such snapshot imagers could compete well against hyperspectral imagers in terms of
detection efficiency while allowing snapshot acquisition, and real-time detection.

L'imagerie hyperspectrale, qui consiste a acquerir l'image d'une scene dans un grand nombre de bandes spectrales, permet de detecter des cibles la ou l'imagerie couleur classique ne permettrait pas de conclure. Les imageurs hyperspectraux a acquisition sequentielle sont inadaptes aux applications de detection en temps reel. Dans cette these, nous proposons d'utiliser un imageur multispectral snapshot, capable d'acquerir simultanement un nombre reduit de bandes spectrales sur un unique detecteur matriciel. Le capteur offrant un nombre de pixels limite, il est necessaire de realiser un compromis en choisissant soigneusement le nombre et les profils spectraux des filtres de l'imageur afin d'optimiser la performance de detection. Dans cet objectif, nous avons developpe une methode de selection de bandes qui peut etre utilisee dans la conception d'imageurs multispectraux bases sur une matrice de filtres fixes ou accordables. Nous montrons, a partir d'images hyperspectrales issues de differentes campagnes de mesure, que la selection des bandes spectrales a acquerir peut conduire a des imageurs multispectraux capables de detecter des cibles ou des anomalies avec une efficacite de detection proche de celle obtenue avec une resolution hyperspectrale. Nous developpons conjointement un demonstrateur constitue d'une matrice de 4 filtres de Fabry-Perot accordables electroniquement en vue de son implantation sur un imageur multispectral snapshot agile. Ces filtres sont developpes en technologie MOEMS (microsystemes opto-electro-mecaniques) en partenariat avec l'Institut d'Electronique Fondamentale. Nous presentons le dimensionnement optique du dispositif ainsi qu'une etude de tolerancement qui a permis de valider sa faisabilite.

Additional excerpts

https://pastel.archives-ouvertes.fr/pastel-00714207/document

Segmented tunable filters advance multispectral imaging

Citations

Adaptive band selection snapshot multispectral imaging in the VIS/NIR domain

Adaptive band selection snapshot multispectral imaging in the VIS/NIR domain

Imagerie multispectrale, vers une conception adaptée à la détection de cibles

Imagerie multispectrale, vers une conception adapt

Related Papers (5)

Three-stage Fabry–Perot liquid crystal tunable filter with extended spectral range

Multispectral imaging with a liquid crystal tunable filter

Tunable mid-wave infrared Fabry-Perot bandpass filters using phase-change GeSbTe

Narrowband multispectral liquid crystal tunable filter.

A New Tunable Filter with a Very Narrow Pass-Band