Multispectral cameras capture images in multiple wavelengths in narrow spectral bands. They offer advanced sensing well beyond normal cameras and many single sensor based multispectral cameras have been commercialized aimed at a broad range of applications, such as agroforestry research, medical analysis and so on. However, the existing single sensor based multispectral cameras require accurate alignment to overlay each filter on image sensor pixels, which makes their fabrication very complex, especially when the number of bands is large. This paper demonstrates a new filter technology using a hybrid combination of single plasmonic layer and dielectric layers by computational simulations. A filter mosaic of various bands with narrow spectral width can be achieved with single run manufacturing processes (i.e., exposure, development, deposition and other minor steps), regardless of the number of bands.
A multispectral image camera captures image data within specific wavelength ranges in narrow wavelength bands across the electromagnetic spectrum. Images from a multispectral camera can extract additional information that the human eye or a normal camera fails to capture and thus may have important applications in precision agriculture, forestry, medicine and object identification. Conventional multispectral cameras are made up of multiple image sensors each fitted with a narrow passband wavelength filter and optics, which makes them heavy, bulky, power hungry and very expensive. The multiple …
Beyond chlorophyll: machine learning estimates of diagnostic phytoplankton pigments from multispectral ocean colour data
Plymouth Marine Laboratory（普利茅斯海洋实验室）；National Center for Earth Observation, Plymouth Marine Laboratory（普利茅斯海洋实验室国家地球观测中心）；University of Exeter（埃克塞特大学）
Optical materials with colour-changing abilities have been explored for display devices, smart windows, or modulation of visual appearance. The efficiency of these materials, however, has strong wavelength dependence, which limits their functionality to a narrow spectral range. Here, we report graphene-based electro-optical devices with unprecedented optical tunability covering the entire electromagnetic spectrum from the visible to microwave. We achieve this non-volatile and reversible tunability by electro-intercalation of lithium into graphene layers in an optically accessible device struct…
A multispectral camera records image data in various wavelengths across the electromagnetic spectrum to acquire additional information that a conventional camera fails to capture. With the advent of high-resolution image sensors and colour filter technologies, multispectral imagers in the visible wavelengths have become popular with increasing commercial viability in the last decade. However, multispectral imaging in longwave infrared (LWIR: 8 to 14 microns) is still an emerging area due to the limited availability of optical materials, filter technologies, and high-resolution sensors. Images …
Computational ghost imaging is a robust and compact system that has drawn wide attentions over the last two decades. Multispectral imaging possesses spatial and spectral resolving abilities, is very useful for surveying scenes and extracting detailed information. Existing multispectral imagers mostly utilize narrow band filters or dispersive optical devices to separate lights of different wavelengths, and then use multiple bucket detectors or an array detector to record them separately. Here, we propose a novel multispectral ghost imaging method that uses one single bucket detector with multip…
Conventional cameras, such as in smartphones, capture wideband red, green and blue (RGB) spectral components, replicating human vision. Multispectral imaging (MSI) captures spatial and spectral information beyond our vision but typically requires bulky optical components and is expensive. Snapshot multispectral image sensors have been proposed as a key enabler for a plethora of MSI applications, from diagnostic medical imaging to remote sensing. To achieve low-cost and compact designs, spatially variant multispectral filter arrays (MSFAs) based on thin-film optical components are deposited ato…
Actively tunable, narrowband spectral filtering across arbitrary optical wavebands is highly desirable in a plethora of applications, from chemical sensing, hyperspectral imaging to infrared astronomy. Yet, the ability to actively reconfigure the optical properties of a solid-state narrowband filter remains elusive. Existing solutions require either moving parts, have slow response times or provide limited spectral coverage. Here, we demonstrate a continuously tunable, spectrally-agnostic, all-solid-state, narrowband phase-change metasurface filter based on a GeSbTe (GST)-embedded plasmonic na…
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 …
We carried out an experimental set-up for reading a hidden drawing under papyrus using an optical technique based on the speckle phenomenon that is observed when a rough surface is illuminated by laser light. We propose the use of several wavelengths of light illumination and adaptive algorithms to process the speckle images. We employ a set of filters to produce better discrimination of the results as visually judged. This approach is a cheap and relatively simple non-destructive and non-invasive procedure that could be extended to other painted objects or subsurface hidings of archaeological…
Nighttime images taken with DSLR cameras from the International Space Station (ISS) can provide valuable information on the spatial and temporal variation of artificial nighttime lighting on Earth. In particular, this is the only source of historical and current visible multispectral data across the world (DMSP/OLS and SNPP/VIIRS-DNB data are panchromatic and multispectral in the infrared but not at visible wavelengths). The ISS images require substantial processing and proper calibration to exploit intensities and ratios from the RGB channels. Here we describe the different calibration steps,…
Multispectral imaging plays an important role in many applications from astronomical imaging, earth observation to biomedical imaging. However, the current technologies are complex with multiple alignment-sensitive components, predetermined spatial and spectral parameters by manufactures. Here, we demonstrate a single-shot multispectral imaging technique that gives flexibility to end-users with a very simple optical setup, thank to spatial correlation and spectral decorrelation of speckle patterns. These seemingly random speckle patterns are point spreading functions (PSFs) generated by light …
We created a novel optical security device that integrates multiple computer-generated holograms within a single colour image. Under white light, this "holographic colour print" appears as a colour image, whereas illumination with a red, green, or blue beam from a handheld laser pointer projects up to three different holograms onto a distant screen. In our design, all dielectric layered pixels comprising phase plates (phase control) and structural colour filters (amplitude control) are tiled to form a monolithic print, wherein pixel-level control over the phase and amplitude of light allows us…
AIT Austrian Institute of Technology（奥地利理工学院）；University of Zurich（苏黎世大学）；ETH Zurich（苏黎世联邦理工学院）；Western Sydney University（西悉尼大学）；University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）
The stomatopod (mantis shrimp) visual system has recently provided a blueprint for the design of paradigm-shifting polarization and multispectral imaging sensors, enabling solutions to challenging medical and remote sensing problems. However, these bioinspired sensors lack the high dynamic range (HDR) and asynchronous polarization vision capabilities of the stomatopod visual system, limiting temporal resolution to \~12 ms and dynamic range to \~ 72 dB. Here we present a novel stomatopod-inspired polarization camera which mimics the sustained and transient biological visual pathways to save pow…
