Airborne measurements in the infrared using FTIR-based imaging hyperspectral sensors

Abstract

Hyperspectral ground mapping is being used in an ever-increasing extent for numerous applications in the military, geology and environmental fields. The different regions of the electromagnetic spectrum help produce information of differing nature. The visible, near-infrared and short-wave infrared radiation (400 nm to 2.5 µm) has been mostly used to analyze reflected solar light, while the mid-wave (3 to 5 µm) and long-wave (8 to 12 µm or thermal) infrared senses the self-emission of molecules directly, enabling the acquisition of data during night time.Push-broom dispersive sensors have been typically used for airborne hyperspectral mapping. However, extending the spectral range towards the mid-wave and long-wave infrared brings performance limitations due to the self emission of the sensor itself. The Fourier-transform spectrometer technology has been extensively used in the infrared spectral range due to its high transmittance as well as throughput and multiplex advantages, thereby reducing the sensor self-emission problem.Telops has developed the Hyper-Cam, a rugged and compact infrared hyperspectral imager. The Hyper-Cam is based on the Fourier-transform technology yielding high spectral resolution and enabling high accuracy radiometric calibration. It provides passive signature measurement capability, with up to 320x256 pixels at spectral resolutions of up to 0.25 cm-1. The Hyper-Cam has been used on the ground in several field campaigns, including the demonstration of standoff chemical agent detection. More recently, the Hyper-Cam has been integrated into an airplane to provide airborne measurement capabilities. A special pointing module was designed to compensate for airplane attitude and forward motion. To our knowledge, the Hyper-Cam is the first commercial airborne hyperspectral imaging sensor based on Fourier-transform infrared technology. The first airborne measurements and some preliminary performance criteria for the Hyper-Cam are presented in this paper.

Influence of soil moisture content on spectral reflectance of bare soils in the 0.4–14 μm domain

“…The main reasons are that most of the current sensors cannot cover this entire optical domain and there is a lack of spectral soil databases as a function of SMC. With the advent of new hyperspectral image sensors such as FIRST (Telops (Quebec, Canada); Puckrin et al 2009), the ASI family (with CASI, SASI, MASI, and TASI of Itres (Calgary, Canada); Achal et al 2007), and SYSIPHE (ONERA (Toulouse, France); Rousset-Rouviere et al 2011), it is now possible to explore the whole optical domain with narrow spectral bands. Thus, the evaluation of the potential of these instruments for SMC estimation is a worthwhile piece of research that needs at first a characterization of the impact of SMC on the spectral signatures of bare soils.…”

A Real-Time Infrared Ultra-Spectral Signature Classification Method via Spatial Pyramid Matching

“…Fortunately, the state-of-the-art ultra-spectral sensor technologies [ 6 ], for example the tropospheric emission spectrometer (TES) [ 7 ] and the infrared atmospheric sounding interferometer (IASI) [ 8 ], have achieved a spectral resolution less than 0.5 cm −1 , which brings new hope for those high precision applications. Nevertheless, the breakthrough of spectral resolution leads to some new problems, which makes spectral signature analysis become more challenging, especially in real-time applications, such as greenhouse gases surveillance [ 9 , 10 ], target detection [ 11 , 12 ], etc.…”

New Airborne Thermal-Infrared Hyperspectral Imager System: Initial Validation

“…All of the above instruments are one-of-a-kind research instruments developed by research institutions and companies, primarily for experimental research. Some companies have also launched their own commercial infrared imaging spectrometers, mainly, e.g., TASI-600 [11], AISA OWL(https://www.specim.fi/products/aisaowl/), and Hyper-Cam [12]. In 2006, Canadian ITRES Research Limited released the first commercial infrared hyperspectral imager, TASI-600.…”