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Using the Hyperspectral Imaging Spectroradiometer MR-I for Infrared Signature Measurements

Using the Hyperspectral Imaging Spectroradiometer MR-I for Infrared Signature Measurements

ABB has more than 40 years of innovation and has been recognized as a globally leading company in spectroscopy. The company is expanding its series of remote sensing products with a newly developed FT-IR hyperspectral imaging spectroradiometer operating in the infrared.

Based on the MR-Series product line, the MR-I offers accurate spatial, temporal (rapid scanning), spectral and radiometric information of infrared targets.

The hyperspectral MR Series of spectroradiometers comprise of a FTIR Michelson interferometer configured with dual output ports used to simultaneously cover the LWIR and the MWIR + SWIR spectral range.

MR-i Technology

Standard mono-pixel FT-IR spectroradiometers provide unique performance, such as higher spectral resolution and improved sensitivity over the instrument field of view (FOV). However, possibilities in infrared characterization are currently extended by multi-pixel FT-IR hyperspectral imagers. They provide accurate spatial characterization of a target’s signature by spatially resolving the vital characteristics over the observed scene.

The captured data is further exploited by combining the spatial and spectral information of the scene. As a result, an FT-IR imaging spectroradiometer has the unique capability of generating 3D images (2D images with spectral bands in the Z axis) providing a spectrum with every pixel of the mapped scene.

Features

The MR-i is the only imaging spectroradiometer solution on the market offering:

  • High NESR sensitivity, allowing weak signals to be characterized in short time periods
  • Wide spectral range (1 - 15 µm), covering LWIR to NIR
  • High time resolution through rapid scanning, allowing measurement of the evolution of rapidly varying target signatures
  • High reliability: Portable and compact for easy use in airborne operation and field operation
  • High spectral resolution, (1 cm−1) equivalent to a filter radiometer with over 9000 channels
  • High spatial resolution with extended FOV homogeneity, leading to improved accuracy no matter where the target is in the FOV
  • High dynamic range and signal-to-noise ratio
  • High radiometric accuracy and stability of response over a wide dynamic range

Spectral Coverage

Wide Spectral Range

The range of possible applications is extended from infrared characterization to gas detection, as it covers the three main atmospheric windows with a single instrument, from 1.5 to 14 µm.

The MR-i imaging spectroradiometer is made up of a dual input and output ports Fourier Transform Infrared (FTIR) Michelson interferometer. The 4 ports configuration allows the simultaneous data acquisition from two complementary cryogenic detectors (MCT and InSb) to cover the long- to the short-wave spectral range (LWIR, MWIR & SWIR) for optimal SNR out of every measurement.

The two detectors are completely independent from each other and feature their own lenses, field stop aperture wheel and filter holder, so each detector is optimized for excellent performance.

  • The FTIR technology allows the equivalent up to 9000 spectral bands per spectrum
  • 2 – 15 μm [667 – 5,000 cm−1] with optional extension to 1 μm [10 000 cm−1] available

Characteristics

Dual-camera Configuration

The MR-i is the first commercially available FT-IR hyperspectral imaging spectoradiometer that has the potential to carry out dual-camera operation, simultaneously covering the LWIR and MWIR of the electromagnetic spectrum.

The MR-i 4-port interferometer is capable of accommodating a combination of two different types of camera modules (MWIR/LWIR), extending the instrument spectral range coverage or a combination of two identical camera modules (MWIR/MWIR), extending the instrument dynamic range.

With this unique feature, the MR-i is capable of simultaneously acquiring and perfectly synchronizing the data of two interchangeable camera modules, enabling the instrument to adapt to multiple measurement scenarios.

Configuring the MR-i with two detection modules is similar to combining the functions of two imaging spectroradiometers in a single instrument, providing the following advantages:

  • Lower maintenance costs
  • Lower acquisition cost
  • Effortlessness operation using one user interface
  • Perfect synchronization of both cameras
  • Fully adjustable settings and easily interchangeable modules

Sensitivity/Extended Dynamic Range

Some applications, such as targeting an infrared signature, frequently require simultaneous measurements of high and low intensity emission sources randomly dispersed over the mapped scene. The integration time of the camera impacts the signal-to-noise performance of each individual detection module.

Setting the integration time according to the energy level of the hot pixels will negatively impact the signal-to-noise performance of the cold pixels in the scene. On the other hand, pre-setting the integration time for maximum signal-to-noise performance of the cold pixels will cause saturation on the hot pixels.

An unmatched sensitivity for the characterization of a target’s IR signature is offered by the MR-i. With both ports equipped with detector modules covering the same spectral range (MWIR- MWIR or LWIR-LWIR), they can be individually set to different gains or integration time in order to extend the dynamic range of the instrument. This majorly improves the brightest and faintest areas of the observed scene.

Fast Scanning Data Acquisition Rate

The MR-i is considered to be the fastest commercially available FT-IR imaging spectroradiometer ever built. The highest datacube measurement rate on the market is generated by the MR-i. The MR-i comprises of state-of-the-art camera modules capable of the highest frame measurement rate available and is perfectly suited for the characterization of rapidly evolving and fast moving targets.

Both camera modules in a single instrument generate an unprecedented measurement rate and provide the best combination of spectral coverage, time resolution, dynamic range and spatial resolution performance ever seen on a COTS FT-IR imaging spectroradiometer instrument.

Differential Optical Subtraction

It is possible to configure the MR-i with a linear array multi-pixel sensor optimized for differential acquisition in the VLWIR (cut off near 14 µm). For this configuration, the instrument is provided with a dual-input telescope capable of optical background subtraction.

The resulting signal is the difference between the spectral radiance entering each input port, eliminating the clutter impact of the background. This particular configuration has been designed to support scientific research associated with stand-off detection and identification of chemical agent threats.

Modular/Self-configurable Instrument

The MR-i can effortlessly adapt to a number of applications. It is designed with user-configurable modular architecture, providing the user with the flexibility to adapt the instrument to the characteristics of a specific measurement scenario. The user can configure the MR-I without the need for re-calibration or factory reworks by just simply interchanging or combining different input telescopes or detection modules.

Applications

These ruggedized instruments are a suitable solution for a variety of applications:

  • Chemical agents signature measurements
  • Military infrared target characterization
  • Industrial emission monitoring
  • Scientific research
  • Imaging

Fourier Transform Infrared (FT-IR) spectroradiometry, suitable for applications ranging from scientific research to deployable operational solutions, has been established as an ideal technology to both develop and improve a wide range of military applications. For the defense industry, FT-IR spectroradiometry is used for:

  • Characterization of thermal emission signatures of aircraft engines
  • Camouflage system development and thermal signature optimization
  • Remote sensing of battlefield conditions for developing different deployable reconnaissance solutions
  • Classifying battlespace detonations, including missile launches, muzzle flash, and bomb-hit detonation
  • Classifying fugitive emissions for developing infrared signature databases
  • Development, analysis and improvement of IR decoy emission spectra and advanced counter-measure systems

Heritage of 20 years of imaging FTS projects at ABB

  • Civil security: Surveillance and security
  • Environment: Detection and identification of pollutants
  • Defense: Troops and strategic resources protection

This innovative and powerful method extends engineering modeling applications. It is also used to enhance a wide range of IR emitting sources. Vital information for modeling IR emitted source of energy and mapping the spatial evolution of the radiance is provided by FT-IR imaging spectroradiometers.

The imaging spectroradiometer radiance measurement when combined with retrieval algorithms allows the mapping of a wide range of atmospheric applications such as:

  • Stand-off detection and monitoring of a chemical cloud
  • Atmospheric composition analysis
  • Meteorological turbulence sounding

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