Abstract
An active hyperspectral sensor (AHS) was developed for target detection and classification applications. AHS measures light scattered from a target, illuminated by a broadband near-infrared supercontinuum (SC) light source. Spectral discrimination is based on a voltage-tunable MEMS Fabry-Pérot Interferometer (FPI). The broadband light is filtered by the FPI prior to transmitting, allowing for a high spectral-power density within the eye-safety limits. The approach also allows for a cost-efficient correction of the SC instability, employing a non-dispersive reference detector. A precision of 0.1% and long-term stability better than 0.5% were demonstrated in laboratory tests. The prototype was mounted on a car for field measurements. Several road types and objects were distinguished based on the spectral response of the sensor targeted in front of the car.
Highlights
Hyperspectral remote sensing refers to a remote spectral detection of light, reflected or scattered from a target
Hyperspectral imaging has been widely applied in applications such as medical imaging and diagnostics [1], food safety inspection [2] and agriculture studies [3]
Active hyperspectral sensing refers to a method where the investigated target is artificially illuminated by a broadband light source
Summary
Hyperspectral remote sensing refers to a remote spectral detection of light, reflected or scattered from a target. Hyperspectral cameras are usually dependent on ambient lighting This limits the accuracy of the spectral signal since any variation in the illumination spectrum translates into a misinterpretation of the target response. Any drifts in the received signal caused by external illumination can be compensated by normalizing the received signal with the reference signal This enables much more accurate measurements of the target spectral response compared to passive. If the SC is already spectrally filtered prior to transmission, separate single-color point detectors can be used to detect both transmitted and received light This approach poses a practical problem of implementing spectral scanning methods, which do not result in wavelength dependent illumination patterns over long distances. We used the FPI to select the illumination band of the in-house built SC source This approach enables the use of low-cost point detectors for both outgoing and received light.
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