Spatial-spectral modulating snapshot hyperspectral imager

Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109-8099, USA.
Applied Optics (Impact Factor: 1.78). 04/2006; 45(9):1898-908. DOI: 10.1364/AO.45.001898
Source: PubMed


Experimental results are presented for a computed tomography imaging spectrometer (CTIS) with imposed spatial-spectral modulation on the image scene. This modulation structure on the CTIS tomographic dispersion created substantial gains in spectral reconstruction resolution after standard iterative, nonlinear, inversion techniques were used. Modulation limits system ambiguities, so high-frequency spectral and low-frequency spatial scene data could be recovered. The results demonstrate how spatial modulation acts as a high-frequency spectral deconvolver for the snapshot hyperspectral imager technology.

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Available from: Greg Bearman, Sep 29, 2015
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    • "-Hyperspectral imaging from limited Radon projections with no spectral noise -In the following example we attempt to reconstruct the 32 by 32 image of the hyperspectral flower [26] using a limited number of projections. The projections at various angles for a typical single-shot CTIS system [17], [27] are shown in Figure 4. Gaussian noise was then added to the measured projections, such that the resulting SNR of the projections was 4.5 dB. This projection operation can be represented through the "
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    Acoustics, Speech, and Signal Processing, 1988. ICASSP-88., 1988 International Conference on 05/2013; DOI:10.1109/ICASSP.2013.6638043 · 4.63 Impact Factor
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    • "Seven patients with drusen and three normal controls were imaged with the snapshot hyperspectral camera previously described [3]. 20 random ROIs were acquired for patient C (see Fig. 3) and used for intra-patient NMF analysis. "
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    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2010; 2010:5363-6. DOI:10.1109/IEMBS.2010.5626463
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    ABSTRACT: This dissertation describes two computational sensors that were used to demonstrate applications of generalized sampling of the optical field. The first sensor was an incoherent imaging system designed for compressive measurement of the power spectral density in the scene (spectral imaging). The other sensor was an interferometer used to compressively measure the mutual intensity of the optical field (coherence imaging) for imaging through turbulence. Each sensor made anisomorphic measurements of the optical signal of interest and digital post-processing of these measurements was required to recover the signal. The optical hardware and post-processing software were co-designed to permit acquisition of the signal of interest with sub-Nyquist rate sampling, given the prior information that the signal is sparse or compressible in some basis. Compressive spectral imaging was achieved by a coded aperture snapshot spectral imager (CASSI), which used a coded aperture and a dispersive element to modulate the optical field and capture a 2D projection of the 3D spectral image of the scene in a snapshot. Prior information of the scene, such as piecewise smoothness of objects in the scene, could be enforced by numerical estimation algorithms to recover an estimate of the spectral image from the snapshot measurement. Hypothesizing that turbulence between the scene and CASSI would introduce spectral diversity of the point spread function, CASSI's snapshot spectral imaging capability could be used to image objects in the scene through the turbulence. However, no turbulence-induced spectral diversity of the point spread function was observed experimentally. Thus, coherence functions, which are multi-dimensional functions that completely determine optical fields observed by intensity detectors, were considered. These functions have previously been used to image through turbulence after extensive and time-consuming sampling of such functions. Thus, compressive coherence imaging was attempted as an alternative means of imaging through turbulence. Compressive coherence imaging was demonstrated by using a rotational shear interferometer to measure just a 2D subset of the 4D mutual intensity, a coherence function that captures the optical field correlation between all the pairs of points in the aperture. By imposing a sparsity constraint on the possible distribution of objects in the scene, both the object distribution and the isoplanatic phase distortion induced by the turbulence could be estimated with the small number of measurements made by the interferometer. Dissertation
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