Snapshot fiber spectral imaging using speckle correlations and compressive sensing

Abstract

Snapshot spectral imaging is rapidly gaining interest for remote sensing applications. Acquiring spatial and spectral data within one image promotes fast measurement times, and reduces the need for stabilized scanning imaging systems. Many current snapshot technologies, which rely on gratings or prisms to characterize wavelength information, are difficult to reduce in size for portable hyperspectral imaging. Here, we show that a multicore multimode fiber can be used as a compact spectral imager with sub-nanometer resolution, by encoding spectral information within a monochrome CMOS camera. We characterize wavelength-dependent speckle patterns for up to 3000 fiber cores over a broad wavelength range. A clustering algorithm is employed in combination with l1-minimization to limit data collection at the acquisition stage for the reconstruction of spectral images that are sparse in the wavelength domain. We also show that in the non-compressive regime these techniques are able to accurately reconstruct broadband information.

Deep learning enabled real time speckle recognition and hyperspectral imaging using a multimode fiber array

“…Mode mixing in each individual fiber results in a characteristic speckle pattern with a wavelength dependence determined by the fiber length and the angle of incidence of the incident light. For a direct comparison with previous results we used in our first calibration experiments the setup as described in [27]. For the projection of animations we developed a new setup as shown in Fig.…”

“…The MCMMF consisted of 3012 fibers with individual core diameters of 50 µm. Fibers of different lengths can be used for different applications depending on the bandwidth required [27]. After transmission through the fiber array, the output facet of the MCMMF was imaged onto the focal plane array of a 12-bit, 5 MPixel monochrome CMOS camera with a pixel size of 2.2 µm × 2.2 µm (AVT Guppy) using a 1:1 imaging system.…”

“…Recently, a multicore multimode fiber bundle has been used as a frequency characterization element in a high-throughput imaging spectrometer for snapshot spatial and spectral measurements with sub nanometer spectral resolution [27]. A compressive sensing (CS) algorithm was successfully employed to retrieve spectral information.…”

Multimode-fiber-based single-shot full-field measurement of optical pulses

“…A multimode fiber (MMF) can be considered as a complex photonic structure [1,2] with diverse degrees of freedom in space, time, spectrum and polarization. As these degrees of freedom are coupled, an MMF provides a versatile and multi-functional platform for communication [3,4], imaging [5][6][7][8] and sensing applications [10][11][12][13][14][15][16]. The abundant spatial degrees of freedom have been utilized for controlling linear [17][18][19][20] and nonlinear light propagation [21][22][23][24][25] in an MMF.…”

“…The spatial, temporal, spectral or polarization states of transmitted light are manipulated by shaping the spatial wavefront of an incident beam. Hence, an MMF can function as a microscope [5][6][7][8], a reconfigurable waveplate [26] or a pulse shaper [17][18][19][20]. In particular, the coupling between spatial and temporal degrees of freedom in an MMF enables tailoring the output state in time by manipulating the input state in space.…”