High spatial sampling light-guide snapshot spectrometer

Abstract

A prototype fiber-based imaging spectrometer was developed to provide snapshot hyperspectral imaging tuned for biomedical applications. The system is designed for imaging in the visible spectral range from 400 to 700 nm for compatibility with molecular imaging applications as well as satellite and remote sensing. An 81 × 96 pixel spatial sampling density is achieved by using a custom-made fiber-optic bundle. The design considerations and fabrication aspects of the fiber bundle and imaging spectrometer are described in detail. Through the custom fiber bundle, the image of a scene of interest is collected and divided into discrete spatial groups, with spaces generated in between groups for spectral dispersion. This reorganized image is scaled down by an image taper for compatibility with following optical elements, dispersed by a prism, and is finally acquired by a CCD camera. To obtain an (x, y, λ) datacube from the snapshot measurement, a spectral calibration algorithm is executed for reconstruction of the spatial–spectral signatures of the observed scene. System characterization of throughput, resolution, and crosstalk was performed. Preliminary results illustrating changes in oxygen-saturation in an occluded human finger are presented to demonstrate the system’s capabilities.

Snapshot multidimensional photography through active optical mapping

“…Noteworthily, unlike previous passive multidimensional imagers 7,26,27 , our active optical mapper can readily tune the mapping relation tailored for a given application. Also, it allows a flexible switch between direct and compressed measurement upon demands.…”

“…In conventional multidimensional optical imaging systems, the range of applicability of an image mapper is fixed upon being fabricated. For example, image spectrometers use passive image mappers, such as custom-designed mirror facets 7,41 or a bundle of fibres 27 , to separate and redirect the incident image. Ideally, the spatial and spectral sampling rates are solely determined by the pixel resolution of the camera provided a full utilisation of camera pixels.…”

Optimization of wavelength selection for multispectral image acquisition: a case study of atrial ablation lesions

“…More recently, the same group reported using Lenslet array based tunable snapshot imaging spectrometry (LATIS) for high resolution fluorescence imaging with reported resolutions of 200x200 at 27 spectral channels and integration time of less than a second [13]. Other recently reported in-vivo systems include 4D snapshot hyperspectral video-endoscope [41], fiber-based prototype imaging spectrometer for oxygen saturation measurements [14] and Lyot filters based multispectral imagers [42].…”

“…Finding combinations of few spectral bands that are sufficient for lesion identification, would allow for simultaneous acquisition using the latest advances in fast scanning and high spatial resolution non-scanning imaging [13][14][15][16][17]. Overall, our studies offer several unbiased quantitative strategies as to how to limit the number of acquisition wavelengths while recognizing the target tissue with high accuracy.…”

Snapshot Imaging Spectrometer Based on Pixel-Level Filter Array (PFA)

“…Snapshot imaging spectrometers can be mainly classified into two categories—direct imaging and computational imaging [ 14 , 15 , 16 ]. The most typical direct imaging systems include integration-field spectroscopy (IFS) [ 17 , 18 ], the multispectral sagnac interferometer (MSI) [ 19 ], the image mapping spectrometer (IMS) [ 20 , 21 ], and the image replicating imaging spectrometer (IRIS) [ 22 , 23 ]. These systems have the advantage of possessing simple data reconstruction algorithms, which need less computational loads and thus can help to display and analyze spatial and spectral information at high frame rates [ 24 ].…”