Near-common-path interferometer for imaging Fourier-transform spectroscopy in wide-field microscopy

Abstract

Imaging Fourier-transform spectroscopy (IFTS) is a powerful method for biological hyperspectral analysis based on various imaging modalities, such as fluorescence or Raman. Since the measurements are taken in the Fourier space of the spectrum, it can also take advantage of compressed sensing strategies. IFTS has been readily implemented in high-throughput, high-content microscope systems based on wide-field imaging modalities. However, there are limitations in existing wide-field IFTS designs. Non-common-path approaches are less phase-stable. Alternatively, designs based on the common-path Sagnac interferometer are stable, but incompatible with high-throughput imaging. They require exhaustive sequential scanning over large interferometric path delays, making compressive strategic data acquisition impossible. In this paper, we present a novel phase-stable, near-common-path interferometer enabling high-throughput hyperspectral imaging based on strategic data acquisition. Our results suggest that this approach can improve throughput over those of many other wide-field spectral techniques by more than an order of magnitude without compromising phase stability.

Phasor-based hyperspectral snapshot microscopy allows fast imaging of live, three-dimensional tissues for biomedical applications

“…Snapshot methods (Fig. 1c ) such as image mapping 10 or spectral decoding 11 can acquire hyperspectral images without scanning, but image remapping/decoding compromises spatial and/or spectral resolution, is computationally demanding, and devices are often associated with high manufacturing cost. In contrast, our approach uses a pair of filters with sine/cosine transmission spectra in the desired detection range (here 400–700 nm) for direct, in-hardware transformation of the spectral information to frequency space (phasor space) (Supplementary Fig.…”

“…While working well, such scanning approaches are generally time consuming and reduce light throughput. Snapshot methods have been developed to overcome these limitations, for example, using image mapping 10 or Fourier transform-based spectral decoding 11 , 12 . Despite being much faster, these methods are limited in spatial and/or spectral resolution, are computationally demanding, and devices are very expensive to manufacture.…”

Optical elastography and tissue biomechanics

“…Peter T. C. So, from Massachusetts Institute of Technology (MIT), USA, presented his recent result on applications of interferometric imaging for quantitative assessment of biomechanical properties of cells and tissues. 4 Interferometric measurements offer high-precision measurements 5 that can be combined with the wide-field illumination measurements 6 for precise, noninvasive measurements of cellular structures and their dynamics. In particular, biomechanical markers of sickle red blood cells can be analyzed on a fly in a cytometric setting.…”

Deep-learning-assisted Fourier transform imaging spectroscopy for hyperspectral fluorescence imaging

“…Typically, more than 1000 images are acquired, which can take tens of seconds even with a high-speed camera. Several efforts have been made to reduce the sampling number with methods such as compressed sensing 12 . Since the interferogram measurements of FTIS are taken in the Fourier space, the signal measurement procedure for FTIS satisfies the incoherence property which is a requirement of compressed sensing 13 , 14 .…”