5,041 research outputs found
Optical Coherence Spectro-Tomography by all-Optical Depth-Wavelength analysis
Current spectroscopic optical coherence tomography (OCT) methods rely on a
posteriori numerical calculation. We present an alternative for accessing
optically the spectroscopic information in OCT, i.e. without any
post-processing, by using a grating based correlation and a wavelength
demultiplexing system. Conventional A-scan and spectrally resolved A-scan are
directly recorded on the image sensor. Furthermore, due to the grating based
system, no correlation scan is necessary. In the frame of this paper we present
the principle of the system as well as first experimental results
Molecular Contrast Optical Coherence Tomography: A Review
This article reviews the current state of research on the use of molecular contrast agents in optical coherence tomography (OCT) imaging techniques. After a brief discussion of the basic principle of OCT and the importance of incorporating molecular contrast agent usage into this imaging modality, we shall present an overview of the different molecular contrast OCT (MCOCT) methods that have been developed thus far. We will then discuss several important practical issues that define the possible range of contrast agent choice, the design criteria for engineered molecular contrast agent and the implementability of a given MCOCT method for clinical or biological applications. We will conclude by outlining a few areas of pursuit that deserve a greater degree of research and development
Visible spectrum extended-focus optical coherence microscopy for label-free sub-cellular tomography
We present a novel extended-focus optical coherence microscope (OCM)
attaining 0.7 {\mu}m axial and 0.4 {\mu}m lateral resolution maintained over a
depth of 40 {\mu}m, while preserving the advantages of Fourier domain OCM. Our
method uses an ultra-broad spectrum from a super- continuum laser source. As
the spectrum spans from near-infrared to visible wavelengths (240 nm in
bandwidth), we call the method visOCM. The combination of such a broad spectrum
with a high-NA objective creates an almost isotropic 3D submicron resolution.
We analyze the imaging performance of visOCM on microbead samples and
demonstrate its image quality on cell cultures and ex-vivo mouse brain tissue.Comment: 15 pages, 7 figure
Electro-optic dual-comb interferometry over 40-nm bandwidth
Dual-comb interferometry is a measurement technique that uses two laser
frequency combs to retrieve complex spectra in a line-by-line basis. This
technique can be implemented with electro-optic frequency combs, offering
intrinsic mutual coherence, high acquisition speed and flexible repetition-rate
operation. A challenge with the operation of this kind of frequency comb in
dual-comb interferometry is its limited optical bandwidth. Here, we use
coherent spectral broadening and demonstrate electro-optic dual-comb
interferometry over the entire telecommunications C band (200 lines covering ~
40 nm, measured within 10 microseconds at 100 signal-to-noise ratio per
spectral line). These results offer new prospects for electro-optic dual-comb
interferometry as a suitable technology for high-speed broadband metrology, for
example in optical coherence tomography or coherent Raman microscopy
Blur resolved OCT: full-range interferometric synthetic aperture microscopy through dispersion encoding
We present a computational method for full-range interferometric synthetic
aperture microscopy (ISAM) under dispersion encoding. With this, one can
effectively double the depth range of optical coherence tomography (OCT),
whilst dramatically enhancing the spatial resolution away from the focal plane.
To this end, we propose a model-based iterative reconstruction (MBIR) method,
where ISAM is directly considered in an optimization approach, and we make the
discovery that sparsity promoting regularization effectively recovers the
full-range signal. Within this work, we adopt an optimal nonuniform discrete
fast Fourier transform (NUFFT) implementation of ISAM, which is both fast and
numerically stable throughout iterations. We validate our method with several
complex samples, scanned with a commercial SD-OCT system with no hardware
modification. With this, we both demonstrate full-range ISAM imaging, and
significantly outperform combinations of existing methods.Comment: 17 pages, 7 figures. The images have been compressed for arxiv -
please follow DOI for full resolutio
The angular spectrum of the scattering coefficient map reveals subsurface colorectal cancer
Abstract Colorectal cancer diagnosis currently relies on histological detection of endoluminal neoplasia in biopsy specimens. However, clinical visual endoscopy provides no quantitative subsurface cancer information. In this ex vivo study of nine fresh human colon specimens, we report the first use of quantified subsurface scattering coefficient maps acquired by swept-source optical coherence tomography to reveal subsurface abnormities. We generate subsurface scattering coefficient maps with a novel wavelet-based-curve-fitting method that provides significantly improved accuracy. The angular spectra of scattering coefficient maps of normal tissues exhibit a spatial feature distinct from those of abnormal tissues. An angular spectrum index to quantify the differences between the normal and abnormal tissues is derived, and its strength in revealing subsurface cancer in ex vivo samples is statistically analyzed. The study demonstrates that the angular spectrum of the scattering coefficient map can effectively reveal subsurface colorectal cancer and potentially provide a fast and more accurate diagnosis
Optical Phase-Space-Time-Frequency Tomography
We present a new approach for constructing optical phase-space-time-frequency
tomography (OPSTFT) of an optical wave field. This tomography can be measured
by using a novel four-window optical imaging system based on two local
oscillator fields balanced heterodyne detection. The OPSTFT is a Wigner
distribution function of two independent Fourier Transform pairs, i.e.,
phase-space and time-frequency. From its theoretical and experimental aspects,
it can provide information of position, momentum, time and frequency of a
spatial light field with precision beyond the uncertainty principle. We
simulate the OPSTFT for a light field obscured by a wire and a single-line
absorption filter. We believe that the four-window system can provide spatial
and temporal properties of a wave field for quantum image processing and
biophotonics.Comment: 11 pages, 6 figure
Simultaneous dual-band optical coherence tomography for endoscopic applications
published_or_final_versio
Biophotonic Tools in Cell and Tissue Diagnostics.
In order to maintain the rapid advance of biophotonics in the U.S. and enhance our competitiveness worldwide, key measurement tools must be in place. As part of a wide-reaching effort to improve the U.S. technology base, the National Institute of Standards and Technology sponsored a workshop titled "Biophotonic tools for cell and tissue diagnostics." The workshop focused on diagnostic techniques involving the interaction between biological systems and photons. Through invited presentations by industry representatives and panel discussion, near- and far-term measurement needs were evaluated. As a result of this workshop, this document has been prepared on the measurement tools needed for biophotonic cell and tissue diagnostics. This will become a part of the larger measurement road-mapping effort to be presented to the Nation as an assessment of the U.S. Measurement System. The information will be used to highlight measurement needs to the community and to facilitate solutions
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