532,184 research outputs found
A digital microarray using interferometric detection of plasmonic nanorod labels
DNA and protein microarrays are a high-throughput technology that allow the
simultaneous quantification of tens of thousands of different biomolecular
species. The mediocre sensitivity and dynamic range of traditional fluorescence
microarrays compared to other techniques have been the technology's Achilles'
Heel, and prevented their adoption for many biomedical and clinical diagnostic
applications. Previous work to enhance the sensitivity of microarray readout to
the single-molecule ('digital') regime have either required signal amplifying
chemistry or sacrificed throughput, nixing the platform's primary advantages.
Here, we report the development of a digital microarray which extends both the
sensitivity and dynamic range of microarrays by about three orders of
magnitude. This technique uses functionalized gold nanorods as single-molecule
labels and an interferometric scanner which can rapidly enumerate individual
nanorods by imaging them with a 10x objective lens. This approach does not
require any chemical enhancement such as silver deposition, and scans arrays
with a throughput similar to commercial fluorescence devices. By combining
single-nanoparticle enumeration and ensemble measurements of spots when the
particles are very dense, this system achieves a dynamic range of about one
million directly from a single scan
High resolution imaging with Fresnel interferometric arrays: suitability for exoplanet detection
We propose a new kind of interferometric array that yields images of high
dynamic range and large field. The numerous individual apertures in this array
form a pattern related to a Fresnel zone plate. This array can be used for
astrophysical imaging over a broad spectral bandwidth spanning from the U.V.
(50 nanometers) to the I.R. (20 microns). Due to the long focal lengths
involved, this instrument requires formation-flying of two space borne vessels.
We present the concept and study the S/N ratio in different situations, then
apply these results to probe the suitability of this concept to detect
exoplanets.Comment: 12 pages, 19 figures, to be published in A&
A digital microarray using interferometric detection of plasmonic nanorod labels
DNA and protein microarrays are a high-throughput technology that allow the simultaneous quantification of tens of thousands of different biomolecular species. The mediocre sensitivity and dynamic range of traditional fluorescence microarrays compared to other techniques have been the technology's Achilles' Heel, and prevented their adoption for many biomedical and clinical diagnostic applications. Previous work to enhance the sensitivity of microarray readout to the single-molecule ('digital') regime have either required signal amplifying chemistry or sacrificed throughput, nixing the platform's primary advantages. Here, we report the development of a digital microarray which extends both the sensitivity and dynamic range of microarrays by about three orders of magnitude. This technique uses functionalized gold nanorods as single-molecule labels and an interferometric scanner which can rapidly enumerate individual nanorods by imaging them with a 10x objective lens. This approach does not require any chemical enhancement such as silver deposition, and scans arrays with a throughput similar to commercial fluorescence devices. By combining single-nanoparticle enumeration and ensemble measurements of spots when the particles are very dense, this system achieves a dynamic range of about one million directly from a single scan.First author draf
Fresnel Interferometric Imager: ground-based prototype
The Fresnel Interferometric Imager is a space-based astronomical telescope
project yielding milli-arc second angular resolution and high contrast images
with loose manufacturing constraints. This optical concept involves diffractive
focusing and formation flying: a first "primary optics" space module holds a
large binary Fresnel Array, and a second "focal module" holds optical elements
and focal instruments that allow for chromatic dispersion correction.
We have designed a reduced-size Fresnel Interferometric Imager prototype and
made optical tests in our lab, in order to validate the concept for future
space missions. The Primary module of this prototype consists of a square, 8 cm
side, 23 m focal length Fresnel array. The focal module is composed of a
diaphragmed small telescope used as "field lens", a small cophased diverging
Fresnel Zone Lens (FZL) that cancels the dispersion and a detector. An
additional module collimates the artificial targets of various shapes, sizes
and dynamic ranges to be imaged.
In this paper, we describe the experimental setup, different designs of the
primary Fresnel array, and the cophased Fresnel Zone Lens that achieves
rigorous chromatic correction. We give quantitative measurements of the
diffraction limited performances and dynamic range on double sources. The tests
have been performed in the visible domain, lambda = 400 - 700 nm.
In addition, we present computer simulations of the prototype optics based on
Fresnel propagation, that corroborate the optical tests. This numerical tool
has been used to simulate the large aperture Fresnel arrays that could be sent
to space with diameters of 3 to 30 m, foreseen to operate from Lyman-alpha (121
nm) to mid I.R. (25 microns).Comment: 10 pages, 13 figures; accepted for publication in Applied Optic
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
Wind dynamic range video camera
A television camera apparatus is disclosed in which bright objects are attenuated to fit within the dynamic range of the system, while dim objects are not. The apparatus receives linearly polarized light from an object scene, the light being passed by a beam splitter and focused on the output plane of a liquid crystal light valve. The light valve is oriented such that, with no excitation from the cathode ray tube, all light is rotated 90 deg and focused on the input plane of the video sensor. The light is then converted to an electrical signal, which is amplified and used to excite the CRT. The resulting image is collected and focused by a lens onto the light valve which rotates the polarization vector of the light to an extent proportional to the light intensity from the CRT. The overall effect is to selectively attenuate the image pattern focused on the sensor
Full field image ranger hardware
We describe the hardware designed to implement a full field heterodyning imaging system. Comprising three key components - a light source, high speed shutter and a signal generator - the system is expected to be capable of simultaneous range measurements to millimetre precision over the entire field of view. Current modulated laser diodes provide the required illumination, with a bandwidth of 100 MHz and peak output power exceeding 600 mW. The high speed shutter action is performed by gating the cathode of an image intensifier, driven by a 50 Vpp waveform with 3.5 ns rise and fall times. A direct digital synthesiser, with multiple synchronised channels, provides high stability between its outputs, 160 MHz bandwidth and tuning of 0.1 Hz
Digital microarrays: single-molecule readout with interferometric detection of plasmonic nanorod labels
DNA and protein microarrays are a high-throughput technology that allow the simultaneous quantification of tens of thousands of different biomolecular species. The mediocre sensitivity and limited dynamic range of traditional fluorescence microarrays compared to other detection techniques have been the technologyâs Achillesâ heel and prevented their adoption for many biomedical and clinical diagnostic applications. Previous work to enhance the sensitivity of microarray readout to the single-molecule (âdigitalâ) regime have either required signal amplifying chemistry or sacrificed throughput, nixing the platformâs primary advantages. Here, we report the development of a digital microarray which extends both the sensitivity and dynamic range of microarrays by about 3 orders of magnitude. This technique uses functionalized gold nanorods as single-molecule labels and an interferometric scanner which can rapidly enumerate individual nanorods by imaging them with a 10Ă objective lens. This approach does not require any chemical signal enhancement such as silver deposition and scans arrays with a throughput similar to commercial fluorescence scanners. By combining single-nanoparticle enumeration and ensemble measurements of spots when the particles are very dense, this system achieves a dynamic range of about 6 orders of magnitude directly from a single scan. As a proof-of-concept digital protein microarray assay, we demonstrated detection of hepatitis B virus surface antigen in buffer with a limit of detection of 3.2 pg/mL. More broadly, the techniqueâs simplicity and high-throughput nature make digital microarrays a flexible platform technology with a wide range of potential applications in biomedical research and clinical diagnostics.The authors wish to thank Oguzhan Avci and Jacob Trueb for thoughtful comments and suggestions regarding numerical optimization of the optical system. This work was funded in part by a research contract with ASELSAN, Inc. and the Wallace H. Coulter Foundation 2010 Coulter Translational Award. (ASELSAN, Inc.; Wallace H. Coulter Foundation Coulter Translational Award)Accepted manuscrip
Three-dimensional measurements with a novel technique combination of confocal and focus variation with a simultaneous scan
The most common optical measurement technologies used today for the three dimensional measurement of technical surfaces are Coherence Scanning Interferometry (CSI), Imaging Confocal Microscopy (IC), and Focus Variation (FV). Each one has its benefits and its drawbacks. FV will be the ideal technology for the measurement of those regions where the slopes are high and where the surface is very rough, while CSI and IC will provide better results for smoother and flatter surface regions. In this work we investigated the benefits and drawbacks of combining Interferometry, Confocal and focus variation to get better measurement of technical surfaces. We investigated a way of using Microdisplay Scanning type of Confocal Microscope to acquire on a simultaneous scan confocal and focus Variation information to reconstruct a three dimensional measurement. Several methods are presented to fuse the optical sectioning properties of both techniques as well as the topographical information. This work shows the benefit of this combination technique on several industrial samples where neither confocal nor focus variation is able to provide optimal results.Postprint (author's final draft
Bits from Photons: Oversampled Image Acquisition Using Binary Poisson Statistics
We study a new image sensor that is reminiscent of traditional photographic
film. Each pixel in the sensor has a binary response, giving only a one-bit
quantized measurement of the local light intensity. To analyze its performance,
we formulate the oversampled binary sensing scheme as a parameter estimation
problem based on quantized Poisson statistics. We show that, with a
single-photon quantization threshold and large oversampling factors, the
Cram\'er-Rao lower bound (CRLB) of the estimation variance approaches that of
an ideal unquantized sensor, that is, as if there were no quantization in the
sensor measurements. Furthermore, the CRLB is shown to be asymptotically
achievable by the maximum likelihood estimator (MLE). By showing that the
log-likelihood function of our problem is concave, we guarantee the global
optimality of iterative algorithms in finding the MLE. Numerical results on
both synthetic data and images taken by a prototype sensor verify our
theoretical analysis and demonstrate the effectiveness of our image
reconstruction algorithm. They also suggest the potential application of the
oversampled binary sensing scheme in high dynamic range photography
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