4,884 research outputs found
FIMic: design for ultimate 3D-integral microscopy of in-vivo biological samples
In this work, Fourier integral microscope (FIMic), an ultimate design of 3D-integral microscopy, is presented. By placing a multiplexing microlens array at the aperture stop of the microscope objective of the host microscope, FIMic shows extended depth of field and enhanced lateral resolution in comparison with regular integral microscopy. As FIMic directly produces a set of orthographic views of the 3D-micrometer-sized sample, it is suitable for real-time imaging. Following regular integral-imaging reconstruction algorithms, a 2.75-fold enhanced depth of field and â2-time better spatial resolution in comparison with conventional integral microscopy is reported. Our claims are supported by theoretical analysis and experimental images of a resolution test target, cotton fibers, and in-vivo 3D-imaging of biological specimens
Non-paraxial design and fabrication of a compact OAM sorter in the telecom infrared
A novel optical device is designed and fabricated in order to overcome the
limits of the traditional sorter based on log-pol optical transformation for
the demultiplexing of optical beams carrying orbital angular momentum (OAM).
The proposed configuration simplifies the alignment procedure and significantly
improves the compactness and miniaturization level of the optical architecture.
Since the device requires to operate beyond the paraxial approximation, a
rigorous formulation of transformation optics in the non-paraxial regime has
been developed and applied. The sample has been fabricated as 256-level
phase-only diffractive optics with high-resolution electron-beam lithography,
and tested for the demultiplexing of OAM beams at the telecom wavelength of
1310 nm. The designed sorter can find promising applications in next-generation
optical platforms for mode-division multiplexing based on OAM modes both for
free-space and multi-mode fiber transmission.Comment: 12 pages, 8 figure
Volume Holographic Hyperspectral Imaging
A volume hologram has two degenerate Bragg-phase-matching dimensions and provides the capability of volume holographic imaging. We demonstrate two volume holographic imaging architectures and investigate their imaging resolution, aberration, and sensitivity. The first architecture uses the hologram directly as an objective imaging element where strong aberration is observed and confirmed by simulation. The second architecture uses an imaging lens and a transmission geometry hologram to achieve linear two-dimensional optical sectioning and imaging of a four-dimensional (spatial plus spectral dimensions) object hyperspace. Multiplexed holograms can achieve simultaneously three-dimensional imaging of an object without a scanning mechanism
Multiplication and division of the orbital angular momentum of light with diffractive transformation optics
We present a method to efficiently multiply or divide the orbital angular
momentum (OAM) of light beams using a sequence of two optical elements. The
key-element is represented by an optical transformation mapping the azimuthal
phase gradient of the input OAM beam onto a circular sector. By combining
multiple circular-sector transformations into a single optical element, it is
possible to perform the multiplication of the value of the input OAM state by
splitting and mapping the phase onto complementary circular sectors.
Conversely, by combining multiple inverse transformations, the division of the
initial OAM value is achievable, by mapping distinct complementary circular
sectors of the input beam into an equal number of circular phase gradients. The
optical elements have been fabricated in the form of phase-only diffractive
optics with high-resolution electron-beam lithography. Optical tests confirm
the capability of the multiplier optics to perform integer multiplication of
the input OAM, while the designed dividers are demonstrated to correctly split
up the input beam into a complementary set of OAM beams. These elements can
find applications for the multiplicative generation of higher-order OAM modes,
optical information processing based on OAM-beams transmission, and optical
routing/switching in telecom.Comment: 28 pages, 10 figure
Compressive Holographic Video
Compressed sensing has been discussed separately in spatial and temporal
domains. Compressive holography has been introduced as a method that allows 3D
tomographic reconstruction at different depths from a single 2D image. Coded
exposure is a temporal compressed sensing method for high speed video
acquisition. In this work, we combine compressive holography and coded exposure
techniques and extend the discussion to 4D reconstruction in space and time
from one coded captured image. In our prototype, digital in-line holography was
used for imaging macroscopic, fast moving objects. The pixel-wise temporal
modulation was implemented by a digital micromirror device. In this paper we
demonstrate temporal super resolution with multiple depths recovery
from a single image. Two examples are presented for the purpose of recording
subtle vibrations and tracking small particles within 5 ms.Comment: 12 pages, 6 figure
Near-field THz imaging and spectroscopy using a multiple subwavelength aperture modulator
We present a near-field, simultaneous multiple pixel subwavelength THz transmission imaging device based on a solid-state THz spatial modulator. Frequency-division multiplexing is used to acquire multiple pixels simultaneously. The modulator was used to acquire THz transmission images with resolution of λ/4 at 118 ”m. The image acquisition speed is 16 times greater than that of a comparable single-aperture subwavelength imaging technique. Additionally, spectroscopic THz imaging with subwavelength spatial resolution can be accomplished with the modulator, and the technique is scalable to at least 100 simultaneous pixels
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