31,439 research outputs found
Solid immersion lens at the aplanatic condition for enhancing the spectral bandwidth of a waveguide grating coupler
We report a technique to substantially boost the spectral
bandwidth of a conventional waveguide grating coupler by using a solid immersion cylindrical lens at the aplanatic condition to create a highly anamorphic beam and reach a much larger numerical aperture, thus enhancing the spectral bandwidth of a free-space propagating optical beam coupled into a single-mode planar integrated optical waveguide
(IOW). Our experimental results show that the broadband IOW spectrometer thus created almost doubles (94% enhancement) the coupled spectral bandwidth of a conventional configuration. To exemplify the benefits made possible by the developed approach, we applied the technique to
the broadband spectroscopic characterization of a protein submonolayer; our experimental data confirm the enhanced spectral bandwidth (around 380–nm) and illustrate the potentials of the developed technology. Besides
the enhanced bandwidth, the broadband coupler of the single-mode IOW spectrometer described here is more robust and user-friendly than those previously reported in the literature and is expected to have an important
impact on spectroscopic studies of surface-adsorbed molecular layers and surface phenomena
CHIRON - A Fiber Fed Spectrometer for Precise Radial Velocities
The CHIRON optical high-resolution echelle spectrometer was commissioned at
the 1.5m telescope at CTIO in 2011. The instrument was designed for high
throughput and stability, with the goal of monitoring radial velocities of
bright stars with high precision and high cadence for the discovery of low-mass
exoplanets. Spectral resolution of R=79,000 is attained when using a slicer
with a total (including telescope and detector) efficiency of 6% or higher,
while a resolution of R=136,000 is available for bright stars. A fixed spectral
range of 415 to 880 nm is covered. The echelle grating is housed in a vacuum
enclosure and the instrument temperature is stabilized to +-0.2deg. Stable
illumination is provided by an octagonal multimode fiber with excellent
light-scrambling properties. An iodine cell is used for wavelength calibration.
We describe the main optics, fiber feed, detector, exposure-meter, and other
aspects of the instrument, as well as the observing procedure and data
reduction.Comment: 15 pages, 10 figures. Accepted by PAS
A multi-object spectral imaging instrument
We have developed a snapshot spectral imaging system which fits onto the side camera port of a commercial inverted microscope. The system provides spectra, in real time, from multiple points randomly selected on the microscope image. Light from the selected points in the sample is directed from the side port imaging arm using a digital micromirror device to a spectrometer arm based on a dispersing prism and CCD camera. A multi-line laser source is used to calibrate the pixel positions on the CCD for wavelength. A CMOS camera on the front port of the microscope allows the full image of the sample to be displayed and can also be used for particle tracking, providing spectra of multiple particles moving in the sample. We demonstrate the system by recording the spectra of multiple fluorescent beads in aqueous solution and from multiple points along a microscope sample channel containing a mixture of red and blue dye
The Visible and Near Infrared module of EChO
The Visible and Near Infrared (VNIR) is one of the modules of EChO, the
Exoplanets Characterization Observatory proposed to ESA for an M-class mission.
EChO is aimed to observe planets while transiting by their suns. Then the
instrument had to be designed to assure a high efficiency over the whole
spectral range. In fact, it has to be able to observe stars with an apparent
magnitude Mv= 9-12 and to see contrasts of the order of 10-4 - 10-5 necessary
to reveal the characteristics of the atmospheres of the exoplanets under
investigation. VNIR is a spectrometer in a cross-dispersed configuration,
covering the 0.4-2.5 micron spectral range with a resolving power of about 330
and a field of view of 2 arcsec. It is functionally split into two channels
respectively working in the 0.4-1 and 1.0-2.5 micron spectral ranges. Such a
solution is imposed by the fact the light at short wavelengths has to be shared
with the EChO Fine Guiding System (FGS) devoted to the pointing of the stars
under observation. The spectrometer makes use of a HgCdTe detector of 512 by
512 pixels, 18 micron pitch and working at a temperature of 45K as the entire
VNIR optical bench. The instrument has been interfaced to the telescope optics
by two optical fibers, one per channel, to assure an easier coupling and an
easier colocation of the instrument inside the EChO optical bench.Comment: 26 page
Photoelectric energy spectrometer Patent
Spectrometer using photoelectric effect to obtain spectral dat
A non-destructive analytic tool for nanostructured materials : Raman and photoluminescence spectroscopy
Modern materials science requires efficient processing and characterization
techniques for low dimensional systems. Raman spectroscopy is an important
non-destructive tool, which provides enormous information on these materials.
This understanding is not only interesting in its own right from a physicist's
point of view, but can also be of considerable importance in optoelectronics
and device applications of these materials in nanotechnology. The commercial
Raman spectrometers are quite expensive. In this article, we have presented a
relatively less expensive set-up with home-built collection optics attachment.
The details of the instrumentation have been described. Studies on four classes
of nanostructures - Ge nanoparticles, porous silicon (nanowire), carbon
nanotubes and 2D InGaAs quantum layers, demonstrate that this unit can be of
use in teaching and research on nanomaterials.Comment: 32 pages, 13 figure
Photoluminescence and attenuation of spray-pyrolysis-deposited erbium-doped Y2O3 planar optical waveguides
Erbium-doped Y20 3 planar optical waveguides have been fabricated by spray-pyrolysis deposition. The attenuation spectrum of the waveguide shows peaks that are due to absorption of the erbium ions. The as-deposited layers also show photoluminescence sharply peaking at 1540 nm with additional Stark splitting. The thin layers of Er 3:Y 203 obtained are promising for the realization of integrated-optic amplifiers and lasers
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