scholarly journals High Resolution Interference Spectroscopy Applied to Astronomical Investigations (2000 to 3000 Å)

1971 ◽  
Vol 41 ◽  
pp. 262-262
Author(s):  
B. Bates
Keyword(s):  
High Resolution ◽  
Time Resolution ◽  
Spectroscopic Studies ◽  
Resolving Power ◽  
Angular Dispersion ◽  
Fabry Perot

For orbiting astronomical telescopes and for spectroscopic studies from rocket and balloon-borne platforms the great angular dispersion of the Fabry-Pérot interferometer should permit easier guidance tolerance for a given spectral resolving power with the added profit of the physical compactness of an etalon spectrometer or spectrograph. In addition, the superiority in luminosity and illumination of the interferometer permits shorter exposures and greater time resolution.

The spherical Fabry—Perot interferometer as an instrument of high resolving power for use with external or with internal atomic beams

1961 ◽  
Vol 263 (1314) ◽  
pp. 289-308 ◽  
Keyword(s):  
High Resolution ◽  
Hyperfine Structure ◽  
Atomic Beam ◽  
Resonance Line ◽  
Resolving Power ◽  
Light Power ◽  
Line Structure ◽  
Fabry Perot ◽  
Atomic Beams ◽  
Very High

The spherical Fabry -Perot interferometer was designed by P. Connes as an instrument capable of realizing higher resolving power than the normal Fabry -Perot interferometer, by virtue of its greater light power at high resolution, and the much lower requirement with regard to accuracy of adjustment. The instrument has now been used successfully in the resolution of structure in the resonance line of the arc spectrum of barium; components with a separation of 2.0x 10 -3 cm -1 have been resolved; they were observed in the absorption produced by a Jackson -Kuhn atomic beam, of high collimation. The instrument has also been used for observing line structure with an absorbing atomic beam traversing the interior of the interferometer; by this means the amount of material required for observing hyperfine structure using an atomic beam , even with very high collimation, can be reduced to a few milligrams, or approximately 100 times less than that required with an atomic beam external to the interferometer, so that enriched isotopes, available in small quantities, can be used; alternatively, adequate absorption can be obtained with much higher collimations of the beam, and correspondingly improved limits of resolution.

scholarly journals Astronomical Performances of the Mepsicron, A New Large Area Imaging Photon Counter

1984 ◽  
Vol 78 ◽  
pp. 177-180
Author(s):  
C. Firmani ◽  
L. Gutiérrez ◽  
E. Ruíz ◽  
L. Salas ◽  
G.F. Bisiacchi ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Resolution ◽  
Photon Counting ◽  
High Time ◽  
High Time Resolution ◽  
Spectroscopic Techniques ◽  
Position Sensor ◽  
Large Area ◽  
Photon Counter ◽  
Fabry Perot

The new detector MEPSICRON (microchannel electron position sensor with time resolution) is an image photomultiplier sensor for high spatial and time resolution, working in a photon counting regime. It has been especially designed for deep sky photometric pictures, for high resolution spectrophotometry with single or crossed dispersion spectrographs for long slit spectroscopic techniques, for high time resolution pictures and spectrophotometry especially related with speckles techniques and very fast varying sources as pulsars, and for Fabry-Pérot interferometry.

scholarly journals Mobile and high spectral resolution Fabry Pérot interferometer spectrographs for atmospheric remote sensing

2021 ◽  
Author(s):  
Jonas Kuhn ◽  
Nicole Bobrowski ◽  
Thomas Wagner ◽  
Ulrich Platt
Keyword(s):  
Remote Sensing ◽  
High Resolution ◽  
Absorption Spectroscopy ◽  
Spectral Resolution ◽  
Trace Gases ◽  
Resolving Power ◽  
Trace Gas ◽  
Oh Radicals ◽  
Fabry Perot ◽  
Atmospheric Trace Gas

Abstract. Grating spectrographs (GS) are presently widely in use for atmospheric trace gas remote sensing in the ultraviolet (UV) and visible spectral range (e.g. differential optical absorption spectroscopy, DOAS). For typical DOAS applications, GSs have a spectral resolution of about half a nm corresponding to a resolving power R (ratio of operating wavelength to spectral resolution) in the range of 1000. This is sufficient to quantify the vibro-electronic spectral structure of the absorption of many trace gases with good accuracy and further allows for mobile (i.e. compact and stable) instrumentation. However, a much higher resolving power (R ≈ 105, i.e. a spectral resolution of about the width of an individual rotational absorption line) would facilitate the measurement of further trace gases (e.g. OH radicals), significantly reduce cross interferences due to other absorption and scattering processes, and provide enhanced sensitivity. Despite of these major advantages, only very few atmospheric studies with high resolution GSs are reported, mostly because increasing the resolving power of a GS leads to largely reduced light throughput and mobility. However, for many environmental studies, light throughput and mobility of measurement equipment are central limiting factors, for instance when absorption spectroscopy is applied to quantify reactive trace gases in remote areas (e.g. volcanoes) or from air borne or space borne platforms. Since more than a century, Fabry Pérot interferometers (FPIs) have been successfully used for high resolution spectroscopy in many scientific fields where they are known for their superior light throughput. However, except for a few studies, FPIs received hardly any attention in atmospheric trace gas remote sensing, despite their advantages. We propose different high resolution FPI spectrograph implementations and compare their light throughput and mobility to GSs with the same resolving power. We find that nowadays mobile high resolution FPI spectrographs can have a more than two orders of magnitude higher light throughput than their immobile high resolution GS counterparts. Compared to moderate resolution GSs (as routinely used for DOAS), a FPI spectrograph reaches a 250 times higher spectral resolution while the signal to noise ratio (SNR) is reduced by only a factor of 10. With a first compact prototype of a high resolution FPI spectrograph (R ≈ 148000, < 8 litres, < 5 kg) we demonstrate that these expectations are realistic. Using mobile and high resolution FPI spectrographs could have a large impact on atmospheric near UV to near IR remote sensing. Applications include the enhancement of sensitivity and selectivity of absorption measurements of many atmospheric trace gases and their isotopes, the direct quantification of OH radicals in the troposphere, high resolution O2 measurements for radiative transfer and aerosol studies and solar induced chlorophyll fluorescence quantification using Fraunhofer lines.

scholarly journals Mobile and high-spectral-resolution Fabry–Pérot interferometer spectrographs for atmospheric remote sensing

2021 ◽  
Vol 14 (12) ◽  
pp. 7873-7892
Author(s):  
Jonas Kuhn ◽  
Nicole Bobrowski ◽  
Thomas Wagner ◽  
Ulrich Platt
Keyword(s):  
Remote Sensing ◽  
High Resolution ◽  
Absorption Spectroscopy ◽  
Spectral Resolution ◽  
Trace Gases ◽  
Resolving Power ◽  
Trace Gas ◽  
Oh Radicals ◽  
Fabry Perot ◽  
Atmospheric Trace Gas

Abstract. Grating spectrographs (GS) are presently widely in use for atmospheric trace gas remote sensing in the ultraviolet (UV) and visible spectral range (e.g. differential optical absorption spectroscopy, DOAS). For typical DOAS applications, GSs have a spectral resolution of about 0.5 nm, corresponding to a resolving power R (ratio of operating wavelength to spectral resolution) of approximately 1000. This is sufficient to quantify the vibro-electronic spectral structure of the absorption of many trace gases with good accuracy and further allows for mobile (i.e. compact and stable) instrumentation. However, a much higher resolving power (R≈105, i.e. a spectral resolution of about the width of an individual rotational absorption line) would facilitate the measurement of further trace gases (e.g. OH radicals), significantly reduce cross interferences due to other absorption and scattering processes, and provide enhanced sensitivity. Despite these major advantages, only very few atmospheric studies with high-resolution GSs are reported, mostly because increasing the resolving power of a GS leads to largely reduced light throughput and mobility. However, for many environmental studies, light throughput and mobility of measurement equipment are central limiting factors, for instance when absorption spectroscopy is applied to quantify reactive trace gases in remote areas (e.g. volcanoes) or from airborne or space-borne platforms. For more than a century, Fabry–Pérot interferometers (FPIs) have been successfully used for high-resolution spectroscopy in many scientific fields where they are known for their superior light throughput. However, except for a few studies, FPIs have hardly received any attention in atmospheric trace gas remote sensing, despite their advantages. We propose different high-resolution FPI spectrograph implementations and compare their light throughput and mobility to GSs with the same resolving power. We find that nowadays mobile high-resolution FPI spectrographs can have a more than 2 orders of magnitude higher light throughput than their immobile high-resolution GS counterparts. Compared with moderate-resolution GSs (as routinely used for DOAS), an FPI spectrograph reaches a 250 times higher spectral resolution while the signal-to-noise ratio (SNR) is reduced by only a factor of 10. Using a first compact prototype of a high-resolution FPI spectrograph (R≈148 000, <8 L, <5 kg), we demonstrate that these expectations are realistic. Using mobile and high-resolution FPI spectrographs could have a large impact on atmospheric near-UV to near-infrared (NIR) remote sensing. Applications include the enhancement of the sensitivity and selectivity of absorption measurements of many atmospheric trace gases and their isotopologues, the direct quantification of OH radicals in the troposphere, high-resolution O2 measurements for radiative transfer and aerosol studies, and solar-induced chlorophyll fluorescence quantification using Fraunhofer lines.

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

An Analysis of Dissociation of Molecules in a High Resolution Electron Microscope

1973 ◽  
Vol 31 ◽  
pp. 486-487
Author(s):  
Mihir Parikh
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Cross Sections ◽  
Resolving Power ◽  
Peak Intensity ◽  
Molecular Film ◽  
Resolution Electron ◽  
Dissociation Cross Section ◽  
High Resolution Electron Microscope ◽  
The Stability

It is well known that the resolution of bio-molecules in a high resolution electron microscope depends not just on the physical resolving power of the instrument, but also on the stability of these molecules under the electron beam. Experimentally, the damage to the bio-molecules is commo ly monitored by the decrease in the intensity of the diffraction pattern, or more quantitatively by the decrease in the peaks of an energy loss spectrum. In the latter case the exposure, EC, to decrease the peak intensity from IO to I’O can be related to the molecular dissociation cross-section, σD, by EC = ℓn(IO /I’O) /ℓD. Qu ntitative data on damage cross-sections are just being reported, However, the microscopist needs to know the explicit dependence of damage on: (1) the molecular properties, (2) the density and characteristics of the molecular film and that of the support film, if any, (3) the temperature of the molecular film and (4) certain characteristics of the electron microscope used

Practical High Resolution Microscopy

1968 ◽  
Vol 26 ◽  
pp. 302-303
Author(s):  
P. A. Marsh ◽  
T. Mullens ◽  
D. Price
Keyword(s):  
High Resolution ◽  
Magnetic Fields ◽  
Low Frequency ◽  
Resolving Power ◽  
Careful Attention ◽  
Electron Microscopes ◽  
The Relationship ◽  
High Resolution Microscopy ◽  
New Facilities

It is possible to exceed the guaranteed resolution on most electron microscopes by careful attention to microscope parameters essential for high resolution work. While our experience is related to a Philips EM-200, we hope that some of these comments will apply to all electron microscopes.The first considerations are vibration and magnetic fields. These are usually measured at the pre-installation survey and must be within specifications. It has been our experience, however, that these factors can be greatly influenced by the new facilities and therefore must be rechecked after the installation is completed. The relationship between the resolving power of an EM-200 and the maximum tolerable low frequency interference fields in milli-Oerstedt is 10 Å - 1.9, 8 Å - 1.4, 6 Å - 0.8.

A Super-High-Resolution HVEM (H-1500) Newly Installed in NIRIM

1990 ◽  
Vol 48 (1) ◽  
pp. 142-143
Author(s):  
S. Horiuchi ◽  
Y. Matsui
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Chromatic Aberration ◽  
Inorganic Materials ◽  
Electron Gun ◽  
Resolving Power ◽  
National Budget ◽  
Voltage Electron ◽  
Specimen Holder ◽  
The Magnetic Field

A new high-voltage electron microscope (H-1500) specially aiming at super-high-resolution (1.0 Å point-to-point resolution) is now installed in National Institute for Research in Inorganic Materials ( NIRIM ), in collaboration with Hitachi Ltd. The national budget of about 1 billion yen including that for a new building has been spent for the construction in the last two years (1988-1989). Here we introduce some essential characteristics of the microscope.(1) According to the analysis on the magnetic field in an electron lens, based on the finite-element-method, the spherical as well as chromatic aberration coefficients ( Cs and Cc ). which enables us to reach the resolving power of 1.0Å. have been estimated as a function of the accelerating As a result of the calculaton. it was noted that more than 1250 kV is needed even when we apply the highest level of the technology and materials available at present. On the other hand, we must consider the protection against the leakage of X-ray. We have then decided to set the conventional accelerating voltage at 1300 kV. However. the maximum accessible voltage is 1500 kV, which is practically important to realize higher voltage stabillity. At 1300 kV it is expected that Cs= 1.7 mm and Cc=3.4 mm with the attachment of the specimen holder, which tilts bi-axially in an angle of 35° ( Fig.1 ). In order to minimize the value of Cc a small tank is additionally placed inside the generator tank, which must serve to seal the magnetic field around the acceleration tube. An electron gun with LaB6 tip is used.

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