scholarly journals Towards an extremely high resolution broad-band flat-field spectrometer in the `water window'

2019 ◽  
Vol 26 (4) ◽  
pp. 1058-1068
Author(s):  
Zhuo Li ◽  
Bin Li
Keyword(s):  
High Efficiency ◽  
Optical Design ◽  
Broad Band ◽  
Resolving Power ◽  
High Spectral Resolution ◽  
Optical Aberrations ◽  
Water Window ◽  
Flat Field ◽  
Line Spacing ◽  
Sase Fel

The optical design of a novel spectrometer is presented, combining a cylindrically convex pre-mirror with a cylindrically concave varied-line-spacing grating (both in the meridional) to deliver a resolving power of 100000–200000 in the `water window' (2–5 nm). Most remarkably, the extremely high spectral resolution is achieved for an effective meridional source size of 50 µm (r.m.s.); this property could potentially be applied to diagnose SASE-FEL and well resolve individual single spikes in its radiation spectrum. The overall optical aberrations of the system are well analysed and compensated, providing an excellent flat-field at the detector domain throughout the whole spectral range. Also, a machine-learning scheme – SVM – is introduced to explore and reconstruct the optimal system with high efficiency.

scholarly journals A sagittally confined high-resolution spectrometer in the `water window'

2018 ◽  
Vol 25 (3) ◽  
pp. 738-747 ◽  
Author(s):  
Zhuo Li ◽  
Bin Li
Keyword(s):  
Optical Properties ◽  
High Resolution ◽  
Grazing Incidence ◽  
Source Size ◽  
Resolving Power ◽  
Detector Plane ◽  
Water Window ◽  
Flat Field ◽  
High Resolution Spectrometer ◽  
Resolution Spectrometer

The authors report a novel scheme for a grazing-incidence spectrometer forming an excellent meridional flat field in its detector domain to deliver the desired spectral resolution throughout the full designated spectral range, while reducing the sagittal astigmatism substantially to enhance the spectral intensity. The optical properties of the system are thoroughly investigated and optimized, and the detector plane is fitted well to the meridional or sagittal focal curves. The authors demonstrated that a resolving power of 6000–18000 could be achieved within the `water window' (2–5 nm) for an effective meridional source size of 200 µm (r.m.s.), and it would be further improved to 20000–40000 if the source size was confined to 50 µm (r.m.s.).

Broad-band high-efficiency optoacoustic generation using a novel photonic crystal-metallic structure

2011 ◽  
Author(s):  
Yunbo Guo ◽  
Hyoung Won Baac ◽  
Sung-Liang Chen ◽  
Theodore B. Norris ◽  
L. Jay Guo
Keyword(s):  
Photonic Crystal ◽  
High Efficiency ◽  
Broad Band ◽  
Metallic Structure

scholarly journals Broad-band and high-efficiency polarization converters around 1550 nm based on composite structures

2017 ◽  
Vol 25 (13) ◽  
pp. 14406 ◽  
Author(s):  
Xiong-Jun Shang ◽  
Xiang Zhai ◽  
Jing Yue ◽  
Xin Luo ◽  
Jian-Ping Liu ◽  
...  
Keyword(s):  
Composite Structures ◽  
High Efficiency ◽  
Broad Band ◽  
Polarization Converters

A high resolution multi-turn TOF mass analyzer

2019 ◽  
Vol 34 (36) ◽  
pp. 1942005 ◽  
Author(s):  
Vyacheslav Shchepunov ◽  
Michael Rignall ◽  
Roger Giles ◽  
Ryo Fujita ◽  
Hiroaki Waki ◽  
...  
Keyword(s):  
High Resolution ◽  
Mirror Symmetry ◽  
Rotational Symmetry ◽  
Optical Design ◽  
Resolving Power ◽  
Mass Analyzer ◽  
Rotationally Symmetric ◽  
Mass Resolving Power ◽  
Operational Modes ◽  
Drift Direction

An ion optical design of a high resolution multi-turn time-of-flight mass analyzer (MT-TOF MA) is presented. The analyzer has rotationally symmetric main electrodes with additional mirror symmetry about a mid-plane orthogonal to the axis of symmetry. Rotational symmetry allows a higher density of turns in the azimuthal (drift) direction compared to MT-TOF MAs that are linearly extended in the drift direction. Mirror symmetry about a mid-plane helps to achieve a high spatial isochronicity of the ions’ motion. The analyzer comprises a pair of polar-toroidal sectors S1 and S3, a pair of polar (trans-axial) lenses, and a pair of conical lenses for longitudinal and lateral focusing. A toroidal sector S2 located at the mid-plane of the analyzer has a set of embedded drift focusing segments providing focusing and spatial isochronicity in the drift direction. The ions’ drift in the azimuthal direction can be reversed by using dedicated reversing deflectors. This gives the possibility of several operational modes with different numbers of turns and passes in the drift direction. According to numerical simulations, the mass resolving power of the analyzer ranges from [Formula: see text]40 k (fwhm) at small (typically below ten) numbers of turns to [Formula: see text]450 k (fwhm) at 96 turns.

scholarly journals Broad-band high-resolution rotational spectroscopy for laboratory astrophysics

2019 ◽  
Vol 626 ◽  
pp. A34 ◽  
Author(s):  
J. Cernicharo ◽  
J. D. Gallego ◽  
J. A. López-Pérez ◽  
F. Tercero ◽  
I. Tanarro ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
Accurate Determination ◽  
Broad Band ◽  
Laboratory Astrophysics ◽  
High Spectral Resolution ◽  
Rotational Spectroscopy ◽  
Rotational Spectrum ◽  
Vibrationally Excited ◽  
Radio Receivers ◽  
Cold Plasmas

We present a new experimental set-up devoted to the study of gas phase molecules and processes using broad-band high spectral resolution rotational spectroscopy. A reactor chamber is equipped with radio receivers similar to those used by radio astronomers to search for molecular emission in space. The whole range of the Q (31.5–50 GHz) and W bands (72–116.5 GHz) is available for rotational spectroscopy observations. The receivers are equipped with 16 × 2.5 GHz fast Fourier transform spectrometers with a spectral resolution of 38.14 kHz allowing the simultaneous observation of the complete Q band and one-third of the W band. The whole W band can be observed in three settings in which the Q band is always observed. Species such as CH3CN, OCS, and SO2 are detected, together with many of their isotopologues and vibrationally excited states, in very short observing times. The system permits automatic overnight observations, and integration times as long as 2.4 × 105 s have been reached. The chamber is equipped with a radiofrequency source to produce cold plasmas, and with four ultraviolet lamps to study photochemical processes. Plasmas of CH4, N2, CH3CN, NH3, O2, and H2, among other species, have been generated and the molecular products easily identified by the rotational spectrum, and via mass spectrometry and optical spectroscopy. Finally, the rotational spectrum of the lowest energy conformer of CH3CH2NHCHO (N-ethylformamide), a molecule previously characterized in microwave rotational spectroscopy, has been measured up to 116.5 GHz, allowing the accurate determination of its rotational and distortion constants and its search in space.

Characteristics of the defocused spherical Fabry-Pérot interferometer as a quasi-linear dispersion instrument for high resolution spectroscopy of pulsed laser sources

1968 ◽  
Vol 263 (1140) ◽  
pp. 209-223 ◽  
Keyword(s):  
Laser Beam ◽  
Optical Design ◽  
Pulsed Laser ◽  
Resolving Power ◽  
High Resolution Spectroscopy ◽  
Radius Of Curvature ◽  
Spherical Mirror ◽  
Linear Dispersion ◽  
Fabry Perot ◽  
Very High

Defocused spherical mirror Fabry—Pérot etalons, in which the mirror separation is slightly less than the common radius of curvature, produce a multiple-beam fringe pattern of concentric rings, with quasi-linear spectral dispersion over an appreciable annular region corresponding to two free spectral ranges. The characteristics of these interferograms are discussed in relation to their many advantages for pulsed laser spectroscopy. These advantages include: (i) accuracy of frequency difference measurement; (ii) high illumination of the detector with moderate energy density in the laser beam; (iii) ease of alinement and permanent adjustment of the mirrors leading to the attainment in practice of a very high instrumental finesse (N R values of up to 90 have been achieved); (iv) measurement of degree of spatial coherence of laser beam; (v) ease of matching the interferogram to the spatial resolution of the detector. A simple optical path relation determines the positions of the fringes and the location of the quasilinear dispersion region. The interfering wavefronts, formed by multiple reflexion, have been numerically computed and summed to provide information on the finesse, fringe profiles, contrast and optimum conditions of use of this new, very high resolving power (107 to 108) quasi-linear spectrographic disperser. Constructional details are described and optical design criteria are discussed, together with the various experimental arrangements for employing the instrument. Comparison is made with the equivalent confocal and plane Fabry—Pérot etalons and methods of simultaneously measuring

scholarly journals High efficiency photomodulators for millimeter wave and THz radiation

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
I. R. Hooper ◽  
N. E. Grant ◽  
L. E. Barr ◽  
S. M. Hornett ◽  
J. D. Murphy ◽  
...  
Keyword(s):  
High Efficiency ◽  
Continuous Wave ◽  
Broad Band ◽  
Cost Effective ◽  
Silicon Wafers ◽  
Thz Radiation ◽  
Limiting Factor ◽  
Switching Speed ◽  
Carrier Lifetimes ◽  
Narrow Frequency Band

AbstractPhotomodulators for mm-wave and THz radiation are an essential component for many imaging and signal processing applications. While a myriad of schemes have been devised to enhance photomodulation by enhancing the light-matter interaction, there has been less focus on the photoconductive materials themselves, which are often the limiting factor. Here, we present an approach to increase the photomodulation efficiency of silicon by orders of magnitude, using post treatment of off-the-shelf silicon wafers. The increase in efficiency removes the need for bulky and costly amplified laser sources, and creates the potential for compact and cost-effective modulators for real-world applications. By passivating the surfaces of long bulk-lifetime silicon wafers with Al2O3, the recombination of the photoexcited carriers at the surfaces is mostly eliminated. This results in vastly longer excess carrier lifetimes (up to ~50 ms), with corresponding increases in photoconductivity. The resulting modulators are highly efficient, with the transmission through them being reduced from ~90% to <10% over a narrow frequency band with a continuous wave excitation intensity of just 10 Wm−2, whilst modulation factors of greater than 80% can be achieved over a broad band with similar intensities. We also discuss the limitations of such long-lifetime modulators for applications where the switching speed or spatial resolution of a modulator may be critical.

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