中国科学院机构知识库网格系统: 检索

宽温紧凑型全量程激光甲烷传感探头设计 期刊论文 OAI收割
光子学报, 2020, 卷号: 49
作者: 庞涛; 孙鹏帅; 张志荣; 吴边; 夏滑

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Tunable semiconductor laser absorption spectrum Second harmonic Direct absorption Temperature compensation Full-range laser methane sensor 可调谐半导体激光吸收光谱二次谐波直接吸收温度补偿全量程激光甲烷传感器

Constraining the X-Ray-Infrared Spectral Index of Second-timescale Flares from SGR 1935+2154 with Palomar Gattini-IR 期刊论文 OAI收割
The Astrophysical Journal, 2020, 卷号: 901, 页码: L7
作者: HXMT

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收藏 | 浏览/下载：29/0 | 提交时间：2022/02/08

Radio transient sources Magnetars Soft gamma-ray repeaters 2008 992 1471 Astrophysics - High Energy Astrophysical Phenomena Astrophysics - Instrumentation and Methods for Astrophysics Abstract: The Galactic magnetar SGR 1935+2154 has been reported to produce the first example of a bright millisecond-duration radio burst (FRB 200428) similar to the cosmological population of fast radio bursts (FRBs). The detection of a coincident bright X-ray burst represents the first observed multiwavelength counterpart of an FRB. However, the search for similar emission at optical wavelengths has been hampered by the high inferred extinction on the line of sight. Here, we present results from the first search for second-timescale emission from the source at near-infrared (NIR) wavelengths using the Palomar Gattini-IR observing system in the J band, enabled by a novel detector readout mode that allows short exposure times of ?0.84 s with 99.9% observing efficiency. With a total observing time of ?12 hr (?47,728 images) during its 2020 outburst, we place median 3Ҡlimits on the second-timescale NIR fluence of ?18 Jy ms (13.1 AB mag). The corresponding extinction-corrected limit is ?125 Jy ms for an estimated extinction of A_J = 2.0 mag. Our observations were sensitive enough to easily detect an NIR counterpart of FRB 200428 if the NIR emission falls on the same power law as observed across its radio to X-ray spectrum. We report nondetection limits from epochs of four simultaneous X-ray bursts detected by the Insight-HXMT and NuSTAR telescopes during our observations. These limits provide the most stringent constraints to date on fluence of flares at 10¹⁴ Hz, and constrain the fluence ratio of the NIR emission to coincident X-ray bursts to R_NIR ? 0.025 (fluence index ?0.35).

An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242 期刊论文 OAI收割
Astronomy and Astrophysics, 2020, 卷号: 641, 页码: A101
作者: HXMT

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accretion accretion disks black hole physics X-rays: binaries time Astrophysics - High Energy Astrophysical Phenomena Abstract:
Aims: Flip-flops are top-hat-like X-ray flux variations, which have been observed in some transient accreting black hole binary systems, and feature simultaneous changes in the spectral hardness and the power density spectrum (PDS). They occur at a crucial time in the evolution of these systems, when the accretion disc emission starts to dominate over coronal emission. Flip-flops remain a poorly understood phenomenon, so we aim to thoroughly investigate them in a system featuring several such transitions.
Methods: Within the multitude of observations of Swift J1658.2-4242 during its outburst in early 2018, we detected 15 flip-flops, enabling a detailed analysis of their individual properties and the differences between them. We present observations by XMM-Newton, NuSTAR, Astrosat, Swift, Insight-HXMT, INTEGRAL, and ATCA. We analysed their light curves, searched for periodicities, computed their PDSs, and fitted their X-ray spectra, to investigate the source behaviour during flip-flop transitions and how the interval featuring flip-flops differs from the rest of the outburst.
Results: The flip-flops of Swift J1658.2-4242 are of an extreme variety, exhibiting flux differences of up to 77% within 100 s, which is much larger than what has been seen previously. We observed radical changes in the PDS simultaneous with the sharp flux variations, featuring transitions between the quasi-periodic oscillation types C and A, which have never been observed before. Changes in the PDS are delayed, but more rapid than changes in the light curve. Flip-flops occur in two intervals within the outburst, separated by about two weeks in which these phenomena were not seen. Transitions between the two flip-flop states occurred at random integer multiples of a fundamental period of 2.761 ks in the first interval and 2.61 ks in the second. Spectral analysis reveals the high and low flux flip-flop states to be very similar, but distinct from intervals lacking flip-flops. A change of the inner temperature of the accretion disc is responsible for most of the flux difference in the flip-flops. We also highlight the importance of correcting for the influence of the dust scattering halo on the X-ray spectra.

Measurement of the second-order spectral diffraction efficiency of polarized dual-grating spectrometers 期刊论文 OAI收割
Optik, 2019, 卷号: 180, 页码: 355-360
作者: H.S.Li; B.Li; S.R.Wang; X.H.Yang; Z.F.Li

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Diffraction efficiency,Second-order spectrum,Polarized light,Dual-grating spectrometer,suppression,Optics

Athermal design of refractive/diffractive hybrid infrared optical system 期刊论文 OAI收割
optik, 2017, 卷号: 131, 页码: 592-597
作者: Jiang, Yanru; Wang, Jing; Xie, Qingkun; Zhang, Wenfei; Qu, Enshi

收藏 | 浏览/下载：104/0 | 提交时间：2016/12/21

Athermal design Refractive/diffractive hybrid system Chromatic correction Second spectrum

A sensitive solid-phase time-resolved fluorescence immunoassay apparatus (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2009: Laser Sensing and Imaging, June 17, 2009 - June 19, 2009, Beijing, China
作者: Song K.-F.; Li J.-L.; Zhang W.-L.; Wang Y.-L.

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In the device a He-Ne laser of flash frequency 1-20 Hz was adopted as exciting light source and three key technical problems have been solved successfully in order to enhance the detecting sensitivity and measuring stability of the device for time-resolved fluorimmunoassays(TRFIA) [1]. The first one is to design optimum exciting optical system so that the exciting light beam excite the sample most effectively. The second one is to have a project spectrum filter which can reduce the affection of the background light to the photomultiplier tube and also ensure influence of the stray light and mixed diffusion light to the sample fluorescence to the least the sample fluorescence through the integrating sphere and come to the grating monochromator The right wavelength will be chosed through changing the angle of incidence of the grating monochromator. The third one is to simulate the principle of sample averaging of BOXCAR averager. In the device SCM was used as primary controller and CPLD was used as timing controller. Through the preparation process signal-to-noise ratio(SNR) will be improved also adjust delay time ampling frequency and sampling number arbitrarily. By testing the sensitivity is 10-12mol/L(substance marked by Eu3+) examination repeat is &le2.5% examination linearity is from 10 -8mol/L to 10-12mol/L correlation coefficient is 99.98%(p&le0.01). The instrument is advanced for ultrasensitive detection of antigen and antibody and solve the tumor genetic variation the virus protein detection. 2009 SPIE.

Tunable ultraviolet laser source from a frequency doubled alexandrite laser (EI CONFERENCE) 会议论文 OAI收割
Optoelectronic Materials and Devices II, November 2, 2007 - November 5, 2007, Wuhan, China
Shuhang L.; Jingjiao L.; Lijun W.

收藏 | 浏览/下载：34/0 | 提交时间：2013/03/25

A tunable ultraviolet laser source in the spectrum range of 0.36-0.388 m was obtained as second harmonics from a frequency doubled Alexandrite laser whose output covers the wave range over 0.72-0.78 m. A LBO crystal was used as frequency doubling crystal. The phase mateching angle in the wide spectrum range of the crystal was calculated and the crystal was cut in the way that the normal incidence at the center wavelength of the fundamental wave at the crystal. The output spectrum line was measured and the highest second harmonics conversion efficiency reached 1.2% from long pulse fundamental wave at the center wavelength.

A novel method of calculation-separating second order spectrum in grating spectrometers (EI CONFERENCE) 会议论文 OAI收割
ICO20: Optical Devices and Instruments, August 21, 2005 - August 26, 2005, Changchun, China
作者: Xiang Y.

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In grating spectrometers according to wavelength short-wave second-order spectrum superimposes on long-wave spectrum with the wavelength twice as long as the short-wave. Usually spectrum of long-wave range is got via preventing the superimposition of short-wave second-order spectrum by cut-off filters. This paper analyses the characteristic of the ratio of short-wave second-order spectrum in long-wave superimposing spectral range to first-order spectrum in short-wave free spectral range of diffraction gratings. The paper studies a novel method of obtaining long-wave spectrum via calculation-separating short-wave second-order spectrum from mixed spectra in long-wave superimposing spectral range by data processing with the spectrum of free spectral range and the ratio (instrumental parameter) of short-wave second-order spectrum to first-order spectrum measured beforehand. Spectrum-measurement experiments were carried out by VIS-NIR spectrometers (0.36 - 1.0m). That the spectrum data got via calculation-separation coincide with those got via cut-off filter indicates that spectrum can be obtained by processing the measured date without filters in whole operating wavelength.

Statistical Distribution of Depth-Integrated Local Horizontal Momentum for Second-Order Random Ocean Waves in Finite Water Depth 期刊论文 OAI收割
China Ocean Engineering, 2004, 期号: 03, 页码: 49-57
作者: Song JB(宋金宝)

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statistical distribution depth-integrated local momentum second-order random waves water depth wave-number spectrum

Statistical Distribution of Depth-Integrated Local Horizontal Momentum for Second-Order Random Ocean Waves in Finite Water Depth CNKI期刊论文 OAI收割
2004
作者: Song JB(宋金宝)

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收藏 | 浏览/下载：2/0 | 提交时间：2024/12/18

statistical distribution depth-integrated local momentum second-order random waves water depth wave-number spectrum