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相关概念视频

Atomic Nuclei: Larmor Precession Frequency01:11

Atomic Nuclei: Larmor Precession Frequency

The earth's gravitational field produces a 'twisting force' perpendicular to the angular momentum of a spinning mass (such as a spinning top) that causes the mass to 'wobble' around the gravitational field axis in a phenomenon called precession. Similarly, the magnetic moment (μ) of a spinning nucleus precesses due to an external magnetic field directed along the z-axis. The precession of the magnetic moment vector about the magnetic field is called Larmor precession, and the angular frequency...
Atomic Emission Spectroscopy: Instrumentation01:22

Atomic Emission Spectroscopy: Instrumentation

The instrumentation of atomic emission spectrometry (AES) involves various components, including atomization devices that convert samples into gas-phase atoms and ions. There are two main types of atomization devices: continuous and discrete atomizers.  Continuous atomizers, like plasmas and flames, introduce samples in a constant stream, while discrete atomizers inject individual samples using syringes or autosamplers. The most common discrete atomizer is the electrothermal atomizer.
NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences01:17

NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences

A pulse is a short burst of radio waves distributed over a range of frequencies that simultaneously excites all the nuclei in the sample. Upon passing a radio frequency pulse along the x-axis, the nuclei absorb energy corresponding to their Larmor frequencies and achieve resonance. This shifts the net magnetization vector from the z-axis toward the transverse plane. This angle of rotation of the magnetization vector, or the flip angle, is proportional to the duration and intensity of the pulse.
Confocal Fluorescence Microscopy01:16

Confocal Fluorescence Microscopy

Confocal microscopy is an advanced microscopic technique. The prime advantage of the confocal microscope over other microscopy techniques is its ability to block the out-of-focus light from the illuminated samples using pinholes. It is widely used with fluorescence optics to obtain high-resolution, sharp contrast images. Unlike optical microscopes, confocal microscopes use a focused beam of light laser to scan the entire sample surface at different z-planes. These microscopes are, therefore,...

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相关实验视频

Updated: Jul 2, 2026

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies
09:38

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies

Published on: December 18, 2015

用于天文观测的激光频率.

Tilo Steinmetz1, Tobias Wilken, Constanza Araujo-Hauck

  • 1Max-Planck Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany.

Science (New York, N.Y.)
|September 6, 2008
PubMed
概括
此摘要是机器生成的。

天文学光谱仪现在可以通过激光频率校准来实现前所未有的多普勒精度. 这一突破使宇宙膨胀历史和加速的直接测量成为可能.

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Generation and Coherent Control of Pulsed Quantum Frequency Combs
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Published on: November 22, 2019

相关实验视频

Last Updated: Jul 2, 2026

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies
09:38

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies

Published on: December 18, 2015

Generation and Coherent Control of Pulsed Quantum Frequency Combs
06:42

Generation and Coherent Control of Pulsed Quantum Frequency Combs

Published on: June 8, 2018

Low-cost Custom Fabrication and Mode-locked Operation of an All-normal-dispersion Femtosecond Fiber Laser for Multiphoton Microscopy
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Low-cost Custom Fabrication and Mode-locked Operation of an All-normal-dispersion Femtosecond Fiber Laser for Multiphoton Microscopy

Published on: November 22, 2019

科学领域:

  • 天文学 天文学
  • 天体物理学 天体物理学
  • 光学工程是指光学工程.

背景情况:

  • 直接测量宇宙的膨胀历史需要观察红移进化.
  • 目前的天文光谱仪缺乏用于多普勒速度漂移测量所需的精度 (约. 1 厘米/秒/年).

研究的目的:

  • 为了展示激光频率的首次使用,用于天文望远镜波长校准.
  • 通过这种新的校准技术来评估可实现的多普勒精度.

主要方法:

  • 使用激光频率子对天文望远镜的高精度波长进行校准.
  • 分析光谱仪和探测器系统数据以识别和跟踪系统效应.

主要成果:

  • 实现了绝对校准,相当于在1.5微米处的多普勒精度约为9米/秒.
  • 证明了激光频率校准在跟踪复杂,时间变化的系统效应方面的优势.

结论:

  • 激光频率校准明显超过了当前最先进的方法的准确性.
  • 这种技术为未来的宇宙学实验提供了一个可行的途径,用于建模和消除系统错误,旨在检测宇宙加速.