Tuesday, October 31, 2006
Nature Physics Published online: 2, 749 - 753 (October 2006)
Because the thickness of the MgF2 window for long tube was different, the old holder can not be used. Excepting the thickness, the other dimensions should not be changed anymore. The material: Aluminum Plate (Al Zn Mg Cu 1.5). Surface: good quality (milled profiles)
Monday, October 30, 2006
Tuesday, October 24, 2006
When we were taking the FROG images, the signal was very strong. I had to use a ND filter (~0.005 transimission) to attenuate the light. The retrieved data is almost match the raw data. But for the old CCD camera, it's not well to match these data.
Tuesday, October 17, 2006
Thursday, October 12, 2006
Nature Physics 2, - pp696 - 699 (2006)
Lasers consist of an active medium of excitable atoms, a pumping mechanism for exciting those atoms, and a cavity for building up a pulse of coherent radiation. At the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung, or GSI) in Darmstadt, Germany, scientists have succeeded for the first time in using a beam of uranium ions as the pump for producing ultraviolet laser light.
It works like this: the uranium beam ionizes argon atoms, which ionize krypton atoms, which in turn form excited molecules with fluorine. The krypton fluoride molecules are the excited entities which emit coherent light at a wavelength of 248 nanometers. A laser that uses this rare gas-halide mixture is called an excimer (excited dimer) laser.
This is not the shortest laser wavelength ever achieved, and the uranium pumping scheme is not all that energy efficient. So why then use this approach to producing laser light, especially when electrically pumped commercial krypton fluoride lasers are available? Because this was a test run for producing laser light in excimers that can't be electrically pumped.
According to Andreas Ulrich of the Technical University of Munich (firstname.lastname@example.org), the goal is to excite excimers of pure rare gases for producing radiation in the VUV (vacuum ultraviolet) and soft X-ray region of the spectrum. Only now have uranium beams at GSI been powerful enough to provide the pumping power for lasers in this wavelength region. Being so heavy, uranium atoms deposit their energy into a gas much more efficiently that lighter particles such as electrons.
Tuesday, October 10, 2006
The main principle behind compound refractive lenses (CRLs) is an ability of a group of thin lenses to greatly shorten the focal length. A series of N lenses with small apertures is used to achieve both one- and two-dimensional focusing and imaging at x-ray photon energies, where refractive imaging has previously been thought to be impossible due to the weak refraction of x rays. Note that the refractive index for x-rays is less than 1.
Therefore, unlike visible light optics which will cause visible rays to diverge, the concave lens will focus x-ray photons. Among the lenses we offer are cylindrical, spherical and 1- and 2- dimensional parabolic units.
From Adelphi Technology Inc.
Friday, October 06, 2006
Thursday, October 05, 2006
Wednesday, October 04, 2006
Sunday, October 01, 2006
Unfortunately, we could not find any interesting spectra when letting the spectrometer scanned in the whole range.