Research of Tumor Cells Atypia Based on Perspective Imaging of Intense Laser Proton
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Laser Ablation
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We have designed a new focusing system with a five-segmented prism array in combination with a beam expander and cylindrical lens assembly for compact x-ray laser experiments using a yttrium–aluminum–garnet (YAG) laser. The focusing characteristics were examined from irradiation patterns on a target. It was found that a beam of 25 mm diameter whose intensity profile was not uniform was condensed to a focused line having about 12 mm length and 50 μm width with a flat intensity distribution along the line on average, though the small-scale intensity modulation due to interference among the beamlets was observed. Spectroscopic observation of the plasma produced by irradiating the YAG laser of 2 J energy onto an Al slab target showed that highly ionized ions were produced up to the Li-like ionic stage. The new lens system is useful for compact x-ray laser research.
Prism
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Laser microfabrication using a diffraction-free beam (Bessel beam) was performed. Microfabrication with a deep focal depth is possible because a diffraction-free beam has a main lobe with a small diameter, which does not depend on propagation length. The diffraction-free beam was generated using an axicon lens, and the generation was confirmed using an optical microscopy image of a laser-fabricated spot on a silicon wafer. Nevertheless using a nanosecond pulsed Nd:YAG laser, microfabrication with a spot diameter < 1µm was realized. As a result of the deep focal depth of the diffraction-free beam, even if we change the work distance within a range of several millimeters, we are still able to maintain the diameter of the laser- fabricated spots to approximately 1µm. Since an almost straight penetration hole with a diameter of 3µm was drilled into SUS304 foil (20µm thick), it was found that the diffraction-free beam has a high feasibility for the high-aspect-ratio laser drilling of an opaque material due to its deep focal depth.
Axicon
Laser drilling
Bessel beam
Laser beam machining
Beam parameter product
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A Q-switched Nd:YAG laser beam is focused by an optical micro-lens array to produce a laser plasma at a target. The spatial intensity distribution in the focal plane is an array of closely-spaced high intensity spots. At a laser output energy of ∼200 mJ (wavelength 1064 nm, pulse duration ∼8 ns, repetition rate 10 Hz), a laser-induced air breakdown is observed in ∼47 spots inside an area of ∼9 mm diameter at the focal plane. For solid targets, a laser plasma is produced with a micro-lens array for spectrochemical analysis, e.g., laser-induced breakdown spectroscopy. Emission spectra of the laser plasma plume as well as pulse-to-pulse measurements with a simultaneous spectrometer are taken from a rotating slag sample with inhomogeneous distribution of species such as SiO2 or CaO. For the micro-lens configuration, the variation of the spectral line emission, e.g., of Si and Ca lines, is reduced in comparison with a single lens focusing showing the averaging effect of the micro-lens array produced plasma. A more representative analysis of the average concentration of inhomogeneous samples can be expected without elaborate and time-consuming sequential scanning of extended sample areas. Calibration curves for SiO2 and Fe2O3 are taken with samples of silicate glasses.
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In order to obtain focal spot size and spatial resolution of X-ray driven by the ultra-intense laser, a new method was designed to diagnose with a 0.2-m-thick knife-edge attached two different meshes, one copper mesh of 400 meshes and another nickel of 394 line pairs per centimeter. The X-ray was obtained by X-ray CCD. Tisapphire laser (1 J/40 fs/10 Hz) with an intensity of approximately 4.41018 W/cm2 shot the disc Cu target by repetition frequency. The experiment was carried out successfully on a 25 TW laser device at CAEP, in which the first focal spot and the X-ray image of the meshes were both obtained. The estimated focal spot of the X-ray was 43 m, and the estimated spatial resolution was 34 m. The results showed that the method of knife-edge and two meshes was suitable for the measurement of focal spot size of X-ray driven by ultra-intense laser.
Focal point
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The Free-Electron Laser Laboratory at the University of Hawai`i has constructed and tested a scanning wire beam position monitor to aid the alignment and optimization of a high spectral brightness inverse-Compton scattering x-ray source. X-rays are produced by colliding the 40 MeV electron beam from a pulsed S-band linac with infrared laser pulses from a mode-locked free-electron laser driven by the same electron beam. The electron and laser beams are focused to 60 μm diameters at the interaction point to achieve high scattering efficiency. This wire-scanner allows for high resolution measurements of the size and position of both the laser and electron beams at the interaction point to verify spatial coincidence. Time resolved measurements of secondary emission current allow us to monitor the transverse spatial evolution of the e-beam throughout the duration of a 4 μs macro-pulse while the laser is simultaneously profiled by pyrometer measurement of the occulted infrared beam. Using this apparatus we have demonstrated that the electron and laser beams can be co-aligned with a precision better than 10 μm as required to maximize x-ray yield.
Free-electron laser
Beam parameter product
M squared
Thomson scattering
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A new method for micro-beam XRF localization is presented. A laser beam along with an incident X-ray hits on the surface of a sample. The micro region on the sample that reached by X-ray beam can be localized by means of the visible spot of the laser beam. This method is suitable for X-ray microprobes using an X-ray tube or synchrotron radiation as excitation sources.
Beam parameter product
Sample (material)
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Single shot
Water window
Photoresist
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The focusing properties of a one-dimensional multilayer Laue lens (MLL) were investigated using monochromatic soft X-ray radiation from a table-top, laser-produced plasma source. The MLL was fabricated by a focused ion beam (FIB) structuring of pulsed laser deposited ZrO2/Ti multilayers. This novel method offers the potential to overcome limitations encountered in electron lithographic processes. Utilizing this multilayer Laue lens, a line focus of XUV radiation from a laser-induced plasma in a nitrogen gas puff target could be generated. The evaluated focal length is close to the designed value of 220 μm for the measurement wavelength of 2.88 nm. Divergence angle and beam waist diameter are measured by a moving knife edge and a far-field experiment, determining all relevant second-order moments based beam parameters. The waist diameter has been found to be approximately 370 nm (FWHM).
Extreme ultraviolet
Extreme Ultraviolet Lithography
X-ray optics
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A new method of making a laser microbeam is presented which uses a pulse UV gas laser in which oscillation of the multi transverse mode takes place. N 2 laser light passing through a pinhole (diameter of 20 µm) is amplified by an amplifier after the beam is collimated with the aid of a lens ( f 1 =200 mm). The amplified laser light is then led to a microscope and focused by an objective lens (×20, f 2 =8.9 mm). Thus the image of the pinhole is projected onto a specimen with the result that the size of the image is reduced by f 2 / f 1 . It is demonstrated that a localized hole with a diameter of less than 1 µm is produced on red corpuscles in human blood.
Microbeam
Pinhole (optics)
Collimated light
Axicon
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The authors focused the beam of currently the most powerful soft x-ray laser at 21nm using a spherical Mo:Si multilayer mirror. Focal spots were directly observed by imaging the fluorescence induced by the soft x-ray beam on a Tb doped phosphor screen. The energy density within the 40×60μm2 focal spot was 48J∕cm2, which corresponds to radiation peak intensity of 5×1011W∕cm2. The first observation of material ablation with a laser at 21nm is reported.
Laser Ablation
Soft X-rays
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