共查询到20条相似文献,搜索用时 156 毫秒
1.
M. O. Kaptakov V. I. Revenko M. E. Kustov I. S. Kurchatov V. V. Skroznikova T. B. Kiseleva V. V. Buchanov E. N. Murav’ev M. A. Kazaryan E. A. Kuznetsova E. F. Solinov V. I. Skachkov 《Bulletin of the Lebedev Physics Institute》2018,45(9):272-278
Some principal aspects of silicate glass cutting by controlled laser through thermal cleavage are considered. In particular, it is shown that the cutting speed in the case of ytterbium fiber laser radiation with a wavelength of 1.065 μm lying in fact in the glass transmission range (more precisely, in the low absorption region) depends linearly on the laser power. It is shown that the glass end face takes various geometrical shapes under various conditions of bulk heating and cooling. Therefore, to obtain a homogeneous end face, it is required to stabilize both the laser radiation power and the laser beam speed at a corresponding laser beam geometry in the cut region. Methods for obtaining various cross section shapes of the glass end face and methods for obtaining blunt edges of end faces are presented. 相似文献
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Hirofumi Hidai Masato Yoshioka Kuniaki Hiromatsu Hitoshi Tokura 《Applied Physics A: Materials Science & Processing》2009,96(4):869-872
We report on a permanent change in the physical properties inside glass that is rapidly heated and quenched with a continuous-wave
(CW) laser beam. The absorption of the glass was enhanced by laser heating, and the heated spot moved by thermal radiation
and conduction. To trigger the heating, an absorbent material was placed on the backside of a glass plate and irradiated through
the glass. The laser beam can modify borosilicate glass with a high aspect ratio (∼100:1) at a rate of ∼130 mm/s. The modified
zone consists of two concentric cylindrical zones and is crack-free. 相似文献
4.
S. Juodkazis N. Murazawa H. Wakatsuki H. Misawa 《Applied Physics A: Materials Science & Processing》2007,87(1):41-45
We report on removal of micrometer-sized bubbles from molten glass by a 1064 nm wavelength cw-laser radiation focused using
an objective lens of numerical aperture 0.55. The heating of a bubble and surrounding glass by tightly focused laser beam
had reduced surface tension and caused disintegration of the bubble. Disintegration occurred at typically 1850±50 °C. Emission
of a heated gas inside the bubble was used to determine the local temperature. Temporal evolution of the bubble disintegration
was imaged by a CCD camera. Physics of the interaction between a focused laser beam and bubble is discussed.
PACS 47.55.Dz; 42.70.Ce; 44.90.+c; 47.27.Te; 47.90.+a 相似文献
5.
Laser pulse heating of metallic surfaces results in rapid rise of temperature in the region irradiated by the laser beam. This in turn results in high temperature gradient in this region. The irradiated substrate material expands as a response to the temperature gradient. Consequently, high thermal stress levels are developed in the region of the high temperature gradient. In the present study, closed form solutions for temperature and stress fields due to a laser pulse decaying exponentially in time are presented. A Laplace transformation method is employed in the analysis. The resulting equations are non-dimensionalized with the appropriate parameters. It is found that temperature rises rapidly during the early heating period in the surface region. In this case, internal energy gain dominates the conduction losses from the surface vicinity. The thermal stress levels attain high values in the surface region. The stress wave developed is compressive and it propagates with a wave speed c1 inside the substrate. 相似文献
6.
Jongho Shin Ki-Soo Lim Youn-Shil Kim Jung-Hyun Choi Jongmin Lee 《Applied Surface Science》2009,255(24):9754-9757
We report the formation of fluorescence patterns inside gold-doped glass medium by femtosecond-laser fabrication. Strong fluorescence images appeared from the irradiated multi-layered region after low temperature annealing. We removed the images by exposing the glass to an electric furnace or a CO2 laser beam for high temperature annealing. The method was also applied to recording, reading, and erasing of fluorescence data by a femtosecond laser, a 405-nm laser diode, and a CO2 laser respectively. 相似文献
7.
Nadezhda M. Bulgakova Vladimir P. Zhukov Yuri P. Meshcheryakov 《Applied physics. B, Lasers and optics》2013,113(3):437-449
The dynamics of ultrashort-laser-induced generation of free electron plasma inside bulk glass is analyzed. The results of modeling are presented for typical glass modification regimes, obtained on the basis of Maxwell’s equations supplemented with the equations describing electron plasma formation and the laser-induced electric current. The model has been demonstrated to allow revealing important features of laser beam propagation in the regimes of dense electron plasma generation such as strong scattering up to complete displacing of light from the plasma region followed by beam refocusing. The geometry of the laser energy absorption zone is determined, and the glass temperature is mapped which may be foreseen at the end of electron–glass matrix relaxation. This, in turn, allows estimating the laser-induced stress levels and making conclusions on the routes of glass modification. Finally, based on the modeling results, the plausible mechanisms are discussed which may be responsible for the formation of volume nanogratings in a number of transparent solids under the action ultrashort laser pulses and laser direct writing anisotropy observed for laser pulses with a tilted front. 相似文献
8.
Analytical modelling of end thermal coupling in a solid-state laser longitudinally bonded by a vertical-cavity top-emitting laser diode
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The intrinsic features involving a circularly symmetric beam
profile with low divergence, planar geometry as well as the increasingly
enhanced power of vertical-cavity surface-emitting lasers (VCSELs)
have made the VCSEL a promising pump source in direct end bonding to
a solid-state laser medium to form the minimized, on-wafer
integrated laser system. This scheme will generate a surface contact
pump configuration and thus additional end thermal coupling to the
laser medium through the joint interface of both materials, apart from
pump beam heating. This paper analytically models temperature
distributions in both VCSEL and the laser medium from the end thermal
coupling regarding surface contact pump configuration using a
top-emitting VCSEL as the pump source for the first time. The
analytical solutions are derived by introducing relative temperature
and mean temperature expressions. The results show that the end
contact heating by the VCSEL could lead to considerable temperature
variations associated with thermal phase shift and thermal lensing
in the laser medium. However, if the central temperature of the
interface is increased by less than 20~K, the end contact heating
does not have a significant thermal influence on the laser medium. In
this case, the thermal effect should be dominated by pump beam
heating. This work provides useful analytical results for further
analysis of hybrid thermal effects on those lasers pumped by a direct
VCSEL bond. 相似文献
9.
D. Braichotte H. van den Bergh 《Applied Physics A: Materials Science & Processing》1989,49(2):189-197
The photolytic laser chemical vapor deposition (LCVD) rate of platinum from its bishexafluoroacetylacetonate precurser has been measured in situ and in real time. Optical transmission of the 350 nm photolysis light through the deposited platinum film and a transparent glass substrate is monitored and analysed in detail. From these measurements, as well as measurements of the reflected light, the fraction of the laser beam power absorbed in the metal film is found. The latter allows a simple estimate of the laser-induced temperature rise at the metal surface. It is shown that even rather small temperature increases of the order of several tens of degrees centigrade can completely change the photolysis mechanism and hence drastically influence the photolytic LCVD rate. A simple modification of Lax's model, in which a temperature dependent thermal conductivity of the substrate is introduced, is used to describe the laser-induced heating of a strongly absorbing thin metal film on a glass substrate. 相似文献
10.
基于一维应力松弛模型和粘弹性本构关系,对1.06μm连续激光照射下K9玻璃板中的温升和应力作了计算,结果表明,由于应力松弛效应,激光停照后的冷却过程中产生的残余拉伸应力可达到玻璃的拉伸断裂强度阈值,而激光加热期间的最大压缩应力却小于压缩断裂强度要求。对3mm厚的K9玻璃板,由应力松弛引起破坏所要求的激光参数为946kWm-2作用0.2s,因而应力松弛可能为1.06 μm连续激光大光斑照射下K9玻璃窗口损伤的主要模式。 相似文献
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硅酸铅玻璃光敏性研究 总被引:3,自引:0,他引:3
采用四倍频的Nd∶YAG脉冲激光 (波长 2 6 6nm ,脉宽 10ns)对氧化铅摩尔分数在 0 3至 0 5的硅酸铅玻璃体样品进行照射 ,并对照射前后样品的折射率及紫外可见吸收光谱进行了测量。研究发现不同能量密度的2 6 6nm激光照射硅酸铅玻璃体样品 ,会使样品的紫外可见吸收光谱产生不同的变化 :当 2 6 6nm激光能量密度较高时 (15 0mJ/cm2 ) ,样品在可见区域的吸收系数明显增大 ,样品表面会产生褐色斑点 ;而当 2 6 6nm激光能量密度较低时 (5 0mJ/cm2 ) ,尽管累计剂量较大 ,样品表面无斑点产生 ,吸收系数稍有增加 ,而折射率下降明显 ,最大Δn =- 0 .2 5± 0 .0 4。对氧化铅摩尔分数为 0 4 3的硅酸铅玻璃用不同能量密度的 2 6 6nm激光进行照射 ,发现当激光能量密度大于某一阈值时 ,样品在可见区域的吸收系数突然增大 ,这可能是由于硅酸铅玻璃吸收 2 6 6nm激光能量导致局部温度升高而引起玻璃结构改变所致。 相似文献
13.
Laser heating of Inconel 718 alloy is considered and the resulting temperature and stress fields are predicted using the finite element method (FEM). An experiment is carried out to treat the alloy surface by a laser beam at high pressure nitrogen environment. The metallurgical and morphological changes in the irradiated region are examined using the Scanning Electron Microscope (SEM), optical microscope, and X-ray Diffraction (XRD). It is found that the surface hardness of the alloy improves after the laser heating process, which is due to the microstructural changes and γ-phase nitride formation in the surface region. The maximum value of the residual stress predicted in the irradiated region is close to the yielding limit of the alloy. 相似文献
14.
针对高重复频率对吸收性滤光片损伤问题,研究了高重复频率(kHz量级)激光脉冲的光束半径大小对吸收玻璃的形貌特征和损伤机理.研究发现在总的激光作用个数、单脉冲能量和脉冲作用频率固定时,吸收玻璃的损伤特性发生很大变化:在光束半径较大时,激光能量分散,主要损伤形貌是熔化破坏;随着光束半径的减小,激光脉冲能量变得集中,热量的累积效果变得明显,逐渐变成熔化破坏和气化破坏;当激光光束半径小到一定程度,则会由于光强过大使得介质表面发生击穿而产生激光等离子体冲击波,同时由于热量沉积的集中使光束作用中心处产生超热液体,当满足相爆炸发生的条件时,气化物、液滴和固体颗粒的混合物会向外飞溅,在损伤凹陷的周围形成气化物、液滴的冷凝区和固体颗粒溅射区.
关键词:
激光诱导损伤
高重复激光脉冲
吸收玻璃
相爆炸 相似文献
15.
The temporal evolution of refractive-index change produced by a tightly focused femtosecond (fs) laser pulse inside a soda-lime glass plate was investigated by use of a transient lens method with subpicosecond time resolution. An oscillating behavior of the light intensity in the central region of the probe beam was observed 0-1500 ps after irradiation of the plate. The oscillation was interpreted in terms of a rapid temperature increase and the ensuing propagation of the pressure wave. This study is to our knowledge the first real-time observation of refractive-index change inside a glass induced by a fs laser pulse. 相似文献
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G. P. Zograf Y. F. Yu K. V. Baryshnikova A. I. Kuznetsov S. V. Makarov 《JETP Letters》2018,107(11):699-704
Local optical heating and Raman nanothermometry based on resonant silicon particles provide a new promising platform for a number of key nanophotonics applications associated with thermally induced processes at the nano- and microscale. In this work, the crystallization of amorphous silicon nanodisks with optical resonances caused by local optical heating has been studied. The crystallization process is controlled by Raman microspectroscopy. The crystallization temperature of a single nanodisk of about 900 K has been determined under the action of a strongly focused cw laser beam. As a result, an annealed resonant silicon nanoparticle has allowed controlled and reversible heating in the temperature range of 300–1000 K with the possibility of mapping the heating region with submicron spatial resolution. 相似文献
18.
This paper presents a heat transfer model to calculate the temperature field in moving glass rods heated by a CO2 laser. Conduction and radiation heat transfer in radial and axial directions are taken into account in the current model. The Rosseland diffusion approximation is incorporated to analyze the radiation heat transfer in the glass rod. A two-band model is used to simulate the spectral property of the glass. Results of the simulation show that glass rods of sufficiently large optical thickness should be treated as a semitransparent medium for radiative transfer, and it is reasonably accurate to assume it to be opaque to CO2 laser irradiation. It has been shown that the resulting temperature profile is strongly dependent on the laser parameters, i.e., the size of laser beam and the power of the laser. The diameter and speed of the moving glass rod are also important in determining the temperature field although the convective heat transfer coefficient between the glass rod and the environment has little effect. 相似文献
19.
G. N. Mikhailova B. P. Mikhailov V. N. Tokarev A. V. Troitskii V. M. Marchenko 《Laser Physics》2007,17(6):831-833
A mathematical model for the heating of a surface layer of HTSC ceramics by a CW laser beam scanned at a constant rate is considered. The calculated depths of the molten region are presented for the heating of the Bi(2223) ceramics by a CW CO2 laser. The theoretical results are in reasonable agreement with the experimental data. The calculations can be used for the optimization of laser processing of superconducting ceramics aimed at increasing the critical current density. 相似文献
20.
Space-selective growth of frequency-conversion crystals in glasses with ultrashort infrared laser pulses 总被引:3,自引:0,他引:3
We report on space-selective growth of a second-harmonic-generation beta-BaB(2)O(4) (BBO) crystal inside a BaO-Al(2)O(3)-B(2)O(3) glass sample at the focal point of an 800-nm femtosecond laser beam. A spherical heated region was formed during the focused laser irradiation through observation with an optical microscope. We moved the heated region by changing the position of the focal point of the laser beam relative to the glass sample. We grew BBO crystal continuously in the glass sample by adjusting the moving speed of the heated zone. Our results demonstrate that functional crystals can be formed three dimensionally in glasses by use of a nonresonant ultrashort pulsed laser. 相似文献