Optical breakdown

Pustovavlov, V. K. 1995. Initiation of explosive boiling and optical breakdown as a result of the action of laser pulses on melanomasome in pigmented biotissues. Kvantovaya Electronika 22 1091-94. 

In 1963 the remarkable phenomenon of gas breakdown by laser radiation was discovered in experiments, which laid the ground for broad new directions in plasma physics and the physics of the interaction of laser radiation with a substance. Soon Ya.B. and Yu. P. Raizer developed the cascade theory of laser breakdown [23]. Hardly a single article of the great number devoted to optical breakdown manages without a reference to this work. 

Loesel, F.H., Niemz, M.H., Bille, J.F., and Juhasz, T. (1996) Laser-Induced Optical Breakdown on Hard and Soft Tissues and Its Dependence on the Pulse Dmation Experiment and Model, IEEE J. Quantum Electrons, Vol. 32, pp. 1717-1732. 

The plasma threshold is the irradiance required to produce the optical breakdown of the vapour. It depends on the nature of the surface (particularly on various optical, thermophysical and thermodynamic properties of the material). The plasma threshold is usually higher than the ablation threshold. Observing optical emission entails applying more energy than that required to reach the plasma threshold. 

Recent measurements have shown that laser ablation (or negatively spoken damage) becomes more deterministic when femtosecond laser pulses are applied [22, 23, 40, 41]. This observation is due to the generation of conduction band (seed) electrons by means of multiphoton ionization (MPI). Based on this knowledge, a model for optical breakdown that takes into account avalanche ionization and MPI was developed [40], The temporal behavior of the free electron density in the conduction band n(t) can be described by a rate equation... 

Fig. 34 Laser-induced optical breakdown (LIOB) threshold fluence vs pulse width for the ablation of human corneal tissue. A=800 nm [93]...

Equation (1) shows that the SH signal should increase with increase of I, A, and T, but is eventually limited by surface optical breakdown. If we assume that the threshold energy for breakdown for a short-pulse excitation is (IT)tjj - 1 J/cm, then the maximum SH signal is given by ... 

Cotton-Mouton effect Miscellaneous Optical breakdown... 

Kabashin AV, Meunier M (2002) Fabrication of photoluminescent Si-based layers by air optical breakdown near the silicon surface. Appl Surf Sci 186 578-582 Kalkan AK, Bae S, Li H, Hayes DJ, Fosash SJ (2000) Nanocrystalline Si thin films with arrayed void-column network deposited by high density plasma. J Appl Phys 88(1) 555-561 Krishnamurthy A, Rasmussen DH, Suni II (2011) Galvanic deposition of nanoporous Si onto 6061 Al alloy Ifom Aqueous HF. J Electrochem Soc 158(2) D68-D71... 

It was pointed out that measurements of laser-induced breakdown suffer from the same artifacts as DC-breakdown measurements. Impurities of low ionization energy, submicroscopic particles (dust or ice), and microscopic gas bubbles may serve as centers for the initiation of the breakdown process and mask the development of a pure avalanche breakdown (Brueck and Kildal, 1981). Subsequent investigations on the optical breakdown of liquid helium (Abrikosova and Anshukov, 1973 ... 

When exposed to apower density of 10 W/cm, the tissue experiences an electric field of lO V/cm associated with the light. This field is considerably larger than the average Coulomb attraction between the electrons and the nuclei and causes a dielectric breakdown of the tissue to create a very large free electron density (plasma) of 10 cm in the focal volume of the laser beam in an extremely short period (less than hundreds of picoseconds). This high-density plasma strongly absorbs UV, visible and IR light which is called optical breakdown and leads to ablation. 

Divide each value by 4.2 xIO to convert into esu. Optical breakdown. 

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