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HEAD Z THRESHOLDS PLAZMOBRAZOVANIJA NEAR TO THE OPTICAL SURFACE AND INFLUENCE OF PLASMA OF AIR ON PASSAGE OF THE LASER IMPULSE THROUGH THE OPTICAL DEVICE. MORPHOLOGY OF ARISING DAMAGES

In this section it is informed on effects of experiments on examination of thresholds of damage of 11 views of optical crystals in a beam pulsing CO2 - the laser at a power density 106÷2? IO7Вт/см2 and the areas of a band of action about 1 sm2, that is in the requirements modelling a real mode of operation of devices of laser optics.

At such sizes of a band of an irradiation influence of separate microinhomogeneities of structure of a material on process of an optical disruption can be averaged owing to the considerable density of flaws in real crystals.

The given experiment is executed for the purpose of finding-out of practical boundaries of applicability of perspective crystals for manufacturing of the transparent power optics powerful pulsing CO2 - lasers, that is definition of a threshold of optical firmness of real crystals. The damages arising at smaller values of intensity of radiation, but not rendering essential influence on working capacity of an optical device, we will term more low doporogovymi.

Also effects of an experimental research of process of passage of an impulse powerful CO2 - the laser through 13 views of optical monocrystals in a gamut intensivnostej - 2 are given? 106÷4? IO8Вт/см2. Carrying out of the given experiment is caused by necessity of revealing of features of passage of laser radiation through optical devices in requirements plazmoobrazovanija near to their surface - in a superthreshold mode of action. Besides it the morphology of the arisen damages is viewed and their influence on working capacity of an optical device is analysed. The obtained data are important for understanding of functioning of optics of the powerful laser working in the field of its limiting energy performances.

These effects are published by us in operations [Al, A2, A12, A16, А25-А27, А34].

In chapter 1 9-11 microns are shown, that most often used for manufacturing of laser optics crystals, transparent in a gamut, it is possible to part on the physicochemical properties on three basic groups:

1) fragile ionic crystals;

2) plastic ionic crystals;

3) semiconductor crystals.

In this section of operation it is informed on effects of examination of thresholds of optical firmness of the most perspective representatives of all three groups, and the most part of these crystals is already applied in devices IK - optics and released by the industry:

1) NaCl, KCl, KBr, RbI;

2) CsI, AgCl, КРС-5, КРС-6;

3) Ge, GaAs, ZnSe.

In experiments on examination of passage of radiation in requirements plazmoobrazovanija were used also barium fluoride - BaF2и zinc sulphide - ZnS.

Carrying out of the given experiment is caused by necessity of revealing of features of passage of laser radiation through optical devices in requirements plazmoobrazovanija near to their surface - in a superthreshold mode of action.

Measurings of parametres of laser radiation were spent under the classical two-beam plan: power of an influencing impulse of generation and power of an impulse of the radiation which has transited through the sample were registered. Time of a cutoff - τoτc which is understood as time of a transparency of an optical device, that is a gamut from the moment of the beginning of generation till the moment when the peak intensity of the radiation which have transited through the sample, decreased 10 times was fixed also.

Thresholds of optical firmness were explored in many operations (see chapter 1). The expedient of measurings of a threshold of optical firmness (C) and the mechanism of damage of the transparent materials which is based on the comparative analysis of amplitude and the past shape through the sample of an impulse of influencing radiation concerning an initial impulse of generation [182] is known. For embodying of this method radiation of the single-mode, single-frequency laser concerning low power (in order to avoid self-focusing) is agglomerated by a short-focus lens in volume or on a surface of the explored sample. Thus the examination mode is realised
pos an ideal material. For value pos in operation [182] accepted peak value of a power density of the past through the sample of an impulse at obviously bolshej power densities of the influencing. The method possesses a split-hair accuracy and reproducibility of effects and is rather convenient for carrying out of technological experiments, for example, for working off of optimum technology of cultivation of optical monocrystals [196].

The procedure used by us in given section of operation, differs from offered in [182] what essentially more powerful laser which radiation was agglomerated on the sample by a long-focus lens in a stain in the size ~ 3 was applied? 4 мм2. The sample settled down in a lens caustic, that is at the moment of radiation passage through the sample, divergence of a ray of light can be neglected practically. Thus, passage requirements through an optical device of a real laser beam of high intensity were modelled. The self-focusing threshold in this case was not exceeded.

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A source: Rogalin Vladimir Efimovich. Firmness of materials of power optics to action of powerful impulses of radiation CO2 - lasers. The dissertation on competition of a scientific degree of the doctor of physical and mathematical sciences. Tver - 2015. 2015

More on topic HEAD Z THRESHOLDS PLAZMOBRAZOVANIJA NEAR TO THE OPTICAL SURFACE AND INFLUENCE OF PLASMA OF AIR ON PASSAGE OF THE LASER IMPULSE THROUGH THE OPTICAL DEVICE. MORPHOLOGY OF ARISING DAMAGES:

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  2. 3.1.2 Experimental technique on examination of passage of a laser impulse through an optical device
  3. 3.5 Features of passage of a peak part of a laser impulse through the transparent optical devices
  4. 3.2 Features of occurrence of plasma formation near to a surface of optical materials and its interrelation with their real optical firmness
  5. 3.3 Morphology of volume and superficial damages of the optical materials resulting action
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  8. Optical microscopy of a surface of films
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  11. Morphology of "laser" damages to germanium
  12. 1.3 Properties of optical materials for field of a spectrum 10 microns. Measure for a select of optical materials of powerful lasers
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  14. CHAPTER 5 IMMERSING MICROINHOMOGENEITIES IN SHCHGK AND THEIR INFLUENCE ON OPTICAL FIRMNESS
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