Methods for controlling the parameters of laser radiation. Labor-Expert. Management. Protecting workers from laser radiation

LASER RADIATION is a forced (by means of a laser) emission of portions-quanta of electromagnetic radiation by atoms of matter. The word "laser" is an abbreviation formed from the initial letters of the English phrase Light Amplification by Stimulated Emission of Radiation (light amplification by induced radiation). Therefore, (optical quantum generator) is a generator of electromagnetic radiation in the optical range, based on the use of stimulated (stimulated) radiation. A laser installation includes an active (laser) medium with an optical resonator, an energy source for its excitation, and, as a rule, a cooling system. Due to the monochromaticity of the laser beam and its low divergence (high degree of collimation), exceptionally high energy exposures are created, which make it possible to obtain a local thermal effect. This is the basis for the use of laser systems in the processing of materials (cutting, drilling, surface hardening, etc.), in surgery, etc.

L. and. can propagate over considerable distances and be reflected from the interface between two media, which makes it possible to use this property for the purposes of location, navigation, communications, etc. By selecting certain substances as an active medium, it can induce at almost all wavelengths, starting from ultraviolet to long-wave infrared. The most widely used in industry are lasers that generate electromagnetic radiation with a wavelength of 0.33; 0.49; 0.63; 0.69; 1.06; 10.6 µm.

The main physical quantities characterizing L. and .:

wavelength, µm;

application of means of protection;

limiting the time of exposure to radiation;

appointment and persons responsible for the organization and conduct of work;

restriction of access to work;

Supervision of the mode of work;

clear anti-emergency work and regulation of the procedure for conducting work in emergency conditions;

Personnel.

Sanitary-hygienic and treatment-and-prophylactic methods:

control over the levels of harmful and dangerous factors in the workplace;

control over the passage of preliminary and periodic medical examinations by the personnel.

From L. and. must ensure the prevention of exposure to radiation or the reduction of its magnitude to a level not exceeding the permissible. To SKZ from L. and. include: fences, protective screens, locks and automatic shutters, casings, etc. PPE from L. and. include:, shields, masks, etc. SKZ should be provided at the design and installation stage of lasers, when organizing workplaces, and when choosing operational parameters. The choice of protective equipment should be made depending on the class of the laser, the intensity of radiation in the working area, the nature of the work performed. The indicators of the protective properties of protective equipment should not decrease under the influence of other harmful and dangerous factors (vibrations, temperatures, etc.). The design of protective equipment should provide the possibility of changing the main elements (light filters, screens, sight glasses, etc.). PPE eyes and face (and shields), reducing the intensity of L. and. to remote control, should be used only in those cases (commissioning, repair and experimental work), when the CPS does not provide personnel.

Laser radiation as a harmful factor in the production environment

Laser radiation is a forced (by means of a laser) emission of portions-quanta of electromagnetic radiation by atoms of matter. The word "laser" is an abbreviation formed from the initial letters of the English phrase Light Amplification by Stimulated Emission of Radiation (light amplification by induced radiation). Therefore, a laser (optical quantum generator) is a generator of electromagnetic radiation in the optical range, based on the use of stimulated (stimulated) radiation.

Photo source: shutterstock.com.

A laser installation includes an active (laser) medium with an optical resonator, an energy source for its excitation, and, as a rule, a cooling system. Due to the monochromaticity of the laser beam and its low divergence (high degree of collimation), exceptionally high energy exposures are created, which make it possible to obtain a local thermal effect. This is the basis for the use of laser systems in the processing of materials (cutting, drilling, surface hardening, etc.), in surgery, etc.

Laser radiation (it can propagate over considerable distances and be reflected from the interface between two media, which makes it possible to use this property for the purposes of location, navigation, communications, etc. By selecting certain substances as an active medium, a laser can induce radiation on almost all wavelengths, ranging from ultraviolet to long-wave infrared.The most widespread in industry are lasers that generate electromagnetic radiation with a wavelength of 0.33; 0.49; 0.63; 0.69; 1.06; 10.6 microns.

BIOLOGICAL EFFECT OF LASER RADIATION

Action LI (hereinafter referred to as LI)very difficult for a person. It depends on the LI parameters, primarily on the wavelength, power (energy) of radiation, duration of exposure, pulse repetition rate, size of the irradiated area (“size effect”) and anatomical and physiological features of the irradiated tissue (eye, skin) . Since the organic molecules that make up the biological tissue have a wide range of absorbed frequencies, there is no reason to believe that the LR monochromaticity can create any specific effects when interacting with the tissue.

Spatial coherence also does not significantly change the mechanism of radiation damage, since the phenomenon of thermal conductivity in the tissues and the constant small movements inherent in the eye destroy the interference pattern already with an exposure duration exceeding a few microseconds. Thus, LI is passed through and absorbed by biological tissues according to the same laws as incoherent LI, and does not cause any specific effects in tissues.

Publication source: shutterstock.com.

The LI energy absorbed by tissues is converted into other types of energy - thermal, mechanical, energy of photochemical processes, which can cause a number of effects: thermal, shock, light pressure, etc. LI is dangerous for the organ of vision. The retina of the eye can be affected by lasers in the visible (0.38 - 0.7 microns) and near infrared (0.75 - 1.4 microns) ranges. Laser ultraviolet (0.18 - 0.38 microns) and far infrared (more than 1.4 microns) radiation do not reach the retina, but can damage the cornea, iris, lens.

Reaching the retina, the LI is focused by the refractive system of the eye, while the power density on the retina increases by 1000 - 10,000 times compared to the power density on the cornea. Short pulses (0.1 s - 10-14 s) that lasers generate can cause damage to the organ of vision in a much shorter period of time than that required for the activation of protective physiological mechanisms (blink reflex 0.1 s) .

The second critical organ for the action of LI is the skin. The interaction of laser radiation with the skin depends on the wavelength and skin pigmentation. The reflectivity of the skin in the visible region of the spectrum is high. The LI of the far infrared region begins to be strongly absorbed by the skin, since this radiation is actively absorbed by water, which makes up 80% of the contents of most tissues, there is a risk of skin burns.

Chronic exposure to low-energy (at the level or less than the maximum limit of LI) scattered radiation can lead to the development of non-specific changes in the health status of persons servicing lasers. At the same time, it is a kind of risk factor for the development of neurotic conditions and cardiovascular disorders. The most characteristic clinical syndromes found in those working with lasers are asthenic, asthenovegetative and vegetovascular dystonia.

REGULATION OF LASER RADIATION

Two approaches to LI standardization have been scientifically substantiated: the first is based on the damaging effects of tissues or organs that occur directly at the site of irradiation; the second - on the basis of detectable functional and morphological changes in a number of systems and organs that are not directly affected. Hygienic regulation is based on the criteria of biological action, primarily determined by the region of the electromagnetic spectrum. In accordance with this, the LI range is divided into a number of areas:

Establishing the MRL value is based on the principle of determining the minimum "threshold" damage in irradiated tissues (retina, cornea, skin) detected by modern research methods during or after LR exposure. The normalized parameters are the energy exposure H (J x (m / 100)) and irradiance E (W x (m / 100)), as well as the energy W (J) and power P (W).

The data of experimental and clinical-physiological studies indicate the prevailing significance of general non-specific reactions of the body in response to chronic exposure to low-energy levels of LI in comparison with local local changes in the organ of vision and skin. At the same time, LI in the visible region of the spectrum causes shifts in the functioning of the endocrine and immune systems, the central and peripheral nervous systems, protein, carbohydrate and lipid metabolism. LI with a wavelength of 0.514 microns leads to changes in the activity of the sympathoadrenal and pituitary-adrenal systems.

Long-term chronic action of LI with a wavelength of 1.06 μm causes vegetative-vascular disorders. Almost all researchers who have studied the health status of persons serving lasers emphasize a higher frequency of detection of asthenic and vegetative-vascular disorders in them. Consequently, low-energy LI under chronic action acts as a risk factor for the development of pathology, which determines the need to take this factor into account in hygienic standards.

The first PDUs for LI in Russia for individual wavelengths were installed in 1972, and in 1981 the first sanitary norms and rules were put into effect. In the USA, there is the ANSI standard - Z 136. The standard of the International Electrotechnical Commission (IEC) - publication 825 has also been developed. but also functional changes in the body.

A wide range of wavelengths, a variety of LR parameters and induced biological effects make it difficult to justify hygienic standards. In addition, experimental and especially clinical verification require a long time and money. Therefore, mathematical modeling is used to solve problems of refining and developing remote control systems for LI. This allows you to significantly reduce the amount of experimental research on laboratory animals. When creating mathematical models, the nature of the energy distribution and the absorption characteristics of the irradiated tissue are taken into account.

The method of mathematical modeling of the main physical processes (thermal and hydrodynamic effects, laser breakdown, etc.), leading to the destruction of the tissues of the eye fundus under the influence of LE in the visible and near infrared ranges with a pulse duration of 1 to 10-12 s, was used when determining and clarifying the remote control of LI included in the latest edition of the "Sanitary norms and rules for the design and operation of lasers" SNiP No. 5804-91 (hereinafter referred to as Rules No. 5804-91, approx. ed.), which are developed on the basis of the results of scientific research and taking into account the main provisions of the following documents:

The fact that these norms are currently subject to application is evidenced by the Letter of Rospotrebnadzor dated May 16, 2007 No. 0100 / 4961-07-32. It contains a List of the main current regulatory and methodological documents on occupational health, and also says the following: in accordance with the legislation of the Russian Federation, sanitary rules, norms and hygiene standards are in force on the territory of the Russian Federation, approved, in particular, by the Ministry of Health of the USSR, in part, not contrary to the sanitary legislation of the Russian Federation. These documents are valid until the abolition or adoption of new regulatory legal acts to replace the existing ones.

Rules No. 5804-91 establish the maximum permissible levels (MPL) of laser radiation under various conditions of human exposure, the classification of lasers according to the degree of danger of the radiation they generate, and the requirements:

It should be borne in mind that the values ​​of the MPL of hazardous and harmful production factors at a workplace equipped with laser technology are also regulated by GOSTs, SNiPs, SNs and other documents listed in Appendix 1 to Rules No. 5804-91. However, many of these documents have become invalid or have been replaced by new regulations. As mentioned above, the biological effect of laser radiation on the body depends on the wavelength of the radiation, the duration of the pulse (exposure), the pulse repetition rate, the area of ​​the irradiated area, as well as on the biological and physicochemical characteristics of the irradiated tissues and organs. The mechanism of interaction of radiation with tissues can be thermal, photochemical, shock-acoustic, etc. The classification of lasers according to the degree of danger of the generated radiation is given in Section 4 of Rules No. 5804-91. The laser class is determined taking into account its power and remote control for a single exposure to the generated radiation. The Regulations mention four hazard classes of generated radiation (see table below).

Hazard classes of radiation generated by lasers

Classification of lasers is carried out by the manufacturer. It uses a calculation method based on the analysis of the radiation output characteristics. An example of calculation is given in the section "Control of levels of hazardous and harmful factors when working with lasers" of Regulation No. 5804-91. This section contains a special table that reflects the dependence of hazardous and harmful factors on the laser class (GOST 12.1.040).

REQUIREMENTS FOR METHODS, INSTRUMENTS FOR MEASURING AND CONTROL OF LASER RADIATION

LI dosimetry is a complex of methods for determining the values ​​of laser radiation parameters at a given point in space in order to identify the degree of danger and harmfulness for the human body. Laser dosimetry includes two sections:

- calculated or theoretical dosimetry (considers methods for calculating the parameters of LI in the zone of possible location of operators and methods for calculating the degree of its danger);
- experimental dosimetry (considers methods and means of direct measurement of LR parameters at a given point in space).

Measuring instruments intended for dosimetric control are called laser dosimeters. Dosimetric control is of particular importance for the evaluation of reflected and scattered radiation, when the calculation methods of laser dosimetry, based on the data of the output characteristics of laser installations, give very approximate values ​​of the LR levels at a given control point.

The use of computational methods is dictated by the inability to measure the LR parameters for the entire variety of laser technology. The calculation method of laser dosimetry makes it possible to assess the degree of danger of radiation at a given point in space, using passport data in the calculations. The method is convenient for work with rarely recurring short-term radiation pulses, when the possibility of measuring the maximum exposure value, determining laser-hazardous zones, and classifying lasers according to the degree of danger of the radiation they generate is limited.

Methods of dosimetric control are established in the "Methodological guidelines for bodies and institutions of the sanitary and epidemiological services for conducting dosimetric control and hygienic assessment of laser radiation" No. 5309-90, and are also partially considered in Rules No. 5804-91.

The methods of laser dosimetry are based on the principle of the greatest risk, according to which the assessment of the degree of danger should be carried out for the worst exposure conditions in terms of biological effects, i.e. measurement of laser irradiation levels should be carried out when the laser is operating in the maximum power output (energy) mode, determined by the operating conditions. In the process of searching for and pointing the measuring device at the radiation object, a position must be found at which the maximum LI levels are recorded. When the laser is operating in a repetitively pulsed mode, the energy characteristics of the maximum pulse of the series are measured.

In the hygienic assessment of laser installations, it is required to measure not the output radiation parameters, but the intensity of irradiation of critical human organs (eyes, skin), which affects the degree of biological action. These measurements are carried out at specific points (zones) in which the presence of service personnel is determined by the program of the laser installation and the levels of reflected or scattered LI cannot be reduced to zero.

The measurement limits of dosimeters are determined by the values ​​of the remote control and the technical capabilities of modern photometric equipment. In Russia, special measuring instruments have been developed for dosimetric control of LI - laser dosimeters. They are distinguished by high versatility, which consists in the ability to control both directional and scattered continuous, monopulse and repetitively pulsed radiation of most laser systems used in practice.

Laser dosimeter ILD-2M (ILD-2) provides measurement of laser radiation parameters in the spectral ranges of 0.49 - 1.15 and 2 - 11 microns. ILD-2M allows you to measure energy (W) and energy exposure (H) from monopulse and repetitively pulsed radiation, power (P) and irradiance (E) from continuous laser radiation. The disadvantages of the ILD-2M device include relatively large dimensions and weight. For industrial research, portable laser dosimeters LD-4 and LADIN are more suitable, which provide measurement of reflected and scattered laser radiation in the spectral range of 0.2 - 20 μm.

The presence of other hazardous and harmful production factors is largely determined by the hazard class of the laser. Their control is carried out in accordance with the current regulatory and methodological documents.

PREVENTION OF HARMFUL EFFECTS OF LASER RADIATION