Positive and negative effects of laser radiation on the human body. What is laser radiation? Laser radiation: its sources and protection from it

28.09.2019

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All our emitters (co2 laser tubes) are tested by the American testing device Synrad Laser Wizard.

IN laser machines made in China, the CO2 emitter (gas tube, (sealed co2 laser) is a consumable item, unlike refillable CO2 emitters from European and American manufacturers, the cost of the emitter is lower than the refilling procedure. But the main advantage is the speed of restoration of the equipment. If to refill the laser, It will take you a week, then the procedure for replacing a Chinese laser emitter will take you 10-20 minutes.

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Reci laser emitters (RECI laser tubes) differ from standard emitters in their increased service life. Despite their slightly higher price, they are more economically advantageous when calculating the operating time/price ratio. For installation in machines equipped for conventional laser emitters, n..

The most common, inexpensive CO2 laser emitters. Despite the cost, they have proven to be a reliable solution for most tasks related to laser cutting and engraving. We supply only high-quality emitters, with mandatory testing before sale using a special device..

Laser radiation– these are narrowly targeted forced energy flows. It can be continuous, of one power, or pulsed, where the power periodically reaches a certain peak. Energy is generated using a quantum generator - a laser. The flow of energy is electromagnetic waves, which propagate parallel to each other. This creates minimum angle

light scattering and a certain precise directionality.

The properties of laser radiation allow it to be used in various fields human life:

science - research, experiments, experiments, discoveries;
military defense industry and space navigation;
production and technical sphere;
local heat treatment– welding, cutting, engraving, soldering;
household use – laser sensors for barcode reading, CD readers, pointers;
laser spraying to increase the wear resistance of metal;
creation of holograms;
improvement of optical devices;
chemical industry - starting and analyzing reactions.

Application of laser in medicine

Laser radiation in medicine is a breakthrough in the treatment of patients requiring surgical intervention. Lasers are used to produce surgical instruments.

The undeniable advantages of surgical treatment with a laser scalpel are obvious. It allows you to make a bloodless soft tissue incision. This is ensured by the instantaneous adhesion of small vessels and capillaries. When using such an instrument, the surgeon fully sees the entire surgical field. The laser energy stream dissects at a certain distance, without contacting the internal organs and vessels.

An important priority is to ensure absolute sterility. The strict direction of the rays allows operations to be performed with minimal trauma. The rehabilitation period for patients is significantly reduced. A person’s ability to work returns faster. Distinctive feature The use of a laser scalpel is painless in the postoperative period.

Development laser technologies allowed to expand the possibilities of its application. The properties of laser radiation to positively influence the condition of the skin were discovered. Therefore, it is actively used in cosmetology and dermatology.

Depending on its type, human skin absorbs and reacts to rays differently. Laser radiation devices can create the desired wavelength in each specific case.

Application:

epilation – destruction of the hair follicle and hair removal;
acne treatment;
removal of age spots and birthmarks;
skin polishing;
use for bacterial damage to the epidermis (disinfects, kills pathogenic microflora), laser radiation prevents the spread of infection.

Ophthalmology is the first industry to use laser radiation. Directions in the use of lasers in eye microsurgery:

laser coagulation - the use of thermal properties for treatment vascular diseases eyes (damage to blood vessels of the cornea, retina);
photodestruction – tissue dissection at the peak of laser power (secondary cataract and its dissection);
photoevaporation - prolonged exposure to heat, used for inflammatory processes of the optic nerve, for conjunctivitis;
photoablation - gradual removal of tissue, used to treat dystrophic changes in the cornea, eliminates its clouding, surgical treatment of glaucoma;
laser stimulation – has an anti-inflammatory, absorbable effect, improves trophism of the eye, is used to treat scleritis, exudation in the eye chamber, hemophthalmos.

Laser irradiation is used for oncological diseases skin. The laser is most effective for removing melanoblastoma. Sometimes the method is used to treat stage 1-2 esophageal or rectal cancer. For deep tumors and metastases, the laser is not effective.

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What danger does laser pose to humans?

The effect of laser radiation on the human body can be negative. Irradiation can be direct, diffuse and reflected. Negative Impact provided by the light and thermal properties of rays. The degree of damage depends on several factors - the length of the electromagnetic wave, the location of the impact, the absorption capacity of the tissue.

The eyes are most susceptible to the effects of laser energy. The retina of the eye is very sensitive, so burns often occur. The consequences are partial loss of vision, irreversible blindness. The source of laser radiation is infrared visible light emitters.

Symptoms of laser damage to the iris, retina, cornea, lens:

pain and spasms in the eye;
swelling of the eyelids;
hemorrhages;
cataract.

Medium-intensity irradiation causes thermal burns to the skin. At the point of contact between the laser and the skin, the temperature rises sharply. Boiling and evaporation of intracellular and interstitial fluid occurs. The skin becomes red. Under pressure, tissue structures rupture. Swelling appears on the skin, and in some cases intradermal hemorrhages. Subsequently, necrotic (dead) areas appear at the burn site. IN severe cases Charring of the skin occurs instantly.

A distinctive sign of a laser burn is the clear boundaries of the skin lesion, and blisters form in the epidermis, and not under it.

With diffuse skin lesions at the site of the lesion, it becomes insensitive, and erythema appears after a few days.

Infrared laser radiation can penetrate deep into tissue and damage internal organs. The characteristic of a deep burn is the alternation of healthy and damaged tissue. Initially, when exposed to rays, a person does not experience pain. The most vulnerable organ is the liver.

The effect of radiation on the body as a whole causes functional disorders of the central nervous systems s, cardiovascular activity.

Signs:

changes in blood pressure;
increased sweating;
unexplained general fatigue;
irritability.

Precautions and protection against laser radiation

People whose activities involve the use of quantum generators are most at risk of exposure.

In accordance with sanitary standards, laser radiation is divided into four hazard classes. For the human body, the danger is the second, third, fourth classes.

Technical methods of protection against laser radiation:

Correct layout of industrial premises, interior decoration must comply with safety regulations (laser beams must not be reflected specularly).
Appropriate placement of radiating installations.
Fencing the area of possible exposure.
Procedure and compliance with the rules of maintenance and operation of equipment.

Another laser protection is individual. It includes the following equipment: laser glasses, protective covers and screens, a set of protective clothing (technological gowns and gloves), lenses and prisms that reflect rays. All employees must regularly undergo preventive medical examinations.

Using a laser at home can also be hazardous to health. Improper use of light pointers and laser flashlights can cause irreparable harm to a person. Protection against laser radiation provides simple rules:

Do not direct the radiation source at glass or mirrors.
It is strictly forbidden to direct the laser into the eyes of yourself or another person.
Gadgets with laser radiation must be stored out of the reach of children.

The action of a laser, depending on the modification of the emitter, can be thermal, energetic, photochemical and mechanical. The greatest danger is posed by a laser with direct radiation, with high intensity, narrow and limited beam direction, high density radiation. TO hazardous factors factors that contribute to exposure include high production voltage, air pollution, intense noise, x-ray radiation. Biological effects from laser radiation are divided into primary (local burn) and secondary (nonspecific changes as a response of the whole organism). It should be remembered that the thoughtless use of homemade lasers, light pointers, lamps, laser flashlights can cause irreparable harm to others.

Laser radiation is electromagnetic radiation generated in the wavelength range l = 180...105 nm. Laser systems have become widespread.

Laser radiation is characterized by monochromaticity (radiation of almost the same frequency), high coherence (preservation of the oscillation phase), extremely low energy divergence of the beam and high concentration of radiation energy in the beam.

The biological effects of laser radiation on the body are determined by the mechanisms of interaction of radiation with tissues and depend on the radiation wavelength, pulse duration (exposure), pulse repetition rate, area of the irradiated area, as well as on the biological and physicochemical characteristics of the irradiated tissues and organs. There are thermal, energetic, photochemical and mechanical (shock-acoustic) effects, as well as direct and reflected (mirror and diffuse) radiation. For the eyes, skin and internal tissues of the body, the greatest danger is posed by energy-saturated direct and specularly reflected radiation. In addition, there are negative functional changes in the functioning of the nervous and cardiovascular systems, endocrine glands, changes arterial pressure, fatigue increases.

Laser radiation with a wavelength from 380 to 1400 nm is most dangerous for the retina of the eye, and radiation with a wavelength from 180 to 380 nm and over 1400 nm is most dangerous for the anterior media of the eye. Skin damage can be caused by radiation of any wavelength in the considered range (180...105 nm).

The tissues of a living organism at low and medium irradiation intensities are almost impenetrable to laser radiation. Therefore, the surface (skin) integuments are most susceptible to its effects. The degree of this effect is determined by the wavelength and intensity of the radiation.

At high intensities of laser irradiation, damage not only to the skin, but also to internal tissues and organs is possible. These injuries are characterized by edema, hemorrhage, tissue necrosis, as well as coagulation or breakdown of blood. In such cases, damage to the skin turns out to be relatively less pronounced than changes in the internal tissues, and no pathological changes are noted in the adipose tissues at all.

Biological effects that occur when exposed to laser radiation on the body are conventionally divided into groups:

a) primary effects - organic changes that occur directly in irradiated living tissues (direct irradiation);

b) secondary effects - nonspecific changes that occur in the body in response to radiation (long-term exposure to diffusely reflected radiation).

When operating laser systems, a person may be exposed to the following dangerous and harmful factors, caused both by the laser radiation itself and the specifics of its formation:

laser radiation (direct, reflected, scattered);
associated with the operation of the installation, ultraviolet, visible and infrared radiation structural components;
high voltage in control and power supply circuits;
EMF industrial frequency and radio frequency range;
X-ray radiation from gas-discharge tubes and elements operating at an anode voltage of more than 5 kV;
noise and vibration;
toxic gases and vapors formed in laser elements and during the interaction of the beam with the environment;
products of interaction of laser radiation with processed materials;
elevated temperature surfaces of the laser product and in the irradiation zone;
danger of explosion in laser pumping systems;
the possibility of explosion and fire when the beam interacts with flammable material.

According to the degree of danger of radiation for human biological structures, lasers are divided into four classes.

To lasers 1st class are completely safe lasers. Their radiation does not pose a danger to the eyes and skin.

Lasers 2 classes- These are lasers, the beam of which poses a danger when irradiating human skin or eyes. However, diffusely reflected radiation is safe for both skin and eyes.

Lasers 3 classes pose a danger when irradiating the eyes and skin with direct, specularly reflected radiation. Diffusely reflected radiation is dangerous for the eyes at a distance of 10 cm from the diffusely reflective surface, but is safe for the skin.

At lasers 4 classes Diffusely reflected radiation at a distance of 10 cm from a diffusely reflective surface poses a danger to the eyes and skin.

Lasers are classified by the manufacturer according to their output radiation characteristics.

When operating installations of classes 2-4, laser safety measures, dosimetric monitoring of laser radiation, sanitary and hygienic measures and medical control should be provided.

Laser safety- is a set of technical, sanitary and hygienic, treatment and prophylactic and organizational events, ensuring safe and harmless working conditions when operating laser systems.

Laser radiation is regulated according to maximum permissible irradiation levels (MALs) in accordance with “Sanitary standards and rules for the design and operation of lasers” No. 5804-91 . Maximum radiation levels with a single exposure can lead to an insignificant probability of reversible abnormalities in the worker’s body. Maximum radiation levels during chronic exposure do not lead to deviations in the state of human health both during work and in the long-term life of the present and subsequent generations.

The normalized parameters are irradiance E, energy exposure H, energy W and radiation power P.

Irradiance is the ratio of the radiation flux incident on a small surface area to the area of this area, W/m2.

Energy exposition determined by the irradiance integral over time, J/m2.

Laser radiation remote control units are set for three wavelength ranges (180...380, 381...1400, 1401...105 nm) and cases of irradiation: single (with exposure time up to one shift), series of pulses and chronic (systematically repeated). In addition, when standardizing, the object of irradiation is taken into account (eyes, skin, eyes and skin at the same time).

When using lasers in theatrical and entertainment events, for demonstration in educational institutions, for illumination and other purposes in medical devices, not directly related to the therapeutic effect of radiation, MRLs for all irradiated persons are established in accordance with the standards for chronic exposure.

Laser products, taking into account their hazard classes, are subject to different requirements. For example, lasers of classes 3 and 4 must contain dosimetric equipment, and their design must

enable remote control. Laser medical products must be equipped with a means to measure the level of radiation exposed to patients and personnel. Lasers of classes 3 and 4 are prohibited from being used in theatrical and entertainment events, in educational institutions and in open spaces. The class of the laser product is taken into account in the requirements for its operation.

Laser products and laser radiation propagation zones must be marked with laser hazard signs with explanatory notes depending on the class of the laser.

Safety when working with open laser products ensured through the use of PPE. Safety when using lasers for demonstration purposes, theatrical entertainment events and open space is ensured by organizational and technical measures (development of a laser placement scheme, taking into account the trajectory of laser beams, strict control over compliance with the rules, etc.).

When using glasses for protection against laser radiation, the illumination levels of workplaces must be increased by one level in accordance with SNiP 23-05-95.

Protective equipment (collective and individual) is used to reduce the levels of laser radiation affecting humans to values below the maximum permissible level. The choice of protective equipment is carried out taking into account the parameters of laser radiation and operating features. PPE against laser radiation includes eye and face protection (safety glasses selected taking into account the radiation wavelength, shields, attachments), hand protection, and special clothing.

Personnel working with laser products must undergo preliminary and periodic (once a year) medical examinations. Persons over 18 years of age and without medical contraindications are allowed to work with lasers.

Laser radiation (LI) - forced emission of electromagnetic radiation quanta by atoms of matter. The word "laser" is an abbreviation formed from the initial letters English phrase Light amplification by stimulated emission of radiation (light amplification by creating stimulated radiation). The main elements of any laser are the active medium, the energy source for its excitation, a mirror optical resonator and a cooling system. Due to the monochromatic nature and low divergence of the beam, LR is capable of propagating over considerable distances and being reflected from the interface between two media, which makes it possible to use these properties for the purposes of location, navigation and communication.

The ability of lasers to create exceptionally high energy exposures allows them to be used for processing various materials (cutting, drilling, surface hardening, etc.).

When used as an active medium various substances Lasers can induce radiation at almost all wavelengths, from ultraviolet to long-wave infrared.

The main physical quantities characterizing LR are: wavelength (μm), irradiance (W/cm 2), exposure (J/cm 2), pulse duration (s), exposure duration (s), pulse repetition frequency (Hz) .

Biological effect of laser radiation. The effect of LI on humans is very complex. It depends on the parameters of laser radiation, 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 characteristics of the irradiated tissue (eye, skin). Since the organic molecules that make up biological tissue have a wide range of absorbed frequencies, there is no reason to believe that the monochromatic nature of LR can create any specific effects when interacting with tissue. Spatial coherence also does not significantly change the mechanism of damage

radiation, since the phenomenon of thermal conductivity in tissues and the constant small movements inherent in the eye destroy the interference pattern even with a duration of exposure exceeding several microseconds. Thus, LI is transmitted and absorbed by biological tissues according to the same laws as incoherent radiation, and does not cause any specific effects in tissues.

The LR 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.

PI pose a danger to 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 does not reach the retina, but can damage the cornea, iris, and lens. Reaching the retina, the LR is focused by the refractive system of the eye, and the power density on the retina increases 1000-10000 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 significantly shorter period of time than that required for the activation of protective physiological mechanisms (blink reflex 0.1 s).

The second critical organ to the action of LI is 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. Far-infrared radiation 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 laser radiation) scattered radiation can lead to the development of nonspecific changes in the health of persons servicing lasers. Moreover, it is a unique 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 vegetative-vascular dystonia.

Rationing LI. In the process of standardization, the parameters of the LR field are established, reflecting the specifics of its interaction with biological tissues, criteria for harmful effects and numerical values of the maximum limit of the normalized parameters.

Two approaches to the regulation of radiation exposure 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, determined, first of all, by the region of the electromagnetic spectrum. In accordance with this, the LI range is divided into a series areas:

From 0.18 to 0.38 microns - ultraviolet region;

From 0.38 to 0.75 microns - visible region;

From 0.75 to 1.4 microns - near infrared region;

Above 1.4 microns - far infrared region.

The basis for establishing the MPL value is the principle of determining the minimum “threshold” damage in irradiated tissues (retina, cornea, eyes, skin), determined modern methods studies during or after exposure to LI. The normalized parameters are energy exposure N (J-m -2) and irradiation E (W-m -2), as well as energy W (J) and power R (W).

Data from experimental and clinical-physiological studies indicate the prevailing importance of general nonspecific reactions of the body in response to chronic exposure to low-energy levels of LR compared to local changes in the organ of vision and skin. In this case, LR in the visible region of the spectrum causes shifts in the functioning of the endocrine and immune systems, central and peripheral nervous systems, protein, carbohydrate and lipid metabolism. LI with a wavelength of 0.514 μm leads to changes in the activity of the sympathoadrenal and pituitary-adrenal systems. Long-term chronic exposure to laser radiation with a wavelength of 1.06 μm causes vegetative-vascular disorders. Almost all researchers who have studied the health status of people servicing lasers emphasize a higher frequency of detection of asthenic and vegetative-vascular disorders in them. Therefore, low energy

With chronic action, LI 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 LI remote control units in Russia for individual wavelengths were installed in 1972, and in 1991 the “Sanitary norms and rules for the design and operation of lasers” SN and P were put into effect? 5804. In the USA there is a standard ANSI-z.136. A standard has also been developed International Electrotechnical Commission(IEC) - Publication 825. A distinctive feature of the domestic document compared to foreign ones is the regulation of MPL values, taking into account not only the damaging effects of the eyes and skin, but also functional changes in the body.

A wide range of wavelengths, a variety of LR parameters and caused biological effects complicate the task of substantiating hygienic standards. In addition, experimental and especially clinical testing require a long time and money. Therefore, mathematical modeling is used to solve problems related to refining and developing LI remote control systems. This allows us to significantly reduce the volume of experimental studies on laboratory animals. When creating mathematical models, the nature of energy distribution and 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 fundus tissues when exposed to visible and near-IR radiation with pulse durations from 1 to 10 -12 s was used to determine and refine PDU LI, included in the latest edition of the “Sanitary norms and rules for the design and operation of lasers” SNiP? 5804-91, which are developed based on the results of scientific research.

The current rules establish:

Extremely permissible levels(remote control) laser radiation in the wavelength range 180-10 6 nm at different conditions impact on humans;

Classification of lasers according to the degree of danger of the radiation they generate;

Requirements to production premises, placement of equipment and organization of workplaces;

Personnel requirements;

Monitoring the state of the production environment;

Requirements for the use of protective equipment;

Requirements for medical control.

The degree of danger of radiation exposure for personnel is the basis for the classification of lasers, according to which they are divided into 4 classes:

1st - class (safe) - output radiation is not dangerous to the eyes;

2nd - class (low-hazard) - both direct and specularly reflected radiation pose a danger to the eyes;

3rd - class (medium hazardous) - diffusely reflected radiation at a distance of 10 cm from the reflecting surface also poses a danger to the eyes;

4th - class (highly dangerous) - already poses a danger to the skin at a distance of 10 cm from the diffusely reflective surface.

Requirements for methods, measuring instruments and control of radiation exposure. LR dosimetry is a set of methods for determining the values of laser radiation parameters in given point space in order to identify the degree of danger and harmfulness to the human body

Laser dosimetry includes two main sections:

- calculated or theoretical dosage measurement, which considers methods for calculating the parameters of LI in the area where operators may be located and methods for calculating the degree of its danger;

- experimental dosimetry, considering methods and means of directly measuring LI parameters at a given point in space.

Measuring instruments intended for dosimetric monitoring are called laser dosimeters. Dosimetric control acquires special meaning for assessing reflected and scattered radiation, when calculation methods of laser dosimetry, based on data from the output characteristics of laser installations, give very approximate values of LR levels at a given control point. The use of calculation methods is dictated by the inability to measure laser parameters for the entire variety of laser technology. The calculation method of laser dosimetry allows one to assess the degree of danger of radiation at a given point in space, using passport data in calculations. Calculation methods are convenient for cases of working with rarely repeating short-term radiation pulses, when the limitations

It is possible to measure the maximum exposure value. They are used to identify laser-hazardous areas, as well as to classify lasers according to the degree of danger of the radiation they generate.

Dosimetric monitoring methods are established in " Guidelines for bodies and institutions of sanitary and epidemiological services for conducting dosimetric monitoring and hygienic assessment of laser radiation" ?

5309-90, and also partially discussed in the “Sanitary norms and rules for the design and operation of lasers” SN and P? 5804-91.

When hygienically assessing laser installations, it is necessary to measure not the radiation parameters at the laser output, 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 operating program of the laser installation determines the presence of maintenance personnel and in which the levels of reflected or scattered radiation cannot be reduced to zero.

The measurement limits of dosimeters are determined by the MPL values and the technical capabilities of modern photometric equipment. All dosimeters must be certified by Gosstandart authorities in in the prescribed manner. Developed in Russia special means measurements for radiation dosimetric monitoring - laser dosimeters. They are distinguished by their high versatility, which consists in the ability to control both directed and scattered continuous, monopulse and pulse-periodic radiation from most laser installations used in practice in industry, science, medicine, etc.

Prevention of the harmful effects of laser radiation (LR). Protection against PI is carried out using technical, organizational and therapeutic methods and means. Methodological tools include:

Selection, layout and interior decoration of premises;

Rational placement of laser technological installations;

Compliance with the procedure for servicing installations;

Using the minimum level of radiation to achieve the goal;

Use of protective equipment. Organizational methods include:

Limiting the time of exposure to radiation;

Appointment and instruction of persons responsible for organizing and carrying out work;

Restriction of access to work;

Organization of supervision over the work schedule;

Clear organization of emergency work and regulation of the procedure for conducting work in emergency conditions;

Conducting briefings, providing visual posters;

Training.

Sanitary, hygienic and therapeutic and preventive methods include:

Monitoring levels of hazardous and harmful factors at workplaces;

Monitoring the passage of preliminary and periodic medical examinations by personnel.

Production facilities in which lasers are operated must meet the requirements of current regulations. sanitary standards and rules. Laser installations are placed in such a way that radiation levels in the workplace are minimal.

Means of protection against radiation must ensure the prevention of exposure or reduction in the amount of radiation to a level not exceeding the permissible level. According to the nature of application, protective equipment is divided into collective protective equipment(SKZ) and facilities personal protection (PPE). Reliable and effective means

protection helps improve labor safety, reduce industrial injuries and occupational morbidity.Table 9.1.

Protective glasses from laser radiation (extract from TU 64-1-3470-84) VCS from LI include: fencing, protective screens

, locks and automatic shutters, casings, etc. PPE against laser radiation include safety glasses(Table 9.1),

shields, masks, etc. Protective equipment is used taking into account the wavelength of the laser radiation, class, type, operating mode of the laser installation, and the nature of the work performed. SCP should be provided at the stages of design and installation of lasers (laser installations), when organizing workplaces, when choosing operational parameters . The choice of protective equipment should be made depending on the class of the laser (laser installation), the radiation intensity in work area

, the nature of the work performed. Indicators of protective properties of protection should not be reduced under the influence of other hazardous

and harmful factors (vibration, temperature, etc.). The design of protective equipment must provide the ability to change the main elements (light filters, screens, sight glasses, etc.). Personal protective equipment for eyes and face (safety glasses and shields) that reduce the intensity of radiation to the maximum permissible level should be used only in those cases (commissioning, repair and experimental work

) when collective means do not ensure the safety of personnel.

When working with lasers, only such protective equipment should be used for which there is regulatory and technical documentation approved in the prescribed manner. Lasers are becoming more and more important tools

research in medicine, physics, chemistry, geology, biology and technology. If used improperly, they can cause blinding and injury (including burns and electrical shock) to operators and other personnel, including bystanders in the laboratory, as well as significant property damage. Users of these devices must fully understand and apply the necessary safety precautions when handling them.

The word "laser" (LASER, Light Amplification by Stimulated Emission of Radiation) is an abbreviation that stands for "light amplification by stimulated emission of radiation." The frequency of the radiation generated by a laser is within or near the visible part of the electromagnetic spectrum. The energy is amplified to extremely high intensity through a process called laser-induced emission.

The term radiation is often misunderstood because it is also used to describe In this context, it means the transfer of energy. Energy is transferred from one place to another through conduction, convection and radiation.

There are many various types lasers operating in different environments. The working medium used is gases (for example, argon or a mixture of helium and neon), solid crystals (for example, ruby) or liquid dyes. When energy is supplied to the working medium, it becomes excited and releases energy in the form of particles of light (photons).

A pair of mirrors at either end of a sealed tube either reflects or transmits light in a concentrated stream called a laser beam. Each operating environment produces a beam of unique wavelength and color.

The color of laser light is typically expressed by wavelength. It is non-ionizing and includes ultraviolet (100-400 nm), visible (400-700 nm) and infrared (700 nm - 1 mm) parts of the spectrum.

Electromagnetic spectrum

Each electromagnetic wave has a unique frequency and length associated with this parameter. Just as red light has its own frequency and wavelength, all other colors - orange, yellow, green and blue - have unique frequencies and wavelengths. Humans are able to perceive these electromagnetic waves, but are unable to see the rest of the spectrum.

Ultraviolet radiation also has the highest frequency. Infrared, microwave radiation and radio waves occupy the lower frequencies of the spectrum. Visible light lies in a very narrow range between the two.

impact on humans

The laser produces an intense, directed beam of light. If directed, reflected, or focused onto an object, the beam will be partially absorbed, raising the temperature of the surface and interior of the object, which can cause the material to change or deform. These qualities, which are used in laser surgery and materials processing, can be dangerous to human tissue.

In addition to radiation that has a thermal effect on tissue, laser radiation that produces a photochemical effect is dangerous. Its condition is a sufficiently short, i.e., ultraviolet or blue part of the spectrum. Modern devices produce laser radiation, the impact of which on humans is minimized. Low-power lasers do not have enough energy to cause harm, and they do not pose a danger.

Human tissue is sensitive to energy, and under certain circumstances electromagnetic radiation, including laser, can cause damage to the eyes and skin. Studies have been conducted on threshold levels of traumatic radiation.

Eye hazard

The human eye is more susceptible to injury than the skin. The cornea (the clear outer front surface of the eye), unlike the dermis, does not have an outer layer of dead cells to protect it from damage. environment. The laser is absorbed by the cornea of the eye, which can cause harm to it. The injury is accompanied by swelling of the epithelium and erosion, and in case of severe injuries - clouding of the anterior chamber.

The lens of the eye can also be susceptible to injury when it is exposed to various laser radiation - infrared and ultraviolet.

The greatest danger, however, is the impact of the laser on the retina in the visible part of the optical spectrum - from 400 nm (violet) to 1400 nm (near infrared). Within this region of the spectrum, collimated beams are focused onto very small areas of the retina. The most unfavorable impact occurs when the eye looks into the distance and is hit by a direct or reflected beam. In this case, its concentration on the retina reaches 100,000 times.

Thus, a visible beam with a power of 10 mW/cm 2 affects the retina with a power of 1000 W/cm 2. This is more than enough to cause damage. If the eye does not look into the distance, or if the beam is reflected from a diffuse, mirror surface, significantly more powerful radiation leads to injury. Laser exposure to the skin does not have a focusing effect, so it is much less susceptible to injury at these wavelengths.

X-rays

Some high-voltage systems with voltages greater than 15 kV can generate X-rays of significant power: laser radiation, the sources of which are powerful electronically pumped ones, as well as plasma systems and ion sources. These devices must be tested to ensure proper shielding, among other things.

Classification

Depending on the power or energy of the beam and the wavelength of the radiation, lasers are divided into several classes. The classification is based on the device's potential to cause immediate injury to the eyes, skin, or fire when directly exposed to the beam or when reflected from diffuse reflective surfaces. All commercial lasers must be identified by markings applied to them. If the device was home-made or otherwise not marked, advice should be obtained regarding its appropriate classification and labeling. Lasers are distinguished by power, wavelength and exposure duration.

Secure Devices

First class devices generate low-intensity laser radiation. It cannot reach dangerous levels, so sources are exempt from most controls or other forms of surveillance. Example: laser printers and CD players.

Conditionally safe devices

Second class lasers emit in the visible part of the spectrum. This is laser radiation, the sources of which cause a normal reaction of rejection in humans. bright light(blink reflex). When exposed to the beam, the human eye blinks within 0.25 s, which provides sufficient protection. However, laser radiation in the visible range can damage the eye with constant exposure. Examples: laser pointers, geodetic lasers.

Class 2a lasers are devices special purpose with an output power of less than 1 mW. These devices only cause damage when directly exposed for more than 1000 seconds in an 8-hour workday. Example: barcode readers.

Dangerous lasers

Class 3a includes devices that do not cause injury during short-term exposure to an unprotected eye. May pose a hazard when using focusing optics such as telescopes, microscopes or binoculars. Examples: 1-5 mW helium-neon laser, some laser pointers and building levels.

Class 3b laser beam may cause injury from direct exposure or mirror image. Example: Helium-neon laser 5-500 mW, many research and therapeutic lasers.

Class 4 includes devices with power levels greater than 500 mW. They are dangerous to the eyes, skin, and are also a fire hazard. Exposure to the beam, its specular or diffuse reflections can cause eye and skin injuries. All safety measures must be taken. Example: Nd:YAG lasers, displays, surgery, metal cutting.

Laser radiation: protection

Each laboratory must provide adequate protection for persons working with lasers. Room windows through which radiation from a Class 2, 3, or 4 device may pass through causing harm in uncontrolled areas must be covered or otherwise protected while such device is operating. To ensure maximum eye protection, the following is recommended.

The bundle must be enclosed in a non-reflective, non-flammable protective enclosure to minimize the risk of accidental exposure or fire. To align the beam, use fluorescent screens or secondary sights; Avoid direct contact with eyes.
Use the lowest power for the beam alignment procedure. If possible, use low-class devices for preliminary alignment procedures. Avoid the presence of unnecessary reflective objects in the laser operating area.
Limit the passage of the beam into the danger zone during non-working hours using shutters and other barriers. Do not use room walls to align the beam of Class 3b and 4 lasers.
Use non-reflective tools. Some equipment that does not reflect visible light becomes mirrored in the invisible region of the spectrum.
Don't wear reflective jewelry. Metal jewelry also increases the risk of electric shock.

Protective glasses

Safety glasses should be worn when working with Class 4 lasers with an open hazardous area or where there is a risk of reflection. Their type depends on the type of radiation. Glasses should be selected to protect against reflections, especially diffuse reflections, and to provide protection to a level where the natural protective reflex can prevent eye injury. Such optical instruments will maintain some visibility of the beam, prevent skin burns, and reduce the possibility of other accidents.

Factors to consider when choosing safety glasses:

wavelength or region of the radiation spectrum;
optical density at a certain wavelength;
maximum illumination (W/cm2) or beam power (W);
type of laser system;
power mode - pulsed laser radiation or continuous mode;
reflection possibilities - specular and diffuse;
line of sight;
the presence of corrective lenses or sufficient size to allow the wearing of glasses for vision correction;
comfort;
Availability ventilation holes, preventing fogging;
influence on color vision;
impact resistance;
ability to perform necessary tasks.

Because safety glasses are susceptible to damage and wear, the laboratory safety program should include periodic inspection of these safety features.