Technologies are developing at an incredible pace. A few decades ago, a laser seemed like a fantasy, but today a laser pointer can literally be bought for pennies at a street kiosk.
But while lasers are becoming more and more firmly established daily life, it is worth remembering that careless handling of them is fraught with serious trouble. This review covers the dangers posed by lasers.
1. I was embarrassed and burned
Doctors at Tokyo Hospital medical university were performing cervical surgery on a 30-year-old female patient when she suddenly passed gas. The laser beam ignited the gases, causing the surgical drapery to catch fire, and then the fire quickly spread to the woman's waist and legs. The committee investigated the incident and concluded that all equipment was functional and used properly, but that it was simply an accident.
2. Five people per day
At West Laser and Cataract Surgery Center (West Springfield, Massachusetts), five patients suffered severe eye injuries when injected with anesthesia prior to laser eye surgery. On his first day work dr Tsai Chiu managed to harm the unfortunate patients. West Center management said he either lied about his qualifications or lacked adequate knowledge of the equipment. Chiu has since resigned and has been banned from practicing medicine in the United States.
3. Road accident
An Albany, Oregon woman was driving her husband to work when she was suddenly blinded by a laser light. Miranda Centers was temporarily blinded by the laser beam and crashed into a crash barrier. One of the drivers shined a light in the others' eyes laser pointer. This ultimately led to several accidents on the highway.
4. Up to five milliwatts!
Following an increase in plane and helicopter accidents involving laser pointers, the UK has decided to crack down on the dangerous devices. In most countries, lasers up to five milliwatts are considered safe. However, despite all the British bans, some high-performance Class 3 lasers are freely sold on the Internet. More than 150 eye injuries have already been reported due to these devices.
5. US Air Force shoots down a UAV
In June 2017, the US Army successfully tested laser cannons mounted on Apache helicopters. According to manufacturer Raytheon, this was the first time that a fully integrated laser system on board an aircraft successfully acquired and fired targets across a wide range of flight conditions, altitudes and speeds. The weapon has a range of about 1.5 km, is silent and invisible to people. They are also extremely accurate. The Army plans to use similar lasers to defend against any future drone attacks.
6. Pursuit of a football player
In 2016, in Mexico City, during an international NFL match between the Houston Texans (USA) and the Oakland Raiders (New Zealand), Texans quarterback Brock Osweiler was pursued by some careless fan. Every time Osweiler received the ball, one of the spectators would shine a green laser pointer in his face so that the player could not see where to run.
7. Viability of vehicle power supply
Despite millions of dollars spent on developing self-driving cars, one security researcher has raised serious questions about their viability in the near future. The scientist was able to interfere with the laser sensors of a self-driving car by simply shining a cheap laser pointer on them. The car system considered this an “invisible obstacle” and slowed the car down until it came to a complete stop.
8. Traumatic liposuction
During the procedure laser liposuction one of the patients received severe burns, and after this the clinic management tried to dissuade her from treatment. Dr. Muruga Raj instead told her that everything was fine, there was nothing to do about the burn, but just apply cream to the affected area. In the end, the case went to court.
9. Laser pointer and helicopter
Connor Brown, 30, only found out when he was charged. A police helicopter was searching for a man causing a disturbance in the park when Brown pointed a laser pointer at his cabin. Both crew members were blinded and the mission had to be aborted to take the police to the hospital. Brown eventually called his action “a terrible mistake for which there is no justification.”
10. Burnt fingers
The Australian wanted to remove some tattoos from his knuckles, but it all ended with severe burns. The doctor said he would need ten to twelve sessions of $170 laser surgery to remove the "Live Free" sign from his fingers, but an anonymous patient began asking questions after nearly 20 sessions failed desired results. The doctor tried to speed things up a little and set the laser machine to the highest power. As a result, my fingers were burned 3 mm.
Sep 17
What happens if a laser beam hits the eye? Or a few words about safety when performing laser procedures in cosmetology
It was 50 years ago that laser was used only to remove tumors, and then only on the face and body. Since the advent of devices with finer settings, anti-aging and tattoo removal procedures began to affect the areas of the eyebrows, the outer corners of the eye, and the ciliary edges of the eyelid. But the eye is not far away! Is it dangerous or not? What happens if the laser does get into the eye? How to eliminate risks for the patient and the doctor?
Lasers are different
Medical laser systems have 4 hazard classes:
- Class 1 considered incapable of generating damaging levels of radiation during operation. It is safe under all conditions of normal use with the naked eye or magnifying optics. These systems are exempt from any controls or other types of surveillance. An example is lasers used in diagnostic laboratories. Class 1M is considered unable to produce hazardous conditions exposure during normal operation if the beam is not viewed using magnifying optics.
- Class 2– low power laser systems; they emit light in the visible part of the spectrum (400-700 nm) and are considered safe because the defense mechanisms (our blink reflex) provide protection. An example is the helium-neon laser (laser pointers).
Class 2M - emits light in the visible part of the spectrum. Eye protection is normally provided by involuntary closing of the eyes when looking at them. However, these systems are potentially dangerous when viewed with some optical devices. - Medium Power Laser Systems class 3. They can be dangerous when viewed directly or when looking at a specular reflection of the beam. They are not sources of diffuse reflection and are not a fire hazard. An example of a Class 3 laser is the Nd:YAG laser used in ophthalmology.
There are 2 subclasses: 3R and 3B. Class 3R. May be dangerous under some direct and specular reflection conditions if the eye is properly focused and stable and there is little chance of actual damage. Class 3B. May be hazardous in direct and specular conditions. - Class 4. These are high power systems. They are the most dangerous; they can be sources of diffuse reflection and are a fire hazard. They can also produce dangerous plasma radiation. These are cosmetic lasers: carbon dioxide, neodymium, argon, alexandrite, pulsed dye laser (PDL).
Laser operating principle
Laser radiation wavelengths fall in the ultraviolet, visible and infrared ranges of the electromagnetic spectrum.
Almost all cosmetic lasers operate on the principle of selective photothermolysis. This means that their laser energy is absorbed by a specific chromophore:
- melanin – for diode, alexandrite and ruby lasers and dye lasers (PDL);
- hemoglobin – for neodymium in yttrium-aluminum garnet and PDL;
- water – for erbium and carbon dioxide lasers, while preserving the surrounding tissue.
For the laser to have the desired effect, three basic requirements must be met:
- Wavelength sufficient for a certain penetration depth.
- An exposure duration (laser pulse width and duration) less than or equal to the thermal relaxation time (TRT) of the target.
- Sufficient energy per unit area (fluence) to cause irreversible damage to the target chromophore.
The power, spot size and duration of the laser are also important. Yes, when larger size spots there is less scattering, but deeper tissue penetration.
Although lasers target specific chromophores, the surrounding scatter and the resulting thermal effect can cause side effects. Thermal damage occurs when sufficient energy is absorbed by a suitable chromophore with more high speed than the resulting heat can be dissipated. While core tissue chromophores are targeted, other ocular structures that are also rich in these chromophores are susceptible to unintentional damage. They can be the retina, rich in hemoglobin and melanin, the choroid, rich in melanin, the cornea and lens, which contain a lot of fluid.
Features of the eyelid and eye
When conducting laser procedures V surrounding the eye area you need to remember the following:
- The skin of the eyelids is very thin.
- The eye contains several targets for different laser beams. This is melanin in the retinal epithelium, the pigment of the iris, as well as water, which makes up most of the eyeball.
- The most vulnerable part of the eye is the retina: a laser beam 400-1400 nm long (and especially 700-1400 nm) is focused directly on it using the convexities of the lens and cornea. As a result, the retina receives 105 times more radiation than the cornea.
- There is such a thing as the Bell phenomenon: when the eye is closed, eyeball naturally rolls upward. In this way, the pigmented iris can enter the laser penetration range and absorb the radiation.
- Pain receptors are located very densely on the cornea. That is, even minor thermal damage leads to severe pain.
Light-eyed patients are especially susceptible to laser injury if the laser is used to target melanin. In them, all the radiation hits the retina immediately, without decreasing when passing through the epithelium of the iris.
How laser damages eye structures
Laser eye injury and the possible extent of damage varies and depends on the type of laser. Thus, devices operating on the basis of potassium titanyl phosphate (KTP) or dyes (PDL) are short in length. They are mainly absorbed by the cornea and lead to photocoagulation, that is, a photothermal effect. In this case, sufficient heat is generated in the eye tissue to denature proteins. The retinal temperature can increase from 40 to 60° C.
Lasers emitting long wavelengths - infrared, diode, Nd: YAG. They pass through the cornea to reach the lens and retina. Their effect is photomechanical, less often the phenomenon of photocoagulation. The photomechanical effect implies that an explosive acoustic shock is generated in the tissues, which can lead to the appearance of fragments and even perforation of individual structures.
For example, clinically the 1064 nm Nd:YAG laser, which causes most laser eye injuries, is capable of causing retinal hemorrhage, in vitreous, as well as scarring, preretinal adhesions, and retinopathy when radiation is absorbed by the melanin-rich retinal pigment epithelium. The Nd:YAG laser can cause significant damage to the eye and surrounding skin compared to shorter wavelength lasers because it can penetrate deeper layers of the skin.
The danger with long wavelength lasers (e.g. 755-795 nm alexandrite and 1064 nm Nd:YAG laser) is that their beam is invisible to the eye. This distinguishes them from shorter wavelength (eg KTP) lasers.
Erbium: The 2940 nm YAG laser is another ablative laser that can also be used fractionally. It is more efficiently absorbed by water and collagen and causes less thermal damage than CO2 laser. Complications of these lasers include erythema, hyper- and hypopigmentation of the iris, skin infections and corneal injury.
Lasers and the radiation from them have been used by humanity for quite some time. In addition to the medical operating environment, such devices have received wide application in technical industries. They were adopted by specialists from the field of decoration and special effects creation. Now not a single large-scale show is complete without a stage with laser beams.
A little later, such radiation ceased to take only industrial forms and began to be found in everyday life. But not everyone knows how the effect of laser radiation on the human body is reflected during regular and periodic irradiation.
What is laser radiation?
Laser radiation is generated according to the principle of light creation. In both cases, atoms are used. But in the situation with lasers there are others physical processes, and the impact can be traced electromagnetic field external type. Because of this, scientists call the radiation from lasers stimulated or stimulated.
In physics terminology, laser radiation refers to electromagnetic waves that propagate almost parallel to each other. Because of this, the laser beam has a sharp focus. In addition, such a beam has a small scattering angle together with a huge intensity of influence on the surface that is irradiated.
The main difference between a laser and a standard incandescent lamp is the spectral range. A lamp is considered a man-made light source that emits electromagnetic waves. The lighting spectrum of a classic lamp is almost 360 degrees.
The impact of laser irradiation on all living things
Contrary to stereotypes, the effect of laser radiation on the human body does not always mean something negative. Due to the widespread use of quantum generators in various spheres of life, scientists decided to use the capabilities of a narrow beam in medicine.
In the course of numerous studies, it became clear that laser irradiation has several characteristic properties:
- Damage from a laser can occur not only in the process of direct exposure to the body from the device. Even scattered radiation or reflected rays can cause damage.
- Between the degree of damage and the main parameters electromagnetic wave there is a direct connection. The location of the irradiated tissue also influences the severity of the lesion.
- The negative effect when energy is absorbed by tissues can be expressed in thermal or light effects.
But the sequence for laser damage always provides for an identical biological principle: 
- fever, which is accompanied by a burn;
- boiling of interstitial and cellular fluids;
- the formation of steam creating significant pressure;
- explosion and shock wave, destroying all tissue in the vicinity.
Often, an incorrectly used laser emitter poses, first of all, a threat to skin. If the influence was particularly strong, the skin will look swollen, with traces of numerous hemorrhages. There will also be large areas of dead cells on the body.
Such radiation also affects internal tissues. But with large-scale internal lesions The scattered impact of the rays is not as strong as direct or specularly reflected. Such damage will guarantee pathological changes in functioning various systems body.
The skin, which suffers the most, is the protection of the internal organs of every person. Because of this, he takes most of negative impact to myself. Depending on the different degrees Skin lesions will show redness or necrosis.
The researchers concluded that people with dark skin less susceptible to deep-seated lesions due to laser irradiation.
Schematically, all burns can be divided into four degrees, regardless of pigmentation:
- I degree. Involves standard epidermal burns.
- II degree. Includes burns of the dermis, which is expressed in the formation of characteristic blisters of the surface layer of the skin.
- III degree. Based on deep burns of the dermis.
- IV degree. The most dangerous degree, which is characterized by destruction of the entire thickness of the skin. Defeat covers subcutaneous tissue, as well as the layers adjacent to it.
Laser eye lesions
In second place in the unofficial ranking of the possible negative effects of laser on the human body are damage to the organs of vision. Short laser pulses can damage the following in a short period of time: 
- retina,
- cornea,
- iris,
- lens
There are several reasons for this impact. The main ones are:
- Inability to react in time. Due to the fact that the pulse duration is no more than 0.1 seconds, a person does not have time to blink. Because of this, the eye remains unprotected.
- Slight vulnerability. Due to their characteristics, the lens and cornea are considered vulnerable organs in themselves.
- Optical eye system. Due to the focusing of laser radiation on the fundus, the irradiation point, when it hits a retinal vessel, can clog it. Since there are no pain receptors there, damage cannot be detected instantly. Only after the burned area becomes larger does a person notice the absence of part of the image.
To quickly navigate a potential injury, experts advise listening to the following symptoms:
- eyelid spasms,
- swelling of the eyelids,
- painful sensations,
- hemorrhage in the retina,
- cloudiness.
Adding to the danger is the fact that retinal cells damaged by the laser lose the ability to recover. Since the intensity of radiation affecting the organs of vision is lower than the identical threshold for the skin, doctors urge caution.
Beware of infrared lasers different types, as well as devices that generate radiation with a power of over 5 mW. The rule applies to equipment that produces rays of the visible spectrum.
Relationship between laser wave and its field of application
Each of the areas of application of laser radiation is oriented towards a strictly defined wavelength.
This indicator directly depends on nature. Or rather, from electronic structure working fluid. This means that the medium in which its radiation is generated is responsible for the wavelength.
There are different types solid-state and gas lasers. The beams involved must be one of the three most common types:
- visible,
- UV,
- infrared.
In this case, the working irradiation range can vary from 180 nm to 30 mnm.
Features of the laser's influence on human body are based on wavelength. For example, a person reacts faster to a green laser than to a red one. The latter is not safe for all living things. The reason lies in the fact that our vision perceives green color almost 30 times more than red.
How to protect yourself from lasers?
In most cases, protection from laser radiation is needed by those people whose work is closely related to its constant use. If an enterprise has any type of quantum generator on its balance sheet, then its managers must instruct their employees.
Experts have developed a separate set of rules of conduct and safety that will protect employees from possible consequences radiation. The main rule is the availability of funds personal protection. Moreover, such means can vary dramatically depending on the predicted degree of danger.
In total, the international classification provides for a division into four hazard classes. The manufacturer must indicate the appropriate marking. Only the first class is considered relatively safe even for the visual organs.
The second class includes direct type radiation that affects the eye organs. Mirror reflection is also included in this category.
Class III radiation is much more dangerous. Its direct exposure threatens the eyes. Reflected diffuse type radiation at a distance of 10 cm from the surface is no less dangerous. Skin lesions will occur not only when direct influence, but also when mirrored.
In the fourth class, both skin and eyes suffer from various exposure formats.
Collective protective measures at work include: 
- special casings,
- protective screens,
- light guides,
- innovative tracking methods,
- alarms,
- blocking.
From relatively primitive, but effective ways allocate a fence for the area where irradiation is performed. This will protect workers from accidental exposure due to negligence.
Also, in particularly dangerous enterprises, it is mandatory to use personal protective equipment for employees. They mean a special set of workwear. While working, you cannot do without wearing glasses that provide a protective coating.
Laser gadgets and their radiation
Many people are unaware of how serious the consequences of uncontrolled exploitation can be. homemade devices with laser principle. This applies to homemade structures like laser ones:
- lamps,
- pointers,
- flashlights.
This is especially true for high school students who strive to conduct a series of experiments without having an idea of the safety rules when constructing them.
It is unacceptable to use homemade lasers in rooms where people are present. Also, do not direct the rays at glass, metal buckles or other objects that may produce reflections.
Even if the beam is of low intensity, it can lead to tragedy. If you point the laser at the driver's eyes while actively driving, he may go blind and not be able to control the car.
Under no circumstances should you look into the lens of a laser source. It is also worth considering that glasses for working with lasers must be designed for the wavelength that the selected devices will generate.
In order to prevent a serious tragedy, doctors are asked to listen to these recommendations and always follow them.
Laser is a very dangerous thing. Tissues and organs that are usually exposed to laser irradiation are the eyes and skin. There are three main types of tissue damage caused by laser irradiation. These are thermal effects, photochemical effects, as well as acoustic transient effects (only the eyes are affected).
- Thermal effects can occur at any wavelength and result from radiation or light effects on the cooling potential of tissue blood flow.
- In air, photochemical effects occur between 200 and 400 nm and ultraviolet wavelengths, as well as between 400 and 470 nm violet wavelengths. Photochemical effects are associated with the duration and also the repetition rate of the radiation.
- Acoustic transient effects associated with pulse duration can occur in short term pulses (up to 1 ms) depending on the specific laser wavelength. The acoustic impact of transient effects is poorly understood, but it can cause retinal damage that is distinct from thermal retinal injury.
Potential eye harm
Potential sites of eye injury (see Figure 1) are directly related to the wavelength of the laser light. Effect of laser radiation on the eye:
- Wavelengths shorter than 300 nm or greater than 1400 nm affect the cornea
- Wavelengths between 300 and 400 nm affect the aqueous humor, iris, lens and vitreous body.
- Wavelengths from 400 nm and 1400 nm are aimed at the retina.
NOTE: Laser damage to the retina can be very large due to the focal gain (optical gain) from the eyes, which is approximately 105. This means that radiation from 1 mW/cm2 through the eye will be effectively increased to 100 mW/cm2 when it reaches the retina .
At thermal burns eyes, the cooling function of the retinal vessels is disrupted. As a result of the damaging effects of the thermal factor, hemorrhages may occur in the vitreous body due to damage to blood vessels.
Although the retina can recover from minor damage, major injuries macular spot retinal damage can lead to temporary or permanent loss of visual acuity or complete blindness. Photochemical injury to the cornea by ultraviolet irradiation can lead to photokeratoconjunctivitis (often called welders' disease or snow blindness). This painful condition can last for several days with very debilitating pain. Long-term ultraviolet exposure can lead to the formation of cataracts.
The duration of exposure also affects eye injury. For example, if the laser is of visible wavelengths (400 to 700 nm), the beam power of which is less than 1.0 MW, and the exposure time is less than 0.25 seconds (the time during which a person closes the eye), there will be no damage to the retina. Class 1, 2A and 2 lasers fall under this category and generally cannot harm the retina. Unfortunately, direct or reflected hits from a Class 3A, 3B, or 4 laser, and diffuse reflections from lasers above Class 4 can cause damage before a person can reflexively close their eyes.
For pulsed lasers, the duration of the pulse also affects the potential for eye harm. Pulses of less than 1 ms upon impact on the retina can cause acoustic transient effects, resulting in significant damage and bleeding in addition to the expected thermal damage. Many pulsed lasers now have pulse times of less than 1 picosecond.
The ANSI standard defines the maximum permissible power (MWP) of laser exposure to the eye without any consequences (under the influence of specific conditions). If the MDM is exceeded, the likelihood of eye damage increases sharply.
The first rule of laser safety: NEVER LOOK AT THE LASER BEAM WITH YOUR EYES UNDER ANY CIRCUMSTANCES!
If you can prevent the laser beam and its reflections from entering the eye, you can avoid painful and possibly blinding injuries.
Potential harm to skin.
Skin injuries from lasers are primarily divided into two categories: thermal injuries (burns) from acute exposure to powerful laser beams and photochemical induced damage from chronic exposure scattered ultraviolet laser radiation.
- Heat injury can result from direct contact with the beam or its specular reflection. These injuries, although painful, are usually not serious and are usually easily preventable with proper control of the laser beam.
- Photochemical damage can occur over time from ultraviolet exposure to direct light, specular reflections, or even diffuse reflection.
The effects may be minor but can cause serious burns, and long-term exposure may contribute to the formation of skin cancer. Good safety glasses and clothing may be necessary to protect your skin and eyes.
Laser safety
When working with lasers, you must have glasses that protect against laser radiation. Are these special glasses really necessary? Many novice laser builders and buyers of laser pointers ask this question. Yes, safety glasses are needed even for a 15mW laser, since without them your eyes get very tired. Glasses cost about 1,600 rubles apiece, but I think you understand that your eyes are worth much more than you will pay for glasses. Do not use sunglasses to protect your eyes!
The same will happen to your eyes...
The degree of protection of glasses from laser radiation is measured in OD. What does OD stand for? OD stands for Optical Density. Optical density shows how many times the glasses attenuate light. One means "10 times". Accordingly, “optical density 3” means an attenuation of 1000 times, and 6 means an attenuation of a million. The correct optical density for a visible laser is such that after the glasses a direct hit from the laser leaves a power corresponding to class II (maximum somewhere around 1 mW). For the invisible, the more the better.
Domestic glasses of the ZN-22 S3-S22 brand protect against red and some infrared lasers. They are similar to welder's glasses, but have lenses blue color. You can sometimes buy them in Medtekhnika stores; they cost about 700 rubles. The disadvantage is that they are rubbery, heavy and ugly. If you're lucky, you can buy other domestic laser glasses. But they are rarely on sale.
On our website in the links section you can find many addresses of stores selling laser accessories, including safety glasses.
