Pulsed lasers are usually used for cleaning surfaces. They differ in nominal power (usually from 50 to 1000W), but an important parameter is also the pulse energy. This must overcome the activation energy necessary to break the chemical bonds in the molecules of the material being removed and to vaporize/sublimate it. The pulse energy of lower-class lasers is usually around 1mJ. Such lasers are used, for example, for cleaning museum exhibits. The middle class of lasers has a pulse power of around 10mJ. The higher category of lasers suitable for industrial applications has a pulse energy of up to 100mJ. In addition to the resonator itself, i.e. the actual source of laser radiation, the optical apparatus, optical fiber, mirror system that oscillates the laser beam onto the surface being cleaned, etc. are very important. A high-quality pulsed laser with lower power can be significantly more effective for cleaning than a cheap product with a high power on paper.

As with most electronic and optical devices, the difference between cheap products from the East and products from reputable manufacturers is both price and quality. Manufacturers from East Asia often use continuous radiation sources for cleaning lasers. These do not allow you to adjust basic parameters such as pulse energy, pulse length, and frequency. Such lasers usually have relatively high power, but it is not possible to adjust the parameters to the given cleaning process. It is essentially like removing dirt with a hacksaw - it works, but the resulting surface corresponds to it.

Yes, and very effectively. Soot, exhaust gases and carbon absorb light very well at the most commonly used wavelength of cleaning lasers, 1064nm , and very readily convert to a gaseous form. Surfaces such as wood or painted surfaces can also be cleaned with a laser. For example, exhaust gases and soot can be removed from facades and walls with a laser, and the effects of fires can be removed. Laser removal of exhaust gases in engines and exhaust systems is also effective.

Laser cleaning is contactless. As a rule, there is no damage to the cleaned surface, however, it is important to set the laser parameters correctly. For example, when cleaning historical objects of high value, such setting may take longer than the cleaning itself. Particular care should be taken when cleaning wood and materials with low thermal conductivity . When cleaning metal objects, secondary heating and subsequent dilation should be taken into account. However, the risk of damage is minimal compared to other cleaning methods, e.g. when cleaning molds, there is practically no wear even with many repeated cleanings . Similarly, the surface is not damaged on polished, brushed or otherwise structured surfaces. Laser cleaning is also very well applied, e.g. when cleaning steel surfaces in tokamaks and nuclear power plants , where the demands on surface preservation are extreme.

The price of laser cleaning is usually based on hourly rates. The price largely reflects the acquisition costs of cleaning lasers (many millions for powerful devices for industrial applications). On the other hand, laser cleaning does not pollute the environment, and it is very often not necessary to dismantle electrical connectors, bearings and other mechanical components, upholstery, etc. The resulting cleaning price can often be lower than with other methods.

The most common surfaces cleaned with a laser are made of various metals, steel, cast iron, stainless steel, aluminum, bronze , etc. Metal-coated surfaces can also be cleaned with a laser. Here, it is necessary to set the appropriate parameters of the pulse laser to avoid damage, however, cleaning is very effective here too. Inorganic building materials such as bricks, concrete, stone and glass (even through glass) or tiles can be cleaned very well. Cleaning wood is more complicated. It is necessary to take into account its low thermal conductivity and thermal stability, however, laser cleaning of wood is advantageous in many applications. For example, we tested the removal of fire-retardant varnishes, which are otherwise very difficult to sand. Surfaces where different materials are next to each other can be cleaned without any problems, e.g. steel with duralumin (alternators, starters, pumps, generators). With the appropriate settings, it is not necessary to dismantle and disassemble the cleaned objects, a sensitively adjusted laser will not damage electrical connectors, oil seals, bearings, etc.

Laser cleaning is based on the so-called laser ablation, when the vast majority of the removed material (usually more than 90%) passes into the gas phase, essentially vaporizing. One of the basic advantages of laser cleaning is that there is no contamination of the surroundings with abrasive dust, as in blasting, or with liquid, as in pressure water washing. Laser cleaning can be used in interiors, facades or structures in public (due to health and safety, it is only necessary to avoid the risk of exposure to the laser beam), in the immediate vicinity of generators, hydraulic equipment, etc. An absolutely minimal amount of secondary waste is generated, there is no spread of, for example, microplastics or particles from coatings containing heavy metals. Laser cleaning is very suitable for removing impurities near watercourses and sources of drinking water .

A pulsed laser can very effectively remove rust and other corrosion products , or most oxides and inorganic complexes of metals such as aluminum, copper, tin, titanium, etc. A laser can very well clean surfaces from grease , i.e. from various oils , from petroleum jelly , temporary anti-corrosion oils and waxes are quite often removed. The laser removes residues of petroleum products very well. A surface degreased by a laser is perfectly prepared, for example, for welding or for applying new paint. Another application of cleaning lasers is the removal of paints and varnishes , where the effectiveness varies, it is usually necessary to test the laser for a given application. Dark colors work better, colorless varnishes work relatively well. If safety rules are followed , paints containing heavy metals such as lead can be effectively removed. There are also a number of special industrial applications, we have removed e.g. deposits formed by nickel and chromium carbides from glass tubes, inorganic deposits in furnaces, comaxit chambers, vacuum chambers, graphite, polyurethane (PUR) foam , polyamide (PA) surfaces from sliding bushings, etc. In combination with mechanical cleaning, we have successfully tested the removal of fire-retardant varnishes . Lasers can be used to decontaminate surfaces from biologically active substances such as pharmaceuticals, or to remove dust in clean rooms.