laser cleaner

## What is Laser Cleaning?

Laser cleaning is a non-contact cleaning process that uses focused laser beams to remove contaminants and unwanted materials from surfaces. It works by irradiating the surface with high-intensity laser pulses, which cause rapid vaporization, decomposition, and detachment of the contaminants.

Compared to conventional cleaning methods that use solvents, abrasives or mechanical forces, laser cleaning is a more precise and gentle process. The laser allows selective and localized removal of contaminants without damaging the underlying surface. There is no contact with the surface so no abrasion occurs and fine details and structures can be preserved.

Some key differences between laser cleaning and other cleaning methods:

- Non-contact and non-abrasive process
- Does not use any solvents, chemicals or produce secondary waste
- Very high spatial resolution and depth precision
- Can be automated and integrated into industrial processes
- Can clean sensitive surfaces and fragile structures without damage
- Removes strongly adhered contaminants like oxides, soot, paint, biological layers etc
- Environmentally friendly with no emissions or waste generated

The precision, control and gentle action of laser cleaning makes it suitable for specialized cleaning applications where conventional methods may damage the surface or fail to thoroughly clean. Examples include cleaning of artwork, heritage sites, industrial parts, microelectronics, aircraft and more.

## History and Development

Laser cleaning was first conceived in the 1960s when lasers were being researched and developed. The earliest working laser was demonstrated in 1960, and by the mid-1960s lasers were being explored for cleaning applications.

One of the pioneers in laser cleaning technology was Claude Phipps. In the late 1960s, Phipps demonstrated that laser pulses could remove particles from surfaces by vaporizing them. This early work showed the potential for lasers to clean delicate objects like artwork without causing damage.

In the 1970s and 1980s, laser cleaning research progressed and the technique started being used in niche applications. Early adopters were conservation and restoration experts who used laser cleaning on artwork and artifacts. Removing dirt and coatings from artwork with traditional abrasive methods risked damaging the surface, but lasers provided a gentler alternative.

Laser cleaning gained broader adoption in the 1990s and 2000s as the technology matured. More powerful lasers became available, allowing faster cleaning. Computer-controlled systems also enabled more precision and control. This expanded the applications from delicate art restoration into industrial cleaning uses like removing paint, corrosion, and contaminants from machinery and infrastructure.

Ongoing innovations in laser power, pulse duration, scanning methods, and safety continue to advance laser cleaning capabilities. The technology is still actively being researched and developed today to create faster, more selective, and lower-cost laser cleaning solutions. Major recent advances include ultrashort femtosecond lasers, handheld laser cleaning tools, and automated laser cleaning robots.

## How Laser Cleaning Works

Laser cleaning utilizes focused laser energy to remove unwanted materials from surfaces. The process involves directing a laser beam onto the surface to ablate or vaporize the contaminants or coatings.

The physics behind laser cleaning centers on the interaction between the laser light and the material being cleaned. When the high-intensity laser beam hits the surface, photons from the beam are absorbed by the material, rapidly heating a very small volume to extreme temperatures. This intense localized heating causes the material to expand and explosively vaporize - a process called ablation. The ablation process effectively blows off particles of the coating or contaminant, removing it from the underlying surface.

Different types of lasers can be used for cleaning, including gas lasers (CO2), solid state lasers (Nd:YAG, fiber), and ultrafast pulsed lasers. Continuous wave (CW) gas and solid state lasers provide a constant beam output that can gradually heat and ablate material. Pulsed lasers deliver energy in short, high peak power pulses just nanoseconds long. This enables extremely precise, micron-scale removal with minimal heating or damage to the underlying substrate.

The wavelength, pulse duration, fluence, and other parameters of the laser can be optimized for the material being removed and the substrate below it. This allows delicate or heat-sensitive surfaces like aircraft coatings, electronics, artwork, and more to be cleaned without damage by precision laser ablation.

## Types of Lasers Used

Lasers used for cleaning applications typically fall into a few main categories:

### CO2 Lasers

- CO2 lasers use a combination of carbon dioxide, nitrogen, and helium gases as the laser medium.
- They typically operate at wavelengths between 9,300–10,600 nanometers, in the far infrared region.
- CO2 lasers can provide high power levels up to tens of kilowatts.
- They are relatively inexpensive to operate.
- CO2 laser beams can be delivered through flexible hollow waveguides for remote laser cleaning applications.
- However, CO2 lasers cannot be transmitted through fiber optics.

### Nd:YAG Lasers

- Nd:YAG (neodymium-doped yttrium aluminum garnet) lasers use a synthetic crystal as the laser medium.
- They operate at near-infrared wavelengths of 1,064 nanometers.
- Nd:YAG lasers can be configured to generate high peak power pulses.
- They can also be delivered through optical fibers for flexible beam transmission.
- However, Nd:YAG lasers have lower average power capabilities than CO2 lasers.

### Excimer Lasers

- Excimer lasers utilize reactive gas mixtures as the gain medium, typically containing noble gas halides.
- They generate ultraviolet light, with wavelengths between 157-351 nm.
- Excimer lasers provide very high peak energies in pulsed beams.
- This makes them ideal for precision ablation cleaning of surfaces.
- However, the toxic gases required limit their applications.

### Fiber Lasers

- Fiber lasers use doped glass or plastic fibers as the gain medium.
- They provide high beam quality, stability, and optical efficiency.
- Fiber laser wavelengths range from 800-2100nm.
- Their flexible fiber delivery is advantageous over rigid CO2 and Nd:YAG lasers.
- However, fiber lasers have more limited power capabilities for cleaning applications.

In summary, CO2 lasers offer high average power for many cleaning uses, while excimer and Nd:YAG lasers provide high pulsed peak powers. Fiber lasers also fill an important niche with their flexible delivery. The ideal laser depends on factors like the target material, contamination, precision, and power requirements.

## Applications and Uses

Laser cleaning has a wide range of applications across many different industries and fields. Some of the most common uses include:

### Conservation and Restoration

Laser cleaning is commonly used in art and antique conservation and restoration. It allows conservators to gently clean paintings, sculptures, and other artifacts without damaging the original material. Lasers can remove layers of dirt, grime, and old varnish or paint without being abrasive.

For example, artwork such as the Parthenon Marbles in the British Museum were cleaned with lasers. This allowed centuries of black gypsum crust to be removed, revealing the original bright marble underneath. Lasers were also used to clean the Donatello and Michelangelo statues that stand outside the Florence Cathedral.

### Industrial Cleaning

Lasers are used in industrial cleaning of metals, composite materials, and other surfaces. They can strip paint, remove rust and corrosion, etch surfaces, and prepare materials for recoating. The aerospace, automotive, and shipbuilding industries commonly use laser cleaning.

Boeing uses large robotic laser systems to clean and etch airplane wings and fuselages. This prepares the surfaces for re-coating and protects against corrosion. Laser cleaning also helps maintain quality control in automotive factories by removing dirt, oil, paint overspray, and corrosion from car bodies before painting.

### Nuclear Decommissioning

Lasers provide a safe, effective method for nuclear decommissioning and waste removal. They can selectively ablate radioactive deposits off surfaces without generating harmful byproducts. The laser beam's precision allows operators to clean even highly radioactive reactor components.

For example, lasers cleaned graphite moderator bricks from nuclear reactors at the Sellafield nuclear plant in the UK. Lasers also cleaned radiated metals inside the damaged Fukushima Daiichi nuclear reactors in Japan after the 2011 tsunami. This made the reactors safer for human entry and ongoing decommissioning.

# Advantages Over Laser Cleaning

Laser cleaning offers several advantages over other cleaning techniques that make it an appealing option for many applications. Here are some of the main benefits that laser cleaning provides:

## Precise Control

Lasers allow for extremely precise and controlled cleaning. The laser can be focused down to clean very small areas or scan across larger surfaces. This level of control is difficult to achieve with many other cleaning methods. Lasers can selectively remove deposits or coatings without damaging the underlying base material.

## Minimal Damage

The laser wavelength, pulse duration, and fluence can be adjusted to gently remove contaminants and coatings. This helps prevent alteration of surfaces at the microscopic and molecular level that other abrasive techniques may cause. Lasers provide a non-contact and non-destructive cleaning in many cases.

## Speed

Lasers can clean incredibly quickly, especially compared to manual techniques. Removing layers by ablation allows for rapid cleaning rates even over large surface areas. The processing speed depends on the laser parameters and material, but lasers can clean in seconds or minutes compared to hours of manual work.

## Automated Process

Lasers lend themselves very well to automation. The cleaning process can be predefined and repeated identically over an entire surface. This automation improves consistency and frees personnel from manual cleaning.

## Environmentally Friendly

Laser cleaning is a dry process that does not require solvents or abrasives. The process generates minimal waste since no consumables or fluids are used. This makes lasers an environmentally friendly cleaning method.

## Versatile

Lasers can be used to clean a wide array of materials like metals, ceramics, stone, composites, plastics, and more. The same laser may clean through surface coatings and prepare the underlying substrate. This versatility makes lasers useful across many industries.

## Cost Savings

While laser systems require an initial capital investment, they can provide significant cost savings over manual cleaning in the long run through faster processing, automation, and minimal consumables. Lasers may also be cheaper than chemical or abrasive techniques that risk damage.

## Limitations and Considerations

Laser cleaning has some downsides and limitations compared to other cleaning methods. Here are some key points to consider:

- **Safety precautions are critical**. Lasers can potentially cause eye and skin damage if proper safety precautions are not followed. Operators need training on laser safety and must wear protective equipment like goggles. The work area also needs to be secured during cleaning.

- **Lasers can damage surfaces if not used properly**. The intensity and wavelength of the laser must be calibrated for each material being cleaned. Using the wrong settings can potentially damage or discolor surfaces. Extensive testing is required beforehand.

- **Removes material, not just grime**. Lasers vaporize the top layer of grime but also a thin layer of the underlying material. This gradually erodes surfaces with repeated cleanings. Gentler traditional methods may be better for delicate materials.

- **Not suitable for some materials or objects**. Lasers cannot be used on flammable or transparent materials. Items with complex geometries or hidden surfaces are also difficult to clean fully with lasers.

- **High power consumption**. The laser generators used require a high electricity supply. This costs more to operate versus simple cleaning solutions.

- **Requires special training and expertise**. Proper laser cleaning requires knowledge of optics, physics, and material science. Extensive training is needed to operate lasers safely and effectively, which not all facilities have the resources for.

- **Higher equipment costs**. Industrial laser cleaning systems have high initial costs compared to pressure washers, media blasters, or chemical cleaners. The laser cleaner investment may only make sense for high-volume cleaning.

- **Regulatory restrictions**. The possession and operation of powerful laser systems may require special licensing. Safety inspectors also need to approve laser installation and procedures.

So while laser cleaning provides benefits like precision, automation, and no-contact cleaning, it also comes with considerable downsides to factor in. Proper training, testing, safety measures, and regulatory compliance are critical. It may not suit all cleaning situations due to restrictions on materials and accessibility. The costs and expertise required also limit adoption for some facilities. Careful analysis is needed to determine if laser cleaning is the optimal solution over other methods.

## Cost Analysis

Laser cleaning equipment represents a significant upfront investment, with industrial laser systems ranging from $50,000 to $500,000 depending on the power and features. However, due to the speed and efficiency of laser cleaning, many businesses find the return on investment worthwhile.

There are several factors that contribute to the ongoing costs of a laser cleaning system:

- **Equipment** - The laser generator and accessories such as fume extraction systems, cooling systems, beam delivery optics, motion systems, and monitoring equipment. These have significant initial costs but long working lifespans.

- **Operation** - The electricity to power the laser and peripheral equipment. Laser cleaning is very energy efficient compared to other cleaning methods.

- **Consumables** - Laser gases, laser tubes, and filters need periodic replacement. Costs vary based on usage.

- **Maintenance** - Routine inspections, alignments, part replacements to keep the laser in working order. Typically a few thousand dollars annually.

- **Training** - Operating personnel need certified laser safety training to use the equipment safely. Often a one-time fixed cost.

- **Facilities** - Proper facilities for housing the laser, including ventilation, cooling, dust control. May require upgrades.

The high speeds of laser ablation mean more throughput and shorter cleaning times, allowing more production with the same equipment. Reduced labor is a major savings, along with not having to purchase and dispose of chemical cleaning agents. The non-contact nature of lasers avoids part wear, waste, and damage associated with other cleaning methods. Greater precision also leads to cost savings through less waste and rework.

Most facilities achieve a complete return on their laser investment in less than 2 years. The high upfront cost is offset by the ongoing savings and production benefits. Support contracts and maintenance help optimize system lifetimes of 10-20 years or more. With laser cleaning increasing efficiency, quality, safety, and environmental-friendliness, the return on investment continues well into the future.

## Future Outlook

The future looks bright for laser cleaning technology as it continues to evolve and find new applications across industries. Here are some key trends and developments to watch in this growing market:

**Emerging Applications**

- Using lasers for art restoration and conservation will likely expand as lasers allow precision cleaning without damaging fragile pieces.

- Superfast laser techniques for industrial cleaning of metals and ceramics will improve manufacturing efficiency.

- Lasers could be used for cleaning in hazardous environments like nuclear sites, avoiding risks to human operators.

- Laser ablation techniques show promise for highly specialized cleaning tasks like contaminant removal from silicon wafers in electronics.

**Innovations**

- Portable laser cleaning tools will become smaller, cheaper and more versatile and popular for everyday cleaning tasks.

- Laser cleaning robots and automated systems will improve consistency and productivity in industrial settings.

- Ultrafast laser cleaning at femtosecond timescales will push the boundaries of precision.

- Green and other non-UV lasers are being developed to reduce environmental/health risks.

**Market Growth**

- The laser cleaning market is forecast to grow from $584 million in 2019 to over $1 billion by 2025, an 8.5% CAGR, as adoption spreads across sectors.

- Key growth factors include demand for less invasive cleaning in art restoration, tighter industrial cleanliness standards, and laser cost reductions.

- Medical, aerospace, electronics, and conservation industries will drive laser cleaning adoption at above average rates.

The future is bright for laser cleaning as constant innovation unlocks new applications across industries. Advancements in laser technology and automated systems will further improve cleaning consistency, precision, speed and environmental sustainability.

## Key Takeaways

Laser cleaning technology offers many benefits over traditional cleaning methods that rely on abrasives or chemicals. As lasers become more advanced and cost-effective, laser cleaning is seeing rapid adoption across industries like art restoration, industrial manufacturing, and infrastructure maintenance.

The precision offered by lasers allows for highly controlled, non-contact cleaning that avoids damage to sensitive surfaces. Lasers can be tuned to target very specific materials, enabling their removal while leaving surrounding areas untouched. This makes laser cleaning ideal for delicate antique and artwork restoration.

Lasers eliminate the need for chemical cleaning agents that can be hazardous. They provide an environmentally-friendly cleaning process. The ability to clean without chemicals also reduces costs associated with purchasing, handling, and disposing of traditional cleaning supplies.

Rapid, large-area cleaning is possible with laser technology. Set up costs can be high, but the operating costs per use are low. This makes laser cleaning cost-effective for regular maintenance cleaning of infrastructure like buildings and transportation.

As laser cleaning becomes standard practice across more industries, continued improvements to laser power, beam delivery, and intelligent scanning will expand its capabilities. Cost reductions as adoption increases will also make laser cleaning accessible to more end users.