Carbon dioxide laser



Carbon dioxide laser are a type of laser (light amplification by stimulated emission of radiation) that uses carbon dioxide, nitrogen, and helium to produce a high intensity beam of light. First invented by Doctor C. Kumar Patel in 1963, CO2 laser technology has developed into the most important types of laser technology with applications in textile, design, architectural, and medical fields.

How They Work
A CO2 laser system consists of several key components necessary for operation: gasses such as carbon dioxide, nitrogen, and helium, an electrical current, a pump, mirrors, and a tube that houses the operation. Depending on the laser system, the necessary electrical current may use direct current (DC), alternating current (AC), or radio frequencies (RF) with positive and negative leads at each end of the tube. The mirrors are positioned at each end with one being a fully reflective mirror and the other a partially reflective mirror (see picture for full diagram). The power supply charges the nitrogen gas, which proceeds to excite the CO2 gas. The point when the carbon dioxide becomes energized is known as the state of population inversion. During this time, the energized particles outnumber those that are not excited. In this state, the nitrogen must release photons in order to lose energy. These photons then collide with the helium gas, producing a high energy beam of light. This beam increases in intensity as it reflects off of the mirrors inside the tube. As the laser reflects between the two mirrors, some photons exit through the partially reflective mirror. All CO2 lasers have a wavelength near 10.6 μm.

The strength of a laser relies on several variables including the size of the tube, the gas mixture, and electrical current magnitude. CO2 lasers systems require a variety of electrical power ratings between several watts and over 1000 watts. The most common carbon dioxide laser systems operate between 25 and 100 watts. Because of the wide variation in power options, these lasers range in ability from cutting light materials such as paper to cutting through metals with the most powerful lasers.

History
Prior to the invention of the carbon dioxide laser, several other laser technologies had been invented, but none with the capabilities of the CO2 laser. In 1963, Dr. C. Kumar N. Patel, conducted research in laser action and discovered the vibrational-rotational transitions of carbon dioxide, which lead the way for his invention of the carbon dioxide laser in 1964. In 1967, Peter Houldcroft, a scientist from the United Kingdom, first cut steel using a CO2 laser. Early versions of surgical carbon dioxide lasers began production as early as 1970.

Applications
Because of the variety in CO2 power options, carbon dioxide lasers have numerous applications. These applications include cutting, engraving and welding.

Laser Cutting: In carbon dioxide laser cutting applications, a laser cuts shapes out of a material capable of absorbing the appropriate wavelength that the laser emits (10.6 μm). In order to cut something, the material must be capable of absorbing the emitted wavelength. Most lasers designed for this application can also be used in etching or engraving. The most common laser cutters are designed for cutting woods, plastics, and paper. These systems usually have power ratings between 20 and 200 watts, but those designed to cut through metals can reach power requirements as high as 1000 watts.

Laser Engraving and Etching: Laser etching is the process wof burning a material in order to leave a lasting mark. Carbon dioxide lasers can engrave and etch many materials including wood, various plastics, and various metals.

Laser welding: Laser welding is the process of bonding two or more pieces of metal together with a laser. A laser provides a precise, high quality weld.

In the metal working field (welding, cutting and engraving metals), CO2 lasers must to compete with newer, more efficient, lasers using smaller wavelengths that are more easily absorbed by the metals.

CO2 lasers also play a significant role in the medical field, with many surgeries being accomplished with the help of a laser (See Surgery).

Surgery
Carbon dioxide lasers are very useful in both the human and animal medical fields as tools to assist in surgery. These lasers can make highly precise surgical incisions and remove the need for a scalpel in some cases. CO2 lasers have been used in hundreds of different types of procedures and notably in cancer treatment. Carbon dioxide lasers have also been used in various cosmetic procedures, and the surgical laser has proven itself useful in excisions surgeries.

Surgical Laser

By using highly amplified light and heat, the Surgical laser provides many benefits over a conventional scalpel. This tool causes less bleeding in a surgery because the heat from the laser causes nearly instant coagulation (thickening) of the blood, making the operation site much cleaner and easier to work on. The surgical laser also reduces the chance of infection by killing bacteria, therefore sterilizing the area. The rapid coagulation of the blood also assists in keeping the area sterile by preventing most bacteria from entering the body. Surgeries by carbon dioxide lasers also involve less pain as they seal nerve endings and lymphatics. The combination of these benefits results in an expedited recovery time after surgery.

Cancer Treatment

When used in cancer treatment, CO2 lasers can be used to precisely target and shrink or destroy a tumor. They are also used to alleviate effects of cancer such as internal bleeding or blockage. In order to perform these treatments, doctors insert an endoscope into a body cavity (mouth, anus, etc.). The endoscope is equipped with fibers that are capable of transmitting the laser's high intensity. Once inside the body, the endoscope must be positioned and targeted correctly. The laser is then transmitted through the fibers and applied to the tumor. Laser treatment can occasionally be used exclusively to treat cancer, but typically, it accompanies chemotherapy or radiation therapy.

Cosmetic Procedures

Carbon dioxide lasers find another application in the field of cosmetics. In the process of carbon dioxide laser resurfacing, they are used to remove various bodily features that people consider undesirable such as wrinkles, warts, scars, birthmarks, facial lines, skin damage from the sun, enlarged oil glands, etc. The laser "scans" over the area of the procedure, firing short pulses and removing thin epidermal layers. The laser effectively removes tissue in the desired area, but refrains from damaging the surrounding bodily features.

Videos
Video 1- Co2 lasers allow for safer, faster, and more precise surgeries than conventional tools.

Video 2- Discoverer of the CO2 laser, Kumar Patel discusses the development of his laser. |rEz3sazVv_0 |7v43P-SY0eU