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Applications and Advantages of UV Lasers
Ultraviolet laser products are primarily intended for use in advanced studies and development in the industrial sphere. Ultraviolet lasers and optical emitters are used in biotechnology and medical markets to create such special tools as sterilization and disinfectant devices. UV lasers offer developers huge opportunities based on a noncontact method of producing microstructures on micro substances on different substances with a minimal effect on surrounding materials. The aforementioned lasers generate light with wavelengths in the range from 150 to 400 nm.
Micro-scale Applications
Ultraviolet lasers are well-suited for micro-scale applications. What makes UV lasers so applicable for micro-drilling and micro-structuring, or for marking synthetics and glass, and for creating safety features on ID or credit cards? Firstly, their short wavelength allows them to create small, focused spot sizes. Secondly, short pulse width and high intensity result in the material removal (every pulse removes only a small amount of material), allowing for the production of well-defined microstructures. The beam intensity is so high that the material is removed in the vapor phase in a process called ablation. Ablation can be characterized as a process of material removal, the result of which is a clean surface. And thirdly, the short wavelength is important because small focused spot sizes allow penetration into the material, where chemical and physical transitions will result in changes in the material. These changes can be observed either by the naked eye or under the special light or proper magnification.
Types of UV Lasers
Solid-state Q-switched Nd:YAG Laser
A special crystal in this laser is used to change the infrared 1064 nm wavelength to the ultraviolet 353 nm wavelength. The beam shape is Gaussian, so the spot of the ultraviolet laser of this type will be round with the intensity of energy falling off gradually from the center to the edge. These ultraviolet lasers are sensitive to temperature variations. These lasers have a special standby condition where all critical components are kept at the operating temperature. Since these lasers are equipped with a high repetition rate and a small focused spot, they are well-suited for machining on a micro scale.
Excimer Laser
An excimer laser typically uses a combination of a noble gas and a reactive gas. The beam-generated shape isn’t round but has a rectangular shape with a more or less constant distribution of the intensity over the cross section of the beam that falls off sharply at the edges.
Metal Vapor Laser
The copper vapor laser is commonly used, although vapors of several other metals are also suitable. Such UV lasers generate radiation at 511 nm and 578 nm wavelengths. The beam shape is Gaussian, so the metal vapor laser is appropriate for the same range of applications as the solid-state ultraviolet laser.
High-power Excimer Lasers for Industrial Applications
The most important type of high-power ultraviolet laser for industrial applications is the excimer laser. Available wavelengths include 351, 308, 248, 193, and 157 nm. The largest commercially available excimer lasers generate up to 200 W stabilized average power and up to 700 mJ pulse energy at 308 nm. The main advantages of this laser are physical compactness, high reliability, and durability. According to the forecasts, UV lasers will be widely used in an expanding range of applications with their recent improvements in performance, cost of ownership, and increasing reliability.
Current Applications of UV Lasers
Ultraviolet lasers have already found various applications at present:
- pulsed high-power ultraviolet lasers can be used for efficient cutting and drilling of holes in a variety of materials
- continuous wave UV lasers are required for microlithography (for instance, in the context of semiconductor chip manufacturing)
- Pulsed and CW UV lasers are irreplaceable for fabricating fiber Bragg gratings
- UV and even deep-UV lasers are required in refractive laser eye surgery of the cornea and in other medical applications