24-11-2012, 05:49 PM
LASER – INDUSTRIAL APPLICATIONS AND ITS IMPACT IN IMPROVING THE QUALITY OF LIFE
[attachment=41081]
ABSTRACT
Laser is one of the most important devices available today. Applications of laser ranges from industries to everyday aspects of daily life, military, medical, scientific, etc. In this paper, the various applications of laser in industries and its impact in the improvement in the quality of everyday life has been explored. Key areas of industries in which lasers are in use are welding, gas monitoring, etc. Other applications that have revolutionized daily life are medical applications, military equipments, printers, etc. A few innovative ideas on the possibilities of future laser applications have also been discussed.
INTRODUCTION
“Laser” is an acronym for “Light Amplification by Stimulated Emission of Radiation”. It was coined by the laser pioneer Gordon Gould. Laser beam has certain very special properties due to which it has become a very lucrative field of research for all scientists all over the world. Some of its features are:
i) It is monochromatic. Only light of a single wavelength is produced in the whole process. This differs from ordinary light such as sunshine or lamplight, which are composed of different wavelengths of light, being close to white light. ii) It is coherent. All photons have the same phase and the same polarization, hence they produce an very high intensity when they superpose. The lights we see in daily life have random phases and polarization, and hence they are relatively much weak iii) It has a very narrow and collimated ray, and hence it is very powerful. In contrast, lamplight diverges towards different directions and has a low intensity.
INDUSTRIAL APPLICATIONS
Today, laser can be found in a broad range of applications within industry, where it can be used for such things as pointing and measuring. In the manufacturing industry, laser is used to measure the ball cylindricity in bearings by observing the dispersion of a laser beam when reflected on the ball. In the pulp mill industry the concentration of lye is measured by observing how the laser beam refracts in it. Laser also works as a spirit level and can be used to indicate a flat surface by just sweeping the laser beam along the surface. In the mining industry, laser is used to point out the drilling direction. Many other applications can be cited. Some are being discussed below –
Laser Cutting.
Laser Cutting is generally used in industrial manufacturing processes. It is preferred to other methods mainly because of its high quality surface finish. The types of lasers employed are CO2 lasers, Nd lasers and Nd-YAG lasers. In this technique, the laser beam is intensified and focused on the desired material sheet using mirrors or lenses or combination of both as shown in fig.1. The original beam generally has a diameter of 0.3175 mm which is brought down to 0.0254 mm. The focal length of the lenses used are of the order of 50 mm. Piercing using pulsed laser is done to start cutting somewhere else other than the edge. The laser machining system consists of a power supply for producing a laser beam, a workpiece positioning table, laser material, a method of stimulation, mirrors, and a focusing lens. The workpiece is held stationary by clamps, straps, pressure blocks, positioning tabs or magnets. The focusing unit moves around the workpiece to cut the desired shape. The thickness of the workpiece should be between 0.508 mm and 12.7 mm for a typical laser beam. Materials with a low thermal conductivity and reflectivity can be cut with a laser. Currently, mild steel, aluminum, stainless steel, titanium, paper, wax, plastics, wood, and fabrics are typical workpiece materials.
Laser Welding.
Laser is widely used for welding of metals as well as other materials. It is a welding technique used to join multiple pieces of metal through the use of a laser. Usually, solid-state lasers and gas lasers are used. In this method, the focal spot is targeted on the workpiece surface which will be welded. At the surface the large concentration of light energy is converted into thermal energy. The surface of the workpiece starts melting and progresses through it by surface conductance. For welding, the beam energy is maintained below the vaporization temperature of the workpiece material, because hole drilling or cutting vaporization is required. As the penetration of the workpiece depends on conducted heat, the thickness of the materials to be welded is generally less than 20 mm. Focusing lenses play an important role in this process because it concentrates the beam energy into a focal spot as small as 0.127 mm diameters or even less.
Laser Monitoring.
The measurement of concentrations of gaseous species is very important in many different areas of modern life, such
as industrial process control, environmental monitoring and security issues. In this context, non-intrusive methods and easy to handle analyzers that do not require sample collection or preparation and provide concentration data with a high temporal resolution are in demand. Therefore, various optical methods are frequently applied, like laser-induced fluorescence spectroscopy, laser-induced breakdown spectroscopy, absorption measurements and evanescent-field spectroscopy.
Particle Size Measurement.
Many different techniques have been devised for determining particle size distribution, but for a wide range of industries laser diffraction has become the preferred choice. Laser diffraction, alternatively referred to as Low Angle Laser Light Scattering (LALLS), can be used for the non-destructive analysis of wet or dry samples, with particles in the size range 0.02 to 2000 micron and has inherent advantages which make it preferable to other options for many different materials.
Cancer Treatment
Laser has a huge importance in the treatment of cancer. It has provided a great pathway for treatment of one of the most serious diseases of present day. The method is called Photo-Dynamic Therapy (PDT). It is based on the use of special drugs that are injected into the patient body.
These drugs accumulate in cancer cells, more than in "normal" cells. The drugs are sensitive to light at specific wavelengths. When exposed to these specific wavelengths: 1. It can release chemical substance that kills the cells around it. 2. It can emit fluorescence light, so the cancer cells can be identified. The most well known drug of this family is a derivative of Hemato-Porfirin (HPD), and called Photofrin. After the drug is injected into the patient, the patient must be kept in a dark room for 24 hours. During this time, the drug is released from healthy cells, and remains at high concentration only in cancer cells. Then, the patient body is illuminated with specific red laser light at wavelength 630 [nm], which causes the release of singlet Oxygen.
Lasers for c-Si Production.
In thin-film labs, laser scribing is now widely regarded as an established process at the panel-to-cell isolation and interconnection stages— known as patterning. For c-Si solar cell manufacturing, on the other hand, cells have traditionally been produced in labs comprised of screen-printing, etching, deposition, and diffusion equipment. Lasers have often been perceived here as more of a luxury than a necessity At least, that largely captures the equipment landscape up until now; with the majority of solar panels made up of c-Si cells manufactured using fu 200pm-thick, p-type silicon wafers, front-surface screen-printed silver fingers, and full aluminum back-surface-fields. While such standard e-Si cells have been the most cost-effective to produce in volume, the cell efficiency and manufacturing levels have considerable scope for improvement.
[attachment=41081]
ABSTRACT
Laser is one of the most important devices available today. Applications of laser ranges from industries to everyday aspects of daily life, military, medical, scientific, etc. In this paper, the various applications of laser in industries and its impact in the improvement in the quality of everyday life has been explored. Key areas of industries in which lasers are in use are welding, gas monitoring, etc. Other applications that have revolutionized daily life are medical applications, military equipments, printers, etc. A few innovative ideas on the possibilities of future laser applications have also been discussed.
INTRODUCTION
“Laser” is an acronym for “Light Amplification by Stimulated Emission of Radiation”. It was coined by the laser pioneer Gordon Gould. Laser beam has certain very special properties due to which it has become a very lucrative field of research for all scientists all over the world. Some of its features are:
i) It is monochromatic. Only light of a single wavelength is produced in the whole process. This differs from ordinary light such as sunshine or lamplight, which are composed of different wavelengths of light, being close to white light. ii) It is coherent. All photons have the same phase and the same polarization, hence they produce an very high intensity when they superpose. The lights we see in daily life have random phases and polarization, and hence they are relatively much weak iii) It has a very narrow and collimated ray, and hence it is very powerful. In contrast, lamplight diverges towards different directions and has a low intensity.
INDUSTRIAL APPLICATIONS
Today, laser can be found in a broad range of applications within industry, where it can be used for such things as pointing and measuring. In the manufacturing industry, laser is used to measure the ball cylindricity in bearings by observing the dispersion of a laser beam when reflected on the ball. In the pulp mill industry the concentration of lye is measured by observing how the laser beam refracts in it. Laser also works as a spirit level and can be used to indicate a flat surface by just sweeping the laser beam along the surface. In the mining industry, laser is used to point out the drilling direction. Many other applications can be cited. Some are being discussed below –
Laser Cutting.
Laser Cutting is generally used in industrial manufacturing processes. It is preferred to other methods mainly because of its high quality surface finish. The types of lasers employed are CO2 lasers, Nd lasers and Nd-YAG lasers. In this technique, the laser beam is intensified and focused on the desired material sheet using mirrors or lenses or combination of both as shown in fig.1. The original beam generally has a diameter of 0.3175 mm which is brought down to 0.0254 mm. The focal length of the lenses used are of the order of 50 mm. Piercing using pulsed laser is done to start cutting somewhere else other than the edge. The laser machining system consists of a power supply for producing a laser beam, a workpiece positioning table, laser material, a method of stimulation, mirrors, and a focusing lens. The workpiece is held stationary by clamps, straps, pressure blocks, positioning tabs or magnets. The focusing unit moves around the workpiece to cut the desired shape. The thickness of the workpiece should be between 0.508 mm and 12.7 mm for a typical laser beam. Materials with a low thermal conductivity and reflectivity can be cut with a laser. Currently, mild steel, aluminum, stainless steel, titanium, paper, wax, plastics, wood, and fabrics are typical workpiece materials.
Laser Welding.
Laser is widely used for welding of metals as well as other materials. It is a welding technique used to join multiple pieces of metal through the use of a laser. Usually, solid-state lasers and gas lasers are used. In this method, the focal spot is targeted on the workpiece surface which will be welded. At the surface the large concentration of light energy is converted into thermal energy. The surface of the workpiece starts melting and progresses through it by surface conductance. For welding, the beam energy is maintained below the vaporization temperature of the workpiece material, because hole drilling or cutting vaporization is required. As the penetration of the workpiece depends on conducted heat, the thickness of the materials to be welded is generally less than 20 mm. Focusing lenses play an important role in this process because it concentrates the beam energy into a focal spot as small as 0.127 mm diameters or even less.
Laser Monitoring.
The measurement of concentrations of gaseous species is very important in many different areas of modern life, such
as industrial process control, environmental monitoring and security issues. In this context, non-intrusive methods and easy to handle analyzers that do not require sample collection or preparation and provide concentration data with a high temporal resolution are in demand. Therefore, various optical methods are frequently applied, like laser-induced fluorescence spectroscopy, laser-induced breakdown spectroscopy, absorption measurements and evanescent-field spectroscopy.
Particle Size Measurement.
Many different techniques have been devised for determining particle size distribution, but for a wide range of industries laser diffraction has become the preferred choice. Laser diffraction, alternatively referred to as Low Angle Laser Light Scattering (LALLS), can be used for the non-destructive analysis of wet or dry samples, with particles in the size range 0.02 to 2000 micron and has inherent advantages which make it preferable to other options for many different materials.
Cancer Treatment
Laser has a huge importance in the treatment of cancer. It has provided a great pathway for treatment of one of the most serious diseases of present day. The method is called Photo-Dynamic Therapy (PDT). It is based on the use of special drugs that are injected into the patient body.
These drugs accumulate in cancer cells, more than in "normal" cells. The drugs are sensitive to light at specific wavelengths. When exposed to these specific wavelengths: 1. It can release chemical substance that kills the cells around it. 2. It can emit fluorescence light, so the cancer cells can be identified. The most well known drug of this family is a derivative of Hemato-Porfirin (HPD), and called Photofrin. After the drug is injected into the patient, the patient must be kept in a dark room for 24 hours. During this time, the drug is released from healthy cells, and remains at high concentration only in cancer cells. Then, the patient body is illuminated with specific red laser light at wavelength 630 [nm], which causes the release of singlet Oxygen.
Lasers for c-Si Production.
In thin-film labs, laser scribing is now widely regarded as an established process at the panel-to-cell isolation and interconnection stages— known as patterning. For c-Si solar cell manufacturing, on the other hand, cells have traditionally been produced in labs comprised of screen-printing, etching, deposition, and diffusion equipment. Lasers have often been perceived here as more of a luxury than a necessity At least, that largely captures the equipment landscape up until now; with the majority of solar panels made up of c-Si cells manufactured using fu 200pm-thick, p-type silicon wafers, front-surface screen-printed silver fingers, and full aluminum back-surface-fields. While such standard e-Si cells have been the most cost-effective to produce in volume, the cell efficiency and manufacturing levels have considerable scope for improvement.