TYPES OF LASER ,PROCESS CHARACTERISTICS AND APPLICATIONS
- 1. TYPES OF LASER ,PROCESS CHARACTERISTICS AND APPLICATIONS
- 2. INTRODUCTION TO LASERS: L=LIGHT A=AMPLIFICATION BY S=STIMULATED E=EMISSION OF R=RADIATION Lasers are devices that produce a focused beam of highly concentrated light. They work by stimulating atoms to emit photons, creating a coherent beam.
- 3. TYPES OF LASERS: 1. SOLID-STATE LASERS 2. GAS LASERS 3. LIQUID LASERS 4. SEMICONDUCTOR LASERS
- 4. SOLID-STATE LASERS: Solid-state lasers utilize a crystal or glass doped with a specific element, which is excited to produce laser light. They offer high power output and versatility. RUBY LASERS: These lasers were among the first developed, producing a red beam. In a ruby laser, a single crystal of ruby (Al₂O₃) doped with small (0.05%)percentage of Cr₂O₃ acts as host material. We assume that the energy levels will be E1 < E2 < E3. The energy level E1 is known as ground state or lower energy state, the energy level E2 is known as metastable state, and the energy level E3 is known as pump state. Let us assume that initially most of the electrons are in the lower energy state (E1) and only a tiny number of electrons are in the excited states (E2 and E3)
- 5. APPLICATIONS: Range finding is one of the first applications of the ruby laser. It was initially used to optically pump tunable dye lasers. It is rarely used in industry due to its low repetition rates and low efficiency. Some typical applications of ruby laser include the following: Laser metal working systems for drilling holes in hard materials High-power systems for frequency doubling into the UV spectrum High-brightness holographic camera systems with long coherent length Medical laser systems for tattoo removal and cosmetic dermatology High-power Q-switched system.
- 6. ND: YAG LASER: Nd: YAG laser is a neodymium based laser. Nd stands for Neodymium (rare earth element) and YAG stands for Yttrium Aluminium Garnet ( Y3Al5 O12) . It is a four level solid state laser. Characteristics: 1. Type: It is a four level solid state laser. 2. Active medium: The active medium is Nd: YAG laser. 3. Pumping method: Optical pumping is employed for pumping action. 4. Pumping source: Xenon or Krypton flash tube is used as pumping source. 5. Optical resonator: Two ends of Nd: YAG rod is polished with silver (one end is fully silvered and the other is partially silvered) are used as optical resonator. 6. Power output: The power output is approximately 70 watt. 7. Nature of output: The nature of output is pulsed or continuous beam of light. 8. Wavelength of the output: The wavelength of the output beam is 1.06μm(infra-red)
- 7. APPLICATION: 1. It finds many applications in range finders and illuminators. 2. It is widely used in engineering applications such as resistor, trimming scribing, micro machining operations as well as welding, drilling etc. 3.It finds many medical applications such as endoscopy, urology, neurosurgery, ENT, gynecology, dermatology, dental surgery and general surgery.
- 8. GAS LASERS A gas laser is a type of laser in which a mixture of gas is used as the active medium or laser medium. Gas lasers are the most widely used lasers. Gas lasers have an active medium made up of one or more gases or vapours. Laser outran Cathode Helium-neon gas reservoir Anode These lasers are classified as: Atomic gas lasers which is He-Ne laser Molecular gas lasers which is CO2 laser lon gas lasers that are Argon laser
- 9. HELIUM-NEON LASERS: The light is extremely monochromatic with wavelength l= 632.8 nm The light is unidirectional and aligned so as to be parallel to the body of the laser. The light is "spatially coherent". The phase of radiation is nearly constant throughout the cross-sectional width of the beam A Brewster-window is often inserted in the laser by the manufacturer to produce light with a definite state of linear polarization. Helium-Neon Laser is the first gas Laser developed by Ali Javan and his co-workers in1961. Helium-neon lasers are the most popular continuous wave (CW) laser. It is a four level laser. The first He-Ne laser emitted infrared at 1.15 m. 𝜇
- 10. Applications He-Ne laser is used widely in commercial and industrial applications, and commonly used in laboratory demonstrations of optics. It is the most common laser used in holography. Other major applications of He-Ne laser include: Barcode scanners Tool alignment Non-contact measuring and monitoring Blood analysis Particle counting and food sorting Alignment of high power CO2 and YAG treatment lasers and pointing beams.
- 11. LIQUID LASERS: Liquid lasers are also known as dye lasers. This is a type of laser in which liquids are used as an active medium. The active material used in the liquid laser is known as a dye and the commonly used dyes are sodium fluorescein, rhodamine B and rhodamine 6G. WORKING: The active medium in this laser type is organic dye and the solvent used for dissolving the dye is either water, alcohol, or ethylene glycol. The dye is pumped to the capillary tube from the storage tank. This dye leaves the tubes with a flash lamp. The output beam then passes through a Brewster window to the output coupler which is a 50% reflective mirror. The output wavelength can vary to a wide range and the maxim output possible is 618 nm.
- 12. Application of Liquid Laser: A Liquid lasers use an organic dye in liquid form as their gain medium. They are also known as dye lasers and are used in laser medicine, spectroscopy, birthmark removal, and isotope separation. These lasers are commonly used for medical purposes as a research tool.
- 13. SEMICONDUCTOR LASERS: Semiconductor diode (the first laser diode) was demonstrated in 1962 by two US groups led by Robert N. Hall at the General Electric research center and by Marshall Nathan at the IBM T.J. Watson Research Center The semiconductor laser is made in mass quantities from wafers of gallium arsenide or similar crystals. PRINCIPLE OF SEMICONDUCTOR LASER When the P-N Junction diode is Forward Biased (i.e) the P end of the diode is connected to the positive terminal of the battery and the N end is connected to the negative terminal of the battery. The poles and electrons diffuse through the junction and combine with each other; meanwhile light radiations or photons are radiated. This is called Recombination Radiation
- 14. CHARACTERISTICS: APPLICATIONS: Laser printers, CD and DVD players, and fiber optic transmission are examples of consumer electronics. Industrial uses: Laser diodes are favored for industrial applications because they are a source of a high- intensity laser beam and may be used for cutting, drilling, welding, and other tasks. Medical applications: Laser diodes are utilized in the removal of undesirable tissues and malignancies, as well as in dental medicine. Scientific instrumentation: Laser diodes can be used to power instruments such as spectrometers, range finders, and contact-less measurements. Most SC lasers operate in 0.8-0.9 µm or 1 - 1.7 µm spectral region Wavelength of emission determined by the band gap Different SC materials used for different spectral regions 0.8-0.9 µm: Based on Gallium Arsenide 1-1.7 µm: Based on Indium Phosphide (InP) Pumping method: Direct Conversion High power lasers usually (1 mV)