Introduction to Laser نظري 1 PDF

LASER Dr. Ahmed Alhashimi  LASER Is abbreviation from Light Amplification by Stimulated Emission of Radiation Laser characteristics Laser Light is : Coherent (all waves have the same phase). Monochromatic (all waves have the same wavelength). Collimated (the wave of light are parallel)....

LASER Dr. Ahmed Alhashimi  LASER Is abbreviation from Light Amplification by Stimulated Emission of Radiation Laser characteristics Laser Light is : Coherent (all waves have the same phase). Monochromatic (all waves have the same wavelength). Collimated (the wave of light are parallel). Laser characteristics -Coherent- same phase Laser characteristics -Monochromatic- Laser characteristics -Collimated- Laser characteristics  The first working laser was demonstrated on May 16, 1960, by Theodore H. Maiman at Hughes Research Laboratories in California. Maiman’s laser used a synthetic ruby crystal as the lasing medium and was the culmination of years of theoretical and experimental work based on the principles of stimulated emission, first proposed by Albert Einstein in 1917.  Production of laser energy: All atoms are most stable in their lowest energy state known as the ground state, Energy is delivered to atoms in a laser active medium by process called pumping, Laser medium which could be solid, liquid, gas, semiconductor. the absorption of energy by an atom elevates its electrons from their ground state to a higher energy level, atoms in the excited state are unstable and their electrons tend to spontaneously return to the ground state by emitting light energy, the active laser medium is housed in a tube which has a mirror at each end, the distance between the mirrors must equal a multiple of the wavelengths of the light emitted.  when a photon encounters an excited electron and stimulated emission occurs the light emitted travels down the tube , and reflected and re-reflected at both mirrors, the light which has traversed the tube is still exactly in phase, meanwhile other stimulated emissions are taking place so that the light traversing the tube gets stronger and stronger while remaining exactly in phase (coherent), if one mirrors is made partially transparent some of the light may be allowed to leave the tube, the light will be coherent, monochromatic and collimated.  Laser are named after their active medium,the active medium contains the atoms or molecules which will undergo stimulated emission, it may be gas (argon, krypton, carbon dioxide), liquid (dye) or solid (Nd:YAG). The source of the energy pumped into the active medium may be electrical discharge, a second laser or light. Laser parameters: 1. Power of laser 2. Pulse duration 3. Exposure time 4. Spot size Lasers have a wide range of applications in various fields. uses include: 1. Medicine: Surgery: Lasers are used in eye surgeries (e.g., LASIK), tumor removal, and cosmetic procedures like tattoo removal and skin resurfacing. Dental treatments: For tooth decay, gum disease, and teeth whitening. Cancer treatment: Certain types of cancer cells are targeted with lasers. Diagnosis: Laser used to diagnosis many diseases. 2. Communication: Fiber optics: Lasers transmit data over long distances in internet. 3. Barcodes and Scanning: Retail and logistics: Lasers are used in barcode scanners. 4. Manufacturing: Cutting and engraving: Lasers are used to cut metals, plastics, and other materials with high precision and use in 3D printing. 5. Entertainment: - Laser shows: Used in light shows and concerts for visual effects. - CD, DVD, Blu-ray players: Lasers read data stored on these discs. 6. Military: - Rangefinders and targeting systems: Lasers measure distances and assist in targeting. - Non-lethal weapons: Laser dazzlers are used to temporarily blind. 7. Scientific Research: Spectroscopy: Lasers are used to study the properties of materials. 8. Astronomy: Lasers are used to measure distances to celestial bodies, including the moon. 9. Security and Authentication: - Laser engraving: Used in ID cards, passports, and currency to prevent counterfeiting. - Biometric systems: Lasers are used in iris and fingerprint scanning for identity verification. Lasers have become integral to many technological advancements, improving precision, speed, and efficiency across various specialities. Advantages and Disadvantages of Lasers Advantages: 1. High Precision and Accuracy Lasers can be focused into a very small, intense beam, allowing them to perform tasks with extreme precision. This property is especially beneficial in fields like surgery (e.g., LASIK eye surgery) and manufacturing (e.g., laser cutting or engraving) 2. Non-Contact Process Since lasers work by emitting light rather than through mechanical interaction, they can perform action without physically touching. This minimizes contamination and making lasers ideal for delicate tasks. 3. High Energy Density Lasers can concentrate a large amount of energy into a small area, making them effective at cutting tissue or photocoagulation or precisely ablating tissues in medical applications without affecting surrounding areas. 4. Controlled Wavelength Lasers emit light at specific, controlled wavelengths, which can be fine-tuned for particular applications. For example, lasers with certain wavelengths can be used for medical procedures or material processing, offering great flexibility. 5. Long Range Lasers can travel over wide distances with minimal energy loss, making them highly useful in communication systems (fiber optics) without significant dispersion. 6. High Speed In communication systems, lasers offer incredibly high data transmission speeds, especially in fiber-optic communications, where they are used to send data over long distances rapidly and efficiently with minimal interference or loss. 7. Lasers are applied in a wide Medical field Used in surgeries, diagnostics, and therapeutic treatments. Disadvantages of Lasers: 1. High Initial Cost The equipment needed to generate and maintain a laser beam can be expensive. Laser systems often require sophisticated components, such as cooling systems, power supplies, and precise optics, which can increase the cost. 2. Complex Maintenance While lasers are often durable, their operation and maintenance can be complex. Many laser systems require regular calibration and upkeep to maintain precision, which may involve skilled technicians and specialized tools. This increases long-term operational costs. 3. Potential Safety Hazards Lasers, particularly high-power lasers, can cause serious health risks. Direct exposure to a laser beam can cause burns or damage to the skin and eyes. Even reflected or scattered beams can be dangerous. 4. Energy Consumption High-power lasers often require significant amounts of energy to function, particularly in industrial or medical applications. 5. Limited Material Compatibility While lasers are versatile, they are not universally effective on all materials. Some materials may reflect the laser light, other absorb it unevenly, or degrade in ways that make laser processing less suitable. 6. Thermal Damage While lasers are precise, their high energy can cause unintended thermal damage to surrounding materials. In delicate applications like surgery or precision manufacturing, care must be taken to ensure that the heat generated by the laser does not damage nearby structures. 7. Environmental Sensitivity Lasers can be sensitive to environmental conditions such as dust, humidity, or vibration. These factors can affect the laser’s performance, reducing its accuracy and efficiency. THANK YOU