Lasers Flashcards
What are the properties of Conventional Light Sources?
- Conventional light sources emit broad
spectra, radiation out form a diffuse point. - Intensity is spread across a wide wavelength
range (poor efficiency), and decays with an
inverse square law (poor utility).
What are the Essential Components of a Solid-state Laser
A solid state laser must include: • An optical (photon) energy-input source, • A laser medium (or lasing material), • An optical resonant cavity, • An output port.
What is a solid-state laser?
A solid-state laser is a laser that uses a lasing material distributed in a solid matrix
What are conventional sources?
Conventional sources emit light in all directions. The light is then modulated in a given direction with optical systems like reflectors and lenses.
What are the types of lasers?
Solid, liquid, gas and free-electron.
What are Gas lasers?
Gas lasers (helium and helium-neon, HeNe, are the most common gas lasers) have a primary output of visible red light.
What are semiconductor lasers?
Semiconductor lasers, sometimes called diode lasers, are not solid-state lasers. These electronic devices are generally very small and use low power.
What are dye lasers?
Dye lasers use complex organic dyes, such as rhodamine 6G, in liquid solution or suspension as lasing media
How does a solid-state laser work?
The crystal produces laser light after light is pumped into it by either a lamp or another laser.
What are the steps in producing Photons?
- The optical stimulus (pump) excites electrons in the lasing medium to a higher energy-level.
- If the pumping power (wattage, i.e. photons per second) is low, then the medium
returns to the ground state by spontaneous emission, depleting the available excited electrons. But, - If the pumping power is great enough, there is a continuously replenished source of
electrons in the excited state – a population inversion. - Now these excited electrons decay by stimulated emission, and as a result have identical wavelength, direction and phase to the passing photon.
When producing a photon, if the pumping power (wattage, i.e. photons per second) is low, then what happens?
the medium returns to the ground state by spontaneous emission, depleting the available excited electrons.
What are the steps in producing a beam?
- Spontaneously emitted photons are randomly directional, we still don’t have a laser beam.
- The pair of mirrors at either end form an optical ‘resonant cavity’,
- Only photons travelling very close to the axis of the laser are internally reflected.
- And so, only these reflected photons go on to give stimulated emission.
- This cavity must be precisely parallel, and an integer multiple of the photon wavelength.
- The front mirror is typically a ~95% mirror so that some light is allowed out, but is mostly reflective to sustain the lasing.
What do solid lasers include?
Solid lasers can include ruby (research), GaN (Blue-ray player), AlGaAs (laser pointers),
What do liquid lasers include?
Liquid lasers (less common) use chemical dyes tunable by wavelength,
What do gas lasers include?
Gas lasers, are pumped by electrical discharge (used mostly for research),
What are free-electron lasers?
Free-electron lasers use a high-speed electron as the lasing medium, can produce x-rays.
What are the risks of lasers and what does it depend on?
Laser exposure risk depends on the wavelength, power and design and includes Tissue burns, eye damage, endotracheal tube fire, drape fire, and explosion of gases
How are the risks of lasers overcome?
- Lasers should carry a classification labelling which dictate the appropriate control processes.
- Common lab PPE are laser glasses/goggles, but these must be appropriate for the wavelength being used.
Give applications of laser beams
Applications of Laser Beams • Measurement (collimation), • Detection (wavelength), • Data storage, • Spectroscopy, • Cutting tools, • Weapons (military research),
How are laser beams used in measurement?
A collimator is a device that narrows a beam of particles or waves. To narrow can mean either to cause the directions of motion to become more aligned in a specific direction (i.e., make collimated light or parallel rays)
What is a laser?
A device that generates an intense beam of coherent monochromatic light (or other electromagnetic radiation) by stimulated emission of photons from excited atoms or molecules (optical amplification)
How is lasers used in spectroscopic techniques?
Ultrafast laser spectroscopy is a spectroscopic technique that uses ultrashort pulse lasers for the study of dynamics on extremely short time scales
How are lasers used in cutting?
Laser cutting is a technology that uses a laser to cut materials, and is typically used for industrial manufacturing applications, but is also starting to be used by schools, small businesses, and hobbyists. …
How can a laser be a weapon?
A laser produces very intense energy that can travel over very long distances. That’s why a laser can become a weapon while the light from an incandescent bulb typically can’t. To do this, a laser has to produce light in a nonconventional way. “Laser” stands for light amplification by stimulated emission of radiation.
How is a laser created?
A laser is created when the electrons in atoms in special glasses, crystals, or gases absorb energy from an electrical current or another laser and become “excited’’. The excited electrons move from a lower-energy orbit to a higher-energy orbit around the atom’s nucleus. When they return to their normal or “ground” state, the electrons emit photons (particles of light).
How is laser light different from normal light?
1) Its light contains only one wavelength (one specific color). The particular wavelength of light is determined by the amount of energy released when the excited electron drops to a lower orbit.
2) Laser light is directional. Whereas a laser generates a very tight beam, a flashlight produces light that is diffuse. Because laser light is coherent, it stays focused for vast distances, even to the moon and back.
Give an application of lasers in biology
The laser is an effective tool for destroying cancer cells
What is LASER an acroymn for?
Light Amplification by Stimulate Emission of Radiation
What are the three laser light properties?
Monochromic, coherent, and directional
What is monochromatic?
Contains one specific wavelength of light (one specific color).
What does the wavelength of light determined by?
The wavelength of light is determined by the amount of energy released when the electron drops to a lower orbit.
How is laser light coherent?
It is “organized”– each photon moves into step with other. Meaning all the photons have waves fronts that lunch in unison
What is directional in terms of laser light vs. flashlight?
A laser light has a very tight beam and is very strong and concentrated. A flashlight in contrast releases light in many directions,t he light is very weak and diffuses.
Why can’t you look at a laser with your eyes?
The reason lasers can do so much damage is that they produce bright light which is well concentrated into a thin beam. … If you hold the laser beam steadily into someone’s eye, then there is a good chance the laser beam will burn up cells on the retina (back of the eyeball), causing a permanent blind spot in his vision.
Where on the electromagnetic spectrum do most lasers operate
UV, visible, and infared
