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Nerd
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I get the photo-electric effect but I am just wandering, is that the only principal on which lasers function? I mean do lasers "cut" materials by ionizing the atoms?
Nerd said:What you say makes sense, however if lasers did cut metal by heating it to melting point, I would think that this happens by exciting the electrons in the metal, which would lead to more kinetic energy and thus increase heat. If this is true than why do mirrors reflect lasers beams, afterall the same that happens to the metal's atoms should happen to the mirror's atoms?
Nerd said:Then we can assume that air (oxygen, nitrogen ect.) have practically no absorption, since the whole electro-magnetic spectrum can travel through air. This means that it would be impossible to cut solid oxygen with any type of laser, right? Do you know if a mirror can reflect X-rays?
All interactions between photons and matter are described as series of absorptions and emissions of photons. When an arriving photon strikes a single molecule at the surface of a material, is absorbed and almost immediately reemitted, the ‘new’ photon may be emitted in any direction, thus causing diffuse reflection.[citation needed]
Specular reflection (following Hero's equi-angular reflection law) is a quantum mechanical effect explained as the sum of the most likely paths the photons can take. Light–matter interaction is a topic in quantum electrodynamics, and is described in detail by Richard Feynman in his book QED: The Strange Theory of Light and Matter.
The energy of the incoming photon may match the energy required to change the molecule from one state to another, causing a transition in kinetic, rotational, electronic or vibrational energy. When this occurs, the photon may not be reemitted or alternatively may be reemitted with a loss of energy. These effects are known as Raman, Brillouin and Compton scattering.
Integral said:Fact is high power laser systems do not use metalized mirrors. They use what is called a dielectric mirror, it consists of multiple layers of a dielectric material, the thickness of a layer is determined by the wavelength of the laser and the angle of reflection needed. These mirrors are transparent to all but the wavelength designed for.
That's refraction, not diffusion. I think it's covered in one of the FAQ threads here. Other than that, I honestly have no idea (I'm actually trying to find out why myself).Nerd said:Thank you.
I have another question though. Diffusion occurs when a wave enters a optical denser material or visa versa, for instance, a light wave moving from air into water will change direction. Does the light wave's direction change at the first water molecule that reemits it or does it happen deeper into the water, and why doesn't the direction of the wave change again as it is reemited from the second molecule?
So was I.dst said:I think he was talking about mirrors outside lasers :). But hey, I didn't actually know that snippet.
Nerd said:Thank you.
I have another question though. Diffusion occurs when a wave enters a optical denser material or visa versa, for instance, a light wave moving from air into water will change direction. Does the light wave's direction change at the first water molecule that reemits it or does it happen deeper into the water, and why doesn't the direction of the wave change again as it is reemited from the second molecule?
Nerd said:Then we can assume that air (oxygen, nitrogen ect.) have practically no absorption, since the whole electro-magnetic spectrum can travel through air. This means that it would be impossible to cut solid oxygen with any type of laser, right? Do you know if a mirror can reflect X-rays?
Nerd said:Do you know if a mirror can reflect X-rays?
A laser, or light amplification by stimulated emission of radiation, is a device that produces a narrow and intense beam of light. It works by stimulating atoms or molecules to emit photons, which then bounce back and forth between two mirrors to create a concentrated beam of light.
The photoelectric effect is the emission of electrons from a material when it is exposed to light. This phenomenon was first observed by Albert Einstein and is used in many technologies, such as solar panels and image sensors in cameras.
Ionization of atoms occurs when an atom gains or loses electrons, resulting in a charged particle called an ion. This can happen through various processes, such as high temperatures, collisions with other atoms, or exposure to radiation.
Lasers have many practical applications, including in scientific research, medical procedures, telecommunications, and manufacturing. They are used in technologies such as barcode scanners, DVD players, and laser printers.
Lasers are often used in spectroscopy, which is the study of the interaction between matter and electromagnetic radiation. The intense and focused light beam of a laser allows for precise measurements and analysis of the absorption and emission of light by atoms and molecules.