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chopficaro
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i know light is also a particle, but if a laser can hit an open slit and spread out i can't see how it couldn't be more spread out when it came out of the laser in the first place
chopficaro said:i know light is also a particle, but if a laser can hit an open slit and spread out i can't see how it couldn't be more spread out when it came out of the laser in the first place
russ_watters said:diffraction is a manifestation of wavelike properties, not particle-like properties.
chopficaro said:i know light is also a particle, but if a laser can hit an open slit and spread out i can't see how it couldn't be more spread out when it came out of the laser in the first place
IttyBittyBit said:Without resorting to the mathematics, you can think of a large beam as being emitted from a large group of point sources with the 'spread-out' of each source canceling the effects of the other sources, except in the direction right in 'front' of the beam. When you thin the beam, in effect making the number of point sources small, the canceling effect stops and you see the diffraction.
This isn't quite right. It would be better to say that the light coming out of a laser can be described in terms of an infinite set of plane waves traveling in slightly different directions. The relationship between the plane waves is such that the interference between them produces a bright spot along a given axis and a Gaussian intensity distribution in the transverse plane normal to this axis. The wavefronts of the resulting beam are curved everywhere except near the waist/focus of the beam.ZapperZ said:The light coming out of the laser are "plane waves". You only can start seeing the diffraction effects when it passes through a slit that has a width comparable to the wavelength. If you let it pass through something large, you still can't detect the diffraction pattern that closely.
While this is certainly true and has been used as one of those "wave-like" property, it should be clarified that one can get such diffraction pattern simply by using photons and applying the HUP. I've described this a few times already. Furthermore, if one looks the Marcella treatment of the diffraction/interference phenomena, one doesn't have to invoke wave mechanics to get the same wave-like results.
Zz.
Tao-Fu said:Given that Maxwell's equations (i.e. the wave equation when dealing with propagation through vacuum) are correct quantum mechanical field equations for light, it seems ill-founded to presume a particle-like object and derive wave-like behavior from this. But the word "photon" can lead to lots of misunderstanding, so I won't assume that this is actually what you meant. A photon seems to most closely correspond to an excitation in the electromagnetic field. It may have a certain energy, in the case of a monochromatic field, or an approximately certain location, in the case of localized pulses of light (wavepackets, not really particles), but not both.
Tao-Fu said:Sorry. It looked like you were saying that diffraction can be gotten at by simply positing a quantum particle and invoking the Heisenberg uncertainty principle.
ZapperZ said:To a certain extent, it can! However, it cannot arrive at the quantitative aspect of diffraction. The diffraction phenomenon, however, can be used to illustrate the HUP.
Zz.
Lasers are created when light waves are amplified and directed in a very specific way. This is achieved by using a medium, such as a crystal or gas, that can amplify the light waves through a process called stimulated emission. This amplification produces a highly concentrated and coherent beam of light that is known as a laser.
A laser is different from other light sources because it produces a very narrow and focused beam of light. This is due to the amplified and coherent nature of the light waves in a laser, which allows for precise control and direction of the light. Additionally, the wavelength of laser light is typically very specific, making it suitable for various applications such as surgery or communication systems.
No, not all light waves can be used to create a laser. Lasers require light waves that can be easily amplified and directed, which is why most lasers use visible or infrared light waves. Ultraviolet light waves can also be used, but require more specialized materials and techniques.
The shape of a laser beam is typically much more uniform and focused compared to other light sources. This is because the light waves in a laser are traveling in the same direction and are in phase with each other, creating a beam with a consistent shape and intensity.
Yes, there are limitations to the power of a laser compared to other light sources. While lasers can produce very strong and concentrated beams of light, there are physical limitations to how much energy can be contained in the beam. Additionally, the materials used to create a laser may have limitations in terms of how much power they can handle before being damaged.