4 ms·

Yes, the so called diffraction limit. Has a lot of applications in optics.

by petschge 5y ago

moralestapia 5y ago
>"Diffraction refers to various phenomena that occur when a wave encounters an obstacle or opening." >In a vacuum. Read more.
- petschge 5y ago
  May I refer you to https://www.edmundoptics.com/knowledge-center/application-notes/lasers/gaussian-beam-propagation/ https://www.edmundoptics.com/knowledge-center/application-no... ? Pay particular attention to the last paragraph: > Achieving a truly collimated beam where the divergence is 0 is not possible, but achieving an approximately collimated beam by either minimizing the divergence or maximizing the distance between the point of observation and the nearest beam waist is possible.
  - moralestapia 5y ago
    You confuse theory w/ practice.
    - petschge 5y ago
      The diffraction limit is a well supported theoretical limit that is caused by the wave nature of light. There is ways to get around it in the near field (up to a few ten wavelength away from the source). But in the far field you can not get a perfectly divergence-free finite-width beam. [1] Nor can you focus a beam to a beam waist smaller than about the wavelength. In practice the situation is even worse and you can't even get the performance that a perfect Gaussian beam would allow. We often express the performance of real beams by a thing called M^2 or beam quality parameter [2]. In some sense is measures how much wider the beam is than it needs to be, and this number is never less than one. [1] Btw such a beam would have infinite brilliance. [2] https://en.wikipedia.org/wiki/M_squared https://en.wikipedia.org/wiki/M_squared
      - moralestapia 5y ago
        >The diffraction limit is a well supported theoretical limit that is caused by the wave nature of light. That's not written in stone yet, it's a good approximation but still falls down under specific conditions.

4 ms·

Yes, the so called diffraction limit. Has a lot of applications in optics.

by petschge 5y ago

Yes, the so called diffraction limit. Has a lot of applications in optics.

moralestapia 5y ago
>"Diffraction refers to various phenomena that occur when a wave encounters an obstacle or opening." >In a vacuum. Read more.
- petschge 5y ago
  May I refer you to https://www.edmundoptics.com/knowledge-center/application-notes/lasers/gaussian-beam-propagation/ https://www.edmundoptics.com/knowledge-center/application-no... ? Pay particular attention to the last paragraph: > Achieving a truly collimated beam where the divergence is 0 is not possible, but achieving an approximately collimated beam by either minimizing the divergence or maximizing the distance between the point of observation and the nearest beam waist is possible.
  - moralestapia 5y ago
    You confuse theory w/ practice.
    - petschge 5y ago
      The diffraction limit is a well supported theoretical limit that is caused by the wave nature of light. There is ways to get around it in the near field (up to a few ten wavelength away from the source). But in the far field you can not get a perfectly divergence-free finite-width beam. [1] Nor can you focus a beam to a beam waist smaller than about the wavelength. In practice the situation is even worse and you can't even get the performance that a perfect Gaussian beam would allow. We often express the performance of real beams by a thing called M^2 or beam quality parameter [2]. In some sense is measures how much wider the beam is than it needs to be, and this number is never less than one. [1] Btw such a beam would have infinite brilliance. [2] https://en.wikipedia.org/wiki/M_squared https://en.wikipedia.org/wiki/M_squared
      - moralestapia 5y ago
        >The diffraction limit is a well supported theoretical limit that is caused by the wave nature of light. That's not written in stone yet, it's a good approximation but still falls down under specific conditions.