What does a diffraction grating do and when is light a particle?

[Dustinsfl]

What does a diffraction grating do, and what is it used for? Are there circumstances under which light must be considered a particle? When?

From wikipedia, diffraction grating is an optical component with a periodic structure, which splits and diffracts light into several beams traveling in different directions. The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as the dispersive element. Because of this, gratings are commonly used in monochromators and spectrometers.

Can this be explained a little simplier? I am not an optics person. Also, what is it used for and are there any circumstances which light must be considered a particle? When?

 

[Nono713]

What does a diffraction grating do, and what is it used for? Are there circumstances under which light must be considered a particle? When?

From wikipedia, diffraction grating is an optical component with a periodic structure, which splits and diffracts light into several beams traveling in different directions. The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as the dispersive element. Because of this, gratings are commonly used in monochromators and spectrometers.

Can this be explained a little simplier? I am not an optics person. Also, what is it used for and are there any circumstances which light must be considered a particle? When?

I strongly recommend you watch the QED lectures from Feynman. They are on youtube, or you could also get the book. They show why light behaves as it does - including things like reflection, refraction, diffraction gratings, lens, etc... from the point of view of quantum electrodynamics, and why the theory simplifies down to older, simpler models when some assumptions are made. It will probably blow your mind.