I was wondering, a while ago, i asked if there is a way to bend light someway, which I got the answer is index of refraction.

Which is when light passes through a material it refracts to a certain degree.

In this question I wish to know if this method when applied with a dense enough index, that that when you turn the light beam to a different direction, do you see it arc or curve in a smooth form, that given enough index of refraction or am I thinking of something else?

I usually thought certain substances like a water tank with oil or sugar can cause a light beam to curve smoothly.


Are you asking if it is possible to get a curved light beam by varying the refraction index?

Yes, it is possible. Every time light propagates in a medium with a non uniform refraction index, the ray trajectory is not rectilinear. If there is a sharp transition between regions with two different values of the refraction index, the Snell law controls the angle the refracted beam gets closer or farther from the normal to the incidence point.

If the refraction index is a smooth function of the position, the light beam is bent smoothly and follows a curve trajectory instead of a piece-wise straight line.

The phenomenon can nicely observed with a laser pointer and a transparent container (like a fish tank) where some salt (NaCl is ok) is put on the bottom and then the container is gently filled by water (without stirring or creating turbulence). After some hours (even one day) there is an almost uniform vertical gradient of salt concentration. A laser beam entering from a side wall is clearly bent as in this picture. The entrance point is the spot on the left.

Laser beam in a NaCl aqueous solution with a vertical gradient of density. The beam is visibly bent.

  • $\begingroup$ Thank you for your answer, it will help in the long run $\endgroup$ – C. Jordan Dec 28 '18 at 6:21

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