“Aether Drag” and Moving Images

We contrast the two situations in which either a light beam is incident on a moving medium or a moving optical image is incident on a stationary medium. The principle of relativity suggests that the effects on the light of propagating through the medium should be similar. We find, however, that there are subtle differences which we can understand in terms of the relative alignment of the Poynting and wave vectors. Our analysis and experiments investigate both translational motion and rotation.

Figure 1

Experimental configuration for producing a rapidly translating fringe pattern based on the inference between two frequency shifted plane waves. The inset shows the two interference patterns that are captured by the camera, one passing through the glass, the other through free space. BS, beam splitter; PBS, polarizing beam splitter; QWP, quarter wave plate; AOM, acousto-optic modulator; L, lens, M, mirror; WP, Wollaston prism; GGS, ground glass screen; ICCD, intensified camera.

Figure 2

The measured displacement of the nonlocalized interference fringes, after transmission through the medium, as a function of their translational velocity.

Figure 3

The transverse photon drag phenomenon interpreted for the rest frame of the medium and the frame in which the medium is moving. The Poynting vector, $\mathbf{S}$, is indicated by the arrow passing through the medium, and the wave vector, $\mathbf{k}$, is normal to the parallel lines.

Figure 4

The measured displacement of the nonlocalized interference fringes as a function of their translational velocity, where the angle of the medium is adjusted to account for the relativistic distortion.

Figure 5

The measured rotational shift of the petal interference pattern after transmission through the glass medium.