Hello I'm trying to picture various light based experiments as described from a frame that is in motion with respect to the experiment devices. For instance the reflection of a photon in a light clock: the atoms (and their fields) that constitute the surface of the mirror are squashed. How is the reflected photon adapted to match this reality? The same question goes for light refraction. The trickiest may be how to deal with light diffraction through a slit: the slit is thinner in the moving frame. Do these questions require Quantum Electrodynamics for understanding, or are there simplified answers for the layman? Thanks in advance for any hint.