The speed of the light when it passes through a transparent or translucent material medium, like glass or water, a silica optical fiber, is actually a little slower than its speed in vacuum. Einstein’s Theory of General Relativity explains how a gravitational potential can affect the apparent speed of distant light in a vacuum. For instance, blue/green light has a wavelength of about 500 nm, corresponding to about 2.48 eV of energy. The photographic industry has been revolutionized by microelectronics technology. Charge-coupled device (CCD) is most widely used for extracting collected photogenerated charges from 2D pixel arrays. CCDs are ubiquitous in digital photography, video cameras, astronomy, optical scanners, satellite-based remote imaging systems, night-vision systems. The emitted photons are coherent, and laser light can thus reach extremely high intensity, and even be switched on and off very, very quickly.