A piece of AAA battery is enough to switch on the laser pointer

 This function of this kind of   green laser pointer can be used by the customer to create the amazing effect and special atmosphere.
The photoelectric effect was found in 1887 by Hz (HRHertz, 1857 a 1894). The study of the photoelectric effect device is a pumped into a high-vacuum glass balls on the inner surface coated with a photosensitive layer (cathode K), the anode A can be made into a straight line or circular ring. When monochromatic radiation through the quartz window to the cathode K, the escape of electrons from the cathode, e-called photoelectron. If both ends in A, K, coupled with the potential difference U, fly photoelectron in the accelerating electric field under the anode, the formation of the photocurrent in the circuit. The strength of the photocurrent is read by the galvanometer. Like this metal by the irradiation of light and emit electronic phenomenon called the photoelectric effect. For this kind of   green laser pointer , a piece of AAA battery is enough to switch on the laser pointer.
The photoelectric effect experiment to make the traditional optical theory to a severe test. The great Albert Einstein in 1905 proposed the light quantum is said to explain the experiment. The idea is revolutionary, just bunches that the particle flow to the speed of light, a light particle carries an energy. Light quanta that be said of the great effects of the Planck quantum. Planck blackbody radiation, with particles of light in the emission and absorption process. Einstein further light with particles in the dissemination process. Light the nature of the fluctuations on the one hand, such as interference, polarization, etc.; the other hand, the nature of the particles, such as the photoelectric effect. A comprehensive description of the light of these two aspects is not a simple wave, is not simple particles, but the wave-particle duality of the material. The quality inspection of  green laser pointer normally includes the self inspection, mutual inspection and final inspection.
Therefore, the tunable laser must have a large adjustment range, high output power and millisecond response speed. In fact, the most dynamic applications are required to have a tunable optical multiplexer, or a 1: N optical switch with the laser work to ensure that its output laser into the fiber can go through proper channels. Tunable lasers as spare parts application may be the operators are most concerned about, the tunable laser technology can help the network to significant savings. Reduce network investment by streamlining laser hardware, simplifying management through remote settings, while significantly reducing maintenance and spare parts requirements. Assume a simple small network with four nodes.