A light detector is a device or device component that is used to recognize the presence of light, often with the goal of initiating a process in response to light. Many devices for personal and commercial use incorporate light detectors for a variety of purposes. A number of styles of cell phones, for instance, have screens that can automatically increase or decrease brightness based on the intensity of ambient light. A light detector in such a device recognizes the presence and intensity of light and initiates a process that changes the screen brightness for ease of viewing. Light detectors are also used by researchers in several different fields, including physics; optics; and in some cases, even chemistry and biology.
Different devices use a wide variety of different light detection methods based on the overall purpose of the device. One light detector may, for instance, be made to detect any light at all while another may only detect certain colors. Light detectors are often designed to detect and respond to very different levels of light intensity as well. A cryogenic light detector, for example, is intended to detect and measure the energy of individual photons while many detectors for personal use only respond to light that is, by comparison, very intense.
Many personal electronics and home appliances make use of light detectors for a variety of purposes. It is not uncommon for an outdoor light, for instance, to have a light detector that enables it to automatically turn on or off based on the presence of light. Likewise, a camera might incorporate a light detector that automatically determines whether or not to activate the flash. Computers, phones, and other devices often have keyboards with backlights that are automatically activated or deactivated based on the presence or absence of ambient light. Many toys and handheld gaming devices also use light detectors for various purposes, such as turning on or off or for some particular function within a handheld video game.
In robotics, a light detector may be used for purposes such as navigation, obstacle avoidance, or activation of the robot. A simple robot with a light detector, for instance, could follow a source of light as it moves through a dark room. More complex robots may use light detectors to guide them to fires or to other specific sources of light. As with consumer electronics, robots use a wide range of types of light detectors optimized to the particular tasks that the robotic systems are expected to perform.