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Security lighting to prevent intrusions may be counter-productive. Turning off lights halved the number of thefts and burglary in Övertorneå Sweden. [2] [3] A test in West Sussex UK showed that adding all-night lighting in some areas made people there feel safer, although crime rates increased 55% in those areas compared to control areas and to the county as a whole.
Ambient light falling on the photoresistor causes the streetlight to turn off. Thus energy is saved by ensuring the light is only on during hours of darkness. Photoresistors are also used in laser-based security systems to detect the change in the light intensity when a person or object passes through the laser beam.
A lighting control system is intelligent network-based lighting control that incorporates communication between various system inputs and outputs related to lighting control with the use of one or more central computing devices. Lighting control systems are widely used on both indoor and outdoor lighting of commercial, industrial, and ...
Light can be used to transmit data and analog signals. For example, lighting white LEDs can be used in systems assisting people to navigate in closed spaces while searching necessary rooms or objects. [100] Assistive listening devices in many theaters and similar spaces use arrays of infrared LEDs to send sound to listeners' receivers.
Solid-state lighting is often used in traffic lights and is also used in modern vehicle lights, street and parking lot lights, train marker lights, building exteriors, remote controls etc. [1] Controlling the light emission of LEDs may be done most effectively by using the principles of nonimaging optics. [2]
The system has a power supply providing at least 5kVDC to the light emitting device, and the electrons transiting from cathode to anode are essentially unfocused. Additional circuits allow TRIAC-type dimmers to control the light level. [6] Sample produced with lights produced so far have a color rendering index of 90.
A graph showing variation of quantum efficiency with wavelength of a CCD chip from Wide Field and Planetary Camera 2, formerly installed on the Hubble Space Telescope.. The term quantum efficiency (QE) may apply to incident photon to converted electron (IPCE) ratio [1] of a photosensitive device, or it may refer to the TMR effect of a magnetic tunnel junction.
Optoelectronics (or optronics) is the study and application of electronic devices and systems that find, detect and control light, usually considered a sub-field of photonics. In this context, light often includes invisible forms of radiation such as gamma rays , X-rays , ultraviolet and infrared , in addition to visible light.