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Quantity Unit Dimension [nb 1]Notes Name Symbol [nb 2] Name Symbol Luminous energy: Q v [nb 3]: lumen second: lm⋅s : T⋅J: The lumen second is sometimes called the talbot.: Luminous flux, luminous power
Use of a light meter for portrait cinematography in a Turkish music video set. A light meter (or illuminometer) is a device used to measure the amount of light.In photography, an exposure meter is a light meter coupled to either a digital or analog calculator which displays the correct shutter speed and f-number for optimum exposure, given a certain lighting situation and film speed.
Diagram of a high-pressure sodium lamp A high-pressure sodium lamp, Philips Master SDW-T 100W. Various types of chemistry are used in the arc tubes of HID lamps, depending on the desired characteristics of light intensity, correlated color temperature, color rendering index (CRI), energy efficiency, and lifespan.
The ambient light sensor of a Google Pixel 4a smartphone under a microscope. An ambient light sensor is a component in smartphones, notebooks, other mobile devices, automotive displays and LCD TVs.
A tea light-type candle, imaged with a luminance camera; false colors indicate luminance levels per the bar on the right (cd/m 2). Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. [1]
The 26th General Conference on Weights and Measures (CGPM) redefined the candela in 2018. [10] [11] The new definition, which took effect on 20 May 2019, is: The candela [...] is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 10 12 Hz, [a] K cd, to be 683 when expressed in the unit lm W −1, which is equal to cd sr W −1 ...
A photodetector salvaged from a CD-ROM drive.The photodetector contains three photodiodes, visible in the photo (in center).. Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. [1]
An illustration of some of the optical devices available for laboratory work in England in 1858. An optical instrument is a device that processes light waves (or photons), either to enhance an image for viewing or to analyze and determine their characteristic properties.