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  1. Illuminance is the total amount of visible light illuminating (incident upon) a point on a surface from all directions above the surface.
  2. Illuminance is a measure of how much luminous flux is spread over a given area.
  3. Illuminance is a measure of photometric flux per unit area, or visible flux density.
  4. Illuminance is the total luminous flux incident on a surface, per unit area.
  5. Illuminance is the intensity or degree to which something is illuminated and is therefore not the amount of light produced by the light source.

Seven Times

  1. At the center of the illumination pattern of the lens, the illuminance is seven times that of the lamp alone.

Light Source

  1. The numerically calculated angular intensity distribution from a light source is converted to an illuminance distribution on the entrance pupil.


  1. Definition: Illuminance is the amount of light falling upon a given area.


  1. Alternatively, it can be defined as the illuminance on a 1-square foot surface of which there is a uniformly distributed flux of one lumen.


  1. Footcandle (fc) A unit of illuminance or light falling onto a surface.


  1. The illuminance is a measure for the luminous flux density on a surface.
  2. Therefore, the lumen value is not as important as the Illuminance value, which is a measure of intensity from a given direction.


  1. The density of incident luminous flux on a surface; illuminance is the standard metric for lighting levels, and is measured in lux (lx) or footcandles (fc).
  2. Illuminance is the density of the luminous flux incident on a surface.


  1. The voltage is converted by a precision AD converter into a signal that is proportional to the expected illuminance in lux.


  1. A source that is farther away provides less illumination than one that is close, so one lux is less illuminance than one footcandle.

Luminous Intensity

  1. Find the illuminance and the luminous intensity at a distance of 1 m, and at 5 m.


  1. If one unit of illuminance falls upon this hypothetical reflector, then 1 unit of luminance is reflected.


  1. Footcandles is a unit of measurement of illuminance (how much light is striking a point on a surface).
  2. A given amount of light will illuminate a surface more dimly if it is spread over a larger area, so illuminance is inversely proportional to area.
  3. Illuminance A measure of the amount of light incident on a surface; measured in foot-candles or Lux.

Square Foot

  1. The footcandle (or lumen per square foot) is a non-SI unit of illuminance.
  2. Footcandle (fc) A unit of illuminance equal to one lumen per square foot.

Square Meter

  1. A flux of 1000 lumens, concentrated into an area of one square meter, lights up that square meter with an illuminance of 1000 lux.
  2. A Lux is a lumen per square meter, which we might call illumination in street jive, but illuminance in sci.optics talk.
  3. S.I. unit of illuminance equal to 1 lumen per square meter.

Unit Area

  1. In photometry, illuminance is the total luminous flux incident on a surface, per unit area.

Luminous Flux

  1. The illumination (illuminance) is measured in luminous flux per unit area.
  2. A phot is a photometric unit of illuminance, or luminous flux through an area.


  1. Lighting a larger area to the same illuminance requires a proportionately greater number of lumens.
  2. However, the same 1,000 lumens, spread out over ten square metres, produces a dimmer illuminance of only 100 lux.


  1. Achieving an illuminance of 500 lux might be possible in a home kitchen with a single fluorescent light fixture with an output of 12,000 lumens.
  2. A single fluorescent light fixture that produces a luminous flux of 12000 lumens might light a residential kitchen with an illuminance of 500 lux.
  3. The lux (symbol: lx) is the SI unit of illuminance and luminous emittance measuring luminous power per area.


  1. In SI derived units, these are both measured in lux (lx) or lumens per square metre (cd·sr·m −2). In the CGS system, the unit of illuminance is the phot.
  2. A flux of 1,000 lumens, concentrated into an area of one square metre, lights up that square metre with an illuminance of 1,000 lux.
  3. For real diffuse reflectors, the ratio of luminance to illuminance in these units is roughly equal to the reflectance of the surface.


  1. Lux
  2. Lumens
  3. Optics > Light > Photometry > Luminous Flux
  4. Square Meter
  5. Thought > Observation > Area > Square Foot
  6. Books about "Illuminance" in

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  Short phrases about "Illuminance"
  Originally created: March 21, 2008.
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