Basic knowledge of the photometry

1, plane Angle, and solid Angle

define units called plane Angle radian, 1 radian is a radius of 1 m garden, one meter long arc zhang's horn in the center of the circle. Unit solid Angle called steradian ( sr) , 1 steradian is the sphere radius is 1 m, 1 square meters of the ball in the face of zhang by its solid Angle.

2, luminous flux,

define flux is the amount of light emitted at a light source in a unit time, also known as radiant flux ( Or radiated power) Can be felt by the human eye vision system that part of the effective equivalent.

to urinate a 40 w fluorescent lamp output flux is about 2100 lumens. Φ flux symbols, unit lm;

common electric light source, luminous efficiency refers to the electric power can be converted into 1 w much luminous flux.

common light source of efficiency (roughly Lumens/watt) 15

incandescent lamp, fluorescent lamp,

sodium lamp, 50 to 120

3, luminous intensity is defined per unit solid Angle of the light source in a given direction, it launches the luminous flux is defined as a light source (at the direction of the Hair) Light intensity ( C) 。

CD Φ Ι = d/d Ω unit 1 CD = 1 lm/sr

the actual light source or the direction of the luminous intensity of different lamps and lanterns. In order to describe the spatial distribution characteristics of light, need to use the luminous intensity distribution curve ( Also called light distribution curve) To represent. It is an important basis for lighting calculation and design. Common light source intensity (

cd)

the sun, 2. 8 e27

highlight flashlight, 10000

4, illuminance defined on the surface of a little illumination is incident luminous flux on contains bin point d phi

divided by the quotient of the bin area of dS.

units ( lx) Unit for lux ( lx) Lx, 1 = 1 lm/m2

intensity of illumination (common Lux)

direct sunlight ( Noon) , the 110000 cloudy outside,

1000 stores, 500 normal room light, 100

the full moon, 0. 2 candle, 20 cm distance) ，10～15LUX。

from 60 w lamp 60 cm desktop, 300 lux.

the evening indoors, 10 lux; Street lights at night, 0. 1LUX;

5,

brightness (brightness, L，Luminance) Nita, unit, namely the nit, or CD/m2.

define the light body, in a certain direction projection area per unit of light intensity. The brightness of the light (

common Nita,)

the sun's surface, 2000000000 incandescent filament, 10000000

the sun paper, 30000 eyes get used to the brightness of the,

3000 full moon surface, 2500

the brightness of the human eye can better distinguish colors, 1

white paper under the full moon, 0. On the night sky, 0. 0001

common photometric units and their mutual relations

o flux Φ ( lm)

o light intensity I ( cd)

o illuminance E ( lx)

Sophy

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