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Optical basics related to lamps and lanterns

I. Light and electromagnetic waves.
Light is a kind of electromagnetic wave, speed: 30 × 10000 km/s
Wavelength of 780-380 nm (nanometers). 1 nanometer = 10 of the -9th square meter
II. Spectrum and color.
Spectrum: red, orange, yellow, green, blue, indigo, purple
Infrared wavelengths: 620 to 780 nm. wavelengths of ultraviolet light: 380 to 420 nm. the following chart.
Wavelength 780 ~ 620 ~ 590 ~ 560 ~ 490 ~ 450 ~ 420 ~ 380nm
Sunlight: wavelength is 780 ~ 380nm, pure white.
Incandescent lamp: wavelength of 780 ~ 400nm, the lack of violet light, so the synthesis of light color slightly reddish yellow.
Fluorescent lamp: wavelength of 750 ~ 310nm, the lack of red light, so the synthesis of a slight green or greenish white.
III. The main role of lamps.
1. fixed and protective lamps;
2. control and distribution of light, highlighting the required light distribution;
3. decorate and beautify the environment;
IV. Light characteristics of lighting fixtures: the light characteristics of lighting fixtures with three main technical data to illustrate, namely.
1. the spatial distribution of luminous intensity;
2. luminaire efficiency;
3. luminance distribution or lamp shading angle;
V. Spatial distribution of luminous intensity
Any luminaire in space in all directions of the luminous intensity are not the same, we can use data or graphics to lighting luminous intensity in the space of the distribution of the record, we usually use
Vertical coordinates to indicate the distribution of light intensity of lighting fixtures, the origin of the coordinates as the center, the luminous intensity in each direction with a vector marked out, connecting the endpoints of the vector, that is, the formation of light intensity distribution curve,
Also called light distribution curve.
Because most of the shape of the lamp is axisymmetric rotating body, its luminous intensity distribution in space is also axisymmetric. Therefore, through the axis of the lamp to take any plane, to the plane of the
Light intensity distribution curve to show the distribution of lighting fixtures in the whole space is enough. If the distribution of luminous intensity of lighting fixtures in space is asymmetrical, such as long strips of fluorescent lamps, it is necessary to
To use a number of light intensity distribution curve of the measurement plane to illustrate the spatial light distribution. Take the long axis of the same luminaire perpendicular to the plane through the center of the luminaire for the C0 plane, and C0 plane perpendicular to the plane and through the center of the luminaire of the sagging plane.
The plane perpendicular to the C0 plane and the plane through the center of the luminaire is the C90 plane. The light intensity distribution in at least two planes, C0 and C90, should be used to illustrate the spatial distribution of the asymmetric luminaire. In order to facilitate the
In order to facilitate the comparison of the light distribution characteristics of various lighting fixtures, a uniform luminous flux of 1000 lumens (lm) is specified to provide data on the distribution of light intensity. Therefore, the actual light intensity should be photometric data
Therefore, the actual luminous intensity should be photometric data provided by the luminous intensity value multiplied by the actual luminous flux of the light source and the ratio of 1000.
The luminous intensity distribution of a luminaire is achieved by controlling the light with a reflector, light-transmitting prism, grille or diffuser of the luminaire. The reflector is the basic light control part of the luminaire, its reflection ratio
The higher the reflection ratio, the stronger the rule reflection, the more significant the light control ability. Anodized or polished aluminum oxide, stainless steel plate is commonly used mirror emitting material. According to the law of regular reflection of the aluminum reflector geometry
The geometry and size of the aluminum reflector are carefully designed in accordance with the law of regular reflection, and the light source is precisely positioned during installation, so that the required light distribution can be obtained. The grille mainly plays the role of shading the light source and reducing the direct glare. Through the grille
The light distribution through the grille is generally narrow.

VI. Illumination and space luminous intensity distribution
The arrangement of lighting fixtures and illuminance meter is an important part of the lighting design, directly affecting the quality of lighting design. Point source illuminance calculation.
E
= F
= IQ-CoSQ
= IQ-CoS 2 Q 2 ΔS D 2 h 2
Where: E : illuminance
ΔS: light receiving area
F : luminous flux
IQ : luminous intensity
The formula shows that: point light source illumination and its distance to the illuminated surface is inversely proportional to the square, and the cosine of the angle of incidence is proportional to, and reflective intensity is proportional to. When the size of the light source is less than its distance to the illuminated surface
When the light source size is less than its distance to the illuminated surface of 1/10 is considered point light source.
VII. Estimated luminaire diagram
The luminaire budget diagram expresses the relationship between the number of luminaires used per unit area. Usually, the luminaire budget diagram gives several different hanging heights of the same luminaire, when the illumination requirement of the working surface is 100Ix,
The number of luminaires required for a certain flat area is used as the basis for selecting luminaires. If the required illumination of the correct working surface is not 100Ix, then the actual number of lamps and lanterns required is the number given on the estimate.
The amount multiplied by the actual illuminance and 100Ix ratio.
VIII. Explanation of terms: 1.
Luminous flux: the energy emitted by a light source into space per unit of time, which makes people feel light. Let the light source in t seconds a total of light energy is radiated W, we put the radiation out of the light energy
W and the ratio of the time elapsed by radiation t is called luminous flux. Luminous flux is a measure of how much light emitted by the light source an indicator. In F, the unit is light watt. Light watt unit is too large, commonly used lumens
(lm) as a practical unit, their relationship is 1 light watt = 683 lumens (lm). 1lm = 1cd-sr
Example: The luminous flux of an ordinary 40W fluorescent lamp is 2200 lumens (100 hours)
The luminous flux produced by domestic incandescent lamps is about 12.5lm (4tlm) for every 1W of electrical energy consumed. 2.
2. luminous intensity: is the spatial density of luminous flux, that is, the luminous flux per unit stereo angle, that is, a measure of the intensity of light source luminous quantity. The unit is candela (cd).
A candle luminous intensity of about 1cd.
Domestic 100W ordinary incandescent lamp luminous intensity of about 100cd. 3.
3. illuminance (abbreviated as illuminance): is the surface density of luminous flux on the surface, that is, the amount of luminous flux per unit area. Therefore, illuminance is a quantity that indicates the degree of illumination of the illuminated surface. To E
expressed, the unit is lux (Lx).
Example: The illuminance of natural light is approximately as follows.
100000Lx Under direct sunlight on a clear day
10,000 Lx sunny day in the shade
20 Lx Indoor corner on a clear day
0.2 Lx Moonlight night
100 to 200 Lx Illuminance required for general office
General study illumination should be not less than 75Lx
The illuminance at 1m directly below the 40W ordinary light bulb is about 30Lx
40W fluorescent lamps directly below the 1.3m illumination of about 90Lx
4. luminosity (referred to as luminance): unit surface in a certain direction of light intensity density, it is equal to the direction of the luminous intensity and this surface in the direction of the ratio of the projected area. That is
Visual object in the direction of the line of sight unit projection surface luminous intensity called the object surface luminance. Brightness is often expressed in a certain direction of brightness. In B, unit: candela per square meter, symbol: cd/m2.
square meters, the symbol: cd/㎡. Or nits (nt), Hiti (sb). 1nt nt = 1cd/㎡, 1sb Hiti = 10000nt nt. Expressed in the formula as follows.
B
= IQ ΔS-CoSQ
The surface illuminance of a 40W fluorescent lamp is 7000cd/㎡
The filament luminance of incandescent lamp is about 400×10 4
Sun brightness is about 20 × 10 8 cd/㎡
General cloudy sky brightness average of 2000 cd/㎡
5. luminous efficiency: the luminous efficiency of the light source, that is, the luminous flux of the light source and the ratio of the electrical power it consumes, referred to as luminous efficiency. Unit: lumens / watt, symbol: lm / W
General incandescent bulb luminous efficiency of about 7 ~ 20lm / W
The luminous efficiency of straight fluorescent lamps is about 30 ~ 60lm/W, so the use of fluorescent lamps than the use of incandescent lamps to save energy.
IX. Light color and distortion
Light color is an important indicator of the quality of the light source. Contains.
1 color table: the human eye directly observe the color of the light seen by the occurrence.
2. color rendering: the objective effect produced by the light striking the surface of the object. 3.
3. color rendering index: the color shown under the light compared to the value of the color under the sun. 4.
4. color temperature: is to indicate the color of incandescent luminous objects have.
X. Scientific and reasonable lighting
1. brightness contrast
When the surrounding brightness and the center of equal brightness, or slightly darker around, the best vision.
2 glare
In the visual environment, if there is a very bright object or strong brightness.
There are direct glare and reflected glare.
Direct glare is caused by the light emitted from the light source directly to the human eye. The causes of visual discomfort caused by glare are.
① . Pupil narrowing due to high stimulation;
② . Light scattering from the cornea or intraocular tissues such as crystalline lens creates a light curtain in the eye;
③ . (3). The visual screen is stimulated by high brightness and the adaptation state is destroyed.
The intensity of direct glare depends on the light source, but the most significant glare is in the following cases.
① . The darker the light source is, the darker the eye adapts, the more significant the glare is.
②. The higher the brightness of the light source, the more significant the glare is.
③ . The closer the light source is to the line of sight, the more significant the glare is.
④ . The larger the surface area of the light source, the more the number of light sources, the more significant the glare.
Generally, the brightness exceeds 160,000 cd/㎡, there will be uncomfortable glare. Avoid methods.
Control the light projection direction of the light source, so that the light source can not be directed to the human eye, which requires a certain protection angle of the lamp (or lampshade).
Some lamps and lanterns with transparent grille type or semi-transparent cover to cover the light source, due to the increase in luminous area and make each luminous brightness is reduced, the light becomes soft and not harsh.

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