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Outdoor led flood lights factory|What does Ra mean in lamps?|Sunshinelux

July 17, 2022

Ra is CIR, color rendering index

When there is little or no main wave reflected by the object under the reference light source in the light source spectrum, the color will produce obvious color shift. The greater the degree of chromatic aberration, the worse the color rendering of the light source. The color rendering index coefficient (Kau fman) is still the common method to define the evaluation of color rendering of light sources.

The color rendering index of incandescent lamps is defined as 100, which is regarded as an ideal reference light source. This system is tested with 8 standard color samples with medium chroma, and compares the degree of deviation (Deviation) of these 8 colors under the test light source and the benchmark of the same color temperature, to measure the color rendering index of the light source, and take the average deviation value. Ra20-100, with 100 as the highest, the larger the average color difference, the lower the Ra value. Light sources below 20 are generally not suitable for general use.

Index (Ra) Grade Color Rendering General Application

90-100 1A Excellent Locations requiring accurate color contrast

80-89 1B Places where correct color judgment is required

60-79 2 Normal Locations requiring medium color rendering

40-59 3 Places with low requirements for color rendering and small color difference

20-39 4 Poor Places with no specific requirements for color rendering

The theoretical color rendering index of incandescent lamps is 100, but there are many kinds of incandescent lamps in real life, and their applications are also different, so their Ra values are not completely consistent. It can only be said that it is close to 100, which is the lamp with the best color rendering. The Ra value of specific lamps can be seen in the table below.

Light source Color rendering index Ra

Incandescent lamp 97

Daylight color fluorescent lamp 80-94

White fluorescent lamp 75-85

Warm white fluorescent lamp 80-90

Tungsten halogen lamp 95-99

High pressure mercury lamp 22-51

High pressure sodium lamp 20-30

Metal Halide Lamp 60-65

Sodium thallium indium lamp 60-65

Dysprosium lamp above 85


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