Judging by the following three attributes.
I. Illuminance
The luminous flux per unit area of the illuminated object is lux (Ix).
The downward light of lamps and lanterns should be distributed reasonably, and the illumination on the working surface should be uniform, and the difference between light and shade should not be too big. Generally, the best writing illumination on the desktop is 700- 1000lx.
Second, color rendering
The degree of color recovery of an object irradiated by a light source is measured by the color rendering index (Ra).
Under the same illumination, the light source with good color rendering makes people see more clearly than the light source with good color rendering. This is an index that reflects the color authenticity of an object under illumination. When buying a desk lamp, reading and studying, you'd better bring a color photo. Look at the difference between the color of the photo and the natural light under the lamp. The smaller the difference, the better the color rendering of the lamp.
Third, the color temperature
Also known as color temperature, it is expressed by absolute temperature scale K.
The color temperature of light source is divided into low color temperature (below 3300K), medium color temperature (3300 ~ 5300K) and high color temperature (above 5300K).
The light source with low color temperature is yellow, which belongs to warm tone and is suitable for rest;
The light source with high color temperature is white, which is cool and exciting;
The light source with medium color temperature is soft and suitable for reading and learning. The lower the color temperature, the warmer the yellow light, the softer the reflected light to the handwriting and the less irritating to the eyes.
Experiments show that the reading effect is the best when the color temperature is around 4000K, and there is basically no reflected glare.