There are three main optical requirements for a writing desk lamp in its normal working position

(1) Shading

Below normal sitting position, the eye of the person looks to horizontal direction, should see the inner wall of chimney and illuminant;

(2) Desktop illumination requirements

The working area illuminated by the desk lamp should be 250Lx -- 500Lx, and the low illumination should be ≥120lx.

(3) Uniformity of illumination

Should ensure the working area that is illuminated by desk lamp, illuminance is relatively even, cannot produce particularly bright or dark spot, only ensure these 3 basic optical performance requirement, ability reduces eye fatigue, ability can be called desk writing desk lamp.