PURPOSE: To remove moire or Newton rings to relieve a burden such as eye fatigue of the observer by placing slantingly a longitudinal array of groups of through-holes at an angle of 10°∼45° against the longitudinal axis of the display screen.

CONSTITUTION: An electro-magnetic shielding net 1 is formed by irradiating a laser beam to a metal film 3 to pierce numerous through-holes 2. In this case, the film 3 is formed of metal such as copper, iron or stainless steel having an electro-magnetic shielding capability with a thickness of 10∼50μ, while surface treatment such as formation of copper oxide or silver film is applied to the surface of the film 3. The longitudinal array of the through-holes 2 on the film 3 is placed slantingly at an angle of 10°∼45° against the longitudinal axis of the display surface. The number of prescribed holes in the transverse direction are pierced, while the position of irradiation of the spot light is shifted transversely each prescribed intervals, thereafter, a line is changed to shift longitudinally a prescribed amount. In line alignment, the position is shifted at an angle of 10°∼45° against the preceding line to pierce the through-holes.