OPTICAL RADIATION LIGHT FILTER OF VARIABLE DENSITY Russian patent published in 1999 - IPC

FIELD: optics. SUBSTANCE: proposed light filter is made of plate of optical material with surface layer manufactured in the form of diffraction grating. Ruled grooves of diffraction grating are made in the form of concentric rings with width varying along circumference. These grooves can be made in surface layer of plate in the form of recesses which depth do not exceed h=h = λ/2(n-1) for light filter used for transmission or do not exceed h=h = λ/4 for light filter used for reflection, where λ is length of wave of optical radiation; n is index of refraction of surface layer of material. EFFECT: improved capability to control radiation in large power range and reproducibility of law of change of transmission coefficient. 1 cl, 4 dwg