Patent ID: 7440205

Claim:
A variable dimming system for dimming an electromagnetic radiation beam, the dimming system comprising at least two dimming units, both being sequentially arranged in relation to the propagation way of the electromagnetic radiation beam and mutually movable, each of the at least two dimming units having an attenuation characteristic which is position dependent with respect to the cross-section of the electromagnetic radiation beam, wherein the attenuation characteristic of each dimming unit is obtained by a position dependent transmissivity behavior or a position dependent reflectivity behavior or a position dependent diffusity behavior, wherein the at least two dimming units are configured such that their combined dimming behavior is spatially substantially constant over a cross-section of the electromagnetic radiation beam perpendicular to a direction of travel of the electromagnetic radiation beam; and wherein the attenuation characteristic of each of the dimming units comprises a substantially complete attenuation of said electromagnetic radiation beam in a first area of said dimming unit, substantially no attenuation of said electromagnetic radiation beam in a second area of said dimming unit and a continuously decreasing attenuation on a trajectory between the first and the second area; wherein said continuously decreasing attenuation of the first dimming unit substantially changes according to a first functional behavior and said continuously decreasing attenuation of the second dimming unit substantially changes according to a second functional behavior, such that combination of the first and the second functional behavior is substantially a constant; and wherein said first functional behavior is expressed by an exponential function and said second functional behavior is expressed by a function which is an inverse of said exponential function.