Patent ID: 7426070
Filing Date: 2008-09-16
Classification: G02B

Abstract:
1. An intensity-dependent attenuation device for light, having a polarizer, which allows linearly polarized light to propagate through in one input polarization direction, and having an analyzer which is crossed relatively thereto by one of a substantial number of degrees and 90 degrees, comprising: a λ/2 phase-retardation plate, an optically addressable, spatially resolving light modulator designed as a λ/4 phase-retardation plate, and a mirror, incident light propagating, in turn, through the polarizer, the λ/2 phase-retardation plate, and the optically addressable, spatially resolving light modulator, and, from there, impinging on the mirror, and, subsequently, in the reverse direction, again propagating through the optically addressable, spatially resolving light modulator and the λ/2 phase-retardation plate and, from there, impinging on the analyzer, the λ/2 phase-retardation plate having a first indicatrix which the optically addressable, spatially resolving light modulator having a second indicatrix, which c) the phase-retardation plate and the optically addressable, spatially resolving light modulator being so oriented to one another and with respect to the polarizer that the first or second external electric field being applied to the phase-retardation plate, and the third or fourth external electric field being applied to the optically addressable, spatially resolving light modulator; and the first and second, and the third and fourth external electric fields, respectively, being selected in such a way that the first angle and the maximum value fulfill the condition 2α−βmax=n·45°+T, n being equal to 0,1,2,3, . . . , α being the first angle, βmax being the maximum value, and T being a tolerance of ±5°.