Patent ID: 7324285
Filing Date: 2008-01-29
Classification: C04B,G02B

Abstract:
1. A refractive, transmittive or diffractive optical element, comprising a polycrystalline, substantially single-phase opto-ceramic which is transparent for visible light and/or for infrared radiation, wherein the opto-ceramic comprises essentially a composition that can be described by the following formulas wherein z1+z2 is less than or equal to 0.92 and preferably less than or equal to 0.90, wherein z1, z2 and m are higher than or equal to zero, wherein m is less than 0.10 and preferably less than 0.06, more preferably less than 0.03, most preferably close to or equal to zero, and X is selected from Y, Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu; M is selected from Ca and Mg; A represents one ore more additional components particularly selected from SiO wherein the crystallites have a cubic crystal structure of the ZrO or wherein z3 is a value in the range of between −1 and +1, m is a value in the range between 0 and 0.05 and M1 is selected from Y, La, Gd, Lu, Yb, Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm or a mixture of one or more of these elements, wherein the active lanthanides Ce, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er and Tm are present in the opto-ceramic in a total amount of either at most 100 ppm by weight, based on the oxides, or at least 15% by mole, based on the oxides; M2 is selected from one or more of the elements of the group III or IIIa of the periodic table, preferably from Al, Ga, In, Sc or a mixture of two or more of the elements, wherein the crystallites have garnet structure, and A represents one ore more additional components particularly selected from SiO