Patent ID: 6927900

Claim:
An optical body comprising at least a first effective optical packet of contiguous optical layers bounded by optically thick layers, the optical layers composed of alternating diverse materials A,B; wherein the optical layers when counted from one end of the first effective optical packet form a plurality of unit cells each having six optical layers arranged in relative optical thicknesses in a first cyclic permutation of 7A1B1A7B1A1B; wherein at normal incidence the first effective optical packet provides a reflection band at infrared wavelengths and substantially transmits light at visible wavelengths; wherein the materials A,B have refractive indices that satisfy a relationship n A >n B along at least one in-plane axis, and wherein the optically thick layers that bound the first effective optical packet have a refractive index n C along the at least one in-plane axis; wherein the optical body exhibits a variability in transmission over a visible wavelength range; and wherein a first optical layer disposed at the one end of the first effective optical packet and a second optical layer disposed at an opposite end of the first effective optical packet are selected from among the sequence of six optical layers 7A1B1A7B1A1B to reduce said variability in transmission.