a spectral content that is unchanged or is changed in a prescribed manner for predetermined aoi over the defined spatial area when compared with light of normal incidence the substrate is typically made transparent to allow incident radiation to pass through from exterior side 24 to interior side 22 the tailored coating may be deposited on the substrate 39 s exterior side as shown in fig1 its interior side or both in addition incoming light may be incident to exterior side 24 to interior side 22 or both one possible optical collection system 30 is an optical sensor mounted on a gimbal 36 the gimbal may arranged such that the sensor can rotate about a single axis such as an axis 38 that would permit vertical rotation over prescribed range 34 in this case the coating need be tailored to provide spectral variation in only one dimension the gimbal might alternatively be arranged such that the sensor can rotate about two axes 38 40 thereby providing horizontal rotation over a different prescribed range of angles not shown in this case the coating is tailored to provide spectral variation in two dimensions the optical interference coating includes a plurality of layers deposited asymmetrically on substrate 20 to achieve the desired stabilized reflectance and transmittance spectra the optical coating 39 s properties are adjusted by varying the thickness of the layers that make up the coating deposition of the layers is preferably done.