A reflective optical film comprises a layer containing a polyester voided with inorganic particles such as barium sulfate in a size and an amount sufficient to provide a visible light reflectivity of at least 93%, a void volume of 40 to 70%, the film at least (1) having a thickness of less than 150 .mu.m, or (2) containing UV particles in amounts sufficient to provide a UV light reflectivity of less than 40%.