Partial reflector having stack of polymer layers for correcting color shift

A wavelength and polarization dependent partial reflector comprising an optical stack, the optical stack comprising a plurality of optical repeat units, each optical repeat unit including first and second polymer layers,

• wherein for wavelengths λ1<λ2<λ3, λ3 being at least 700 nm and no more than 2500 nm, the partial reflector has:
• for normally incident light polarized along a first axis, a transmittance of at least 85% for each wavelength between λ1 and λ3;
• and
• for normally incident light polarized along a second axis orthogonal to the first axis, a first reflection band having:
• first and second band edges comprising first and second band edge wavelengths at λ2 and λ3, respectively, a transmittance of the partial reflector generally decreasing with increasing wavelength along the first band edge and generally increasing with increasing wavelength along the second band edge, such that for each of the first and second band edge wavelengths, the transmittance is halfway between a minimum transmittance in the first reflection band and a baseline value of the transmittance defined by the transmittance in wavelength ranges adjacent to, and on opposite sides of, the first reflection band;
• and
• an average reflectance between 15% and 97%.