Optical film and optical system

A display comprising:

• a light source;
• a two-dimensionally pixelated display surface for displaying an image, each pixel comprising at least three spaced apart subpixels;
• and
• a multilayer optical film disposed on the display surface and comprising first and second optical layers defining a two-dimensional grating interface therebetween extending along mutually orthogonal first and second directions, the first and second directions defining mutually orthogonal first and second diagonal directions therebetween, the grating diffracting at least one subpixel in each pixel into a zero diffraction order and a plurality of first diffraction orders along each of the first, second, first diagonal and second diagonal directions at a wavelength λ in a range from about 580 nm to about 650 nm, such that intensities of the zero and first diffraction orders are within 10% of each other,
• wherein an emission spectrum of the display surface comprises a first peak wavelength λa, a second peak wavelength λb, and a third peak wavelength λc, wherein λc>λ>λb>λa, and wherein λ=(1−α)*λb+α*λc, α being in a range of 0.5 to 0.95.

An optical system comprising:

• a light source;
• a two-dimensionally pixelated display surface for displaying an image;
• and
• first and second optical layers disposed on the display surface and defining a two-dimensional grating interface therebetween, an absolute value of a difference between indices of refraction of the first and second optical layers at a wavelength λ in a range from about 580 nm to about 650 nm being in a range from about 0.10 to about 0.25, the grating interface having a period T in a range from about 7.5 micrometers to about 10 micrometers and an average height H in a range from about 1.1 micrometers to about 2.4 micrometers, such that when the display surface displays an image having a spatial frequency of about 10 line pairs per mm, the optical system magnifies the displayed image through the grating interface as a virtual image for viewing by a viewer, a modulation transfer function (MTF) of the virtual image greater than about 0.4.