An optical system

An optical system comprising:

• a display adapted to emit an image for viewing by a viewer, the emitted image comprising a central image ray propagating along a folded optical axis between the display and the viewer;
• a reflective polarizer, the central image ray incident on the reflective polarizer at a first incident angle between about 30 degrees to about 60 degrees, for each of at least one wavelength λb in a blue wavelength range and at least one wavelength λg in a green wavelength range and at least one wavelength λr in a red wavelength range, the reflective polarizer transmits at least 70% of the incident central image ray having a first polarization state and reflects at least 70% of the incident central image ray having an orthogonal second polarization state, and for each of at least one wavelength λbg between λb and λg and at least one wavelength λgr between λg and λr, the reflective polarizer transmits at least 70% of the incident central image ray having each of the first and second polarization states;
• a mirror, the minor and the display disposed on opposite sides of the reflective polarizer, the central image ray substantially normally incident on the minor, such that for at least λb, λg, and λr, the minor reflects at least 70% of the incident central image ray for each of the first and second polarization states;
• and
• a partial reflector, the partial reflector and the viewer disposed on opposite sides of the reflective polarizer, the central image ray substantially normally incident on the partial reflector, such that for at least λb, λg, and λr and for each of the first and second polarization states, the partial reflector reflects, and transmits, at least 30% of the incident central image ray.