| 摘要 |
A diffractive optical element for guiding a light having a color spectrum characterized by a plurality of wavelengths longer than a shortest wavelength, lambda B, and shorter than a longest wavelength, lambda R, the light striking the diffractive optical element at an angle greater than a first field-of-view angle, alpha <->FOV, and smaller than a second field-of-view angle, alpha <+>FOV. The diffractive optical element comprising a linear grating being formed in a light-transmissive substrate. The linear grating is characterized by a pitch, d, selected so as to allow total internal reflection of a light having wavelength of lambda B and a striking angle of alpha <->FOV. The light-transmissive substrate is characterized by an index of refraction, nS, larger than a minimal index of refraction, nMIN, which is selected so as to allow total internal reflection of a light having wavelength of lambda R and a striking angle of alpha <+>FOV. |
