| 摘要 |
<p>A diffractive optical element (10) for guiding a light having a color spectrum characterized by a plurality of wavelengths longer than a shortest wavelength, λ B, and shorter than a longest wavelength λ R, the light striking the diffractive optical element (10) at an angle greater than a first field-of-view angle, α-FOV, and smaller than a second field-of-view angle, α+FOV. The diffractive optical element comprising a linear grating (12) being formed in a light-transmissive substrate (14). The linear grating (12) is characterized by a pitch, d, selected so as to allow total internal reflection of a light having wavelength λB and a striking angle of α -FOV. The light-transmissive substrate is characterized by an index of refraction, ηS, larger than a minimal index of refraction, ηmin, which is selected so as to allow total internal reflection of a light having wavelength of λR and a striking angle of α +FOV.</p> |
