| Popis: |
In both design and fabrication, diffractive optical elements (DOEs) are more flexible and powerful than traditional refractive/reflective optical elements, hence an optical system with one or more diffractive elements may provide better optical performance at lower cost with small, light and compact structure. However due to its inherent large spectral dispersion, a DOE is generally designed and fabricated for one specific wavelength or a narrow spectral bandwidth. In the case of a wide band light source, chromatic aberration and loss of diffraction efficiency will occur. In this paper, the chromatic dispersion of DOE is discussed, and four achromatic strategies, namely hybrid diffractive/refractive strategy, harmonic diffraction strategy, multi-material strategy, and bi-blazed strategy are introduced and analyzed respectively. A comparison has also been made among them to guide the application. |
