Diffraction optical element is a kind of optical element with high diffraction efficiency, which is based on the diffraction theory of light wave and uses computer-aided design and semiconductor chip manufacturing process to etch the step or continuous relief structure on the substrate (or the surface of traditional optical device). Diffracted optical elements are thin, light, small in size, with high diffraction efficiency, multiple design degrees of freedom, good thermal stability and unique dispersion characteristics. They are important components of many optical instruments. Since diffraction always leads to the limitation of high resolution of optical system, traditional optics always try to avoid the adverse effects caused by diffraction effect until the 1960s, with the invention and successful production of analog holography and computer hologram as well as phase diagram caused a great change in concept. In the 1970s, although the technology of computer hologram and phase diagram was becoming more and more perfect, it was still difficult to make hyperfine structure elements with high diffraction efficiency in visible and near infrared wavelengths, thus limiting the practical application range of diffractive optical elements. In the 1980s, A research group led by W.B.Veldkamp from MIT Lincoln Laboratory in the United States first introduced the lithography technology of VLSI manufacturing into the production of diffractive optical components, and proposed the concept of “binary optics”. After that, various new processing methods continue to emerge, including the production of high-quality and multifunctional diffractive optical components. Thus greatly promoted the development of diffractive optical elements.
Diffraction efficiency of a diffractive optical element
Diffraction efficiency is one of the important indexes to evaluate diffractive optical elements and mixed diffractive optical systems with diffractive optical elements. After the light passes through the diffractive optical element, multiple diffraction orders will be generated. Generally, only the light of the main diffraction order is paid attention to. The light of other diffraction orders will form stray light on the image plane of the main diffraction order and reduce the contrast of the image plane. Therefore, the diffraction efficiency of diffractive optical element directly affects the imaging quality of diffractive optical element.
Development of diffractive optical elements
Due to the diffractive optical element and its flexible control wave front, the optical system and device are developing to light, miniaturized and integrated. Until the 1990s, the study of diffractive optical elements has become the forefront of the optical field. These components can be widely used in laser wavefront correction, beam profile forming, beam array generator, optical interconnection, optical parallel calculation, satellite optical communication and so on.
Post time: May-25-2023