The diffractive optical element is based on the diffraction theory of light waves, using computer-aided design, and through the semiconductor chip manufacturing process, etched on the substrate (or the surface of the traditional optical device) to produce a stepped or continuous relief structure, forming a coaxial reproduction, and has A type of optical element with very high diffraction efficiency. The diffractive optical element is thin and light, small in size, high diffraction efficiency, multiple design freedom, good thermal stability and unique dispersion characteristics, and is an important element of many optical instruments. Since diffraction always leads to the limitation of the high resolution of the optical system, traditional optics always try to avoid the adverse effects caused by the diffraction effect. Until the 1960s, with the invention and successful The production caused a major change in concept. In the 1970s, although the technology of computer holograms and correlation diagrams became more and more perfect, the production of ultra-fine structure elements with high diffraction efficiency in the visible and near-infrared light bands still faced difficulties, thus limiting the practical application range of diffractive optical elements In the 1980s, the research group led by WB Veldkamp of MIT Lincoln Laboratory first introduced the lithography technology for manufacturing very large scale integrated circuits (VLSI) into the production of diffractive optical elements, and proposed the concept of “binary optics”. After that, a variety of new processing methods continued to emerge, high-quality and multi-functional diffractive optical element production, which greatly promoted the development of diffractive optical elements.
Diffraction efficiency
Diffraction efficiency is one of the important indicators for evaluating diffractive optical elements and refractive-diffractive hybrid optical systems containing diffractive optical elements. After the light passes through the diffractive optical element, multiple diffraction orders are generated. Generally, only the light of the main diffraction order is concerned, and the light of other diffraction orders forms stray light on the image surface of the main diffraction order, which reduces the contrast of the image surface. Therefore, the diffraction efficiency of the diffractive optical element directly affects the imaging quality of the diffractive optical element.
Due to the diffractive optical element and its flexible control of the wavefront, the excellent characteristics of integrating multi-function and integration and reproducibility, optical systems and devices are developing towards lightness, miniaturization and integration. Since the 1990s, the research of diffractive optical elements has become the frontier work of the optics field. These components can be widely used in laser wavefront correction, beam profile shaping, beam array generator, optical interconnection, optical parallel computing, satellite optical communications, etc.
Post time: Aug-19-2021