ABSTRACT
Diffractive optical elements (DOEs) may be used as a single optical component with dedicated functionality (e.g. focusing), or as one of the elements in complex hybrid optical systems to reduce the number of the elements and improve imaging quality. It is desirable to cover DOE's surface with antireflective coating. In this paper, we show the results of simulations using the Fourier modal method and measure the efficiency of a diffractive lens with antireflective (AR) coating. Results were compared with a previously proposed model of AR covered DOE by Mao et al. [Opt. Express25, 11673 (2017)10.1364/OE.25.011673]. Contrary to the previously published model, we have not observed a shift of the efficiency curve. Our findings prove that AR coatings improve the efficiency of DOEs and it is not necessary to take them into account when calculating optimal profile height.
ABSTRACT
A new fabrication method of apodized diffractive optical elements is proposed. It relies on using high energy beam sensitive glass as a halftone mask for variable diffraction efficiency phase masks generation in a resist layer. The presented technology is especially effective in mass production. Although fabrication of an amplitude mask is required, it is then repeatedly used in a single shot projection photolithography, which is much simpler and less laborious than the direct variable-dose pattern writing. Three prototypes of apodized phase masks were manufactured and characterized. The main advantages as well as limitations of the proposed technology are discussed.