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Computational simulation method was used in two models of calcium carbonate aqueous solution to explore the mechanism of anti-scaling under electrostatic field on the molecular level. The binding energy between the surface and ions indicated that the surface (104) was more favorable for the growth of the new crystal, while it was much easier to decompose under field strength 1300 V/m. The diffusion coefficients of Ca2+ and CO3 2- revealed that the chemical reaction of Ca2+ and CO3 2- ions in Model-II was much difficult to form calcium carbonate crystal under electrostatic field. The hydration degree of Ca2+ with O atoms from water molecules showed that the electric field could enhance the hydration degree of Ca2+ under certain field length, hence preventing the chemical reaction with CO3 2- to produce crystal. In short, the scale inhibition effect under electrostatic field in Model-II was much better.

In fabrication of free form optical surfaces, spot exposure is a typical mode in laser photolithography. Proper selection of spot exposure superposing ratio is the key to optimize etching quality and writing speed. In this paper, a new composite diffractive grating structure is modeled for the influence on diffraction efficiency of binary optical elements caused by spot exposure superposing ratio. Composite grating can be transformed into one simple rectangular grating and two triangular gratings. Angular spectrum theory is used to describe the mathematical expression of the composite diffractive grating. Through simulation analysis, the relationships between diffraction efficiency and the other three items as grating depth, spot radius, and blaze wavelength, has been shown. Simulation results indicate that shape error caused by spot exposure ratio impact the diffraction efficiency greatly in deep etching, and the transmittance will reach maximal point approximately while spot exposure ratio is over 60%. This conclusion can be taken as the theoretical foundation for exposure frequency selection in laser photolithography figure generation.