Low-stress multilayer film optical filter and preparation method thereof

Abstract

The invention discloses a low-stress multilayer film optical filter and a preparation method thereof, a substrate is 3.3 borosilicate glass, and the multilayer film optical filter is a double-half-wave narrow-band interference optical filter. 3.3 borosilicate glass has a linear expansion coefficient of 3.3 * 10 <-6 > / degree; in order to reduce the junction stress of the optical filter, two technologies of substrate heating and ion assistance are adopted. When the temperature of the substrate is 250 DEG C, the aggregation density of the TiO2 film is close to 1, the aggregation density of the SiO2 film is close to 0.92, and the accumulated tensile stress of the optical filter is 10.8 MPa; if the ion energy is selected to be 350 eV, the ratio JI / JM of the number of the auxiliary ions reachingthe substrate to the number of the deposited integrators is 0.15 and 0.05 respectively, so that the aggregation densities of TiO2 and SiO2 are close to 1 and 0.96 respectively, and the junction cumulative pressure stress of the optical filter is-7MPa. The low-stress film optical filter can be widely applied to various photoelectric instruments.

Description

technical field [0001] The invention relates to the field of optical films, in particular to a low-stress multilayer film filter and a preparation method thereof. Background technique [0002] The optical thin film formed by vacuum thermal evaporation or sputtering of bulk solid material usually has a great stress. Thin film stress is composed of three parts: surface tension, thermal stress and internal stress. Since the surface tension is small and the surface tension of different materials does not change much, it can be ignored. Thermal stress is caused by the difference in thermal expansion coefficient between the substrate and the film due to the temperature difference when the film is prepared and cooled to room temperature after the preparation is completed. If the thermal expansion coefficient of the substrate is not equal to the thermal expansion coefficient of the film, thermal stress must be generated, and the thermal stress usually appears as Tensile stress. I...

AI Technical Summary

Problems solved by technology

So far, although the research on thin film stress has made remarkable progress, it has not been solved fundamentally, and it is still an insurmountable obstacle in some important applications.

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