3D structured light 940nm narrow-band optical filter and preparation method thereof

Abstract

The invention discloses a 3D structured light 940 nm narrow-band optical filter and a preparation method thereof; the optical filter includes a substrate, wherein a silicon oxide layer and a siliconhydride layer are alternately evaporated on one surface of the substrate; the other surface of the substrate is alternately evaporated with silicon oxide layers and silicon hydride layers, the total number of the silicon oxide layers and the silicon hydride layers on each surface is set to be 20-40, the thickness of the silicon oxide layer on each surface is set to be 1300-2000nm, and the thickness of the silicon hydride layer on each surface is set to be 400-800nm. According to the optical filter, the refractive index of silicon hydride can be controlled to 3.8-4.5, the refractive index of silicon dioxide can reach 1.4-1.6, and the requirement for large angle and small offset can be met; the adopted film system scheme is accurate in wavelength positioning and good in steepness; the spacelayer is made of a high-refractive-index silicon hydride material, and the coupling layer is made of a low-refractive-index silicon dioxide material, so that the offset caused by the angle effect is smaller than that caused by the low-refractive-index material.

Description

technical field [0001] The invention relates to the technical field of optical filters, in particular to a 3D structured light 940nm narrow-band optical filter and a preparation method thereof. Background technique [0002] At present, the narrow-band filter in the visible and near-infrared bands is a multilayer film composed of commonly used coating materials titanium dioxide and silicon dioxide alternately. The refractive indices of the two materials are 2.4 and 1.46 respectively, and their refractive index ratio is 1.64. When testing its spectral transmittance, it will be found that under the conditions of 0 degrees and 30 degrees, the wavelength shift is about 30nm (near the wavelength of 900nm). With the development of 3D camera technology, the corresponding filter is required The smaller the offset of the center wavelength (940nm) is, the better, and at the same time cut off the light in the rest of the bands to avoid interference caused by stray light. In this way, t...

AI Technical Summary

Problems solved by technology

In this way, the conventional titanium dioxide / silicon dioxide combination cannot meet the requirements; for this reason, we propose a 3D structured light 940nm narrow-band filter and its preparation method

Images