Infrared filter with broadband of 3.65 to 5 microns, and manufacturing method for infrared filter

Abstract

The invention discloses an infrared filter with a broadband of 3.65 to 5 microns, and a manufacturing method for the infrared filter. The infrared filter with the broadband of 3.65 to 5 microns is characterized in that: monocrystalline germanium Ge with the size of phi 18*1.0mm is used as a base plate 1, wherein the surface aperture N of the monocrystalline germanium Ge is less than or equal to 5, and the local aperture delta N is less than or equal to 0.5, the depth of parallelism theta is less than or equal to 1', and the surface finish is more than 60/40; coating materials are silicon monoxide SiO and the monocrystalline germanium Ge, and multiple layers of interference films are deposited on two surfaces of the base plate; Sub 1.33(.5HL.5H)<5>3.39(.5LH.5L)<5> Air is adopted by the design of a first surface film system interference film 2; Sub 0.92(.5HL.5H)<3> 1.1(.5HL.5L)<4> Air is adopted by the design of a second surface film system interference film 3; and according to the infrared filter with the broadband of 3.65 to 5 microns, gradient of two sides is less than 3 percent, namely the wavelength of a transition area from the transmissivity of 5 percent to the transmissivity of 80 percent is less than 20nm, the transmissivity of a high-transmissivity area is more than or equal to 90 percent, the cut-off depth in a cut-off area is less than or equal to 0.1 percent, the transmissivity reaches more than 92 percent in the range of thermal imager wavelength of 3.7 to 4.9mu m, excellent signal-to-noise ratio is achieved, and the requirements of sensitivity and accuracy of a high-performance thermal imager can be met.

Description

technical field [0001] The invention relates to an infrared filter production technology, in particular to a 3.65 micron to 5 micron broadband infrared filter and a manufacturing method thereof Background technique [0002] In nature, all objects radiate infrared rays, so using a detector to measure the infrared difference between the target itself and the background, different infrared images can be obtained, which are called thermal images. The thermal image of the same target is different from the visible light image. It is not the visible light image that the human eye can see, but the target surface temperature distribution image, or the infrared thermal image is the surface temperature distribution that the human eye cannot directly see the target. , into a thermal image representing the temperature distribution of the target surface that can be seen by the human eye. [0003] A device that uses infrared thermal imaging technology to detect the infrared radiation of a...

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Problems solved by technology

[0004] However, the 3.65 micron to 5 micron broadband infrared filter provided by the existing technolo

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