Method for preparing pixel-level multispectral optical filter

A multi-spectral and optical filter technology, applied in the direction of optical filters, optics, optical components, etc., can solve the problems of spectral channel unit size variation, poor spectral passband characteristics and limitations of optical filters, etc., and achieve improved passband Features, Ensuring Dimensional Integrity, Effects of Reduced Shadowing Effects

Active Publication Date: 2020-01-17
CHANGCHUN INST OF OPTICS FINE MECHANICS & PHYSICS CHINESE ACAD OF SCI +1
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Problems solved by technology

[0004] At present, there are roughly two preparation methods for pixel-level multispectral filters. One method is based on the Fab cavity film structure. The intermediate cavity layer is etched to form micron-scale steps of different thicknesses to adjust the spectral peak position, and finally the second reflective film stack is plated to form an array-like periodic arrangement of pixel-level multi-spectral filters. The spectral channel transmittance of the filter is low, the half-width of the channel is narrow, and the spectral range is also very limited
The other is based on a wide-band pass film structure. First, use the Lift-off photolithography process to pattern micron-scale spectral channel units on the substrate, then plate a wide-band pass film stack, and finally remove the photoresist to form a A spectral channel, repeating the above steps to form an array-type periodic arrangement of pixel-level multi-spectral filters, this method due to the shadow shielding effect during coating causes the size of the spectral channel unit to deteriorate, and the thickness of the coated broadband pass-through film stack is limited. The prepared optical filter has poor spectral passband characteristics

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  • Method for preparing pixel-level multispectral optical filter

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preparation example Construction

[0030] The invention provides a preparation method of a pixel-level multispectral filter, comprising the following steps:

[0031] S1: Use the film system design software to design the structure of the broadband pass filter film stack, the average transmittance of the designed passband is better than 85%, and the average transmittance of the stopband is less than 5%;

[0032] S2: clean the substrate, and coat the first broadband pass filter film stack on the substrate;

[0033] S3: depositing a metal thin film on the first broadband pass filter film stack, and patterning the metal thin film, the patterned metal thin film is a metal thin film unit structure arranged periodically in an array, and the size of each metal thin film unit structure is 5-30 microns, one-to-one correspondence with the detector chip pixels;

[0034] S4: Using the patterned metal thin film as a mask layer, use a dry etching method to etch the first broadband pass filter film stack other than the metal m...

Embodiment 1

[0044] Preparation of 4-channel Pixel-level Multispectral Filters for Visible and Near Infrared

[0045] like figure 1 As shown, it is a schematic diagram of the preparation process of the visible and near-infrared 4-channel pixel-level multispectral filter, including the following steps:

[0046] S1: Use Macleod film system design software to design a broadband filter film stack structure with a working range from 400 nm to 900 nm and a total of 4 spectral channels. The film stack structure is made of high-refractive index material TiO 2 and low refractive index material SiO 2 Alternate composition, the passband center wavelengths of the spectral channels are 500 nm, 600 nm, 700 nm, 800 nm respectively, the half-peak width of each channel is 50 nm, the passband transmittance is better than 95%, and the stopband average transmittance rate is less than 1%.

[0047] S2: The designed first broadband-pass filter film stack, that is, a film stack with a center wavelength of 500 ...

Embodiment 2

[0054] Preparation of short-wave infrared 6-channel pixel-level multispectral filter

[0055] S1: Use Macleod film system design software to design a wide-band-pass filter film stack structure with a working range of 1.2 microns to 2.5 microns and a total of 6 spectral channels. The film stack structure is composed of high refractive index material Si and low refractive index material Al 2 O 3 The central wavelengths of the passbands of the spectral channels are 1.4 microns, 1.6 microns, 1.8 microns, 2.0 microns, 2.2 microns and 2.4 microns respectively, the half-peak width of each channel is 100 nanometers, and the passband transmittance is better than 90%. The stop-band average transmittance is less than 5%.

[0056] S2: Using magnetron sputtering coating equipment to coat a designed first broadband filter film stack on a clean K9 glass substrate, that is, a film stack with a center wavelength of 1.4 microns. The vacuum degree is 5×10 when depositing the film -1 Pa, Al 2...

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Abstract

The invention provides a method for preparing a pixel-level multispectral optical filter, which comprises the following steps: depositing a thick wide band-pass filter film stack with a good spectralpassband characteristic on a substrate; preparing a graphical metal film on the band-pass filter film stack; dry etching the band-pass filter film stack on the graphical metal film to prepare a steepstep-shaped spectrum channel unit; repeating the steps to prepare other spectrum channel units; and finally removing the metal films on all the spectrum channel units. The method provided by the invention has the beneficial effects that: a band-pass filter film stack which is 5-15 microns thick and is arranged in an arrayed and periodical mode can be formed, the passband characteristics of a spectral channel of the pixel-level multispectral optical filter can be improved, the graphical metal film is used as a mask layer and an etching stop layer to prevent a formed spectral channel unit from being etched, and a shadow shielding effect in the preparation process is reduced to ensure the integrity of the appearance size of the channel unit.

Description

technical field [0001] The invention relates to the technical field of optical films, in particular to a preparation method of a pixel-level multispectral filter. Background technique [0002] The imaging spectrometer with spectroscopic technology as the core combines imaging technology and spectral technology, which can not only image the detection target, but also obtain its rich spectral information, which is used in precision agriculture and forestry monitoring, environmental monitoring, natural disaster assessment, mineral The fields of exploration, biomedical testing, security monitoring, and early warning and identification of military targets are being widely and deeply applied. At present, imaging spectrometers often perform remote sensing work in the form of aviation, aerospace and UAV loads, and their volume and weight are very critical. Especially as aerospace loads, the difficult-to-compress volume and weight greatly increase their launch costs. Therefore, ther...

Claims

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Application Information

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IPC IPC(8): G02B5/20G02B5/28
CPCG02B5/201G02B5/285
Inventor 杨海贵张建王笑夷杨飞张卓高劲松
Owner CHANGCHUN INST OF OPTICS FINE MECHANICS & PHYSICS CHINESE ACAD OF SCI
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