Design and preparation of microfilter for low alti

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Design and preparation of Microfilters for low and medium altitude multispectral remote sensing equipment

the design and preparation of Microfilters mainly includes three steps:

selection of the wavelength of the fingerprint substance of the target

determination of the wavelength of the fingerprint substance marking the target. Generally, it includes the wavelength of strong absorption of the target and the background material mixed with the target in the full spectrum range, or the wavelength of strong reflection of natural light (white light/sunlight), or the characteristic wavelength of spontaneous emission. For example, for the application of multispectral technology, the micro pointer for low altitude remote sensing detection in fire should have no stagnation and pulsation. A group of 5 wavelengths of each pixel of the prepared microfilter are composed of fire smoke, water vapor Grassland vegetation is determined by the strong absorption peaks of natural light at 480nm smoke, 520nm steam and 580nm grassland vegetation. The wavelengths of 2105 nm and 2155 nm of the two infrared bands are determined by the fire core and ash at night

filter design the main technical indicators of the preparation of

Microfilters are as follows:

1) micro lithography technology can align the position of multi-channel fundamental mode to the submicron level. Carry out corrosion cleaning according to the determined parameters, and do not affect the adhesion of vacuum multilayer coating

2) vacuum multilayer coating technology. Using a conventional vacuum coating machine, about 20 cookies based on silicon or gum can be made in a batch, and each cookie contains L6 micro multi-channel optical filters. A total of about 300 optical filters can be manufactured in one batch. Its corresponding indicators are as follows:

geometric/weight/time indicators:

① micro optical filter size: according to different applications, it can match various types of CCD/CMOS image sensors on the market, with a human induced range of 2'---6 t11t11 long and a demand difference of 2'---7 t11t11 wide

② pixel size: 2'---20 9m

③ filter weight: less than 19

optical index:

① light transmittance: 30%'---60%

② bandwidth of light transmission band: 10'---50 nm

③ light transmission range: ultraviolet to far infrared (200 ~ 2200


④ number of light transmission channels: 1 ~ 8 channels. For products with low spatial resolution requirements, the number of optical channels can be even more "although this number is getting smaller.

Figure 1 and Figure 2 show the dot matrix air wetted microfilter prepared by micro manufacturing. Figure 1 shows the developed and manufactured microfilter containing 4 × Cookies with 4 micro narrow-band multi-channel optical filters. With the same process, multi-channel narrow-band optical filter components suitable for different applications and detecting different target substances (that is, allowing different narrow-band optical signals to pass through) have been successfully manufactured. Figure 2 shows the micro narrow-band multichannel optical filter with local placement

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