Sun blind filter
In the 1950s, scientists discovered that sunlight with a wavelength less than 285 nm was almost completely absorbed by the ozone layer as it penetrated the atmosphere to sea level. This made it almost impossible to detect sunlight in this wavelength range from sea level to an altitude of 20 kilometers. Therefore, this wavelength range is called the sun blind ultraviolet band.
By utilizing the characteristics of ozone in the Earth's atmosphere, solar blind filters have strong absorption and scattering effects on natural light in the 200-280nm wavelength range. Therefore, 200nm to 280nm (abbreviated as "200nm to 280nm"); Sun Blind Belt; ）It is difficult to reach the surface of the Earth. Therefore, many research institutions have the advantages of low background noise, low false alarm rate, strong concealment, simple structure, and wide applicability. Using a solar blind filter to detect weak ultraviolet signals under sunlight irradiation. This solar blind filter has good performance, high transmittance, and sufficiently deep cutoff in the visible and near-infrared bands.
The sun blind ultraviolet filter is the core component of the sun blind ultraviolet detection system. It is used to filter out interference from other spectral bands in the detection environment, allowing the detector to better detect ultraviolet radiation in the sun blind zone, thereby improving the signal-to-noise ratio of the detection system and reducing false alarm rates. Therefore, the testing of the out of band cutoff depth of the sun blind ultraviolet filter is extremely important, and its requirements are becoming increasingly strict. At present, the instruments for measuring the cut-off depth of optical filters mainly include spectrophotometers, DF reflectometers, and acousto-optic modulation detection systems. Among them, spectrophotometers and DF reflectometers are suitable for measuring filters with a cut-off depth below 2-OD. In 2009, an acousto-optic modulation detection system was introduced, which used devices such as acousto-optic modulators, transmissive attenuators, and integrating spheres to extend the measurement range of the cut-off depth of the filter to 6-OD. However, for out of band depth cut-off and some spectral bands that can reach 10-OD for sun blind ultraviolet filters, the dynamic measurement range of their cut-off depth is still insufficient.
At present, solar blind filters are widely used in optical fields such as power lines, corona detection, high-voltage equipment corona discharge detection, forest fire detection, remote sensing detection equipment, atmospheric environment research, ultraviolet imaging, space-based warning, guidance, ultraviolet communication, etc. They have great commercial and military application value in many fields such as biochemical analysis, biomedical analysis, and public security reconnaissance.
By utilizing the characteristics of ozone in the Earth's atmosphere, solar blind filters have strong absorption and scattering effects on natural light in the 200-280nm wavelength range. Therefore, 200nm to 280nm (abbreviated as "200nm to 280nm"); Sun Blind Belt; ）It is difficult to reach the surface of the Earth. Therefore, many research institutions have the advantages of low background noise, low false alarm rate, strong concealment, simple structure, and wide applicability. Using a solar blind filter to detect weak ultraviolet signals under sunlight irradiation. This solar blind filter has good performance, high transmittance, and sufficiently deep cutoff in the visible and near-infrared bands.
The sun blind ultraviolet filter is the core component of the sun blind ultraviolet detection system. It is used to filter out interference from other spectral bands in the detection environment, allowing the detector to better detect ultraviolet radiation in the sun blind zone, thereby improving the signal-to-noise ratio of the detection system and reducing false alarm rates. Therefore, the testing of the out of band cutoff depth of the sun blind ultraviolet filter is extremely important, and its requirements are becoming increasingly strict. At present, the instruments for measuring the cut-off depth of optical filters mainly include spectrophotometers, DF reflectometers, and acousto-optic modulation detection systems. Among them, spectrophotometers and DF reflectometers are suitable for measuring filters with a cut-off depth below 2-OD. In 2009, an acousto-optic modulation detection system was introduced, which used devices such as acousto-optic modulators, transmissive attenuators, and integrating spheres to extend the measurement range of the cut-off depth of the filter to 6-OD. However, for out of band depth cut-off and some spectral bands that can reach 10-OD for sun blind ultraviolet filters, the dynamic measurement range of their cut-off depth is still insufficient.
At present, solar blind filters are widely used in optical fields such as power lines, corona detection, high-voltage equipment corona discharge detection, forest fire detection, remote sensing detection equipment, atmospheric environment research, ultraviolet imaging, space-based warning, guidance, ultraviolet communication, etc. They have great commercial and military application value in many fields such as biochemical analysis, biomedical analysis, and public security reconnaissance.