In surveillance environments where infrared light supplementation is not required, regular lenses can be used; in surveillance environments where infrared light supplementation is required, infrared lenses are necessary for optimal monitoring results. Of course, using a regular lens with infrared supplementation can still capture images, but the images will become blurry, and this is something we are all familiar with.
Professional infrared lenses are several times more expensive than regular lenses because they provide clear and high-quality images both during the day and at night. The reason for the significant difference in performance and price between the two types of lenses lies in the fact that different wavelengths of light are refracted differently by glass, resulting in a difference in the focal point's position. Currently available regular lenses can successfully focus light within a wavelength difference of around 250nm, which means they can focus light within the range of 430 to 650nm or 650 to 900nm, resulting in clear images. This is why regular lenses may be clear during the day but blurry at night, or clear at night but blurry during the day.
Optical lenses work with light waves within a certain range of wavelengths. Light waves emitted from an object can form a clear image on a focal plane within this wavelength range with minimal energy attenuation. However, light waves outside this range are difficult to correct for aberrations, resulting in poor image quality, low resolution, and significant energy attenuation, or even complete blockage by the optical material, making it impossible to pass through the lens. Infrared lenses have been optimized to provide the best response to different ranges of infrared wavelengths and block unwanted wavelengths.
During light propagation, shorter wavelengths such as natural light can be obstructed by fog, rainwater, dust, etc., and cannot pass through, while longer wavelengths such as infrared light can easily pass through. After passing through the obstacles, the infrared light can form a clear image on the lens due to the infrared correction of the ED glass and the infrared transparency of the IR coating. With an infrared-corrected lens using ED glass, near-infrared focus can be guaranteed, achieving high-definition imaging for 24 hours a day, both during the day and at night.
Short-wave infrared lenses are used to capture images in day and night scenes, primarily in the security monitoring industry. They can work normally under visible light during the day and can clearly capture nighttime activities, similar to daytime imaging, without the need for traditional night vision technology. The main applications of infrared lens technology in the market include border patrols, surveillance, food sorting, semiconductor fault analysis, toll station monitoring, and other typical machine vision applications.