Development history of short wave pass filters
Interference film is a typical short wave filter, which has been used as an anti reflection film for lenses in periscopes and binoculars since World War II. Infrared filters, as indispensable optical components for military use, are widely used in missile automatic guidance, infrared communication systems, aircraft beacons, and land and sea infrared detection and tracking systems.
Since modern times, with the further development of optical communication technology and the gradual industrialization of display technology, the development speed of optical thin films has accelerated. Interference film filters are adopted by some solar energy companies. Compared with traditional solar technology, the absorption ratio of 1000 wafer film is increased by 12%, and the emission ratio is reduced by 30-40. In solar technology, the interference film uses two layers of metal components with different absorption layers, and the interference between them greatly improves the absorption ratio and reduces the emissivity. In addition, the anti reflection layer reduces the effects of light reflection and thermal radiation, further increasing absorption and reducing emissivity, thereby improving heat collection efficiency. The quality of the interference film depends on the thickness of the film. Although the absorption layer of the interference film is only two layers, it is thicker than the gradient film. Therefore, at high temperatures, the film is not easily detached and does not affect the stability of the film.
Infrared filters have been widely used in image sensors based on charge coupled devices (CCD) or complementary metal oxide semiconductors (CMOS). Mainly used for visible light filtering and infrared light response in the range of 780-1100nm to obtain high-quality images. The application of infrared filters in radiometers and pyrometers, infrared cameras, monochromators, spectrometers, infrared microscopes and telescopes, continuous process analyzers, and infrared search and tracking systems has led to rapid development in the research and development of infrared filters, detectors, and related devices.
Infrared cut-off filters are widely used in military, digital products, optical holography, and optoelectronic technology. With the rapid development of information technology, the high-quality and product requirements of digital video products such as digital cameras, rear projection televisions, digital projectors, and small CMOS cameras have also driven the development of infrared cut-off filters. In digital product systems, infrared light can cause color temperature deviation and reduced clarity of images. This requires installing an infrared cut-off filter between the lens and CCD. It can be foreseen that infrared cut-off filters will still play an important role in the next generation of digital products.
In projection display systems, minimizing volume, achieving high-quality projection brightness, and high contrast are common requirements for manufacturers and consumers today. This requires a more precise optical system (objective lens and shortwave filter) to obtain high-purity tricolor light, which is then received by a CCD to produce video. Signal.
Short wave filters have a wide range of applications in medical instruments and fluorescence fiber bronchoscopy, playing an important role in the early diagnosis of lung cancer. Lung tissue is excited by deep blue light with a wavelength of 442 nm. The difference between normal tissue and cancerous tissue is significant, while the difference between red light is minimal. Short wave filter overlays two light bands under bronchoscopy. The image is transmitted through optical fiber and processed by a computer. Finally, normal tissue appears green, while cancer tissue appears brown or reddish brown.
Short wave filters have a wide range of applications in medical instruments and fluorescence fiber bronchoscopy, playing an important role in the early diagnosis of lung cancer. Lung tissue is excited by deep blue light with a wavelength of 442 nm. The difference between normal tissue and cancerous tissue is significant, while the difference between red light is minimal. Short wave filter overlays two light bands under bronchoscopy. The image is transmitted through optical fiber and processed by a computer. Finally, normal tissue appears green, while cancer tissue appears brown or reddish brown.
By the end of the 20th century, a new technology - biochar scanning technology - had developed, which collected the fluorescence generated by laser excitation of objects into parallel light and reflected the parallel light through a filter to a narrowband filter via short waves. Parallel light is transmitted through a photomultiplier tube and a universal serial bus (USB) to the pinhole of a regular roll probe via a receiving objective lens.