Introduction and Commercial Application of Optical Film (2)
Absorb or reflect unwanted wavelength bands, and only allow specific wavelength bands to pass through. The types of filters can be divided into cut-off filters (long-wave pass filters, short-wave pass filters) according to the transmittance waveband, wave domain range, and purpose. Optical film, UV/IR cut-off filter), band-pass filter (broadband filter, narrow-band filter), band-stop filter (also called negative filter).
- UV/IR cut filter：Filter unnecessary UV or IR according to requirements. For example, IR cut filter can be used in lighting equipment to block heat and avoid affecting the operation of other components around, or it can be applied to camera lens to prevent image distortion caused by infrared rays. UV light is destructive, so UV cut filters are usually used in protective covers to prevent damage to sensors or lenses that are more sensitive to UV light.
- Bandpass filter：Common bandpass filters include three primary color filters and broadband/narrowband filters. Usually it can be combined with short-pass and long-pass filters. Based on process considerations, most of the two design stacks are plated on the same side of the substrate. The most effective design method is to use a symmetric periodic film.
- Dielectric reflective film：The technical requirements of the plated dielectric reflective film are relatively high, but the advantage lies in the controllability of the high reflection wave domain and the selection of special wavebands, and because the film layer has a low absorption value, it can be used in the mirror of the laser system.
Filters are used in many industries, such as eye glasses, agriculture, biomedicine, and also consumer electronics, such as camera lenses, projectors, electronic panels, etc.
Image Source: AAXA Technologies
Light is an electromagnetic wave, and its vibration direction is asymmetrical with its propagation direction. Therefore, light is polarized and is also called polarized light. Polarized light often causes unnecessary effects on images. For example, the reflected light from the water surface causes eye discomfort, road glare causes the recognition of passersby or drivers to decrease, and linearly polarized light interferes with the camera's metering and distance measurement. To eliminate these effects , You can use a polarizer to filter out harmful light.
Polarized sunglasses can be worn in outdoor areas with strong light, such as driving a car, snow, beach, etc., or a polarizing filter can be added to the camera lens to improve the contrast of the photo.
3. Attenuation Ｍirror
Also known as a neutral attenuator, it reduces or controls the light intensity by a certain ratio within a specified wavelength band. If it is used in the visible light band, because the spectral attenuation ratio is the same, its color will not be affected, only the luminous flux will be reduced.
It is widely used in various medical equipment detectors, testing instruments, and camera systems.
Image Source:GIE Optics Inc.