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The classification of filters and the principle of optical filters
Incident angle: the angle between the incident light and the normal of the filter surface. When the light is normally incident, the incident angle is 0°.
Spectral characteristics: filter spectral parameters (transmittance T, reflectance R, optical density OD, phase, polarization state s How to clean all the optics on the surface of the filter The components are all precision, you should pick and place as carefully as possible and try not to touch the surface.
We know any object, as long as its temperature is above zero, that is -273℃ , The object itself emits energy, and the change of energy changes with the change of wavelength. Infrared rays are mainly radiated by hot objects, so the color temperature of the light is also a kind of light color. Sign—The higher the color temperature of light, the more bluish the light color; the lower the color temperature of light, the more reddish the light. For example, the color temperature of sunlight and incandescent light in the morning and evening is below 3000K. This kind of light has a low color temperature. Polychromatic light (spectrogram) The general light source is the polychromatic light that is mixed with monochromatic light of different wavelengths. The so-called 'monochromatic light' refers to the spectral color light separated by white light or sunlight by the refraction of the Mitsubishi mirror-red, Orange, yellow, green,
The classification of filters
The filter products are mainly based on the spectral band and spectral characteristics , Coating materials, application characteristics, laser protective mirrors, etc. Classification. Spectral bands: ultraviolet filters, visible filters, infrared filters; spectral characteristics: bandpass filters, cut-off filters
What is an OLPF optical low-pass filter
The full name of OLPF is Opticallowpassfilter, which is an optical low-pass filter, which is mainly used to filter Input light signals of different frequencies and wavelengths to transmit to the CCD, and avoid different frequency signals from interfering with the color of the CCD
What is the anti-reflection coating
Anti-reflection film, also known as anti-reflection film, AR film, its main function is to reduce or eliminate the reflected light of optical surfaces such as lenses, prisms, and flat laser collimators, thereby increasing the transmission of these elements. The amount of light reduces or eliminates the stray light of the system.
The filter is made by adding special dyes to the plastic or glass substrate or evaporating optical film on its surface. It is used to attenuate (absorb) some of the light wavebands or pass through light waves in a small range of precise selection, while reflecting (or absorbing) other undesired wavebands. By changing the structure of the filter and the optical parameters of the film , Can obtain various spectral characteristics, so that the filter can control, adjust and change the transmission, reflection, polarization or phase state of the light wave. The classification method of the filter is generally according to the spectral optical lens band, spectral characteristics, film material, Application characteristics and other characteristics are classified.
Filters can be classified into band-pass filters (such as NBF808, BPF940, etc.) according to their spectral characteristics. Cut-off filters (such as IBG) -650), two-way spectroscopic filter Optical filters (such as semi-transparent half mirrors), neutral density filters, reflective filters, etc.;
filters can be classified into ultraviolet bands according to spectral bands Filters, visible light filters and infrared band filters, etc.;
filters can be divided into soft film filters and hard films according to the applied film material classification Filters, etc.;
filters can be classified according to the characteristics of the applied optical lens and can be divided into filters for medical biochemical instruments, filters for fluorescence microscopes, and multi-band for police Hard film filters and so on.
As far as the optical lens is concerned, the filter on it is generally coated with a special film to allow a part of the light to pass through or to prevent a part of the light from passing, and there are also those now The dual-band filter is a dual-channel coating. Two layers of film are plated on a lens to achieve the effect of two filters, such as IR650+950, u200bu200bwhich allows 650nm visible light to enter during the day and at night. Let the infrared light with a wavelength of 950nm enter, but the two do not affect each other.