filter related parameters

Central wavelength (CWL): the wavelength used by the filter in practical application. If the main peak value of the light source is 850nm LED lamp, the required central wavelength is 850nm.

Transmittance (T): assuming that the initial value of light is 100%, there is a loss after passing through the filter, and the evaluation shows that it is only 85%, then the optical transmittance of this filter can be only 85%. In short, we all hope that the smaller the loss, the better.

Peak transmittance (TP) > 85%: the maximum value of transmission after filter loss is more than 85%.

Half bandwidth (FWHM): in short, it is the wavelength corresponding to 1 / 2 of the highest transmittance, and the values of the left and right wavelengths are subtracted. For example, the peak is preferably 90%, 1 / 2 is 45%, and the left and right wavelengths corresponding to 45% are 800nm and 850nm, and the half bandwidth is 50nm.

Blocked: the transmittance corresponding to the cut-off area Because it is very difficult to achieve a transmittance of 0%, it is necessary to know that the sun can turn underground trees into carbon. It is difficult to cover everything only by this thin film. The smaller the transmittance, the better, that is, the smaller the unwanted spectral transmittance, the better.

Cut off band: the smallest region of acceptable unwanted wavelength.

Hard coating: oxide material plating (such as Ta2O5, SiO2, etc.).

Soft film: in addition to oxide materials, such as fluoride (MgF2), sulfide, commonly used gold, silver, aluminum and so on.

Antireflective film (AR): antireflective film, which increases the penetration of light and makes the most effective use of light energy.

Bbar: back broadband antireflective film.

High reflection (HR): light is returned or reflected more through a certain wavelength, such as a mirror used at ordinary times.

High transmittance (HT): the loss of light passing through a certain wavelength is less. For example, the glass window used at ordinary times belongs to visible light high transmittance.


Hanzhong Brisun Optics Co., Ltd. Is the high precision optical element manufacturer provides customized production of Various optical lenses, including spherical lens, cylindrical lens, optical window, mirror, prism, filter, metal base mirror and other high-precision optical elements. The base materials include various optical glass, fused quartz, calcium fluoride (CaF2), zinc selenide (ZnSe), germanium (GE), silicon (SI), sapphire, metal and other materials. And provide antireflective film, high reflection film, spectroscopic film, metal film and other optical coatings.

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