Ultra-narrow band optical filter with high optical stability and preparation method thereof

Abstract

The invention discloses an ultra-narrow-band optical filter with high optical stability and a preparation method thereof. The ultra-narrow-band optical filter comprises a substrate and an ultra-narrow-band optical filter film arranged on the substrate. The substrate is made of FEP optical plastic, and the ultra-narrow band filter film is of a modified three-cavity structure. The film system selects a TiO2 film with a high refractive index and a SiO2 film with a low refractive index; all the film layers are subjected to ion-assisted deposition, the ion energy is 350 eV, the ratio JI / JM of the number of argon ions reaching the substrate to the number of molecules of the deposited film is greater than 0.19, and it is ensured that the aggregation density of the film layers reaches 1, so that wavelength drift caused by water absorption is eliminated. The thermal expansion coefficient of the FEP plastic reaches 140 * 10 <-6 > / degree, and a film material with a small thermal expansion coefficient and positive and negative matched refractive index temperature coefficients is selected to eliminate wavelength drift caused by ambient temperature. The ultra-narrow band optical filter can be widely applied to optical, photoelectric and laser systems and instruments to serve as a stable signal filter.

Description

technical field [0001] The invention relates to an ultra-narrow-band optical filter with high optical stability and a preparation method thereof, which belongs to the field of optical thin films and can be widely used in optical, photoelectric and laser systems and instruments as signal filters. Background technique [0002] As an optical filter, thin-film bandpass filters have irreplaceable important applications in the fields of optics, spectroscopy, laser, astrophysics and so on. The main parameters that characterize the characteristics of bandpass filters include the central wavelength or peak wavelength λ 0 , peak transmittance T m and the half-width Δλ. Such as figure 1 As shown, the half-width is the wavelength width at half the peak transmittance, and is commonly used as Δλ / λ 0 Indicates relative width. Δλ / λ 0 Filters greater than 5% are called broadband filters, those between 5% and 1% are called narrowband filters, and those less than 1% are called ultra-narr...

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Problems solved by technology

However, ion-assisted deposition must be based on a reasonable and accurate use of ion sources, otherwise even with ion-assisted deposition, nm-level drift still often exists

[0007] Not only the relative humidity above, but also the ambient temperature will produce wavelength shift of the filter

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