WO2023065627A1 - Optical filter and manufacturing method therefor - Google Patents

Abstract

An optical filter and a manufacturing method therefor. The optical filter comprises a substrate (1), and a band-pass film (2) and an antireflection film (3) which are provided on two sides of the substrate (1); and the band-pass film (2) and the antireflection film (3) are both formed by alternately arranging high and low refractive index film layers. At an incident angle of 0°-50°, the transmittance of the optical filter within a wave band of 1000 nm-2000 nm is 95% or above. The optical filter can achieve high transmittance within a wave band of 1000 nm-2000 nm and at an incident angle of 0°-50°.

Description

Optical filter and its preparation method

This application claims the priority of a Chinese patent application with application number 202111223221.1 and application title "Optical Filter and Its Preparation Method" filed with the China Patent Office on October 20, 2021, the entire contents of which are hereby incorporated by reference in this application .

technical field

The invention relates to an optical filter and a preparation method thereof.

Background technique

With the development of science and technology, laser detection technology is widely used in distance detection, biometric identification and various industrial production. Therefore, the requirements for laser anti-interference ability are getting higher and higher. According to the principle of laser detection, with the red shift of the laser detection wavelength, the anti-interference ability of the laser can be effectively improved. However, in the prior art, infrared laser products near the 940nm band cannot meet the requirement of high anti-interference ability. In addition, the long shift of the laser wavelength band will inevitably lead to an increase in film thickness, which in turn will lead to greater stress in the film layer, making the lens surface prone to distortion. When light passes through a distorted surface, there will be reflection loss, and the energy value of reflection loss is closely related to the amount of surface distortion, that is, the greater the amount of distortion, the more serious the energy loss, which will seriously reduce the transmittance of the product. It can be seen that the above-mentioned defects in the prior art put forward higher requirements for infrared laser products with longer wavelengths.

Contents of the invention

The object of the present invention is to provide an optical filter and a preparation method thereof.

In order to achieve the purpose of the above invention, the present invention provides an optical filter and a preparation method thereof. The optical filter includes a substrate and a band-pass film and an anti-reflection film arranged on both sides of the substrate, the band-pass film and the anti-reflection film The transparent films are formed by alternating high and low refractive index film layers.

According to one aspect of the present invention, the refractive index of the material of the high refractive index film layer is above 2.0, and the refractive index of the material of the low refractive index film layer is below 2.0.

According to one aspect of the present invention, the material of the high refractive index film layer in the bandpass film includes germanium oxide, titanium oxide, niobium oxide, tantalum oxide, lanthanum oxide, silicon hydride, titanium hydride, germanium hydride, niobium hydride, hydride Tantalum, lanthanum hydride, silicon nitride, germanium nitride, titanium nitride, niobium nitride, tantalum nitride, lanthanum nitride, silicon hydrogen nitride, germanium hydrogen nitride, titanium hydrogen nitride, niobium hydrogen nitride, hydrogen Tantalum nitride, lanthanum hydrogen nitride;

The material of the low-refractive-index film layer in the band-pass film includes silicon oxide, magnesium fluoride, and cryolite.

According to one aspect of the present invention, the material of the high refractive index film layer in the antireflection film includes titanium oxide, niobium oxide, tantalum oxide, lanthanum oxide, hafnium oxide, zirconium oxide, germanium oxide;

The material of the low refractive index film layer in the anti-reflection film includes aluminum oxide, magnesium oxide, silicon oxide, magnesium fluoride, lanthanum fluoride, and aluminum fluoride.

According to one aspect of the present invention, the thickness of the bandpass film is between 10000nm and 20000nm, and the thickness of the antireflection film is between 10000nm and 20000nm.

According to one aspect of the present invention, the ratio of the thickness of the bandpass film to the thickness of the antireflection film is between 1:1 and 1:1.8.

According to one aspect of the present invention, the bandpass film has 15-30 pairs of high and low refractive index film layers;

The anti-reflection coating has 20-50 pairs of high and low refractive index film layers.

According to one aspect of the present invention, the transmittance of the optical filter in the 1000nm-2000nm band is above 95% at an incident angle of 0°-50°.

According to one aspect of the present invention, the surface PV value of the filter is less than 20 microns within a diameter of 17 mm.

The method used to prepare the optical filter is to sequentially plate a bandpass film and an anti-reflection film on the substrate, and the anti-reflection film is plated in an environment above 150°C. The first layer must be made of silicon dioxide, and the coating ions The source power is higher than that of other layers of silicon dioxide, which is 1.5 times of that of other layers; the coating rate is lower than that of other layers of silicon dioxide, about 0.8 times of that of other layers.

According to the idea of the present invention, through reasonable selection of coating material and film thickness, the optical filter can achieve high transmittance in the range of 1000nm-2000nm and large angle incidence within the range of 0°-50°. Moreover, it can ensure that the PV value of the lens surface within the diameter range of 17mm is less than 20 microns.

According to the solution of the present invention, the ratio of the thickness of the band-pass film to the thickness of the anti-reflection film satisfies a certain relationship, so that stress balance can be better achieved.

According to the solution of the present invention, when making an optical filter, a band-pass film with a relatively large stress is plated first, and then an anti-reflection film is plated, and the anti-reflection film is plated in a high temperature environment, so that the film can be effectively eliminated. layer stress.

Description of drawings

Fig. 1 schematically represents the structure diagram of the optical filter of an embodiment of the present invention;

Fig. 2 schematically represents the spectrogram of the optical filter of an embodiment of the present invention in the 1300nm band;

Fig. 3 schematically represents the spectrogram of the optical filter of an embodiment of the present invention in the 1550nm band;

Fig. 4 schematically shows the spectrum of an optical filter in an embodiment of the present invention in the 1800nm band.

Detailed ways

In order to more clearly describe the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that are used in the embodiments. Apparently, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to these drawings without creative efforts.

When describing the embodiments of the present invention, the terms "vertical", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", " The orientation or positional relationship expressed by "horizontal", "top", "bottom", "inner" and "outer" is based on the orientation or positional relationship shown in the relevant drawings, which are only for the convenience of describing the present invention and simplifying the description, and It is not to indicate or imply that the device or element referred to must have a particular orientation, be constructed, or operate in a particular orientation, and thus the above terms should not be construed as limiting the invention.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, and the embodiments cannot be repeated here one by one, but the embodiments of the present invention are not therefore limited to the following embodiments.

Referring to Fig. 1, (band-pass) optical filter of the present invention comprises substrate 1 and band-pass film 2 and anti-reflection film 3 that are arranged on both sides of substrate 1, band-pass film 2 and anti-reflection film 3 are all by high, low The refractive index film layers are arranged alternately. Wherein, the material refractive index of the high refractive index film layer is above 2.0, and the material refractive index of the low refractive index film layer is below 2.0. In the present invention, the bandpass film 2 has 15-30 pairs of high and low refractive index film layers, and the antireflection film 3 has 20-50 pairs of high and low refractive index film layers.

In the present invention, the material of the high refractive index film layer in the bandpass film 2 can be metal, semiconductor and all or part of their oxides, nitrides, hydrides, hydroxides and oxynitrides. For example, germanium oxide, titanium oxide, niobium oxide, tantalum oxide, lanthanum oxide, silicon hydride, titanium hydride, germanium hydride, niobium hydride, tantalum hydride, lanthanum hydride, silicon nitride, germanium nitride, titanium nitride, niobium nitride , tantalum nitride, lanthanum nitride, silicon hydrogen nitride, germanium hydrogen nitride, titanium hydrogen nitride, niobium hydrogen nitride, tantalum hydrogen nitride, lanthanum hydrogen nitride (such as titanium oxide mixture with lanthanum oxide, mixture of lanthanum oxide and aluminum oxide). The material of the low refractive index film layer in the bandpass film 2 includes one or more mixtures of silicon oxide, magnesium fluoride and cryolite. Therefore, the selection of these materials can enable the filter to achieve high transmittance under large-angle incidence in a certain wavelength band.

The material of the high refractive index film layer in the anti-reflection film 3 is metal oxide, for example, one or more mixtures of titanium oxide, niobium oxide, tantalum oxide, lanthanum oxide, hafnium oxide, zirconium oxide, and germanium oxide. The material of the low refractive index film layer in the anti-reflection film 3 includes one or more mixtures of aluminum oxide, magnesium oxide, silicon oxide, magnesium fluoride, lanthanum fluoride, and aluminum fluoride. At the same time, the above-mentioned materials of the low-refractive index film layer can also be mixed with materials of the high-refractive index film layer to form other mixtures.

Of course, in the band-pass film 2 and the anti-reflection film 3, the material of the high-refractive index film layer and the low-refractive index film layer is not limited to one of the above-mentioned ones, and film layers of various materials can also be selected to form various film systems.

In the present invention, the thickness of the bandpass film 2 is between 10000nm and 20000nm, and the thickness of the antireflection film 3 is between 10000nm and 20000nm. Moreover, as the film layer of the anti-reflection film 3 becomes thicker, the stresses of the film layers on both sides of the substrate 1 will gradually maintain a relative balance. Therefore, in the present invention, the ratio of the thickness of the bandpass film 2 to the thickness of the anti-reflection film 3 is set between 1:1 and 1:1.8, so as to achieve stress balance.

The following describes the optical filter of the present invention in detail in the implementation manner of three different wavelength bands:

first implementation

In conjunction with FIG. 2, the composition of the bandpass film 2 and the antireflection film 3 in the optical filter of the present embodiment is shown in Table 1 below:

Table 1

Second implementation

In conjunction with FIG. 3, the composition of the bandpass film 2 and the antireflection film 3 in the optical filter of the present embodiment is shown in Table 2 below:

Table 2

third implementation

In conjunction with FIG. 4, the composition of the bandpass film 2 and the antireflection film 3 in the optical filter of the present embodiment is shown in Table 3 below:

table 3

In the preparation method of the optical filter of the present invention, the band-pass film 2 is coated on one side of the substrate 1 first, and then the antireflection film 3 is coated on the other side of the substrate 1 . Moreover, when coating the anti-reflection film 3, it should be carried out in a high-temperature environment above 150°C, so that when the anti-reflection film 3 is plated, the formed band-pass film 2 can be baked at a high temperature at the same time to release the stress, and The stress of the antireflection film 3 can be used to gradually balance the stress of the bandpass film 2 . Moreover, the first layer needs to be made of silicon dioxide during plating, and the power of the ion source of the coating should be about 1.5 times higher than that of the rest of the silicon dioxide layers, and the coating rate should be about 0.8 times lower than that of the rest of the silicon dioxide layers.

Satisfying the above settings can make the filter achieve a transmittance of more than 95% in any wavelength band of 1000nm-2000nm near infrared at an incident angle of 0°-50°. Combined with the special structural design of the optical filter of the present invention, the surface PV value of the optical filter can be less than 20 microns within a diameter of 17 mm.

The above description is only an embodiment of the present invention, and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (8)

1. An optical filter, characterized in that it comprises a substrate (1) and a bandpass film (2) and an anti-reflection film (3) arranged on both sides of the substrate (1), the bandpass film (2) and The anti-reflection film (3) is formed by alternating high and low refractive index film layers;

   The transmittance of the optical filter in the 1000nm-2000nm band is above 95% at an incident angle of 0°-50°.
2. The optical filter according to claim 1, characterized in that, the refractive index of the material of the high refractive index film layer is above 2.0, and the material refractive index of the low refractive index film layer is below 2.0.
3. The optical filter according to claim 2, characterized in that, the material of the high refractive index film layer in the bandpass film (2) comprises germanium oxide, titanium oxide, niobium oxide, tantalum oxide, lanthanum oxide, silicon hydride , titanium hydride, germanium hydride, niobium hydride, tantalum hydride, lanthanum hydride, silicon nitride, germanium nitride, titanium nitride, niobium nitride, tantalum nitride, lanthanum nitride, silicon hydrogen nitride, germanium hydrogen nitride, Titanium hydrogen nitride, niobium hydrogen nitride, tantalum hydrogen nitride, lanthanum hydrogen nitride;

   The material of the low-refractive-index film layer in the band-pass film (2) includes silicon oxide, magnesium fluoride, and cryolite.
4. The optical filter according to claim 2, characterized in that, the material of the high refractive index film layer in the antireflection film (3) comprises titanium oxide, niobium oxide, tantalum oxide, lanthanum oxide, hafnium oxide, zirconium oxide , germanium oxide;

   The material of the low refractive index film layer in the anti-reflection film (3) includes aluminum oxide, magnesium oxide, silicon oxide, magnesium fluoride, lanthanum fluoride, and aluminum fluoride.
5. The optical filter according to claim 1, characterized in that, the thickness of the bandpass film (2) is between 10000nm-20000nm, and the thickness of the antireflection film (3) is between 10000nm-20000nm.
6. The optical filter according to claim 1, characterized in that, the ratio of the thickness of the bandpass film (2) to the thickness of the antireflection film (3) is between 1:1 and 1:1.8.
7. The optical filter according to claim 1, wherein the surface PV value of the optical filter is less than 20 microns within a diameter of 17 mm.
8. A method for preparing the optical filter according to claims 1-7, characterized in that, on the substrate (1), a bandpass film (2) and an anti-reflection film (3) are sequentially plated, and the anti-reflection film (3) is The transparent film (3) is plated in an environment above 150°C.

Images