阅读说明：本技术 一种球面镜窄带滤光片及其制备方法 (Narrow-band optical filter for spherical mirror and preparation method thereof ) 是由 陆张武 柴建龙 王迎 李恭剑 于 2021-05-28 设计创作，主要内容包括：本发明属于镀膜技术领域,具体涉及一种球面镜窄带滤光片及其制备方法,包括球面镜基底、设于球面镜基底一侧的窄带通膜系、设于球面镜基底另一侧的长波通膜系；所述长波通膜系包括从内往外逐层交替沉积的低折射率膜层和高折射率膜层,以及作为低折射率膜层的最外层；所述窄带通膜系包括从内往外逐层交替沉积的高折射率膜层和低折射率膜层。提供了一种947nm透过球面镜窄带滤光片,所述滤光片达到优良技术指标：在入射角为0°时,900-930nm光谱波段具有高透过率,887nm&950nm处的透过率小于10％,890nm&940nm处的透过率小于50％,在200nm-870nm、965-1050nm光谱波段截止,截止区域内最大透过率＜1％,入射角为0°和22°是曲线偏移小于8nm的球面镜窄带滤光片。(The invention belongs to the technical field of coating, and particularly relates to a narrow-band pass filter of a spherical mirror and a preparation method thereof, wherein the narrow-band pass filter comprises a spherical mirror substrate, a narrow-band pass membrane system arranged on one side of the spherical mirror substrate, and a long-wave pass membrane system arranged on the other side of the spherical mirror substrate; the long-wave pass film system comprises low-refractive-index film layers and high-refractive-index film layers which are alternately deposited layer by layer from inside to outside, and the long-wave pass film layers are used as the outermost layers of the low-refractive-index film layers; the narrow band-pass film system comprises high-refractive-index film layers and low-refractive-index film layers which are alternately deposited layer by layer from inside to outside. The 947nm narrow-band filter for the transmission of the spherical mirror is provided, and the filter achieves excellent technical indexes: when the incident angle is 0 degree, the 900-930nm spectral band has high transmittance, the transmittance at 887nm &950nm is less than 10%, the transmittance at 890nm &940nm is less than 50%, the spectral band is cut off at 200nm-870nm and 965-1050nm, the maximum transmittance in the cut-off region is less than 1%, and the incident angles of 0 degree and 22 degree are spherical mirror narrow-band filters with curve deviation less than 8 nm.)

1. The narrow-band filter for the spherical mirror is characterized in that: the optical fiber surface mirror comprises a spherical mirror substrate, a narrow band pass membrane system arranged on one side of the spherical mirror substrate and a long wave pass membrane system arranged on the other side of the spherical mirror substrate; the long-wave pass film system comprises low-refractive-index film layers and high-refractive-index film layers which are alternately deposited layer by layer from inside to outside, and the long-wave pass film layers are used as the outermost layers of the low-refractive-index film layers; the narrow band-pass film system comprises high-refractive-index film layers and low-refractive-index film layers which are alternately deposited layer by layer from inside to outside.

2. The spherical mirror narrowband filter according to claim 1, wherein the structure of the narrowband bandpass membrane system is (HL2HLHL) ^5, and the central wavelength is 915 nm; h is a high refractive index film layer with basic thickness, and L is a low refractive index film layer with basic thickness; 5 of (HL2HLHL) 5 is the cycle number of the basic film stack (HL2 HLHL).

3. The narrow band filter for spherical mirror of claim 1, wherein said long-wave pass film system has a structure of (0.5HL0.5H) ^17, and the central wavelength of the transition band is 835 nm; h is a high refractive index film layer with basic thickness, and L is a low refractive index film layer with basic thickness; 0.5H represents a high index film thickness of 0.5 base thicknesses; 17 of (0.5HL0.5H) ^17 is the number of cycles of the base film stack (0.5 HL0.5H).

4. The narrow band filter of spherical mirror in claim 1, wherein the high refractive index film layer or the low refractive index film layer in said narrow band-pass film system has a basic thickness of one quarter of the center wavelength of the optical thickness of said narrow band-pass film system; the basic thickness of the high refractive index film layer or the low refractive index film layer in the long-wave passing film system is one fourth of the central wavelength of the optical thickness of the long-wave passing film system.

5. The narrow band filter for spherical mirrors according to any one of claims 1-4, wherein said low refractive index film layer is a silicon oxide film layer, and said high refractive index film layer is a silicon hydroxide/silicon nitride hydride film layer.

6. The narrow band filter for spherical mirror of claim 1, wherein said long-pass film system and said narrow-pass film system are coated by magnetron sputtering method.

7. A preparation method of a narrow-band filter of a spherical mirror is realized in a vacuum sputtering coating machine and is characterized by comprising the following steps:

step S01, putting the spherical mirror substrate into a low vacuum chamber and vacuumizing to below 5.0E-0 Pa;

step S02, putting the spherical mirror substrate into a high vacuum chamber and vacuumizing to below 1.0E-03 Pa;

step S03, bombarding the surface of the spherical mirror substrate by plasma emitted by a radio frequency source;

step S04, depositing a long-wave pass film system on one side of the spherical mirror substrate by adopting a magnetron sputtering method, wherein the long-wave pass film system comprises a low-refractive-index film layer and a high-refractive-index film layer which are alternately deposited layer by layer from inside to outside, and the long-wave pass film system is used as the outermost layer of the low-refractive-index film layer;

step S05, depositing a narrow band-pass film system on the other side of the spherical mirror substrate by adopting a magnetron sputtering method, wherein the narrow band-pass film system comprises a high-refractive-index film layer and a low-refractive-index film layer which are alternately deposited layer by layer from inside to outside;

and step S06, naturally cooling the spherical mirror substrate to room temperature to obtain the spherical mirror narrow-band filter.

8. The method according to claim 7, wherein the low refractive index film layer is a silicon oxide film layer, and the high refractive index film layer is a silicon hydroxide/silicon nitride hydride film layer; the step S04 includes:

step S41, depositing silicon oxide film, operating the second RF oxidation source with Ar flow of 50-500sccm and O₂The flow rate is 100-500sccm, the power of the sputtering source of the second target material is 5-12 kw, the power of the second radio-frequency oxidation source is 2-4kw, and the flow rate of the working gas Ar of the second target material is 30-300 sccm;

step S42, depositing a silicon hydroxide/silicon nitride film, operating the first RF oxidation source with Ar flow of 50-500sccm and H₂The flow rate is 10-100sccm, O₂The flow rate is 0-50sccm/N₂The flow rate is 0-50sccm, the power of a sputtering source of the first target material is 5-12 kw, the power of the first radio-frequency oxidation source is 2-4kw, and the flow rate of the working gas Ar of the first target material is 30-300 sccm;

step S43, looping steps S41-S42 in this manner until the last second tier;

and step S44, depositing a silicon oxide film layer on the last layer.

9. The method of claim 7, wherein the low refractive index film is a silicon oxide film, the high refractive index film is a silicon hydroxide/silicon nitride film,

the step S05 includes:

step S51, depositing a silicon hydroxide/silicon nitride film, operating the first RF oxidation source with Ar flow of 50-500sccm and H₂The flow rate is 10-100sccm, O₂The flow rate is 0-50sccm/N₂The flow is 0-50sccm, the power of a sputtering source of the first target material is 5-12 kw, the power of the first radio-frequency oxidation source is 2-4kw, and the film deposition rate of the silicon hydroxide/silicon nitride hydride film is 0.3-0.7 nm/s;

step S52, depositing silicon oxide film, operating the second RF oxidation source with Ar flow of 50-500sccm and O₂The flow rate is 100-500sccm, the power of the sputtering source of the second target material is 5-12 kw, the power of the second radio-frequency oxidation source is 2-4kw, and the film deposition rate of the silicon oxide film is 0.5-1.2 nm/s;

step S53, looping steps S51-S52 in this manner until the last layer.

10. The method for preparing a spherical mirror narrowband filter according to claim 6, wherein: when the incidence angle of the prepared spherical mirror narrow band filter is 0 degree, the 900-930nm spectral band has high transmittance, the transmittance at 887nm &950nm is less than 10%, the transmittance at 890nm &940nm is less than 50%, the spectral band at 200nm-870nm and 965-1050nm is cut off, and the incidence angles of 0 degree and 22 degree are curve deviation less than 8 nm.

Technical Field

The invention belongs to the technical field of film coating, relates to an optical filter and a preparation method thereof, and particularly relates to a spherical mirror narrowband optical filter and a preparation method thereof.

Background

In a camera receiver module of an electronic product such as a mobile phone, an optical filter meeting the following requirements is urgently needed:

(1) when the incident angle is 0 DEG, the transmittance is high in the 900-930nm spectrum;

(2) when the incident angle is 0 DEG, the light signal can be inhibited from passing through the spectrum segments of 200nm-870nm and 965-1050nm,

(3) when the incident angle is 0 degrees, the transmittance at 887nm &950nm is less than 10 percent, and the transmittance at 890nm &940nm is less than 50 percent;

(4) the curve shift is less than 8nm at incident angles of 0 DEG and 22 DEG

(5) The appearance of the product is a spherical mirror, the perfect combination of the characteristics of the light filtering film and the characteristics of the spherical mirror is realized, and the practicability of the light filter is improved;

(6) can be used after being placed for a long time in the environment with low temperature (-40 ℃), high temperature (+85 ℃), high humidity (90%) and cold-hot cycle change.

(7) The thickness of the substrate is small (less than or equal to 0.3mm) so as to meet the miniaturization requirement of the whole structure of the module.

(8) The film layer is not damaged under the repeated friction of slight external force (pressure < 5N).

(9) The membrane layer was not damaged by gentle repeated rubbing with an alcohol-ether mixture (alcohol: ether: 1: 2).

(10) Soaking in high temperature pure water (95 deg.C) for more than 2 hr, and pulling the film (using CT-18 adhesive tape) to prevent the film layer from falling off.

The prior invention application CN201910165758.3 discloses an optical filter and a method for manufacturing the same, and specifically discloses an optical filter comprising a transparent substrate, and a first long-wavelength pass film system and a second long-wavelength pass film system respectively disposed on two sides of the transparent substrate; the first long-wave pass film system and the second long-wave pass film system respectively comprise a high-refractive-index film layer and a low-refractive-index film layer which are alternately superposed. The invention only obtains the 830-950nm transmission near-infrared filter, and the substrate is a parallel flat plate, so that the filter meeting the requirements can not be obtained.

Disclosure of Invention

The invention aims to solve the technical problems and provides a spherical mirror narrowband filter and a preparation method thereof, wherein when the incident angle is 0 degree, the 900 and 930nm spectral band has high transmittance, the transmittance at 887nm and 950nm is less than 10 percent, the transmittance at 890nm and 940nm is less than 50 percent, the spectral band is cut off at 200nm-870nm and 965 and 1050nm spectral bands, and the curve deviation is less than 8nm when the incident angles are 0 degree and 22 degrees.

The purpose of the invention can be realized by the following technical scheme:

a narrow-band filter for spherical mirror comprises a spherical mirror substrate, a narrow-band pass membrane system arranged on one side of the spherical mirror substrate, and a long-wave pass membrane system arranged on the other side of the spherical mirror substrate; the long-wave pass film system comprises low-refractive-index film layers and high-refractive-index film layers which are alternately deposited layer by layer from inside to outside, and the long-wave pass film layers are used as the outermost layers of the low-refractive-index film layers; the narrow band-pass film system comprises high-refractive-index film layers and low-refractive-index film layers which are alternately deposited layer by layer from inside to outside.

Furthermore, the structure of the narrow band-pass membrane system is (HL2HLHL) ^5, and the central wavelength is 915 nm; h is a high refractive index film layer with basic thickness, and L is a low refractive index film layer with basic thickness; 5 of (HL2HLHL) 5 is the cycle number of the basic film stack (HL2 HLHL).

Further, the structure of the long-wave pass membrane system is (0.5HL0.5H) ^17, and the central wavelength of the transition band is 835 nm; h is a high refractive index film layer with basic thickness, and L is a low refractive index film layer with basic thickness; 0.5H represents a high index film thickness of 0.5 base thicknesses; 17 of (0.5HL0.5H) ^17 is the number of cycles of the base film stack (0.5 HL0.5H).

Further, the high refractive index film layer or the low refractive index film layer in the narrow band-pass film system has a basic thickness of one quarter of the center wavelength of the optical thickness of the narrow band-pass film system; the basic thickness of the high refractive index film layer or the low refractive index film layer in the long-wave passing film system is one fourth of the central wavelength of the optical thickness of the long-wave passing film system.

Further, the low refractive index film layer is a silicon oxide film layer, and the high refractive index film layer is a silicon hydroxide/silicon nitride hydride film layer.

Further, the long-wave pass film system and the narrow-band pass film system are coated by a magnetron sputtering method.

A preparation method of a narrow-band filter of a spherical mirror is realized in a vacuum sputtering coating machine, and comprises the following steps:

step S01, putting the spherical mirror substrate into a low vacuum chamber and vacuumizing to below 5.0E-0 Pa;

step S02, putting the spherical mirror substrate into a high vacuum chamber and vacuumizing to below 1.0E-03 Pa;

step S03, bombarding the surface of the spherical mirror substrate by plasma emitted by a radio frequency source;

step S04, depositing a long-wave pass film system on one side of the spherical mirror substrate by adopting a magnetron sputtering method, wherein the long-wave pass film system comprises a low-refractive-index film layer and a high-refractive-index film layer which are alternately deposited layer by layer from inside to outside, and the long-wave pass film system is used as the outermost layer of the low-refractive-index film layer;

step S05, depositing a narrow band-pass film system on the other side of the spherical mirror substrate by adopting a magnetron sputtering method, wherein the narrow band-pass film system comprises a high-refractive-index film layer and a low-refractive-index film layer which are alternately deposited layer by layer from inside to outside;

and step S06, naturally cooling the spherical mirror substrate to room temperature to obtain the spherical mirror narrow-band filter.

Further, the low-refractive-index film layer is a silicon oxide film layer, and the high-refractive-index film layer is a silicon hydroxide/silicon nitride hydride film layer; the step S04 includes:

step S41, depositing silicon oxide film, operating the second RF oxidation source with Ar flow of 50-500sccm and O₂The flow rate is 100-4kw, the flow rate of the working gas Ar of the second target material is 30-300 sccm;

step S42, depositing a silicon hydroxide/silicon nitride film, operating the first RF oxidation source with Ar flow of 50-500sccm and H₂The flow rate is 10-100sccm, O₂The flow rate is 0-50sccm/N₂The flow rate is 0-50sccm, the power of a sputtering source of the first target material is 5-12 kw, the power of the first radio-frequency oxidation source is 2-4kw, and the flow rate of the working gas Ar of the first target material is 30-300 sccm;

step S43, looping steps S41-S42 in this manner until the last second tier;

and step S44, depositing a silicon oxide film layer on the last layer.

Further, the low refractive index film layer is a silicon oxide film layer, the high refractive index film layer is a silicon hydroxide/silicon nitride hydride film layer,

the step S05 includes:

step S51, depositing a silicon hydroxide/silicon nitride film, operating the first RF oxidation source with Ar flow of 50-500sccm and H₂The flow rate is 10-100sccm, O₂The flow rate is 0-50sccm/N₂The flow is 0-50sccm, the power of a sputtering source of the first target material is 5-12 kw, the power of the first radio-frequency oxidation source is 2-4kw, and the film deposition rate of the silicon hydroxide/silicon nitride hydride film is 0.3-0.7 nm/s;

step S52, depositing silicon oxide film, operating the second RF oxidation source with Ar flow of 50-500sccm and O₂The flow rate is 100-500sccm, the power of the sputtering source of the second target material is 5-12 kw, the power of the second radio-frequency oxidation source is 2-4kw, and the film deposition rate of the silicon oxide film is 0.5-1.2 nm/s;

step S53, looping steps S51-S52 in this manner until the last layer.

Further, when the incidence angle of the prepared spherical mirror narrow-band filter is 0 degree, the 900 and 930nm spectral band has high transmittance, the transmittance at 887nm &950nm is less than 10%, the transmittance at 890nm &940nm is less than 50%, and the spectral band is cut off at 200nm-870nm and 965 and 1050nm, and the incidence angles of 0 degree and 22 degree are curve deviation less than 8 nm.

Compared with the prior art, the invention has the outstanding and beneficial technical effects that:

1. the 947nm narrow-band filter for the transmission of the spherical mirror is provided, and achieves excellent technical indexes: when the incident angle is 0 degree, the 900-930nm spectral band has high transmittance, the transmittance at 887nm &950nm is less than 10%, the transmittance at 890nm &940nm is less than 50%, the spectral band is cut off at 200nm-870nm and 965-1050nm, the maximum transmittance in the cut-off region is less than 1%, and the incident angles of 0 degree and 22 degree are spherical mirror narrow-band filters with curve deviation less than 8 nm.

2. The characteristics of the pass band and the cut-off band of the spectral filter can be greatly improved, and the use requirement of the camera module can be met.

3. The optical filter is formed by alternately superposing a silicon hydroxide/silicon nitride film layer with high refractive index and a silicon oxide film layer with low refractive index, the number of the film layers is small, the thickness of the film layers can meet the plating requirements on two surfaces of an ultrathin substrate (the thickness is less than 0.3mm), and the optical filter meets the use requirements of working in the environment of low temperature (-40 ℃), high temperature (+85 ℃), high humidity (90%) and the like.

Drawings

Fig. 1 is a flowchart of a method for manufacturing a narrow-band filter of a spherical mirror according to the present invention.

FIG. 2 is a theoretical transmission spectrogram of a narrow band-pass film system of a narrow band-pass filter of a spherical mirror according to the present invention.

FIG. 3 is a theoretical transmission spectrogram of a long-wave pass film system of a narrow-band filter of a spherical mirror according to the present invention.

FIG. 4 is a diagram of the transmission theoretical spectrum of the filter after coating the film layers on both sides of the narrow-band filter of the spherical mirror according to the present invention.

Fig. 5 is a transmission spectrogram after the performance test of the narrow-band filter of the spherical mirror of the present invention.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

As shown in fig. 1-5, a narrow band pass filter of a spherical mirror includes a spherical mirror substrate, a narrow band pass membrane system disposed on one side of the spherical mirror substrate, and a long wave pass membrane system disposed on the other side of the spherical mirror substrate; the long-wave pass film system comprises low-refractive-index film layers and high-refractive-index film layers which are alternately deposited layer by layer from inside to outside, and the long-wave pass film layers are used as the outermost layers of the low-refractive-index film layers; the narrow band-pass film system comprises high-refractive-index film layers and low-refractive-index film layers which are alternately deposited layer by layer from inside to outside. The low refractive index film layer is a silicon oxide film layer, and the high refractive index film layer is a silicon hydroxide/silicon nitride hydride film layer.

The substrate is a spherical mirror with a concave spherical surface with the radius of 110mm and a convex spherical surface with the radius of 10 mm. The material of the spherical mirror substrate comprises glass, quartz, sapphire or silicate optical glass.

The narrow band-pass film system can be coated by a magnetron sputtering method and is realized by utilizing the existing vacuum sputtering coating machine. The structure of the narrow band-pass film system is (HL2HLHL) ^5, the central wavelength is 915nm, the H layer is a silicon hydroxide/silicon nitride layer, H represents that the thickness of the silicon hydroxide/silicon nitride layer is 1 basic thickness, L is a silicon oxide layer which represents that the thickness of the silicon oxide is 1 basic thickness, and 5 in the (HL2HLHL) ^5 is the period number of the basic film stack (HL2 HLHL). The basic film stack of the narrow band-pass film system is not limited to this structure, and may be a basic structure such as HL2HL or HL2 hlhl.

The long-wave through film system can be coated by a magnetron sputtering method and is realized by utilizing the existing vacuum sputtering coating machine. The method can also be realized by vacuum evaporation and ion-assisted coating. The structure of the long-wave pass membrane system is (0.5HL0.5H) ^17, the central wavelength of a transition band is 835nm, an H layer is a silicon hydroxide/silicon nitride hydride layer, 0.5H represents that the thickness of the silicon hydroxide/silicon nitride hydride is 0.5 basic thickness, L is a silicon oxide layer which represents that the thickness of the silicon oxide is 1 basic thickness, and 17 is the period number of a basic membrane stack (0.5 HL0.5H).

The basic thickness of the high refractive index film layer or the low refractive index film layer in the narrow band-pass film system is one quarter of the central wavelength of the optical thickness of the narrow band-pass film system; the basic thickness of the high refractive index film layer or the low refractive index film layer in the long-wavelength pass film system is one fourth of the central wavelength of the optical thickness of the long-wavelength pass film system.

Preferably, optical design software such as Macleod/TFC/Optilayer is adopted to optimize the structure of the long-wave pass membrane system, and the obtained narrow-band pass membrane system is shown in the table I; wherein the film layer with the number of layers of 1 is deposited on the spherical mirror substrate and is the innermost layer of the narrow band-pass film system; the film layer with the number of layers 34 is the outermost layer of the narrow band-pass film system.

Parameter table of table-narrow band-pass film system

Preferably, optical design software such as Macleod/TFC/Optilayer is adopted to optimize the structure of the long-wave passing membrane system, and the obtained long-wave passing membrane system is shown in the table II; wherein the film layer with the number of layers of 1 is deposited on the spherical mirror substrate and is the innermost layer of the long-wave pass film system; the film layer with the number of layers of 35 is the outermost layer of the long-wave passing film system.

Parameter table of table two long wave pass film system

Referring to fig. 1, the present invention provides a method for manufacturing a narrow-band filter of a spherical mirror, which can be used for manufacturing the narrow-band filter of a spherical mirror. The method is realized in a vacuum sputtering coating machine. The method comprises the following steps:

step S01, putting the spherical mirror substrate into a low vacuum chamber and vacuumizing;

step S02, putting the spherical mirror substrate into a high vacuum chamber and vacuumizing;

step S03, bombarding the surface of the spherical mirror substrate by plasma emitted by a radio frequency source;

step S04, depositing a long-wave pass film system on one side of the spherical mirror substrate by adopting a magnetron sputtering method, wherein the long-wave pass film system comprises a low-refractive-index film layer and a high-refractive-index film layer which are alternately deposited layer by layer from inside to outside, and the long-wave pass film system is used as the outermost layer of the low-refractive-index film layer;

step S05, depositing a narrow band-pass film system on the other side of the spherical mirror substrate by adopting a magnetron sputtering method, wherein the narrow band-pass film system comprises a high-refractive-index film layer and a low-refractive-index film layer which are alternately deposited layer by layer from inside to outside;

and step S06, naturally cooling the spherical mirror substrate to room temperature to obtain the spherical mirror narrow-band filter.

In the above step, the low refractive index film layer is a silicon oxide film layer, and the high refractive index film layer is a silicon hydroxide/silicon nitride hydride film layer.

The step S01 specifically includes: and putting the cleaned spherical mirror substrate into a clean low-vacuum chamber and vacuumizing to be below 5.0E-0 Pa.

The step S02 specifically includes: the spherical mirror substrate is carried into a high vacuum chamber and is evacuated to below 1.0E-03 Pa.

The step S03 specifically includes: bombarding the surface of the spherical mirror substrate for 0.5-10min by using plasma emitted by a radio frequency oxidation source, wherein the power of the radio frequency oxidation source is 2-4kw, the working gas of the radio frequency oxidation source is Ar, and the gas flow of the Ar is 50-500 sccm. The working gas of the target is Ar, and the gas flow of the Ar is 30-300sccm per pair of targets.

The step S04 includes:

step S41, depositing silicon oxide film, operating the second RF oxidation source with Ar flow of 50-500sccm and O₂The flow rate is 100-500sccm, the power of the sputtering source of the second target material is 5-12 kw, the power of the second radio-frequency oxidation source is 2-4kw, and the flow rate of the working gas Ar of the second target material is 30-300 sccm;

step S42, depositing a silicon hydroxide/silicon nitride film, operating the first RF oxidation source with Ar flow of 50-500sccm and H₂The flow rate is 10-100sccm, O₂The flow rate is 0-50sccm/N₂The flow rate is 0-50sccm, the sputtering source power of the first target material is 5-12 kw, the power of the first radio-frequency oxidation source is 2-4kw, and the working gas Ar flow rate of the first target material is 30-300sccm。

Step S43, looping steps S41-S42 in this manner until the last second tier;

and step S44, depositing a silicon oxide film layer on the last layer.

Specifically, the sputtering rate of the silicon hydroxide/silicon nitride hydride is 0.3-0.7nm/s, and the sputtering rate of the silicon oxide is 0.5-1.2 nm/s; the first target material and the second target material both adopt 99.999 percent pure silicon targets.

The step S05 includes:

step S51, depositing a silicon hydroxide/silicon nitride film, operating the first RF oxidation source with Ar flow of 50-500sccm and H₂The flow rate is 10-100sccm, O₂The flow rate is 0-50sccm/N₂The flow is 0-50sccm, the power of a sputtering source of the first target material is 5-12 kw, the power of the first radio-frequency oxidation source is 2-4kw, and the film deposition rate of the silicon hydroxide/silicon nitride hydride film is 0.3-0.7 nm/s;

step S52, depositing silicon oxide film, operating the second RF oxidation source with Ar flow of 50-500sccm and O₂The flow rate is 100-500sccm, the power of the sputtering source of the second target material is 5-12 kw, the power of the second radio-frequency oxidation source is 2-4kw, and the film deposition rate of the silicon oxide film is 0.5-1.2 nm/s; step S53, looping steps S51-S52 in this manner until the last layer.

Specifically, the sputtering rate of the silicon hydroxide/silicon nitride hydride is 0.3-0.7nm/s, and the sputtering rate of the silicon oxide is 0.5-1.2 nm/s; and (3) adopting 99.999% purity silicon targets as the first target material and the second target material, and performing layer-by-layer deposition coating by a vacuum sputtering coating machine according to the steps S51-S53 under the condition.

Wherein, the step is not limited to filling oxygen, and can also be filled with nitrogen with the amount of 0-50 sccm; or may not be inflated. Whether other gases are doped or not, it is intended that the optical filter can be made to meet the refractive index requirements of the present invention.

The step S06 specifically includes: the spherical mirror substrate is naturally cooled to room temperature to obtain the 947nm high-transmittance spherical mirror narrowband filter in the embodiment.

And analyzing the data in the table II by adopting optical design software such as Macleod/TFC/optical layer and the like to obtain a theoretical transmission spectrogram of the long-wave pass film system, wherein as shown in FIG. 2, the result shows that when the incident angle is 0 degree, the long-wave pass film system has a wide cutoff in a spectrum band of 350-825nm and has a high transmittance in a spectrum band of 910-1100 nm.

The theoretical transmission spectrogram result of the band-pass membrane system obtained by analyzing the data in the second table by using optical design software such as Macleod/TFC/optical layer and the like shows that the narrow band-pass membrane system has high transmittance at the 900 and 930nm spectral band, less than 10% transmittance at the 887nm and 950nm, less than 50% transmittance at the 890nm and 940nm, and cutoff at the 200nm-870nm and 965 and 1050nm spectral bands, wherein the incidence angles of 0 DEG and 22 DEG are curve shifts of less than 8nm (as shown in FIG. 5).

The transmission theoretical spectrogram of the filter after the double-sided coating (shown in figure 4) is completed.

The optical filter of the embodiment is prepared by adopting an NSP-1650 vacuum sputtering coating machine of Japan photonics corporation, and the specific steps are as follows:

(1) removing impurities in a LL vacuum chamber of the coating machine by using a dust collector, mounting a clean spherical mirror substrate subjected to ultrasonic cleaning on a coating clamp, quickly loading the spherical mirror substrate into a clean vacuum chamber, and vacuumizing to 5.0 EPa; the coating jig was exchanged to a PR film forming chamber, and the film was formed by vacuuming the PR film forming chamber to a constant value of 1.0E-3Pa or less.

(2) Bombarding the surface of the substrate of the ball mill for 0.5-10min by using plasma emitted by a radio frequency oxidation source, wherein the power of the radio frequency oxidation source is 2-4kw, the working gas of the radio frequency oxidation source is Ar, and the flow rate of the Ar gas is 50-500 sccm. The target gas is Ar, and the gas flow of the Ar is 30-300sccm per pair of targets.

(3) Adopting a magnetron sputtering method to alternately deposit a silicon hydroxide/silicon nitride film layer and a silicon oxide film layer in a long-wavelength pass film system layer by layer on one side of a spherical mirror substrate until the deposition of the long-wavelength pass film system is completed; and alternately depositing a silicon hydroxide/silicon nitride film layer and a silicon oxide film layer in the narrow band-pass film system on the other side of the spherical mirror substrate layer by layer until the deposition of the narrow band-pass film system is completed.

(4) The spherical mirror substrate is naturally cooled to room temperature, and the 947nm high-transmittance spherical mirror narrow-band filter of the embodiment is obtained.

(5) The following performance tests were performed on the filters:

(6) the transmission spectrum of the filter was measured using a spectrophotometer of the Cary 7000 universal type from Agilent, USA (as shown in FIG. 5). When the incident angle of the optical filter is 0 DEG, the average transmittance in the spectrum band of 900 and 930nm is more than 95%, the transmittance at 887nm and 950nm is less than 10%, the transmittance at 890nm and 940nm is less than 50%, the maximum transmittance in the spectrum bands of 200nm-870nm and 965 and 1050nm is less than 1%, and the curve deviation is less than 8nm when the incident angles are 0 DEG and 22 deg.

In the above spectral specifications, the center wavelength may be shifted, the transmission bandwidth may be widened or narrowed, and the cutoff wavelength may be changed to optimize the design. The spectral specification described above, without limitation thereto, can be achieved with a transmission bandwidth and cut-off band wavelength variation of +/-10 nm.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.