Band-pass filter and preparation method thereof
阅读说明:本技术 带通滤光片及其制备方法 (Band-pass filter and preparation method thereof ) 是由 张睿智 王迎 孙瑞乔 项争 张康 何冰晓 刘风雷 于 2020-05-08 设计创作,主要内容包括:一种带通滤光片及其制备方法,涉及滤光片技术领域。该带通滤光片包括基底层,以及依次在基底层上形成的第一介质膜堆、第一金属膜层、第二介质膜堆、第二金属膜层以及第三介质膜堆,第一介质膜堆、第二介质膜堆以及第三介质膜堆分别由介质膜层形成,且相邻两层介质膜层的折射率不同。其能够针对特殊的带通要求进行很好的匹配,以使得滤光片获得大角度范围内均匀平滑的光谱曲线图。(A band-pass filter and a preparation method thereof relate to the technical field of filters. The band-pass filter comprises a substrate layer, a first dielectric film stack, a first metal film layer, a second dielectric film stack, a second metal film layer and a third dielectric film stack, wherein the first dielectric film stack, the second metal film stack and the third dielectric film stack are sequentially formed on the substrate layer, the first dielectric film stack, the second dielectric film stack and the third dielectric film stack are respectively formed by dielectric film layers, and the refractive indexes of the two adjacent dielectric film layers are different. The filter can be well matched according to special band-pass requirements, so that the filter can obtain a uniform and smooth spectral curve diagram in a large-angle range.)
1. The band-pass filter is characterized by comprising a base layer, a first dielectric film stack, a first metal film layer, a second dielectric film stack, a second metal film layer and a third dielectric film stack, wherein the first dielectric film stack, the second metal film layer and the third dielectric film stack are sequentially formed on the base layer, the first dielectric film stack, the second dielectric film stack and the third dielectric film stack are respectively formed by dielectric film layers, and the refractive indexes of the two adjacent dielectric film layers are different.
2. The bandpass filter of claim 1, wherein two adjacent dielectric film layers are a high refractive index film layer and a middle refractive index film layer, a high refractive index film layer and a low refractive index film layer, and one of a middle refractive index film layer and a low refractive index film layer, wherein the refractive index of the high refractive index film layer is greater than 1.90, the refractive index of the middle refractive index film layer is between 1.52 and 1.90, and the refractive index of the low refractive index film layer is less than 1.52.
3. The bandpass filter according to claim 1, wherein the first dielectric film stack is formed by stacking a first predetermined stack structure in the form of: (AB)nC or (AB)n+1Wherein, A and B are respectively dielectric film layers with different refractive indexes, C is a dielectric film layer with a refractive index different from that of B, n is the cycle number, and n is an integer greater than or equal to 0.
4. The bandpass filter according to claim 3, wherein the first predetermined stacking structure is in the form of (AB)nAnd C, the C is a middle refractive index film layer, and the refractive index of the middle refractive index film layer is between 1.52 and 1.90.
5. The bandpass filter according to claim 1 or 3, wherein the third dielectric film stack is formed by stacking a second predetermined stack structure in the form of: c (BA)nOr (BA)n+1Wherein, A and B are respectively dielectric film layers with different refractive indexes, C is a dielectric film layer with a refractive index different from that of B, n is the cycle number, and n is an integer greater than or equal to 0.
6. The bandpass filter according to claim 5, wherein the second predetermined stacking structure is C (BA)nWhen C is the middle refractive index film layer, the refractive index of the middle refractive index film layer is between 1.52 and 1.90.
7. The bandpass filter according to claim 1, wherein the first metal film layer and the second metal film layer are made of the same material and are any one of gold, gold alloy, silver alloy, aluminum, and aluminum alloy.
8. The bandpass filter according to claim 7, wherein the first metal film layer and the second metal film layer are made of the same material and are both silver.
9. The bandpass filter according to claim 1, wherein the materials of two adjacent dielectric film layers are different, and the material of the dielectric film layer is any one of aluminum oxide, titanium oxide, silicon oxide, magnesium fluoride, silicon monoxide, silicon hydride, silicon hydroxide and silicon nitride.
10. A method for manufacturing a band-pass filter is characterized by comprising the following steps:
providing a base layer;
and depositing each film layer on the substrate layer in sequence according to a film system structure to obtain the band-pass filter, wherein the film system structure is set as a first dielectric film stack, a first metal film layer, a second dielectric film stack, a second metal film layer and a third dielectric film stack which are formed on the substrate layer in sequence, the first dielectric film stack, the second dielectric film stack and the third dielectric film stack are formed by stacking the dielectric film layers respectively, and the refractive indexes of the two adjacent dielectric film layers are different.
11. The method of claim 10, wherein depositing the film layers on the substrate layer in sequence according to the film structure to obtain the bandpass filter further comprises:
and respectively carrying out admittance matching treatment between the first dielectric film stack and the first metal film layer and between the second metal film layer and the third dielectric film stack so as to optimize the film system structure.
12. The method of claim 10, wherein the depositing the film layers on the substrate layer in sequence according to the film structure to obtain the bandpass filter comprises:
and depositing each film layer on the substrate layer by adopting any one of radio frequency magnetron sputtering, electron beam evaporation, ion beam auxiliary coating, atomic layer epitaxy and MOCVD (metal organic chemical vapor deposition) to obtain the band-pass filter.
Technical Field
The invention relates to the technical field of optical filters, in particular to a band-pass optical filter and a preparation method thereof.
Background
The hyperspectral imaging technology is based on image data technology of a plurality of narrow wave bands, combines the imaging technology with the spectrum technology, detects two-dimensional geometric space and one-dimensional spectral information of a target, and acquires continuous and narrow wave band image data with hyperspectral resolution. The method can obtain a picture with higher reducibility, obtain the color of wall paint, or identify the maturity of apples and the like by analyzing the spectral composition. In the hyperspectral imaging technology, a band-pass filter which is insensitive to an angle and has a low transmittance in a cut-off band is generally used, and the transmittance of all light rays in a certain angle range is required to have certain band-pass characteristics (namely, the light rays in a specific wave band are allowed to pass through, and the light rays in other wave bands are cut off).
Disclosure of Invention
The invention aims to provide a band-pass filter and a preparation method thereof, which can be well matched according to special band-pass requirements so that the filter can obtain a uniform and smooth spectral curve diagram in a large-angle range.
The embodiment of the invention is realized by the following steps:
in one aspect of the invention, a bandpass filter is provided, which includes a substrate layer, and a first dielectric film stack, a first metal film layer, a second dielectric film stack, a second metal film layer, and a third dielectric film stack sequentially formed on the substrate layer, where the first dielectric film stack, the second dielectric film stack, and the third dielectric film stack are respectively formed by dielectric film layers, and refractive indexes of two adjacent dielectric film layers are different. The filter can be well matched according to special band-pass requirements, so that the filter can obtain a uniform and smooth spectral curve diagram in a large-angle range.
Optionally, the two adjacent dielectric film layers are a high refractive index film layer and a medium refractive index film layer, a high refractive index film layer and a low refractive index film layer, and one of the medium refractive index film layer and the low refractive index film layer, wherein the refractive index of the high refractive index film layer is greater than 1.90, the refractive index of the medium refractive index film layer is between 1.52 and 1.90, and the refractive index of the low refractive index film layer is less than 1.52.
Optionally, the first dielectric film stack is formed by stacking a first preset stack structure, wherein the first preset stack structure is in the form of: (AB)nC or (AB)n+1Wherein, A and B are respectively dielectric film layers with different refractive indexes, C is a dielectric film layer with a refractive index different from that of B, n is the cycle number, and n is an integer greater than or equal to 0.
Optionally, when the first predetermined stacking structure is in the form of (AB)nAnd C, the C is a middle refractive index film layer, and the refractive index of the middle refractive index film layer is between 1.52 and 1.90.
Optionally, the third dielectric film stack is formed by stacking a second preset stack structure, where the second preset stack structure is in the form of: c (BA)nOr (BA)n+1Wherein, A and B are respectively dielectric film layers with different refractive indexes, C is a dielectric film layer with a refractive index different from that of B, n is the cycle number, and n is an integer greater than or equal to 0.
Optionally, when the second predetermined stacking structure is in the form of C (BA)nWhen C is the middle refractive index film layer, the refractive index of the middle refractive index film layer is between 1.52 and 1.90.
Optionally, the first metal film layer and the second metal film layer are made of the same material and are any one of gold, gold alloy, silver alloy, aluminum and aluminum alloy.
Optionally, the first metal film layer and the second metal film layer are made of the same material and are both silver.
Optionally, the materials of two adjacent dielectric film layers are different, and the material of the dielectric film layer is any one of aluminum oxide, titanium oxide, silicon oxide, magnesium fluoride, silicon monoxide, silicon hydride, silicon hydroxide and silicon nitride.
In another aspect of the present invention, a method for manufacturing a bandpass filter is provided, the method including:
providing a base layer;
and depositing each film layer on the substrate layer in sequence according to a film system structure to obtain the band-pass filter, wherein the film system structure is set as a first dielectric film stack, a first metal film layer, a second dielectric film stack, a second metal film layer and a third dielectric film stack which are formed on the substrate layer in sequence, the first dielectric film stack, the second dielectric film stack and the third dielectric film stack are formed by stacking the dielectric film layers respectively, and the refractive indexes of the two adjacent dielectric film layers are different.
Optionally, the depositing the film layers on the substrate layer in sequence according to the film system structure to obtain the bandpass filter further includes:
and respectively carrying out admittance matching treatment between the first dielectric film stack and the first metal film layer and between the second metal film layer and the third dielectric film stack so as to optimize the film system structure.
Optionally, the depositing the film layers on the substrate layer in sequence according to the film system structure to obtain the bandpass filter includes:
and depositing each film layer on the substrate layer by adopting any one of radio frequency magnetron sputtering, electron beam evaporation, ion beam auxiliary coating, atomic layer epitaxy and MOCVD (metal organic chemical vapor deposition) to obtain the band-pass filter.
The beneficial effects of the invention include: the application discloses band-pass filter, including the stratum basale to and first dielectric film heap, first metal rete, second dielectric film heap, second metal rete and the third dielectric film heap that forms on the stratum basale in proper order, first dielectric film heap, second dielectric film heap and third dielectric film heap are formed by the dielectric film layer respectively, and the refracting index of adjacent two-layer dielectric film layer is different. So, the bandpass filter of this application adopts the five-layer membrane system structure of dielectric film stack + metal membranous layer + dielectric film stack, it is different with traditional chemical dye filter and traditional induced filter, it has lower angle skew characteristic, can carry out fine matching to special bandpass requirement, so that bandpass filter obtains the even smooth spectral curve graph in the wide-angle range, be particularly useful for toper light incidence (light is incident with half cone angle promptly), and then make the light that gets into the sensor present good bandpass characteristic.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic structural diagram of a bandpass filter according to an embodiment of the invention;
FIG. 2 is a graph of a spectrum of a green filter at 0 incident of light in the prior art;
FIG. 3 is a graph showing the spectrum of a green filter when light is incident at 0 °, 20 °, 40 ° and 60 ° respectively in the prior art;
fig. 4 is a second schematic structural diagram of a bandpass filter according to an embodiment of the invention;
FIG. 5 is a graph of the spectrum of a bandpass filter according to an embodiment of the invention at 0 ° incidence or cone-shaped light incidence;
FIG. 6 is a graph of the spectrum of Table 1 at cone-shaped light incidence provided by an embodiment of the present invention;
FIG. 7 is a graph of the spectrum of Table 2 at cone light incidence provided by an embodiment of the present invention;
FIG. 8 is a graph of the spectrum of Table 3 at cone light incidence provided by an embodiment of the present invention;
fig. 9 is a flowchart of a method for manufacturing a bandpass filter according to an embodiment of the invention.
Icon: 100-band pass filter; 10-a base layer; 20-a first dielectric film stack; 30-a first metal film layer; 40-a second dielectric film stack; 50-a second metal film layer; 60-third dielectric film stack.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or the orientations or positional relationships that the products of the present invention are conventionally placed in use, and are only used for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.
Furthermore, the terms "horizontal", "vertical" and the like do not imply that the components are required to be absolutely horizontal or pendant, but rather may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Referring to fig. 1 and 4, the present embodiment provides a
FIG. 2 is a graph showing a spectrum curve (normalized) of a green filter at 0 degree incidence in the prior art, which uses a dielectric film such as TiO when light is incident at 0 degree2And SiO2The multilayer is stacked, the number of layers is about 50-100, and the thickness is about 5-9 μm.
However, as shown in fig. 3, fig. 3 is a graph of a spectrum of a green filter when light is incident from 0 °, 20 °, 40 ° and 60 ° respectively in the prior art, and when the incident angle of the light is changed, the spectrum curve has a large angle deviation problem, which causes the spectrum curve to be deformed and the overall transmittance to be deteriorated at different incident angles, and a high transmittance cannot be obtained within a certain angle range (in the embodiment shown in fig. 2 and 3, the range from 0 ° to 60 °). Therefore, the green filter in the prior art is sensitive to the incident angle, the shape of the spectral curve is poor in a large-angle range of light incidence, the pass band and the cut-off band are greatly changed, and the spectral curve is not smooth any more. This results in the energy not exhibiting a band pass characteristic when light rays enter the sensor at various angles.
Different from the prior art, firstly, as shown in fig. 1, the
Therefore, the film layers with different layers and different thicknesses are combined to form a multilayer film system with a layered structure, and compared with a multilayer film of a pure dielectric film, the multilayer film combination of two metal film layers and a plurality of dielectric film stacks has smoother spectrum of transmittance when the light enters at a large angle, which is greatly helpful for the energy stability of the light received by the sensor. The
The filter with the low-angle offset effect can be designed by adopting the film system structure, and the filter with the low-angle offset effect has different transmission rate peak values, different peak transmission rates, different transmission band widths, different cut-off band depths and ranges. The method can be used for a multispectral technology to obtain a plurality of segmented band-pass spectrums in near ultraviolet, visible light and near infrared spectrum regions. The film system is particularly suitable for the case of cone light incidence (for the sake of simplicity, the spectral curve obtained according to the film system structure provided by the application is mainly based on cone light incidence shown in the embodiment of the application), and meets the requirement of transmittance in a wide angle range. The signal sensing chip has better performance.
Second, the first
Third, in order to form the film system structure of the
To sum up, the
In this embodiment, the two adjacent dielectric film layers are a high refractive index film layer and a middle refractive index film layer, a high refractive index film layer and a low refractive index film layer, and one of the middle refractive index film layer and the low refractive index film layer, wherein the refractive index of the high refractive index film layer is greater than 1.90, and for example, titanium oxide, niobium oxide, tantalum oxide, hafnium oxide, zirconium oxide, silicon nitride, or the like may be selected as the high refractive index material. The refractive index of the medium refractive index film layer is between 1.52 and 1.90, and silicon oxide is taken as a medium refractive index material for example. The low refractive index film layer has a refractive index of less than 1.52. By way of example, silicon oxide, magnesium fluoride are chosen as low refractive index materials. That is, the film system structure of the present application is a dielectric film stack in which high and low refractive indexes are alternately increased on opposite sides of the first
In the first
It should be understood that when the first
Illustratively, when the first
Further, in the present embodiment, when the first predetermined stacking structure is in the form of (AB)nC, C is preferably a medium refractive index film layer, wherein the refractive index of the medium refractive index film layer is between 1.52 and 1.90. Thus, the dielectric film layer directly contacting the first
In the third
It should be understood that when the third
Illustratively, when the third
Further, in the present embodiment, when the second predetermined stacking structure is C (BA)nWhen C is the middle refractive index film layer, the refractive index of the middle refractive index film layer is between 1.52 and 1.90. It is to be understood that, when in this configuration, the first predetermined stacking configuration is (AB)nAt time C, the effect of using the middle refractive index film layer as the dielectric film layer in contact with the first
Illustratively, in the present embodiment, the dielectric film layers in the second
In addition, the second
Further, in the present embodiment, the first
In addition, the materials of the two adjacent dielectric film layers are different, and specifically, the dielectric film layer in this embodiment may be aluminum oxide, titanium oxide, silicon oxide, magnesium fluoride, silicon monoxide, silicon hydride, silicon hydroxide, silicon nitride, or other materials that can meet the requirements of spectral characteristics.
Preferably, any one of alumina, titania and silica is selected as the dielectric film layer of each layer, because these three materials have good and stable performance, are suitable for mass production and have environmental tolerance.
Referring to fig. 9, the present embodiment further provides a method for manufacturing a
s200: a
S300: the
According to the preparation method of the
In consideration of the requirements of different filtering effects, the method for manufacturing the
admittance matching processing is respectively performed between the first
That is, after the film-based structure is subjected to admittance matching processing to optimize the film-based structure, the film layers are sequentially deposited on the
First, in this embodiment, the parameters of the admittance matching process that mainly require the optimization process are the thickness of each dielectric film layer and the number of layers of each dielectric film stack. By adjusting the number of layers and the thickness of each layer, the
Second, admittance matching processes are performed between the first
Thus, after the optimized film system structure is obtained according to the number of layers and the thickness, the
For example, when the application needs to realize the red color filtering effect, in the embodiment, after the number of layers and the thickness of the film structure are optimized, each parameter can be referred to as table 1.
Table 1:
it should be noted that the materials and the corresponding thicknesses of the film layers shown in the above table are only one example given in the embodiments of the present application, and are not specific limitations on the parameters for achieving the red color filtering effect. The spectral curve of the
For example, when the application needs to realize the green color filtering effect, in the embodiment, after the number of layers and the thickness of the film structure are optimized, each parameter can be referred to table 2.
Table 2:
number of layers
Film material
Thickness nm
1
30
2
TiO2
122
3
SiO2
240
4
TiO2
67
5
SiO2
129
6
TiO2
15
7
Al2O3
18
8
Ag
52
9
Al2O3
18
10
TiO2
19
11
Al2O3
69
12
Ag
31
13
Al2O3
19
14
TiO2
18
15
SiO2
95
16
TiO2
69
17
SiO2
174
18
TiO2
35
19
SiO2
99
Similarly, the materials and the corresponding thicknesses of the film layers shown in the above table are only one example given in the embodiments of the present application, and are not specific limitations on the parameters for achieving the green color filtering effect. The spectral curve of the
For example, when the application needs to realize the blue filtering effect, in the embodiment, after the number of layers and the thickness of the film structure are optimized, each parameter can be referred to as table 3.
Table 3:
number of layers
Film material
Thickness nm
1
50
2
TiO2
89
3
SiO2
57
4
TiO2
57
5
SiO2
69
6
TiO2
15
7
Al2O3
15
8
Ag
46
9
Al2O3
15
10
TiO2
15
11
Al2O3
45
12
Ag
55
13
Al2O3
111
14
TiO2
57
15
SiO2
69
16
TiO2
24
17
SiO2
104
Similarly, the materials and the corresponding thicknesses of the film layers shown in the above table are only one example given in the embodiments of the present application, and are not specific limitations on the parameters for achieving the blue filtering effect. The spectral curves obtained after the test treatment of the
Further, in step S300, the present application deposits each film layer on the
depositing each film layer on the
For example, when the
Table 4:
for example, when the
Table 5:
it should be understood that the above two preparation methods are only two examples of the present application and should not be construed as limiting the present application.
The above description is only an alternative embodiment of the present invention and is not intended to limit the present invention, and various modifications and variations of the present invention may occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.