Optical filter

Abstract

To solve the problem that structure of an existing optical filter gradually cannot cope with current various requests.SOLUTION: An optical filter includes a board, a bonding layer formed on the board, and a matching composite layer formed on the bonding layer. The matching composite layer includes first multiple refraction layers, second multiple refraction layers, and third multiple refraction layers. The number of the second multiple refraction layers is smaller than the number of the first multiple refraction layers and the number of third multiple refraction layers. The refractive index of the first refractive layers is larger than the refractive index of the bonding layer, and the refractive index of the second refractive layers is larger than the refractive index of the first refractive layers and is smaller than the refractive index of the third refractive layers. The first refractive layers are sandwiched inside the two adjacent second refractive layers, the outside is sandwiched by the two third refractive layers, and these collectively define a bidirectional incremental module.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to filters, and more particularly to optical filters. [Background technology]

[0002] Existing optical filters often employ multiple refractive layers stacked in sequence, resulting in large differences in refractive indexes. However, the structures of existing optical filters are finding it increasingly difficult to meet today's diverse requirements. The inventors therefore believed it possible to overcome these drawbacks, and after extensive research incorporating scientific principles, have finally proposed the present invention, which effectively overcomes these drawbacks through a rational design. Summary of the Invention [Problem to be solved by the invention]

[0003] SUMMARY OF THE INVENTION An embodiment of the present invention provides an optical filter that can effectively improve the drawbacks that may be caused by existing optical filters. [Means for solving the problem]

[0004] An embodiment of the present invention relates to an optical filter. The optical filter includes a substrate, a bonding layer formed on the substrate and having a refractive index less than 1.42, and a matching composite layer formed on the bonding layer and having N (N is a positive integer) film layers stacked in sequence. The N film layers include a plurality of first refractive layers, a plurality of second refractive layers, and a plurality of third refractive layers. Each of the plurality of first refractive layers has a first refractive index that is greater than the refractive index of the bonding layer. Each of the plurality of second refractive layers has a second refractive index that is greater than the first refractive index, and the number of the plurality of second refractive layers is less than the number of the plurality of first refractive layers. Each of the plurality of third refractive layers has a third refractive index that is greater than the second refractive index, and the number of the plurality of second refractive layers is less than the number of the plurality of third refractive layers. In the matching composite layer, the third refractive layer adjacent to the bonding layer is defined as the first film layer, and in the matching composite layer, the first refractive layer is disposed at the end far from the bonding layer, and the first refractive layer is defined as the Nth film layer. The first refractive layer is located inside two adjacent second refractive layers, and is sandwiched between two third refractive layers on the outside, and these together are defined as a bidirectional incremental module.

[0005] In this embodiment, an optical filter is disclosed. The optical filter includes a substrate, a bonding layer formed on the substrate and having a refractive index less than 1.42, and a matching composite layer formed on the bonding layer and having N (N is a positive integer) film layers stacked in sequence. The N film layers include a plurality of first refractive layers, a plurality of second refractive layers, and a plurality of third refractive layers. Each of the first refractive layers has a first refractive index greater than the refractive index of the bonding layer. Each of the second refractive layers has a second refractive index greater than the first refractive index. Each of the third refractive layers has a third refractive index greater than the second refractive index. In the matching composite layer, the third refractive layer adjacent to the bonding layer is defined as the first film layer. In addition, in the matching composite layer, a first refractive layer is disposed at an end farther from the bonding layer, and this first refractive layer is defined as the Nth film layer. The second refractive layer is sandwiched between the first and third refractive layers, which together define a unidirectional incremental module.

[0006] This embodiment discloses another optical filter. The optical filter includes a substrate having a first surface and a second surface, a bonding layer formed on the first surface of the substrate and having a refractive index less than 1.42, and a matching composite layer formed on the bonding layer and the second surface of the substrate, the matching composite layer including a plurality of film layers. The matching composite layer includes a plurality of first refractive layers, a plurality of second refractive layers, and a plurality of third refractive layers. Each first refractive layer has a first refractive index greater than the refractive index of the bonding layer. Each second refractive layer has a second refractive index greater than the first refractive index. The number of second refractive layers is less than the number of first refractive layers. Each third refractive layer has a third refractive index greater than the second refractive index, and the number of second refractive layers is less than the number of third refractive layers. The plurality of film layers includes N front film layers stacked in order on the bonding layer and M back film layers stacked in order on the second plate surface, where N and M are positive integers. Among the N front film layers, a third refractive layer adjacent to the bonding layer is defined as a first front film layer. Among the N front film layers, a first refractive layer defined as the Nth front film layer is disposed at an end away from the bonding layer. Among the N front film layers, the first refractive layer is located inside two adjacent second refractive layers, and is sandwiched between two third refractive layers on the outside, and these together are defined as a bidirectional incremental module. [Effects of the Invention]

[0007] In summary, the optical filter disclosed in this embodiment has a structure different from that of the conventionally known bidirectional incremental module, in which the refractive index of the bidirectional incremental module can be gradually increased in two opposite directions from the first refractive layer, which allows the overall refractive index profile of the matching composite layer to be adjusted, and further contributes to the design of optical filters to meet a variety of different requirements.

[0008] Furthermore, the optical filter disclosed in this embodiment can adjust the overall refractive index distribution of the matching composite layer by forming a unidirectional incremental module, which helps the optical filter to be designed to meet a wider variety of different requirements.

[0009] In order to better understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention, which are merely illustrative of the present invention and do not limit the protection scope of the present invention. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a plan view schematically illustrating the optical filter according to the first embodiment. [Figure 2] 2 is a diagram showing the specific layout of FIG. 1. [Figure 3] FIG. 10 is a schematic plan view of an optical filter according to a second embodiment. [Figure 4] 4 is a diagram showing the specific layout of FIG. 3. [Figure 5] FIG. 10 is a schematic plan view of an optical filter according to a third embodiment. [Figure 6] 6 is a diagram showing the specific layout of FIG. 5. [Figure 7] 6A and 6B are schematic diagrams showing simulation tests at different angles using the optical filter of FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes the embodiments of the present invention through specific examples relating to the "optical filter" of the present application. Those skilled in the art can understand the merits and advantages of the present invention from the disclosure of this specification. The present invention can be implemented or applied in other different embodiments. Each clause in this specification can also be modified and changed equivalently based on various aspects or applications without departing from the spirit of the present invention. In addition, the drawings of the present invention are for simple and schematic illustration only and do not represent actual dimensions. The following embodiments will further explain the technical matters related to the present invention, but the disclosed contents do not limit the present invention. In addition, the term "or" used in this specification may include any one or more combinations of related items according to actual circumstances.

[0012] Throughout this specification, terms such as "first," "second," and "third" may be used to describe various components or signals, but it should be understood that these components or signals should not be limited by these terms. These terms are used primarily to distinguish one component from another or one signal from another. Furthermore, as used herein, the term "or" can include any one or combination of the associated listed items, where appropriate.

[0013] [First embodiment] Please refer to Figures 1 and 2, which show a first embodiment of the present invention. In this embodiment, an optical filter 1000 is disclosed, which preferably has a flat strip structure. In this embodiment, the optical filter 1000 is applicable to visible light (e.g., 420 nanometers to 680 nanometers).

[0014] In this embodiment, the optical filter 1000 includes a substrate 200, a bonding layer 300 formed on the substrate 200, and a matching composite layer 100 formed on the bonding layer 300. The substrate 200 is, for example, a glass substrate, and the matching composite layer 100 is bonded to the substrate 200 via the bonding layer 300, but the present invention is not limited thereto.

[0015] Specifically, the matching composite layer 100 includes N film layers 10 stacked in order. The N film layers 10 are preferably stacked in the thickness direction, and the side edges of the N film layers 10 are aligned with each other, and more preferably aligned with the side edges of the bonding layer 300. Furthermore, N is a positive integer (e.g., limited to between 30 and 50), and is illustrated as 37 in this embodiment (i.e., the plurality of film layers 10 and bonding layers 300 are illustrated as a total of 38 layers in this embodiment), but the present invention is not limited thereto.

[0016] More specifically, the N film layers 10 are divided by refractive index and include a plurality of first refractive layers 10-1, a plurality of second refractive layers 10-2, and a plurality of third refractive layers 10-3. Each of the first refractive layers 10-1 has a first refractive index that is greater than the refractive index of the bonding layer 300. Each of the second refractive layers 10-2 has a second refractive index that is greater than the first refractive index, and each of the third refractive layers 10-3 has a third refractive index that is greater than the second refractive index.

[0017] To understand the overall configuration of the matching composite layer 100, the multiple film layers 10 may also be described by their stacking order. That is, in the matching composite layer 100, the third refractive layer 10-3 adjacent to the bonding layer 300 is defined as the first film layer 1. In addition, in the matching composite layer 100, the first refractive layer 10-1 is disposed at the end farthest from the bonding layer 300 and is defined as the Nth film layer N.

[0018] In this embodiment, the refractive index of the bonding layer 300 is less than 1.42 (for example, in the range of 1.35 to 1.42), the first refractive index is in the range of 1.45 to 1.52, the second refractive index is in the range of 1.62 to 1.71, and the third refractive index is in the range of 2.2 to 2.8. In other words, in this embodiment, the optical filter 1000 has four types of optical layers with different refractive indices stacked on top of each other, providing more diverse optical configurations and structures.

[0019] To further explain, for ease of understanding this embodiment, the bonding layer 300, the first refractive layer 10-1, the second refractive layer 10-2, and the third refractive layer 10-3 are described using examples of possible materials, but the present invention is not limited thereto. For example, the bonding layer 300 is a magnesium fluoride (MgF2) layer, the first refractive layer 10-1 is a silicon dioxide (SiO2) layer, the second refractive layer 10-2 is an aluminum oxide (Al2O3) layer, and the third refractive layer 10-3 is a titanium dioxide (TiO2) layer.

[0020] Furthermore, the number of the plurality of second refractive layers 10-2 is less than the number of the plurality of first refractive layers 10-1 and the plurality of third refractive layers 10-3. In this embodiment, the number of the plurality of second refractive layers 10-2 is limited to three, and these three second refractive layers 10-2 are combined with some of the first refractive layers 10-1 and some of the third refractive layers 10-3 to form the bidirectional incremental module 10a and the unidirectional incremental module 10b, respectively, but the present invention is not limited thereto. For example, in other embodiments not shown in the present invention, the number of the second refractive layers 10-2 can be adjusted to two or four or more according to design requirements, and the matching composite layer 100 can only have the bidirectional incremental module 10a and omit the unidirectional incremental module 10b.

[0021] In this embodiment, one first refractive layer 10-1 is sandwiched between two adjacent second refractive layers 10-2, and two third refractive layers 10-3 are sandwiched between them on the outside, which are collectively defined as a bidirectional incremental module 10a. From another perspective, in the bidirectional incremental module 10a, any second refractive layer 10-2 is sandwiched between one first refractive layer 10-1 and one third refractive layer 10-3, thereby exhibiting a gradually increasing refractive index distribution.

[0022] As described above, the optical filter 1000 in this embodiment has a different structure from the conventional bidirectional incremental module 10a. The refractive index of the bidirectional incremental module 10a can gradually increase in two opposite directions from the first refractive layer 10-1. This allows the overall refractive index profile of the matching composite layer 100 to be adjusted, which helps the optical filter 1000 to be designed to meet a wider variety of different requirements.

[0023] Furthermore, the unidirectional incremental module 10b is preferably located at a position away from the bidirectional incremental module 10a in this embodiment. Specifically, one second refractive layer 10-2 located at a position away from the bidirectional incremental module 10a is sandwiched between one first refractive layer 10-1 and one third refractive layer 10-3, thereby defining the unidirectional incremental module 10b, which exhibits a gradually increasing refractive index distribution.

[0024] In this embodiment, the optical filter 1000 can further include a unidirectional incremental module 10b, which can be combined with the bidirectional incremental module 10a and the unidirectional incremental module 10b (e.g., the unidirectional incremental module 10b and the bidirectional incremental module 10a are disposed on opposite ends of the matching composite layer 100) to adjust the overall refractive index profile of the matching composite layer 100, thereby enabling the optical filter 1000 to be designed to meet a wider variety of different requirements.

[0025] To further explain, the matching composite layer 100 is arranged such that the film layers 10 other than the unidirectional incremental module 10b and the bidirectional incremental module 10a are stacked such that the first refractive layers 10-1 and the third refractive layers 10-3 are alternately stacked (i.e., any first refractive layer 10-1 is sandwiched between two adjacent third refractive layers 10-3).

[0026] Furthermore, in order to maintain a low average reflectance when the optical filter 1000 disclosed in this embodiment allows normal incident light to be incident at a deflection angle of 30 degrees, the bidirectional incremental module 10a and the unidirectional incremental module 10b preferably satisfy at least some of the following arrangement conditions, but are not limited to these:

[0027] The bidirectional incremental module 10a is located adjacent to the first membrane layer 1, and the unidirectional incremental module 10b is located adjacent to the Nth membrane layer N. Furthermore, it is desirable that the number and thickness of the membrane layers 10 disposed between the bidirectional incremental module 10a and the first membrane layer 1 be different from the number and thickness of the membrane layers 10 disposed between the unidirectional incremental module 10b and the Nth membrane layer N.

[0028] Specifically, one first refractive layer 10-1 (e.g., the second film layer 2) is disposed between the bidirectional incremental module 10a and the first film layer 1, and the unidirectional incremental module 10b (including its third refractive layer 10-3) is connected to the Nth film layer N. From another perspective, in this embodiment, the bidirectional incremental module 10a is from the third film layer 3 to the seventh film layer 7, and the unidirectional incremental module 10b is from the N-3th film layer N-3 to the N-1th film layer N-1.

[0029] Furthermore, in this embodiment, the thickness T10a of the bidirectional incremental module 10a is 165% to 180% of the thickness T10b of the unidirectional incremental module 10b, and the thickness T10-2a of any second refractive layer 10-2 of the bidirectional incremental module 10a is greater than the thickness T10-2b of the second refractive layer 10-2 of the unidirectional incremental module 10b.

[0030] More specifically, the bonding layer 300 and the matching composite layer 100 of the optical filter 1000 adopt the specific arrangement shown in FIG. 3 in this embodiment, and related simulation results confirm that when a normal incident light source (e.g., visible light) is incident at a deflection angle of 30 degrees, the average reflectance is less than 1%.

[0031] [Second embodiment] Please refer to Figures 3 and 4, which show a second embodiment of the present invention. This embodiment is similar to the first embodiment described above, so the commonalities between the two embodiments will not be described in detail. The main differences between this embodiment and the first embodiment are as follows:

[0032] In this embodiment, N is further limited to a value between 30 and 50, and the number of second refractive layers 10-2 is limited to one. This one second refractive layer 10-2 is sandwiched between one first refractive layer 10-1 and one third refractive layer 10-3, thereby defining a unidirectional incremental module 10b. That is, the number of film layers 10 used in the optical filter 1000 in this embodiment is the same as that in the first embodiment, but the optical filter 1000 in this embodiment does not include the bidirectional incremental module 10a (e.g., FIG. 1) shown in the first embodiment.

[0033] Incidentally, the matching composite layer 100 is arranged such that the film layers 10 other than the unidirectional incremental module 10b are stacked alternately with the first refractive layers 10-1 and the third refractive layers 10-3 (i.e., any first refractive layer 10-1 is sandwiched between two adjacent third refractive layers 10-3).

[0034] More specifically, the bonding layer 300 and the matching composite layer 100 of the optical filter 1000 adopt the specific arrangement shown in FIG. 4 in this embodiment, and related simulation results confirm that when a normal incident light source (e.g., visible light) is incident at a deflection angle of 30 degrees, the average reflectance is less than 2%.

[0035] Therefore, in this embodiment, the optical filter 1000 can form a unidirectional incremental module 10b, and by combining the structure and arrangement of the unidirectional incremental module 10b, the overall refractive index distribution of the matching composite layer 100 can be adjusted, which helps the optical filter 1000 to be designed to meet more diverse different requirements.

[0036] [Third embodiment] Please refer to Figures 5 to 7, which show a third embodiment of the present invention. This embodiment is similar to the first embodiment described above, so the commonalities between the two embodiments will not be described in detail. The main differences between this embodiment and the first embodiment are as follows:

[0037] In this embodiment, the substrate 200 has a first plate surface 201 and a second plate surface 202 located on opposite sides thereof, the bonding layer 300 is formed on the first plate surface 201 of the substrate 200, and the matching composite layer 100 is formed on the bonding layer 300 and the second plate surface 202 of the substrate 200. The matching composite layer 100 includes a plurality of film layers 10, including a plurality of first refractive layers 10-1, a plurality of second refractive layers 10-2, and a plurality of third refractive layers 10-3, but these first refractive layers 10-1, second refractive layers 10-2, and third refractive layers 10-3 are generally the same as those described in the first embodiment, so they will not be described in detail here.

[0038] More specifically, in this embodiment, the multiple film layers 10 are divided into N front film layers 10F stacked in order on the bonding layer 300 and M back film layers 10B stacked in order on the second surface 202 of the substrate 200. Here, N and M are both positive integers, and the difference between N and M is preferably 5 or less, and further, N and M are both limited to a range of 10 to 30. In this embodiment, N and M are equal and are each 22, but the present invention is not limited thereto.

[0039] To facilitate understanding of the overall arrangement of the matching composite layer 100, the N front film layers 10F and the M back film layers 10B are described by their respective stacking orders. That is, in the N front film layers 10F, the third refractive layer 10-3 is adjacent to the bonding layer 300 and is defined as the first front film layer F1. In the N front film layers 10F, the first refractive layer 10-1 is disposed at the end away from the bonding layer 300 and is defined as the Nth front film layer FN. In addition, in the M back film layers 10B, the first refractive layer 10-1 is adjacent to the second plate surface 202 and is defined as the first back film layer B1. In the M back film layers 10B, another first refractive layer 10-1 is disposed at the end away from the second plate surface 202 and is defined as the Mth back film layer BM.

[0040] In this embodiment, the number of the second refractive layers 10-2 is limited to eight, of which three second refractive layers 10-2 are arranged in the N front film layers 10F and combined with some of the first refractive layers 10-1 and some of the third refractive layers 10-3 to form a bidirectional incremental module 10a and a bidirectional incremental sub-module 10c. The remaining five second refractive layers 10-2 are arranged in the M back film layers 10B and combined with some of the first refractive layers 10-1 and some of the third refractive layers 10-3 to form two bidirectional incremental modules 10a and a unidirectional incremental module 10b, but the present invention is not limited thereto.

[0041] For example, in other embodiments not shown in the present invention, the number of second refractive layers 10-2 may be adjusted to two or more according to design requirements, and the bidirectional incremental sub-modules 10c may be omitted from the N front film layers 10F, and at least one bidirectional incremental module 10a or one unidirectional incremental module 10b may be omitted from the M back film layers 10B according to design requirements.

[0042] Among the N front film layers 10F, one first refractive layer 10-1 is sandwiched between two adjacent second refractive layers 10-2 and is sandwiched between two third refractive layers 10-3 on the outside, and these are together defined as a bidirectional incremental module 10a. Furthermore, among the N front film layers 10F, one second refractive layer 10-2 located away from the bidirectional incremental module 10a is sandwiched between two third refractive layers 10-3, and these are together defined as a bidirectional incremental sub-module 10c.

[0043] More specifically, among the N front film layers 10F, one first refractive layer 10-1 is disposed between the bidirectional incremental module 10a and the first front film layer F1, and the bidirectional incremental sub-module 10c is adjacent to the Nth front film layer FN, i.e., the bidirectional incremental module 10a and the bidirectional incremental sub-module 10c are located at opposite ends of the corresponding N front film layers 10F, respectively.

[0044] Among the M back surface film layers 10B, one first refractive layer 10-1 is sandwiched between two adjacent second refractive layers 10-2 on the inside and two third refractive layers 10-3 are sandwiched between them on the outside, and these are together defined as a bidirectional incremental module 10a. Furthermore, among the M back surface film layers 10B, one second refractive layer 10-2 located away from the substrate 200 is sandwiched between one first refractive layer 10-1 and one third refractive layer 10-3, and these are together defined as a unidirectional incremental module 10b.

[0045] More specifically, among the M back membrane layers 10B, one first refractive layer 10-1 and one third refractive layer 10-3 are disposed between a certain bidirectional incremental module 10a and the first back membrane layer B1, and the unidirectional incremental module 10b is adjacent to the Mth back membrane layer BM. That is, a certain bidirectional incremental module 10a and a certain unidirectional incremental module 10b are located at opposite ends of the corresponding M back membrane layers 10B, with another bidirectional incremental module 10a disposed therebetween. This bidirectional incremental module 10a has one first refractive layer 10-1 sandwiched between two adjacent second refractive layers 10-2 and two third refractive layers 10-3 on the outside.

[0046] Furthermore, among the M back surface film layers 10B, only one first refractive layer 10-1 may be sandwiched between two of the bidirectional incremental modules 10a, thereby enhancing the mutual cooperation effect between the two bidirectional incremental modules 10a.

[0047] When viewed from another angle, the thickness of each of the bidirectional incremental modules 10a of the M back film layers 10B is 90% to 110% of the thickness of the bidirectional incremental modules 10a of the N front film layers 10F. Furthermore, among the M back film layers 10B, the distance between the bidirectional incremental module 10a closest to the substrate 200 and the second plate surface 202 is 90% to 110% of the distance between the bidirectional incremental modules 10a of the N front film layers 10F and the first plate surface 201.

[0048] Furthermore, the matching composite layer 100 includes the bidirectional incremental module 10a, the unidirectional incremental module 10b, and the bidirectional incremental sub-module 10c, while the other film layers 10 are stacked with the first refractive layer 10-1 and the third refractive layer 10-3 alternately (e.g., any first refractive layer 10-1 is sandwiched between two adjacent third refractive layers 10-3).

[0049] As described above, in this embodiment, the optical filter 1000 is configured such that the matching composite layer 100 is disposed on opposite sides of the substrate 200, and the bidirectional incremental module 10a, the unidirectional incremental module 10b, and the bidirectional incremental sub-module 10c are mutually combined to adjust the overall refractive index distribution of the matching composite layer 100, thereby facilitating the optical filter 1000 to be designed to meet a wider variety of different requirements.

[0050] More specifically, as shown in FIG. 7, curves A1 and B1 are the simulated test results at different angles using the optical filter 1000 of this embodiment, while curves A2 and B2 are the simulated test results at different angles using an existing optical filter that has multiple refractive layers in a unidirectional stack of plate materials and does not use the bidirectional incremental module 10a, the unidirectional incremental module 10b, and the bidirectional incremental sub-module 10c.

[0051] This shows that the optical filter 1000 of this embodiment can reduce reflection by approximately 2.8% within the range of 435 nanometers (nm) to 630 nanometers, effectively reducing ripples. Furthermore, when the entire spectrum is within the range of 435 nanometers to 630 nanometers, the optical filter 1000 of this embodiment has a significantly superior effect compared to existing optical filters, and can even expand the applicable spectral range to 400 nanometers to 700 nanometers.

[0052] [Beneficial Effects of the Present Embodiment] In general, the optical filter disclosed in this embodiment is different from the conventionally known bidirectional incremental module in that the refractive index of the bidirectional incremental module is gradually increased in two opposite directions from its first refractive layer, thereby adjusting the overall refractive index distribution of the matching composite layer, and thereby helping the optical filter to be designed to meet more diverse different requirements.

[0053] Furthermore, the optical filter disclosed in this embodiment also adjusts the overall refractive index distribution of the matching composite layer by forming the unidirectional incremental module, thereby helping the optical filter to be designed to meet more diverse and different requirements.

[0054] Furthermore, the optical filter disclosed in this embodiment can form both the bidirectional incremental module and the unidirectional incremental module, and by combining the structures and arrangements of these modules (for example, when the unidirectional incremental module and the bidirectional incremental module are respectively arranged at opposite ends of the matching composite layer), the overall refractive index distribution of the matching composite layer can be adjusted, thereby helping the optical filter to be designed to meet more diverse different requirements.

[0055] The above disclosure is merely a preferred embodiment of the present invention, and does not limit the scope of the claims of the present invention. Therefore, all equivalent technical modifications made based on the contents of the specification and accompanying drawings of the present invention shall be included in the scope of the claims of the present invention. [Explanation of symbols]

[0056] 1000 Optical Filters 100 matching composite layers 10 membrane layers 10F front membrane layer 10B Back membrane layer 10-1 First refractive layer 10-2 Second refractive layer 10-3 Third Refraction Layer 1. First membrane layer 2 Second membrane layer 3 Third membrane layer 4 Fourth membrane layer 5 Fifth membrane layer 6 Sixth membrane layer 7 Seventh membrane layer Nth membrane layer N-1 N-1 membrane layer N-2 N-2 membrane layer N-3 N-3 membrane layer F1 First front membrane layer FN Nth front membrane layer B1 First backing layer BM Mth back surface film layer 10a Bidirectional Incremental Module 10b One-Way Incremental Module 10c Bidirectional Incremental Submodule 200 boards 201 First board 202 Second board 300 bonding layers T10a Thickness T10b Thickness T10-2a Thickness T10-2b Thickness A1, A2, B1, B2 curve

Claims

1. A substrate; a bonding layer formed on the substrate and having a refractive index of less than 1.42; a matching composite layer formed on the bonding layer and having N (N is a positive integer) film layers stacked in sequence; An optical filter comprising: the N film layers include a plurality of first refractive layers, a plurality of second refractive layers, and a plurality of third refractive layers; each of the plurality of first refractive layers has a first refractive index greater than the refractive index of the bonding layer; each of the second refractive layers has a second refractive index greater than the first refractive index, and the number of the second refractive layers is less than the number of the first refractive layers; each of the plurality of third refractive layers has a third refractive index greater than the second refractive index, and the number of the plurality of second refractive layers is less than the number of the plurality of third refractive layers; One of the first refractive layers is sandwiched between two adjacent second refractive layers, and the two third refractive layers are sandwiched between the first refractive layer and the second refractive layer, thereby defining a bidirectional incremental module. An optical filter characterized by:

2. 2. The optical filter of claim 1, wherein one of the second refractive layers apart from the bidirectional incremental module is sandwiched between one of the first refractive layer and one of the third refractive layer, thereby defining it as a unidirectional incremental module.

3. 2. The optical filter of claim 1, wherein in the matching composite layer, one of the third refractive layers adjacent to the bonding layer is defined as a first film layer, and one of the first refractive layers is disposed between the bidirectional incremental module and the first film layer.

4. In the matching composite layer, one of the first refractive layers is disposed at an end remote from the bonding layer, and the first refractive layer is defined as an Nth film layer; The optical filter of claim 2 , wherein the unidirectional incremental module is adjacent to the Nth film layer.

5. In the matching composite layer, one of the first refractive layers is disposed at an end remote from the bonding layer, and the first refractive layer is defined as an Nth film layer; The optical filter of claim 4 , wherein the unidirectional incremental module is coupled to the Nth film layer.

6. 3. The optical filter of claim 2, wherein the thickness of the bidirectional incremental module is 165% to 180% of the thickness of the unidirectional incremental module, and the thickness of the second refractive layer of any of the bidirectional incremental modules is greater than the thickness of the second refractive layer of the unidirectional incremental module.

7. 2. The optical filter of claim 1, wherein the refractive index of the bonding layer is between 1.35 and 1.42, the first refractive index is between 1.45 and 1.52, the second refractive index is between 1.62 and 1.71, and the third refractive index is between 2.2 and 2.

8.

8. 10. The optical filter of claim 1, wherein N is further limited to between 30 and 50, and the number of the plurality of second refractive layers is limited to three.

9. A substrate; a bonding layer formed on the substrate and having a refractive index of less than 1.42; a matching composite layer formed on the bonding layer and having N (N is a positive integer) film layers stacked in sequence; An optical filter comprising: the N film layers include a plurality of first refractive layers, a second refractive layer, and a plurality of third refractive layers; each of the plurality of first refractive layers has a first refractive index greater than the refractive index of the bonding layer; the second refractive layer has a second refractive index greater than the first refractive index; each of the plurality of third refractive layers has a third refractive index greater than the second refractive index; the second refractive layer is sandwiched between one of the first refractive layer and one of the third refractive layer, thereby defining a unidirectional incremental module; An optical filter characterized by:

10. 10. The optical filter of claim 9, wherein N is further limited to between 30 and 50, and the number of said second refractive layers is limited to one.

11. a substrate having a first surface and a second surface located opposite the first surface; a bonding layer formed on the first surface of the substrate and having a refractive index of less than 1.42; a matching composite layer formed on the bonding layer and the second surface of the substrate, the matching composite layer having a plurality of film layers; An optical filter comprising: the plurality of film layers includes a plurality of first refractive layers, a plurality of second refractive layers, and a plurality of third refractive layers; each of the plurality of first refractive layers has a first refractive index greater than the refractive index of the bonding layer; each of the plurality of second refractive layers has a second refractive index greater than the first refractive index, and the number of the plurality of second refractive layers is less than the number of the plurality of first refractive layers; each of the plurality of third refractive layers has a third refractive index greater than the second refractive index, and the number of the plurality of second refractive layers is less than the number of the plurality of third refractive layers; The plurality of film layers include N front film layers stacked in order on the bonding layer and M back film layers stacked in order on the second plate surface, where N and M are both positive integers; Among the N front film layers, one first refractive layer is sandwiched between two adjacent second refractive layers, and the other is sandwiched between two third refractive layers, thereby defining a bidirectional incremental module. An optical filter characterized by:

12. 12. The optical filter of claim 11, wherein among the N front film layers, one second refractive layer away from the bidirectional incremental module is sandwiched between two third refractive layers, thereby defining it as a bidirectional incremental sub-module.

13. 13. The optical filter of claim 12, wherein, among the N front film layers, one of the third refractive layers adjacent to the bonding layer is defined as a first front film layer, and among the N front film layers, one of the first refractive layers is disposed between the bidirectional incremental module and the first front film layer.

14. 12. The optical filter of claim 11, wherein among the M rear film layers, one of the first refractive layers is sandwiched between two adjacent second refractive layers on the inside and is sandwiched between two of the third refractive layers on the outside, thereby defining the optical filter as a bidirectional incremental module.

15. 15. The optical filter of claim 14, wherein the thickness of the bidirectional incremental modules of the M rear film layers is 90% to 110% of the thickness of the bidirectional incremental modules of the N front film layers.

16. 15. The optical filter of claim 14, wherein the distance between the bidirectional incremental modules of the M rear film layers and the second plate surface is 90% to 110% of the distance between the bidirectional incremental modules of the N front film layers and the first plate surface.

17. 15. The optical filter of claim 14, wherein among the M rear film layers, one second refractive layer away from the substrate is sandwiched between one first refractive layer and one third refractive layer, thereby defining a unidirectional incremental module.

18. 18. The optical filter of claim 17, wherein, among the M rear film layers, one of the first refractive layers adjacent to the second plate surface is defined as a first rear film layer, and among the M rear film layers, another first refractive layer is arranged at an end away from the second plate surface, and the other first refractive layer is defined as an Mth rear film layer, and among the M rear film layers, one of the first refractive layer and one of the third refractive layer are arranged between the bidirectional incremental module and the first rear film layer, and the unidirectional incremental module is connected to the Mth rear film layer.

19. 18. The optical filter of claim 17, wherein in the M rear film layers, another bidirectional incremental module is disposed between the bidirectional incremental module and the unidirectional incremental module, and is defined by one first refractive layer sandwiched inside two adjacent second refractive layers and sandwiched on the outside by two third refractive layers.

20. 12. The optical filter of claim 11, wherein the refractive index of the bonding layer is between 1.35 and 1.42, the first refractive index is between 1.45 and 1.52, the second refractive index is between 1.62 and 1.71, and the third refractive index is between 2.2 and 2.

8.

21. 12. The optical filter of claim 11, wherein the difference between N and M is 5 or less, and N and M are each further limited to be between 10 and 30, and the number of the plurality of second refractive layers is limited to 8.

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