A coating method and an angle adjusting device for realizing a linear gradient filter

Abstract

The application provides a coating method for realizing a linearly graded filter and an angle adjusting device for an intermediate layer of the filter, and the coating method comprises the following operation steps: S1. correcting the uniformity of a plane; S2. establishing a database; S3. matching the product tilt angle through the angle and slope database; and S4. completing the preparation of the interval layer. The method utilizes the uniformity principle of an evaporation coating machine, changes the substrate tilt angle, changes the included angle between the normal line of the substrate and the single point-evaporation source connecting line, makes the included angles and distances of each point on the substrate present linear changes, and finally realizes the linear change of the film thickness in the substrate tilt direction.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high integration spectrum detection device manufacturing technology, in particular to a coating method for realizing a linearly variable filter and an angle adjusting device for the filter intermediate layer. BACKGROUND

[0002] The linearly variable filter is a new type of spectral device with linearly variable spectral characteristics at different positions. According to the principle of the Fabry-Perot filter, the central wavelength is related to the optical thickness of the spacer layer, and the linear variation rule is presented. Therefore, as a spectral element, the linearly variable filter can obtain a very narrow band of progressive linear filter film to achieve high-precision spectral resolution.

[0003] According to the Fabry-Perot filter, the peak transmission wavelength λ0 can be given by the following formula:

[0004]

[0005] In the formula, n and d respectively represent the refractive index and physical thickness of the spacer layer; ψ1 and ψ2 respectively represent the phases of the upper and lower reflection film systems; m is k+(ψ1, ψ2) / 2π, k=0, 1, 2…

[0006] From the above formula, it can be seen that the peak transmission wavelength of the Fabry-Perot filter is proportional to the optical thickness (nd) of the intermediate layer. Therefore, in theory, as long as the linearly variable spacer layer is prepared along a certain direction, the peak transmission wavelength λ0 will also change synchronously along this direction.

[0007] Taking a full dielectric F-P type filter as an example, it is divided into a reflection layer and a spacer layer. The reflection layer is composed of high and low refractive indexes such as HLH…HL. The spacer layer is composed of an even number of half-wavelengths 2mL or L2mHL. The final film system structure A=(HL)^ n 2mH(LH)^ n Or B=(HL)^ n H2mLH(LH)^ n .

[0008] The main parameters of the linear filter include:

[0009] The linear dispersion coefficient is an important parameter for characterizing the spectral characteristics of the linearly variable filter. An important indicator for evaluating its performance is the linear dispersion coefficient, which is defined as:

[0010] Liner Dispersion=(λ end -λ start ) / (x end -x start )

[0011] In the formula, xend and x start are the start and end positions of the linear filter respectively, and λ end and λ start are the start and end wavelengths of the linear filter respectively.

[0012] Ideally, the center wavelength of the linearly variable filter changes linearly along the working direction, which can be expressed as

[0013] λ(x)=kx+b k is the linear dispersion coefficient of the linear filter, and b is the center wavelength of the start position of the filter.

[0014] Currently, there are two main methods for preparing linearly variable filters:

[0015] One method is to use ion beam etching. First, a bottom reflective layer and a spacer layer are prepared by coating. Then, a baffle with a triangular window is placed between the ion beam exit window and the sample to be processed, perpendicular to the ion beam exit direction. During ion beam etching, the sample moves back and forth at a constant rate, and the thickness difference perpendicular to the sample movement direction is obtained by etching. Finally, the spacer layer with the desired wedge-shaped thickness distribution is obtained, and then the outer reflective layer is supplemented.

[0016] This method controls the dispersion coefficient by controlling the size of the triangular window and the etching thickness. The etching process has the advantage of simple process control. Different working wavebands and dispersion coefficients can be obtained by changing the etching times. However, due to the uniformity of ion beam etching, there is a great impact on the uniformity of the product. Moreover, the etching method is prone to deviations in film thickness control accuracy, especially when preparing complex multi-cavity filter products.

[0017] The second method is to use a modified uniformity baffle to modify the film thickness distribution on the umbrella. By modifying the uniformity shape, the film thickness distribution at specific positions on the umbrella is changed to meet the purpose of linearly variable filter spacer layer thickness variation.

[0018] The traditional uniformity baffle modification method has many problems, and has the following technical defects: the same uniformity baffle can only complete one thickness gradient; secondly, the sample placement needs to be relatively fixed with the uniformity baffle, and the umbrella utilization rate is low, which can only be at specific positions; in addition, the test point positions of the uniformity baffle modification are generally discontinuous. If the uniformity baffle is not properly trimmed, it will affect the actual thickness distribution of these non-test points, and there is a blind area.

[0019] Therefore, how to design a film plating method for a linearly variable filter that changes the film growth uniformity to achieve a linearly variable filter with a thickness variation, and an angle adjusting device for the intermediate layer of the filter, has become a problem that needs to be solved. SUMMARY

[0020] In view of the problems existing in the prior art, the present application provides a coating method for realizing a linearly graded filter and an angle adjusting device for the filter intermediate layer to solve at least one of the above technical problems.

[0021] The technical solution of the present application is: a coating method for realizing a linearly graded filter, comprising the following steps:

[0022] S1. correcting the uniformity of the plane,

[0023] The sample mounting plane of the angle adjusting device at horizontal zero degree is used as the initial plane, the fixed link member is fixed to the umbrella frame through the nut, and the uniformity of the plane is corrected through the uniformity baffle;

[0024] S2. establishing a database,

[0025] The bearing is used as the center, the angle of the sample tray is adjusted, the angle is measured through the nut locking interface, the preparation of the interval layer at different angles is completed, the transmittance of the fixed interval point in the inclined direction of the sample is tested, the thickness of each interval point is calculated through the transmittance inversion, the thickness variation slope is calibrated, and the database of the relationship among the angle, the slope and the tooling is established;

[0026] S3. matching the product inclination angle through the angle and slope database,

[0027] According to the linear dispersion coefficient requirement of the product, the thickness variation slope requirement of the interval layer is calculated, and the required inclination angle of the product is matched through the angle and slope database;

[0028] S4. completing the preparation of the interval layer,

[0029] The end point thickness is determined, the crystal control thickness is set according to the tooling, and the preparation of the interval layer is completed.

[0030] The method of the present application utilizes the uniformity principle of the evaporation coating machine, changes the inclination angle of the substrate, changes the included angle between the normal line of the substrate and the single point and the evaporation source, makes the included angle and the distance of each point on the substrate present linear variation, and finally realizes the linear variation of the film thickness in the inclined direction of the substrate.

[0031] The technical solution of the present application is: an angle adjusting device for realizing the intermediate layer of a linearly graded filter, comprising a rotating mechanism at one end in a cavity, one end of the rotating mechanism is connected with an umbrella frame, the end of the umbrella frame away from the rotating mechanism is fixedly connected with the angle adjusting device, symmetrically arranged evaporation sources are arranged at the other end in the cavity, an ion source is arranged between the two evaporation sources, and uniformity baffles are arranged between the umbrella frame and the two evaporation sources.

[0032] The device of the application only needs to adjust the initial height for planar uniformity, and the thickness variation slope of each inclination angle is obtained through experiment collection, then the matched angle setting is selected according to the requirement of the gradual change filter with different linear dispersion coefficients, so that the efficiency is greatly improved, the production cost is reduced, and the technical defects of the traditional uniformity baffle, such as repeated correction and modification, and single baffle corresponding to only one linear dispersion coefficient, are solved. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The schematic view of the angle adjusting device of the application in a cavity.

[0034] Figure 2 The schematic view of the angle adjusting device of the application in a cavity.

[0035] Figure 3 The schematic view of the angle adjusting device of the application in a cavity.

[0036] Figure 4 The uniformity graph of the standard plane TiO2 film in the sixth embodiment of the application.

[0037] Figure 5 The thickness uniformity graph of the TiO2 film along the inclination direction under the condition of 60-degree inclination of the sample tray in the sixth embodiment of the application.

[0038] Figure 6 The schematic view of the uniformity adjusting principle of the application.

[0039] Figure 7 The thickness variation schematic view of the sample one along the inclination direction in the first embodiment of the application with the TiO2 film adjusting the inclination angle to 45°&60°.

[0040] Figure 8 The thickness variation schematic view of the sample two along the inclination direction in the first embodiment of the application with the TiO2 film adjusting the inclination angle to 45°&60°.

[0041] In the figure: 1. rotating mechanism; 2. umbrella frame; 3. uniformity baffle; 4. evaporation source; 5. ion source; 6. angle adjusting device; 601. sample tray; 602. fixed link; 603. bearing; 604. nut locking interface. DETAILED DESCRIPTION

[0042] The application will be further described below with reference to the accompanying drawings.

[0043] Reference Figures 1-8The structure, proportion, size, etc. shown in the drawings attached to the present specification are only used to cooperate with the content disclosed in the specification, to be understood and read by those skilled in the art, and are not used to limit the defined conditions under which the present application can be implemented, so they do not have technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effect and purpose that the present application can produce, should still fall within the scope covered by the disclosed technology.

[0044] Example one, a coating method for realizing linearly graded filter, comprising the following steps:

[0045] S1. Correcting the uniformity of the plane,

[0046] The sample mounting plane of the horizontal zero degree angle adjusting device 6 is the initial plane, the fixed link member 602 is fixedly linked with the umbrella stand 2 through the nut, and the uniformity of the plane is corrected through the uniformity baffle 3; the sample is a K9L40*40mm glass coating sample substrate, prepared by using a single layer of TiO2 film, and an electronic book thermal evaporation device, HAV2050 coating machine; similar to the traditional uniformity baffle in principle, it belongs to changing the film thickness by changing the film layer growth uniformity. But different from the traditional way of changing the uniformity distribution by manually modifying the uniformity baffle, it uses the single-point film thickness formula in the coating machine to change the film thickness by changing the placement angle. Its advantages are: first, because the plane is placed at an angle, the film forming angle and distance of each point appear uniform and continuous, resulting in a continuous and uniform distribution of film thickness; second, unlike the traditional uniformity baffle method, which needs to repeatedly modify the uniformity baffle for different product linear dispersion coefficients, it can be changed by changing the placement angle; in addition, after adjusting the initial uniformity of the standard plane, the change rate of the film thickness is mainly related to the sample placement angle, and the position correlation is small, and the loadable rate of the umbrella stand is improved within a certain range;

[0047] The uniformity adjusting principle is that the film thickness from the evaporation source to the single point P can be represented by the following formula:

[0048]

[0049] In the above formula, t p is the single-point film thickness, m is the total amount of material evaporation, μ is the density, r is the distance from the evaporation source to the substrate P point, θ is the angle between the substrate normal and r, and reference Figure 6Under the condition of material selection and certain amount of evaporated material, the single-point film thickness is related to r and θ.

[0050] According to the uniformity principle, the film layer will have a gradual change with the change of the radius p in the coating machine, which meets the principle requirement of the linear gradient filter. However, due to the limitation of the position of the evaporation source and the loading of the sample, only the original film thickness gradient in the coating machine cannot match the linear dispersion coefficient of the linear filter, and lacks of adjustment variable. Therefore, the angle adjustment variable can effectively solve this problem. In order to avoid the influence of the original uniformity of the equipment, a standard plane uniformity baffle needs to be prepared to normalize the original uniformity of the equipment, and then the angle variable is used to control the film thickness change slope.

[0051] Firstly, according to the size of the lens, the distance R between the nut locking interface of the sample tray and the center of the bearing is determined. The uniformity baffle is adjusted to the same uniformity as the standard plane at this height.

[0052] The sample placement angle is adjusted, a single-layer dielectric layer is prepared, and the thickness in the tilt direction is simulated through spectral testing. The thickness change slope and tooling are calculated. Taking TiO2 as an example, the tilt angle is adjusted to 45° and 60° respectively, and the sample is a 40*40mm co-evaporated piece. The thickness gradient of the sample in the tilt direction is shown in the following table. Figure 7 、 Figure 8 ,

[0053] As can be seen from the figure, as the angle increases from 45° to 60°, the film thickness tilt rate increases. At the same angle, there is no obvious change in the tilt rate between the inner and outer circles, which shows that within a certain range of the umbrella frame, the film thickness tilt rate is related to the angle, and there is no obvious difference between the inner and outer circles. According to the cosine curve law, as the angle increases, the cosine becomes smaller and approaches 0. In theory, as the angle increases, the thickness tilt rate also increases and approaches infinity.

[0054] S2. Establish a database. According to the Fabry-Perot filter center wavelength calculation formula, combined with the linear dispersion coefficient requirement of the gradient filter, the physical thickness change slope requirement of the spacer layer is calculated. Taking the bearing 603 as the center, the angle of the sample tray 601 is adjusted, the angle is measured through the nut locking interface 604, the spacer layer is prepared at different angles, the transmittance of the sample at fixed interval points in the tilt direction is tested, the thickness of each interval point is calculated by transmittance inversion, the thickness change slope is calibrated, and the database of the relationship among angle, slope and tooling is established.

[0055] S3. Match the product tilt angle through the angle and slope database,

[0056] According to the product linear dispersion coefficient requirements, the interval layer thickness change slope requirements are calculated, and the required tilt angle of the product is matched through the angle and slope database.

[0057] S4. completing the interval layer preparation,

[0058] The end point thickness is determined, the tooling setting crystal control thickness is determined, and the interval layer preparation is completed.

[0059] The method utilizes the uniformity principle of the evaporation coating machine, changes the substrate tilt angle, changes the included angle between the substrate normal and the single point and the evaporation source, makes the included angle and the distance of each point on the substrate present linear change, and finally realizes the linear change of the film thickness in the tilt direction of the substrate.

[0060] Example two, an angle adjusting device for realizing the intermediate layer of a linear gradient filter, referring to Figure 1 , a rotating mechanism 1 is arranged at one end of the cavity, one end of the rotating mechanism 1 is connected with an umbrella frame 2, the umbrella frame 2 is fixedly connected with an angle adjusting device 6 at an end away from the rotating mechanism 1, symmetrically arranged evaporation sources 4 are arranged at the other end of the cavity, an ion source 5 is arranged between the two evaporation sources 4, and uniformity baffles 3 are arranged between the umbrella frame 2 and the two evaporation sources 4. The device only needs to adjust the planar uniformity of the initial height, and the thickness change slope of each tilt angle can be obtained through experiment collection, then the matching angle setting is selected according to the linear dispersion coefficient requirements of different linear gradient filters, the efficiency is greatly improved, the production cost is reduced, and the technical defects that the traditional uniformity baffles need to be repeatedly corrected and modified and a single baffle can only correspond to one linear dispersion coefficient are solved.

[0061] Example three, based on example two, referring to Figure 2 , Figure 3 , the angle adjusting device 6 comprises a fixed connecting piece 602, a sample plate 601 is arranged in the fixed connecting piece 602, a sample is placed in the sample plate 601, a nut locking interface 604 is arranged at one end of the sample plate 601, a bearing 603 is arranged at the other end of the sample plate 601, a slide is arranged on the fixed connecting piece 602, and the nut locking interface 604 can move along the slide.

[0062] Example four, based on example three, the slide is an arc structure, and the bearing 603 is located at the center of the arc structure.

[0063] Example five, based on example four, the distance between the nut locking interface 604 and the bearing 603, that is, the radius R of the sample rotation angle, determines the size of the sample that can be loaded and the height of the initial standard plane.

[0064] Example six, on the basis of example five, the rotation angle φ of the sample tray 601, the value directly affects the change of film thickness slope.

[0065] Example seven, reference Figure 4 , Example seven, reference Figure 5 , the experimental substrate is K9L40*40mm glass, the experiment uses single layer TiO2 film preparation, the experimental electronic book thermal evaporation equipment is a Korean HAV2050 coating machine;

[0066] 1) according to Figure 1 Configuration, angle adjusting device 6 according to Figure 2 State and umbrella frame 2 fixed link, according to K9L40mm size of the substrate, 40mm from the umbrella frame 2 installation surface as a standard plane to move down 40mm to adjust the uniformity, get K9L40*40mm uniformity of thin film distribution on the substrate, thickness fitting uniformity as Figure 4 ;

[0067] 2) according to Figure 3 Adjust the sample tray 601, the adjustment angle is 60°, which can be determined according to the nut locking interface 604 and the center line of bearing 603, prepare 60° single layer TiO2, get K9L40*40mm substrate on the TiO2 film with tilt direction of gradual change, thickness uniformity test as Figure 5 , at the same time, according to the crystal control thickness, the tooling of each point can be calculated, and the optical parameters n, k value of TiO2 film can be calculated;

[0068] 3) according to 60° thickness uniformity, the thickness gradient slope can be calculated as 0.12% / mm;

[0069] 4) taking 550nm band pass film system as an example, the interval layer refractive index n = 2.12, m = 4, the interval layer thickness d = 519nm can be calculated according to the center wavelength formula λ0=2nd / m, the thickness gradient is 0.62nm / mm, then in 40 aperture, the thickness gradient slope is 25nm / 40mm, which is the linear dispersion coefficient of the filter made by the sample inclined 60°, the band pass center wavelength λ0from 550nm-> 524nm, the linear dispersion coefficient of the linear gradient filter is 25nm / 40mm;

[0070] 5) The above is the specific sample inclination angle, back to 40 mm size 524-550 nm linear gradient filter experimental calculation, actual preparation, can be calculated by linear gradient filter size and center wavelength λ0gradient range, linear dispersion coefficient, and then according to the center wavelength formula λ0=2nd / m, the thickness of the gradient slope. Different thickness gradient slope by inclination angle adjustment can be calculated and obtained, thus completing the preparation of the sample.

[0071] The above is only the preferred embodiment of the present application, it should be noted that, for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the scope of the present application.

Claims

1. An angular adjustment device for a linearly graded filter interlayer comprising a rotating mechanism (1) at one end of a cavity, characterised in that: One end of the rotating mechanism (1) is connected with the umbrella stand (2), and the other end of the umbrella stand (2) away from the rotating mechanism (1) is fixedly connected with the angle adjusting device (6); the other end of the umbrella stand (2) in the cavity is provided with two evaporation sources (4) arranged symmetrically; the two evaporation sources (4) are provided with the ion source (5) therebetween; and the umbrella stand (2) and the two evaporation sources (4) are provided with the uniformity baffle (3) therebetween. The angle adjusting device (6) comprises a fixed link member (602), and the sample mounting plane of the angle adjusting device (6) at the horizontal zero degree is taken as an initial plane; the fixed link member (602) is fixedly connected with the umbrella stand (2) through a nut; the uniformity of the plane is corrected through the uniformity baffle (3); the sample tray (601) is arranged in the fixed link member (602); the sample is placed in the sample tray (601); one end of the sample tray (601) is provided with a nut locking interface (604); the other end of the sample tray (601) is provided with a bearing (603); a slide is arranged on the fixed link member (602); and the nut locking interface (604) can move along the slide. The slide is in an arc structure, and the bearing (603) is located at the center of the arc structure. The distance between the nut locking interface (604) and the bearing (603), i.e. the radius R of the sample rotation angle, determines the size of the sample that can be loaded and the height of the initial standard plane.

2. An angular adjustment device for a linearly-varying filter interlayer according to claim 1, wherein: The rotation angle φ of the sample tray (601) directly affects the change slope of the film layer thickness.

3. A coating method for implementing a linearly graded filter, characterized by, The angle adjusting device for realizing the intermediate layer of the linearly variable optical filter according to claim 1 comprises the following steps: S1. correcting the uniformity of the plane, the sample mounting plane of the angle adjusting device (6) at the horizontal zero degree is taken as an initial plane; the fixed link member (602) is fixedly connected with the umbrella stand (2) through a nut; the uniformity of the plane is corrected through the uniformity baffle (3); S2. establishing a database, the bearing (603) is taken as the center, the angle of the sample tray (601) is adjusted, the angle is measured through the nut locking interface (604), the spacer layer preparation at different angles is completed, the transmittance of the fixed interval points in the inclined direction of the sample is tested, the thickness of each interval point is calculated through the transmittance inversion, the thickness change slope is calibrated, and the database of the relationship among the angle, the slope and the tooling is established; S3. matching the product inclination angle through the angle and slope database, according to the linear dispersion coefficient requirement of the product, the thickness change slope requirement of the spacer layer is calculated, and the required inclination angle of the product is matched through the angle and slope database; S4. completing the spacer layer preparation, the end point thickness is determined, the crystal control thickness is set according to the tooling, and the spacer layer preparation is completed.

4. The coating method for realizing a linearly variable filter according to claim 3, wherein: In step S2, according to the Fabry-Perot filter center wavelength calculation formula, the linear dispersion coefficient requirement of the variable optical filter is combined to calculate the physical thickness change slope requirement of the spacer layer.

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