Array laser beam optical film stress on-line monitoring method and system

Abstract

The invention provides an array laser beam optical thin film stress on-line monitoring method and system, and is applied to the technical field of optical thin film preparation, thin film stress on-line detection and thin film preparation process optimization. The array laser is incident to a thin film deposited on the substrate, and the thin film reflects the incident laser; acquiring the position information of the reflected laser, acquiring the deposition thickness of the thin film, acquiring the thin film stress according to the position information of the incident laser, the position information of the reflected laser, the information of the substrate and the deposition thickness of the thin film, and monitoring the stress size and state distribution of the optical thin film online in real time. The growth mode and dynamics related information in the film growth process are obtained, the film preparation technology is guided and optimized, the surface shape error caused by stress is reduced, the success rate of high-surface-shape optical film element preparation is increased, and the ultralow-stress film layer is prepared.

Description

Technical Field

[0001] The present application relates to technical fields such as optical film preparation, online detection of film stress, and optimization of film preparation processes, and specifically to an array laser beam optical film stress online monitoring method and system. Background Art

[0002] With the development and progress of various optical instruments, such as gravitational wave detection systems, controlled nuclear fusion systems, intersatellite communication systems, etc., the requirements for optical films are becoming more and more stringent. Not only are optical films required to have strict spectral characteristics, mechanical firmness and environmental resistance tests, but also the surface shape requirements of thin film components are getting higher and higher. Especially for intersatellite communication systems, the surface shape requirements of thin film components are at least better than λ / 50, λ is 632.8nm, and the surface shape error directly causes the wavefront distortion of the communication beam, resulting in an increase in the communication bit error rate and a decrease in the communication quality. The direct cause of the change in the surface shape of thin film components is the stress of the film. Almost all films have stress, so the control and monitoring of film stress are particularly important.

[0003] At present, optical thin film stress detection is mainly carried out offline after the film is prepared. Common detection methods include: substrate curvature method, X-ray diffraction (XRD) technology, Raman spectroscopy (Raman) analysis method, Magnetic Barkhausen noise (MBN), fiber bragg grating (FBG) and Kelvin probe force microscopy (KPFM), etc., which can only characterize the stress state of the thin film element after the film is prepared, and cannot be detected online in real time. According to research, there is currently no system on the market for real-time online detection of thin film stress.

[0004] Based on this, a new technical solution is needed. Summary of the invention

[0005] In view of this, the embodiments of the present specification provide an array laser beam optical thin film stress online monitoring method and system.

[0006] The embodiments of this specification provide the following technical solutions:

[0007] An array laser beam optical thin film stress online monitoring method provided in an embodiment of the present specification includes: obtaining a parallel array laser; depositing a thin film on a substrate by evaporating and depositing a coating material in a vacuum chamber of a vacuum coating machine; the array laser is incident on the thin film deposited on the substrate; the thin film reflects the incident laser; collecting position information of the reflected laser; obtaining the deposition thickness of the thin film; obtaining the film stress according to the position information of the incident laser, the position information of the reflected laser, the information of the substrate and the deposition thickness of the thin film, so as to realize online monitoring of the stress magnitude and stress state distribution of the thin film.

[0008] Preferably, the two incident laser beams in the array laser with a spacing of D0 are irradiated onto the thin film deposited on the substrate at an incident angle α; the corresponding emission optical path of the reflected laser is L, and the spacing between the two reflected laser beams is D0-d; the angle between the two reflected laser beams is θ, and the curvature radius of the substrate is R, and the following is obtained:

[0009]

[0010] Where d represents the difference between the spacing between incident lasers and the spacing between corresponding reflected lasers;

[0011] Then we get:

[0012]

[0013] Correlating the film stress with the substrate curvature change yields:

[0014]

[0015] Among them, t s represents the thickness of the substrate; t f represents the deposition thickness of the film; E s is the elastic modulus of the substrate; γ s is the Poisson's ratio of the substrate; σ represents the film stress; R0 represents the initial curvature radius of the substrate;

[0016] Calculate the film stress σ:

[0017]

[0018] Preferably, the monitoring method further comprises: before depositing the thin film on the substrate, the array laser is incident on the coating surface of the substrate, and the coating surface of the substrate reflects the incident laser to obtain position information of the incident laser.

[0019] Preferably, the array laser is emitted in parallel through an array laser source; the reflected laser is received through an image sensor; the image sensor is connected through a data acquisition system to record in real time the position information of the reflected laser received by the image sensor; the deposition thickness of the film is acquired in real time through a film thickness control system; the film thickness control system and the data acquisition system are connected through a processing device to obtain the film stress according to the information of the substrate, the deposition thickness of the film, the position information of the reflected laser and the position information of the incident laser;

[0020] The monitoring method also includes: connecting a first laser beam expansion and contraction system and a second laser beam expansion and contraction system through the processing device, the first laser beam expansion and contraction system performing expansion and contraction processing on the incident laser so that the incident laser reaches a preset aperture; the second laser beam expansion and contraction system performing expansion and contraction processing on the reflected laser so that the reflected laser is irradiated on the image sensor.

[0021] Preferably, the revolution system of the vacuum coating machine rotates a mounting plate in the vacuum chamber during the evaporation deposition process; the mounting plate has a plurality of the substrates, and the plurality of substrates are arranged around the rotation axis of the mounting plate, so that the array laser can rotate through the mounting plate and be incident on the thin film deposited on each substrate.

[0022] This specification provides an array laser beam optical thin film stress online monitoring system, wherein the vacuum coating machine is used to deposit a thin film on a substrate by evaporating and depositing a coating material in its own vacuum chamber;

[0023] The monitoring system includes an array laser source, an image sensor, a data acquisition system, a film thickness control system and a processing device; the array laser source emits parallel array lasers to be incident on a thin film deposited on a substrate; the thin film reflects the incident laser; the image sensor receives the reflected laser; the data acquisition system is connected to the image sensor to record in real time the position information of the reflected laser received by the image sensor; the film thickness control system collects the deposition thickness of the thin film in real time; the processing device is connected to the film thickness control system and the data acquisition system to obtain the film stress according to the deposition thickness of the thin film, information of the substrate, position information of the reflected laser and position information of the incident laser, so that the monitoring system can realize online monitoring of the stress magnitude and stress state distribution of the thin film.

[0024] Preferably, the processing device obtains the film stress:

[0025]

[0026] Wherein, D0 represents the spacing between two incident laser beams in the array laser; α represents the incident angle of the incident laser; θ represents the angle between the two reflected laser beams; R represents the curvature radius of the substrate; L represents the emission optical path of the reflected laser; d represents the difference between the spacing between the incident laser beams and the spacing between the corresponding reflected laser beams; the spacing between the two reflected laser beams is D0-d;

[0027] get:

[0028]

[0029] Relating the film stress to the substrate curvature change yields:

[0030]

[0031] Among them, t s Indicates the thickness of the substrate; t f Indicates the deposition thickness of the film; E s is the elastic modulus of the substrate; γ s is the Poisson's ratio of the substrate; σ represents the film stress; R0 represents the initial curvature radius of the substrate bending;

[0032] Calculate the film stress σ:

[0033]

[0034] Preferably, the monitoring system comprises a first laser beam expansion and contraction system and a second laser beam expansion and contraction system connected to the processing device; the first laser beam expansion and contraction system performs expansion and contraction processing on the incident laser so that the incident laser reaches a preset caliber; the second laser beam expansion and contraction system performs expansion and contraction processing on the reflected laser so that the reflected laser is irradiated on the image sensor;

[0035] The first laser beam expansion and contraction system and the second laser beam expansion and contraction system both adopt a combination of fiber optical waveguide and coupled expansion and contraction system, and the first laser beam expansion and contraction system and the second laser beam expansion and contraction system both include two free-form surface lenses to adjust the optical spacing of the two free-form surface lenses to obtain laser beams of different sizes, so that the uniformity of the multiple beams after expansion and contraction reaches more than 99%.

[0036] Preferably, the revolution system of the vacuum coating machine is used to rotate the mounting plate during the evaporation deposition process; the mounting plate is provided with a plurality of substrates, and the plurality of substrates are arranged around the rotation axis of the mounting plate so that the array laser can rotate through the mounting plate and be incident on the thin film deposited on each substrate; the crystal control probe in the vacuum chamber is used to detect the deposition rate of the thin film; and the evaporation source in the vacuum chamber is used to evaporate the coating material.

[0037] Preferably, the array laser source comprises a laser, a laser beam splitting coupling system, an array laser disk, multiple optical fibers and multiple laser coupling collimation devices; the laser beam splitting coupling system is connected to multiple optical fibers; the optical fibers are correspondingly connected to the laser coupling collimation devices; multiple laser coupling collimation devices are arranged in an array and installed on the array laser disk;

[0038] The laser emits laser light; the laser beam splitting coupling system couples the laser beam splitting into multiple optical fibers; the laser coupling collimator collimates the laser light emitted from the corresponding optical fibers; the laser coupling collimators arranged in an array are used to arrange the collimated laser light into a parallel array laser light;

[0039] The laser includes a visible light laser; the visible light laser includes one of a blue laser, a green laser, a yellow laser and a red laser; the blue laser is one of 450nm, 457nm and 473nm; the green laser is 532nm; the yellow laser is 589nm; the red laser is one of 632.8nm, 660nm and 670nm.

[0040] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0041] The present application uses an array laser to irradiate a thin film on a substrate, and the thin film reflects the incident laser. The position information of the reflected laser is collected to obtain the deposition thickness of the thin film. The film stress is obtained based on the position information of the incident laser, the position information of the reflected laser, the information of the substrate, and the deposition thickness of the thin film. The stress size and state distribution of the optical thin film are monitored online in real time, and the growth mode and dynamics-related information during the film growth process are obtained to guide the optimization of the thin film preparation process, reduce the surface error caused by stress, improve the success rate of the preparation of high-surface optical thin film components, and prepare ultra-low stress film layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 is a schematic diagram of the stress detection principle of the present application;

[0044] Figure 2 is a schematic diagram of real-time online film stress detection of the present application;

[0045] Figure 3is a schematic diagram of an array laser disk of the present application;

[0046] Figure 4 is a schematic diagram of a laser beam expansion / contraction system of the present application;

[0047] Figure 5 It is the system workflow diagram of this application;

[0048] Figure 6 It is a schematic diagram of the distribution of the array laser system of the present application.

[0049] Figure numerals: 1. laser light source; 2. laser beam splitting coupling system; 3. array laser system; 401. first laser beam expansion and contraction system; 402. second laser beam expansion and contraction system; 5. substrate; 6. revolution system; 7. crystal control probe; 801. first evaporation source; 802. second evaporation source; 9. high-resolution CCD image sensor; 10. PCI data acquisition system; 11. vacuum chamber. DETAILED DESCRIPTION

[0050] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0051] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0052] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0053] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0054] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the examples can be practiced without these specific details.

[0055] The technical solutions provided by various embodiments of the present application are described below in conjunction with the accompanying drawings.

[0056] The embodiment of this specification provides an array laser beam optical film stress online monitoring method, such as Figure 1 and Figure 2 As shown, it includes: obtaining parallel array lasers; coating the substrate 5 by evaporating and depositing the coating material in the vacuum chamber 11 of the vacuum coating machine to deposit a thin film on the substrate 5; the array laser is incident on the thin film on the substrate 5; the thin film reflects the incident laser; collecting the position information of the reflected laser; obtaining the deposition thickness of the thin film; obtaining the film stress according to the position information of the incident laser, the position information of the reflected laser, the information of the substrate 5 and the deposition thickness of the thin film, so as to realize online monitoring of the stress magnitude and stress state distribution of the thin film. The array range and array density of the array laser are set according to the needs.

[0057] In one embodiment, if Figure 1 and Figure 2 As shown, the monitoring method further includes: before depositing the thin film on the substrate 5, the array laser is incident on the coating surface of the substrate 5, and the coating surface of the substrate 5 reflects the incident laser to obtain position information of the incident laser.

[0058] In one embodiment, if Figure 2As shown, a parallel array laser is emitted by an array laser source; a reflected laser is received by an image sensor; the image sensor is connected by a data acquisition system to record the position information of the reflected laser received by the image sensor in real time; the deposition thickness of the film is collected in real time by a film thickness control system; the film thickness control system and the data acquisition system are connected by a processing device to obtain the film stress according to the information of the substrate 5, the deposition thickness of the film, the position information of the reflected laser and the position information of the incident laser. The processing device is, for example, a computer, the image sensor is, for example, a high-resolution CCD image sensor 9, and the data acquisition system is, for example, a PCI data acquisition system 10. The full name of CCD in English is Charge Coupled Device, which is translated into Chinese as Charge Coupled. The full name of PCI in English is Peripheral Component Interconnect, which is translated into Chinese as Peripheral Component Interconnect Standard.

[0059] The monitoring method further includes: connecting the first laser beam expansion and contraction system 401 and the second laser beam expansion and contraction system 402 through a processing device, the first laser beam expansion and contraction system 401 performs expansion and contraction processing on the incident laser so that the incident laser reaches a preset caliber; the second laser beam expansion and contraction system 402 performs expansion and contraction processing on the reflected laser so that the reflected laser is irradiated on the image sensor. The first laser beam expansion and contraction system 401 and the second laser beam expansion and contraction system 402 can also be written as laser beam expansion / contraction systems. Figure 4 As shown, the laser beam expansion / contraction system consists of two free-form surface lenses. By adjusting the distance L1 between the two lenses, the laser beam expansion and contraction functions can be achieved. After expansion (contraction), the uniformity of the multiple beams reaches more than 99%.

[0060] This application mainly focuses on the current research status of the core optical thin film stress online monitoring system of high-precision coating equipment at home and abroad, and develops a high-precision optical thin film stress online monitoring system. The research scope includes array laser source, laser beam expansion / reduction system, high-resolution CCD image sensor 9, PCI data acquisition system 10, signal filtering, extraction and processing algorithm, etc.

[0061] Array laser source: First, couple the laser beams emitted by the laser into multiple optical fibers, use laser coupling collimation devices on the optical fiber output end face to collimate the laser into parallel light, and arrange the laser coupling collimation devices into an array. The fixed fixture needs to be stable and adjustable to ensure that multiple parallel lasers can be formed. Laser light source 1 can choose lasers of different types and wavelengths, and preferably visible light lasers (such as blue lasers: 450nm, 457nm, 473nm; green lasers: 532nm; yellow lasers 589nm; red lasers 632.8nm, 660nm, 670nm) to facilitate the alignment and adjustment of the optical path.

[0062] High-precision fiber-coupled beam expansion (reduction) system: It combines high-light-throughput fiber optical waveguides with coupled beam expansion (reduction) systems. By designing free-form surface lens groups and optimizing the optical spacing of lens groups, monitoring array laser beams of different sizes are obtained. The uniformity of multiple beams after beam expansion (reduction) is required to reach more than 99%.

[0063] In one embodiment, if Figure 1 and Figure 2 As shown, two incident laser beams with a spacing of D0 in the array laser are irradiated onto the thin film on the substrate 5 at an incident angle α; the corresponding emission optical path of the reflected laser is L, and the spacing between the two reflected laser beams is D0-d; the angle between the two reflected laser beams is θ, and the curvature radius of the curved substrate 5 is R.

[0064] like Figure 1 As shown in the figure, the principle of optical film stress detection is shown, where t s represents the thickness of the coating substrate 5, t f Represents the thickness of the deposited film. Two beams of parallel light with a spacing of D0 are irradiated onto the coated substrate 5 at a certain incident angle α. According to the law of reflection, if the substrate 5 is not bent, the two beams of reflected light remain parallel and the spacing is still D0. However, in the actual coating process, as the film layer is deposited, the stress of the film causes the substrate 5 to bend, resulting in a change in the spacing of the two reflected parallel light beams from D0 to D0-d, resulting in a change of d. When the reflected optical path is L, the angle between the two beams of reflected light is θ, and the radius of curvature of the bent substrate 5 is R, then

[0065]

[0066] and,

[0067] θ=d / L (2);

[0068] Wherein, d represents the difference between the spacing between incident lasers and the spacing between corresponding reflected lasers.

[0069] From equation (1) and (2), we can get:

[0070]

[0071] The film stress is related to the change of substrate curvature 5. According to the classic Stoney formula, the film stress is related to the change of substrate curvature, and then:

[0072]

[0073] Substituting (3) into (4) we can obtain:

[0074]

[0075] Among them, t s represents the thickness of the substrate 5; t f Indicates the deposition thickness of the film; E s is the elastic modulus of the substrate 5; γ s is the Poisson's ratio of the substrate 5; σ represents the film stress; and R0 represents the initial curvature radius of the substrate 5.

[0076] The position of each light spot is recorded in real time using a CCD (charge coupled device), so as to calculate the displacement change d between the two light spots, and then substitute it into equation (5) to obtain the film stress. s is the elastic modulus of substrate 5 (sample), γ s is the Poisson's ratio of the sample, t s is the sample thickness, t f is the thickness of the bottom film layer.

[0077] In one embodiment, if Figure 2 As shown, the revolution system 6 of the vacuum coating machine rotates the mounting plate in the vacuum chamber 11 during the evaporation deposition process; the mounting plate has a plurality of substrates 5, and the plurality of substrates 5 are arranged around the rotation axis of the mounting plate so that the array laser can rotate through the mounting plate and be incident on the thin film on each substrate 5.

[0078] like Figure 2 As shown, the laser light source 1 generates laser light, which is coupled into a multi-beam optical fiber through a beam splitting coupling system. The laser light is transmitted to the output end through the optical fiber and collimated into a parallel light of a small spot by a collimation system. Each collimation system is clamped on an array laser disk to form a multi-beam parallel laser light. The parallel laser beam passes through a first laser beam expansion and contraction system 401, which can expand or contract the parallel multi-beam laser beam as a whole. Then, the multi-beam parallel laser light is irradiated on the surface of a substrate 5. The surface of the substrate 5 reflects the multi-beam parallel laser light to form a reflected multi-beam parallel laser light. Then, the multi-beam parallel laser light enters a second laser beam expansion and contraction system 402, which expands or contracts the reflected multi-beam parallel laser light as a whole, and then irradiates a high-resolution CCD image sensor 9. The PCI data acquisition system 10 records the position change information of the parallel multi-beam laser beam in real time. Finally, the signal filtering and extraction algorithm extracts the effective signal. At the same time, the film thickness control system collects the thickness of the deposited film in real time. The real-time stress magnitude and stress distribution state of the film can be obtained by formula (5).

[0079] like Figure 3 The array laser disk shown arranges the fiber laser coupling collimation devices into an array and fixes them on a clamping disk to ensure that each laser beam remains parallel to each other, thus forming multiple parallel laser beams.

[0080] The embodiment of the present invention also discloses an array laser beam optical thin film stress online monitoring system. Figure 1 and Figure 2As shown, the vacuum coating machine is used to coat the substrate 5 by evaporating and depositing the coating material in its own vacuum chamber 11 , so as to deposit a thin film on the substrate 5 .

[0081] The monitoring system includes an array laser source, an image sensor, a data acquisition system, a film thickness control system and a processing device; the array laser source emits parallel array lasers to be incident on a thin film on a substrate 5; the thin film reflects the incident laser; the image sensor receives the reflected laser; the data acquisition system is connected to the image sensor to record in real time the position information of the reflected laser received by the image sensor; the film thickness control system collects the deposition thickness of the thin film in real time; the processing device is connected to the film thickness control system and the data acquisition system to obtain the film stress according to the deposition thickness of the thin film, information of the substrate 5, the position information of the reflected laser and the position information of the incident laser, so that the monitoring system can realize online monitoring of the stress magnitude and stress state distribution of the thin film.

[0082] In one embodiment, if Figure 1 and Figure 2 As shown, the processing equipment obtains the film stress:

[0083]

[0084] Wherein, D0 represents the spacing between two incident laser beams in the array laser; α represents the incident angle of the incident laser; θ represents the angle between the two reflected laser beams; R represents the radius of curvature of the curved substrate 5; L represents the emission optical path of the reflected laser; d represents the difference between the spacing between the incident lasers and the spacing between the corresponding reflected lasers; the spacing between the two reflected laser beams is D0-d.

[0085] get:

[0086]

[0087] Relating the film stress to the substrate curvature change yields:

[0088]

[0089] Among them, t s represents the thickness of the substrate 5; t f Indicates the deposition thickness of the film; E s is the elastic modulus of the substrate 5; γ s is the Poisson's ratio of the substrate 5; σ represents the film stress; and R0 represents the initial curvature radius of the substrate 5.

[0090] Calculate the film stress σ:

[0091]

[0092] In one embodiment, if Figure 2As shown, the monitoring system includes a first laser beam expansion and contraction system 401 and a second laser beam expansion and contraction system 402 connected to a processing device; the first laser beam expansion and contraction system 401 performs expansion and contraction processing on the incident laser so that the incident laser reaches a preset aperture; the second laser beam expansion and contraction system 402 performs expansion and contraction processing on the reflected laser so that the reflected laser is irradiated on the image sensor.

[0093] The first laser beam expanding and contracting system 401 and the second laser beam expanding and contracting system 402 both adopt a combination of fiber optic waveguide and coupled expanding and contracting system, and the first laser beam expanding and contracting system 401 and the second laser beam expanding and contracting system 402 both include two free-form surface lenses to adjust the optical spacing of the two free-form surface lenses to obtain laser beams of different sizes, so that the uniformity of the multi-beams after expansion and contraction reaches more than 99%.

[0094] In one embodiment, if Figure 2 As shown, the revolution system 6 of the vacuum coating machine is used to rotate the mounting plate during the evaporation deposition process; the mounting plate has multiple substrates 5, and the multiple substrates 5 are arranged around the rotation axis of the mounting plate, so that the array laser can be rotated through the mounting plate and incident on the thin film on each substrate 5; the crystal control probe 7 in the vacuum chamber 11 is used to detect the deposition rate of the thin film; the evaporation source in the vacuum chamber 11 is used to evaporate the coating material. The evaporation source includes a first evaporation source 801 and a second evaporation source 802, which can evaporate two coating materials.

[0095] In one embodiment, if Figure 2 As shown, the array laser source includes a laser, a laser beam splitting coupling system 2, an array laser disk, multiple optical fibers and multiple laser coupling collimation devices; the laser beam splitting coupling system 2 is connected to the multiple optical fibers; the optical fibers are correspondingly connected to the laser coupling collimation devices; multiple laser coupling collimation devices are arranged in an array and installed on the array laser disk to form an array laser system 3, and the array range and array density are set according to requirements.

[0096] The laser emits laser light; the laser beam splitting coupling system 2 couples the laser beam splitting into multiple optical fibers; the laser coupling collimator collimates the laser light emitted from the corresponding optical fiber; the array-arranged laser coupling collimators are used to arrange the collimated laser light into parallel array laser light. The laser is used as a laser light source 1.

[0097] The laser includes a visible light laser; the visible light laser includes one of a blue laser, a green laser, a yellow laser and a red laser; the blue laser is one of 450nm, 457nm and 473nm; the green laser is 532nm; the yellow laser is 589nm; and the red laser is one of 632.8nm, 660nm and 670nm.

[0098] like Figure 2 , Figure 5 as well as Figure 6 As shown, the basic process of the system working is:

[0099] Step 1: Power on / start the system.

[0100] Step 2: After the laser light source 1 works normally for 3 minutes, adjust the first laser beam expansion and contraction system 401 according to the aperture of the optical element to make the parallel laser beam reach a suitable aperture. After the laser beam is reflected, adjust the second laser beam expansion and contraction system 402 to make the entire laser beam irradiate the high-resolution CCD image sensor 9, and the optical path adjustment is completed.

[0101] Specifically, after the laser light source 1 works normally for 3 minutes, the first laser beam expansion and contraction system 401 is adjusted according to the optical element aperture Φ100mm to expand the 19 laser beams to Φ90mm. After the laser beam is reflected, the second laser beam expansion and contraction system 402 is adjusted to shrink the 19 laser beams to Φ30mm to ensure that all laser beams are irradiated on the high-resolution CCD image sensor 9, and the optical path adjustment is completed.

[0102] Step 3: Perform self-inspection on the laser light source 1, beam expansion / reduction system, CCD detection system, PCI data acquisition system 10 and software algorithm system in the system. After the self-inspection is completed, the thin film deposition begins.

[0103] Step 4: During the thin film deposition process, the CCD detects the initial position of each laser beam in real time, as well as the change in the spot position between the laser beams as the thin film is deposited, and collects the data through the PCI data acquisition card. Then, the change d of the spot position of adjacent laser beams is obtained through the software algorithm. According to formula (5), the computer is used to solve the stress change and distribution of the thin film (thin film element), and the real-time stress size and stress distribution state of the thin film element during the coating process are obtained.

[0104] Step 5: coating film layer, receiving coating end signal, coating is finished.

[0105] The present application can directly monitor the stress state of optical thin films in real time, quickly and accurately online, and directly monitor the stress state and stress distribution of optical thin films online; the optical thin film stress online monitoring system is the core control system of precision coating equipment, which can directly, in real time and accurately monitor the stress state and distribution of optical thin films, which is conducive to studying the growth mode and dynamics related information during the growth of thin films, and can also guide the optimization of coating processes and realize the preparation of ultra-low stress film layers. The present application can facilitate the preparation of high-surface-shaped thin film components, monitor the stress of thin films in real time online, guide the optimization of thin film preparation processes, and thus reduce the surface errors caused by stress and improve the success rate of preparing high-surface-shaped optical thin film components.

[0106] The present specification also discloses an array laser beam optical film stress online monitoring system. Figure 2 and Figure 6 As shown, this experiment was completed on a 1300 electron beam vacuum coating machine, which is equipped with a dual electron gun evaporation system, a radio frequency ion assist system, a cryopump + dry pump oil-free vacuum system, and a 6-probe quartz crystal monitoring system.

[0107] A Ta3O5 film with a thickness of 600 nm was deposited on a JGS1 substrate 5 with a size of Φ100 mm*3 mm, and the real-time state of the film stress was detected.

[0108] (1) Light source type: Select 632.8nm stable helium-neon laser.

[0109] (2) Array laser: Figure 6 As shown, the array laser beam distribution is shown. A 19-beam laser array is used, and the center interval between two adjacent laser spots is 10 mm.

[0110] (3) Laser beam expansion / reduction system: It consists of two free-form surface lenses. By adjusting the distance between the lenses, continuous beam expansion (or reduction) from Φ35mm to Φ100mm (or Φ100mm to Φ35mm) can be achieved. The uniformity of the 19 laser beams after expansion / reduction reaches 99.0%.

[0111] (4) High-resolution CCD image sensor 9: size 35 mm*60 mm.

[0112] Experimental principle and process: Real-time online film stress detection Figure 2 As shown, a helium-neon laser generates a laser with a wavelength of 632.8 nm. The laser passes through a beam splitting coupling system and is coupled into 19 optical fibers. The laser passes through the optical fiber to the output end and is collimated into a Φ5 mm parallel light by a collimation system. Each collimation system is clamped on an array laser disk to form a multi-beam parallel laser. The center interval between two adjacent laser spots is 10 mm. The parallel laser beams pass through a laser beam expansion / contraction system 1 to expand the multi-beam parallel lasers into Φ90 mm as a whole. Then, 19 parallel laser beams are irradiated on the surface of a substrate 5. The surface of the substrate 5 converts the 19 parallel laser beams into a Φ90 mm parallel laser beam. The light is reflected to form 19 reflected parallel laser beams, which then enter the laser beam expansion / contraction system 2, and the reflected 19 parallel laser beams are shrunk into Φ30mm as a whole, and then irradiated on the high-resolution CCD image sensor 9. The PCI data acquisition system 10 records the initial position and the distance D0 between each adjacent laser beam is 6mm. With the deposition of the Ta3O5 film, the centers of the two adjacent laser spot beams produce d transformation. The real-time stress magnitude and stress distribution state of the film can be obtained by formula (5), where the elastic modulus E of the JGS1 substrate 5 is s is 72Gpa, Poisson's ratio γ s is 0.17, the thickness of substrate 5 is t s 3mm, deposited Ta3O5 film tf Obtained by a quartz crystal monitoring system, the incident angle α in this embodiment is 12°.

[0113] In this specification, the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the partial description of the previous embodiments.

[0114] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for online monitoring of optical thin film stress using an array laser beam, characterized in that: The method includes: obtaining a parallel array laser; depositing a thin film on a substrate by evaporating and depositing a coating material in a vacuum chamber of a vacuum coating machine; the array laser is incident on the thin film deposited on the substrate; the thin film reflects the incident laser; collecting position information of the reflected laser; obtaining the deposition thickness of the thin film; obtaining the film stress according to the position information of the incident laser, the position information of the reflected laser, the information of the substrate and the deposition thickness of the thin film, so as to realize online monitoring of the stress magnitude and stress state distribution of the thin film.

2. The method for online monitoring of optical thin film stress using an array laser beam according to claim 1, wherein: The two incident laser beams in the array laser beam with a spacing of D0 are irradiated onto the thin film deposited on the substrate at an incident angle α; the corresponding emission optical path of the reflected laser is L, and the spacing between the two reflected laser beams is D0-d; the angle between the two reflected laser beams is θ, and the curvature radius of the substrate is R, and the following is obtained: Where d represents the difference between the spacing between incident lasers and the spacing between the corresponding reflected lasers; Then we get: Correlating the film stress with the substrate curvature change yields: Among them, t s represents the thickness of the substrate; t f represents the deposition thickness of the film; E s is the elastic modulus of the substrate; γ s is the Poisson's ratio of the substrate; σ represents the film stress; R0 represents the initial curvature radius of the substrate; Calculate the film stress σ:

3. The method for online monitoring stress of optical thin films using an array laser beam according to claim 1, wherein: The monitoring method further includes: before depositing the thin film on the substrate, the array laser is incident on the coating surface of the substrate, and the coating surface of the substrate reflects the incident laser to obtain position information of the incident laser.

4. The method for online monitoring of optical thin film stress using an array laser beam according to claim 1, wherein: The array laser is emitted in parallel by an array laser source; the reflected laser is received by an image sensor; and the image sensor is connected to a data acquisition system to record position information of the reflected laser received by the image sensor in real time; The deposition thickness of the thin film is collected in real time by a film thickness control system; the film thickness control system and the data acquisition system are connected through a processing device to obtain film stress based on information about the substrate, the deposition thickness of the thin film, position information of the reflected laser, and position information of the incident laser; The monitoring method also includes: connecting a first laser beam expansion and contraction system and a second laser beam expansion and contraction system through the processing device, the first laser beam expansion and contraction system performing expansion and contraction processing on the incident laser so that the incident laser reaches a preset aperture; the second laser beam expansion and contraction system performing expansion and contraction processing on the reflected laser so that the reflected laser is irradiated on the image sensor.

5. The method for online monitoring of optical thin film stress using an array laser beam according to claim 1, wherein: The revolution system of the vacuum coating machine rotates the mounting plate in the vacuum chamber during the evaporation deposition process; the mounting plate is provided with a plurality of substrates, and the plurality of substrates are arranged around the rotation axis of the mounting plate, so that the array laser can rotate through the mounting plate and be incident on the thin film deposited on each substrate.

6. An array laser beam optical thin film stress online monitoring system, characterized in that: The vacuum coating machine is used to deposit a thin film on a substrate by evaporating and depositing a coating material in its own vacuum chamber; The monitoring system includes an array laser source, an image sensor, a data acquisition system, a film thickness control system and a processing device; the array laser source emits parallel array lasers to be incident on a thin film deposited on a substrate; the thin film reflects the incident laser; the image sensor receives the reflected laser; the data acquisition system is connected to the image sensor to record the position information of the reflected laser received by the image sensor in real time; the film thickness control system collects the deposition thickness of the thin film in real time; the processing device is connected to the film thickness control system and the data acquisition system to obtain the film stress based on the deposition thickness of the thin film, information of the substrate, position information of the reflected laser and position information of the incident laser, so that the monitoring system can realize online monitoring of the stress magnitude and stress state distribution of the thin film.

7. The array laser beam optical thin film stress online monitoring system according to claim 6, characterized in that: The processing device obtains film stress: Wherein, D0 represents the distance between the two incident laser beams in the array laser; α represents the incident angle of the incident laser; θ represents the angle between the two reflected laser beams; R represents the curvature radius of the substrate; L represents the emission optical path of the reflected laser; d represents the difference between the distance between the incident laser beams and the distance between the corresponding reflected laser beams; the distance between the two reflected laser beams is D0-d; get: Relating the film stress to the substrate curvature change, we obtain: Among them, t s Indicates the thickness of the substrate; t f Indicates the deposition thickness of the film; E s is the elastic modulus of the substrate; γ s is the Poisson's ratio of the substrate; σ represents the film stress; R0 represents the initial curvature radius of the substrate; Calculate the film stress σ:

8. The array laser beam optical thin film stress online monitoring system according to claim 6, characterized in that: The monitoring system includes a first laser beam expansion and contraction system and a second laser beam expansion and contraction system connected to a processing device; the first laser beam expansion and contraction system performs beam expansion and contraction processing on an incident laser beam so that the incident laser beam reaches a preset aperture; the second laser beam expansion and contraction system performs beam expansion and contraction processing on a reflected laser beam so that the reflected laser beam is irradiated on an image sensor; The first laser beam expansion and contraction system and the second laser beam expansion and contraction system both adopt a combination of fiber optic waveguide and coupled expansion and contraction system, and the first laser beam expansion and contraction system and the second laser beam expansion and contraction system both include two free-form surface lenses to adjust the optical spacing of the two free-form surface lenses to obtain laser beams of different sizes, so that the uniformity of the multi-beams after expansion and contraction reaches more than 99%.

9. The array laser beam optical thin film stress online monitoring system according to claim 6, characterized in that: The revolution system of the vacuum coating machine is used to rotate the mounting plate during the evaporation deposition process; the mounting plate is provided with multiple substrates, and the multiple substrates are arranged around the rotation axis of the mounting plate so that the array laser can rotate through the mounting plate and be incident on the thin film deposited on each substrate; the crystal control probe in the vacuum chamber is used to detect the deposition rate of the thin film; the evaporation source in the vacuum chamber is used to evaporate the coating material.

10. The array laser beam optical thin film stress online monitoring system according to claim 6, characterized in that: The array laser source includes a laser, a laser beam splitting coupling system, an array laser disk, multiple optical fibers, and multiple laser coupling collimation devices; the laser beam splitting coupling system is connected to the multiple optical fibers; the optical fibers are correspondingly connected to the laser coupling collimation devices; the multiple laser coupling collimation devices are arranged in an array and mounted on the array laser disk; The laser emits laser light; the laser beam splitting coupling system couples the laser beams into multiple optical fibers; the laser coupling collimator collimates the laser light emitted from the corresponding optical fibers; the array-arranged laser coupling collimators are used to arrange the collimated laser light into a parallel array laser light; The laser includes a visible light laser; the visible light laser includes one of a blue laser, a green laser, a yellow laser and a red laser; the blue laser is one of 450nm, 457nm and 473nm; the green laser is 532nm; the yellow laser is 589nm; and the red laser is one of 632.8nm, 660nm and 670nm.

Images