A thin film spectrum on-line measuring device integrated with a coating machine

Abstract

The utility model embodiment relates to the field of thin film spectrum measurement technology provides a kind of with the thin film spectrum online measurement device integrated with coating machine, comprising: bottom plate, the surface of bottom plate is as reflecting surface;Light transmission substrate, place in the top of bottom plate, light transmission substrate and bottom plate are separated by preset distance;Coating head, for preparing thin film on light transmission substrate;Spectrum measurement system, including light source, incident light path structure, emergent light path structure and spectrometer;Light source is used to provide incident light beam, incident light path structure is used to guide incident light beam to the upper surface of thin film;Emergent light path structure is used to collect the reflected light beam after the reflection incident light beam of thin film, light transmission substrate and bottom plate;Spectrometer is used to receive reflected light beam and carry out spectrum measurement analysis;Wherein, incident light path structure and emergent light path structure are fixedly connected with coating head, and move synchronously with coating head. Thus, realize the in-situ high-speed spectrum measurement of thin film during the film preparation process of coating machine.

Description

Technical Field

[0001] This utility model relates to the field of thin film spectroscopy measurement technology, and in particular to an online thin film spectroscopy measurement device integrated with a coating machine. Background Technology

[0002] A coating machine is a device that uniformly coats the surface of a substrate material with coatings (such as adhesives, inks, films, pastes, etc.). It offers advantages such as high coating uniformity, stable quality, high production efficiency, minimal material waste, and low production costs, and is widely used in printing, packaging, electronics, building materials, medical, and other industries. Real-time, in-situ monitoring of the spectral evolution of the film during the coating process is crucial for optimizing the coating process and implementing closed-loop control.

[0003] Currently, due to compatibility issues (large size and optical path conflicts), spectroscopic measurement instruments are difficult to integrate freely with coating equipment. For example, ellipsometers and spectrophotometers are too bulky to integrate (on the order of meters), as the incident angle θ of an ellipsometer is approximately 70° and the reflection angle is approximately -70°. Spectrophotometers and similar devices use transmission methods, whose optical paths conflict with coating equipment, making integration impossible. Furthermore, thin-film production lines for coating machines operate at extremely high speeds (e.g., 50-150 m / min in photovoltaic coating lines), requiring detection equipment to complete data acquisition and analysis within milliseconds, a requirement that current detection equipment cannot meet. Utility Model Content

[0004] This invention provides an online thin film spectral measurement device integrated with a coating machine to solve the defects of existing technologies, such as difficulty in integration with coating machine equipment, optical path conflicts, and inability to achieve millisecond-level measurement, thereby realizing online in-situ high-speed spectral measurement of thin films during the coating process.

[0005] This utility model provides an online thin film spectral measurement device integrated with a coating machine, comprising: The base plate, with its surface serving as a reflective surface; A light-transmitting substrate is placed above a base plate, with a predetermined distance separating the light-transmitting substrate from the base plate; The coating machine also includes a coating head, which is used to prepare thin films on a transparent substrate; A spectral measurement system, which includes a light source, an incident light path structure, an outgoing light path structure, and a spectrometer; The light source is used to provide the incident light beam, and the incident light path structure is used to guide the incident light beam to the upper surface of the thin film; The outgoing optical path structure is used to collect the reflected beam after the incident beam has been reflected by the thin film, the transparent substrate and the base plate; A spectrometer is used to receive reflected light beams and perform spectral measurements and analysis. The incident light path structure and the exit light path structure are fixedly connected to the coating head and move synchronously with the coating head.

[0006] In one possible implementation, the spectral measurement system includes an optical fiber transmission system; The incident optical path structure includes an incident optical fiber and an optical fiber probe, and the exit optical path structure includes an exit optical fiber and an optical fiber probe. The fiber optic probe is fixed to the coating head, and the fiber optic probe is at a preset angle to the vertical direction, which is greater than the fiber divergence angle.

[0007] In one possible implementation, the spectral measurement system includes a free-space transport system; The incident light path structure includes a first lens and a beam splitter, and the outgoing light path structure includes a second lens and a beam splitter. The beam splitter is fixed to the coating head and moves synchronously with it.

[0008] In one possible implementation, the surface of the base plate is non-mirror, and the base plate is either the original base plate of the coating machine or an additional base plate, the additional base plate being made of metal, plastic, glass or paper.

[0009] In one possible implementation, the incident beam is a parallel beam or a diverging beam.

[0010] In one possible implementation, the spectrometer is used to calculate the transmittance of the thin film by measuring the reflectance of the system consisting of the thin film, the transparent substrate, and the base plate.

[0011] In one possible implementation, the online spectral measurement device for thin films is used to: measure in real-time, in-situ the transmission and absorption spectra of the thin film during the coating process, as well as the spectral evolution during the annealing process.

[0012] In one possible implementation, the device further includes a distance adjustment mechanism for adjusting a preset distance between the light-transmitting substrate and the base plate online during the coating or annealing process, or for adjusting the distance between the incident light path structure and the film under test.

[0013] In one possible implementation, the spectral measurement system further includes a synchronization triggering unit connected to the coating machine.

[0014] In one possible implementation, the coating head and the spectral measurement system are connected by a quick-release mechanism, which allows for the overall assembly and disassembly of the spectral measurement system and the coating head.

[0015] This invention provides an online thin film spectral measurement device integrated with a coating machine, comprising a base plate, the surface of which serves as a reflective surface; a transparent substrate placed above the base plate, with a preset distance separating the substrate from the base plate; a coating head for preparing a thin film on the transparent substrate; and a spectral measurement system including a light source, an incident light path structure, an exit light path structure, and a spectrometer. The light source provides an incident light beam, the incident light path structure guides the incident light beam to the upper surface of the thin film, the exit light path structure collects the reflected light beam after reflection from the thin film, the transparent substrate, and the base plate, and the spectrometer receives the reflected light beam and performs spectral measurement and analysis. The incident and exit light path structures are fixedly connected to the coating head and move synchronously with it. Compared to the shortcomings of existing technologies, such as difficulty in integration with coating machine equipment, optical path conflicts, and the inability to achieve millisecond-level measurements, this device enables online, in-situ, high-speed spectral measurement of the thin film during the coating process. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the online thin film spectral measurement device integrated with a coating machine provided by this utility model.

[0018] Figure 2 This is a schematic diagram of the optical fiber transmission system provided by this utility model, in which a diverging light beam is incident on the surface of a thin film.

[0019] Figure 3 This is a schematic diagram of the free space transmission system provided by this utility model, in which a parallel light beam is incident on the surface of a thin film.

[0020] Figure 4 This is a schematic diagram of the free space transmission system provided by this utility model, in which a diverging light beam is incident on the surface of a thin film.

[0021] Figure 5 This is a schematic diagram showing the comparison between the transmission spectrum of the FAPbI3 thin film measured by this utility model and the transmission spectrum of the FAPbI3 thin film measured by a spectrophotometer.

[0022] Figure 6 This is a schematic diagram of the transmission spectrum of 0.75 M FAPbI3 ink during the coating process, provided by this utility model for real-time in-situ measurement.

[0023] Figure 7This is a schematic diagram of the transmission spectrum of a wet film measured in real time and in situ during the annealing process on a coating machine, provided by this utility model.

[0024] Explanation of reference numerals in the attached figures: 1. Base plate; 2. Transparent substrate; 3. Coating head; 4. Thin film; 5. Light source; 6. Spectrometer; 7. Quick release mechanism; 8. Incident optical fiber; 9. Outgoing optical fiber; 10. First lens; 11. Beam splitter; 12. Second lens. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0026] To facilitate understanding of the embodiments of this utility model, the following will provide further explanation and description with reference to the accompanying drawings and specific embodiments. These embodiments do not constitute a limitation on the embodiments of this utility model.

[0027] Figure 1 This is a schematic diagram of the online thin film spectral measurement device integrated with a coating machine provided by this utility model, as shown below. Figure 1 As shown, the device includes: a base plate 1, a light-transmitting substrate 2, a coating head 3, and a spectral measurement system.

[0028] The surface of the substrate 1 serves as a reflective surface; the transparent substrate 2 is placed above the substrate 1, with a preset distance between the transparent substrate 2 and the substrate 1; the coating head 3 is used to prepare a thin film 4 on the transparent substrate 2; the spectral measurement system includes a light source 5, an incident light path structure, an outgoing light path structure, and a spectrometer 6; the light source 5 is used to provide an incident light beam, and the incident light path structure is used to guide the incident light beam to the upper surface of the thin film 4; the outgoing light path structure is used to collect the reflected light beam after the incident light beam is reflected by the thin film 4, the transparent substrate 2, and the substrate 1; the spectrometer 6 is used to receive the reflected light beam collected by the outgoing light path structure and perform spectral measurement and analysis; wherein, the incident light path structure and the outgoing light path structure are fixedly connected to the coating head 3 and move synchronously with the coating head 3; the spectral measurement system also includes a synchronous triggering unit, which is connected to the coating machine and is used to trigger the spectrometer 6 to acquire data at a preset position or preset time point of the coating head 3.

[0029] Using the aforementioned device, the surface of the coating machine base plate 1, or other surfaces placed on the base plate 1, serves as a reflective surface. Based on Lambert's cosine law, millisecond-level measurements of the transmission spectrum are achieved using small-angle enhancement. The device is also demonstrated for real-time, in-situ monitoring of changes in the transmission spectrum of the thin film during coating and annealing. No modifications to the coating machine are required during this process, thus preserving its basic functions and enabling seamless integration with the coating machine while providing online monitoring capabilities.

[0030] Specifically, the principle of spectral measurement is as follows: A light-transmitting substrate 2 is placed on the base plate 1 of the coating machine, and the distance between the light-transmitting substrate 2 and the base plate 1 of the coating machine is [missing information]. t ,like Figure 1 As shown; the coating head 3 of the coating machine prepares a thin film 4 on a light-transmitting substrate 2, with the environment on top of the thin film 4; the complex refractive index of the environment is... n 1. The complex refractive index of thin film 4 is n 2 (unknown), thickness is h (Unknown), the complex refractive index of the transparent substrate 2 is... n 3. The transmittance of the light-transmitting substrate 2 is ≥5%; The base plate of the coating machine is the original base plate or an added metal, plastic, glass or paper plate.

[0031] A light beam is incident on the surface of thin film 4 from above, and the reflected light is measured using a detector or spectrometer. The incident beam can be categorized into two cases: a parallel beam and a diverging beam, as follows: Parallel beam incidence: A parallel beam of light is incident on thin film 4 through the incident light path structure; the incident light is at an incident angle α Incident on the surface of thin film 4 α >0. A portion of the light is absorbed by the thin film 4. α The light reflected into the environment at an angle cannot be received by the detector or spectrometer 6 because the detector direction and the incident light are in the same direction. Another part of the light is refracted by the thin film 4 and the transparent substrate 2 and then incident on the base plate 1 of the coating machine. Since the base plate 1 is not a mirror, based on Lambert's cosine law and using small angle enhancement, this part of the light is diffusely reflected by the base plate 1, and part of the diffusely reflected light returns along the original path and is received by the detector or spectrometer 6.

[0032] Diverging beam incidence: The diverging beam is incident on thin film 4 through the incident optical path structure, with a divergence angle of . γ The central ray of the diverging beam, i.e., the principal ray, is incident on the surface of thin film 4 at an angle α. α > γPart of the light is reflected into the environment by the surface of the thin film 4. The principal ray of the reflected light is along an angle of -α. Since the detector direction and the incident light are in the same direction, this part of the reflected light is not received by the detector or spectrometer 6. Another part of the light is refracted by the thin film 4 and the transparent substrate 2 and then incident on the substrate 1. Since the substrate 1 is not a mirror, based on Lambert's cosine law and using small-angle enhancement, this part of the light is diffusely reflected by the substrate 1. Part of the diffusely reflected light returns along the original path of the principal ray and is received by the detector or spectrometer 6.

[0033] In the aforementioned thin-film-transparent substrate-base plate measurement system, an empty transparent substrate 2 (without a thin film) is first placed on the base plate 1 of the coating machine, and the reflected light intensity I0 of the transparent substrate-base plate system is measured at this time. Then, a transparent substrate with a thin film 4 is placed on the base plate 1 of the coating machine, and the reflected light intensity I of the thin-film-transparent substrate-base plate system is measured at this time. Therefore, the reflectance of the entire thin-film-transparent substrate-base plate system is... R = I / I 0 (1) Since light passes through film 4 twice during the entire process, the transmittance of film 4 is [missing information]. T= R 1 / 2 (2) Therefore, by measuring this thin film-transparent substrate-base plate system ( Figure 1 The reflectivity of ) R The light transmittance of thin film 4 can be directly calculated. T The dielectric constant and thickness of the material do not need to be known in advance throughout the process. The absorption rate of thin film 4 can be used... A =1- T The absorbance of film 4 can be directly calculated using logarithm. 10 (1 / T The transmittance and absorbance of the film at different wavelengths can be directly calculated. The transmittance and absorbance spectra of film 4 during the coating process can be obtained online.

[0034] Online in-situ spectral measurement during the coating process can be performed using an optical fiber transmission system. Figure 1 (The short dashed box in the image). The incident optical path structure uses incident optical fiber, and the exit optical path structure uses exit optical fiber; the position (x, y, z) and pitch (x, y, z) of the fiber optic probe are adjusted by the quick-release mechanism 7 (e.g., a five-axis fiber optic holder). θx , θy ), let the fiber optic probe and y The included angle of the axis is αThe fiber optic probe is fixed to the coating head 3 of the coating machine and moves with the movement of the coating head 3. In the incident light path structure, the incident light is transmitted to the fiber optic probe via the incident fiber, and then transmitted to the thin film-transparent substrate-base plate system; the light reflected back from this system is coupled to the detector or spectrometer 6 via the output fiber. The fiber optic holder is fixed on the coating head 3, and the fiber optic probe moves with the movement of the coating head 3. The coating head 3 of the coating machine does not affect the incident light path or the output light path.

[0035] Figure 1 The short dashed box in the image illustrates how light from an optical fiber becomes parallel after passing through a collimating lens. Light from an optical fiber can also become divergent after passing through a collimating lens or lens, or it can become divergent without passing through any optical components, such as... Figure 2 As shown. Online in-situ spectral measurements during the coating process can be performed using a free-space transport system, such as... Figure 3 and Figure 4 As shown. The incident light path structure uses a first lens, and the exit light path structure uses a second lens; in the incident light path, after the incident light passes through the beam splitter 11, the principal ray of the parallel beam or divergent beam is at the incident angle. α The incident light is incident on the upper surface of the thin film 4; in the outgoing light path structure, the outgoing light is collected by the second lens after passing through the beam splitter 11 and coupled to the detector or spectrometer 6. The beam splitter prism is fixed on the coating head 3 and moves with the movement of the coating head 3. The coating head 3 of the coating machine does not affect the incident light path structure or the outgoing light path structure.

[0036] Adopting such Figure 3 An experiment was conducted using the fiber optic transmission system shown. The numerical aperture (NA) of the fiber used in the experiment was 0.22, corresponding to a divergence angle of [missing information]. γ =arcsin(NA)=12.7°. The angle between the principal ray of the incident light and the vertical direction. α Set to 15°. The angle between the principal ray of the incident light and the vertical direction. α The divergence angle of the thin film is greater than that of the optical fiber, so the reflected light cannot enter the optical fiber probe. The light collected by the optical fiber probe is the light that has passed through the thin film twice. Using a halogen lamp as the experimental light source, the transmission spectrum T of the thin film can be directly calculated from the light intensity reflection spectrum R of the thin film-substrate-base plate system obtained by the formula (2).

[0037] like Figure 5 As shown, in this embodiment, the transmission spectrum of a FAPbI3 thin film with a thickness h of 200 nm was tested in the experiment. Figure 5 The short dashes represent the reflection spectrum R of the thin film-transparent substrate-base plate system. Next, the thin film transmission spectrum T can be directly calculated using formula (2), as shown below. Figure 5 The solid line indicates the thin film transmission spectrum, as measured using a transmission spectrophotometer. Figure 5The underlined text indicates this. A comparison shows that the thin film transmission spectrum obtained by the proposed spectral measurement method in this embodiment shows a good agreement with the trend of wavelength variation of the thin film transmission spectrum measured by a spectrophotometer, proving the feasibility of this embodiment. The similarity of the transmission spectra obtained by the two measurement methods, calculated using the spectral angle metric (SAM), is 1.03°. Based on the obtained thin film transmission spectrum, the absorbance of the thin film can be expressed as log... 10 (1 / T ) was calculated.

[0038] Furthermore, real-time in-situ spectral measurements were performed during the coating process: Coating machines offer advantages such as high coating uniformity, stable quality, high production efficiency, minimal material waste, and low production costs, making them widely used in printing, packaging, electronics, building materials, medical, and other industries. Real-time, in-situ monitoring of the spectral evolution of the film during the coating process is crucial for optimizing the coating process and implementing closed-loop control.

[0039] like Figure 1 As shown, to achieve real-time in-situ monitoring of the changes in the spectral transmission spectrum of the thin film 4 during the coating process, it is only necessary to fix the fiber optic probe on the coating head 3 of the coating machine. During coating, the fiber optic probe will move along with the coating head 3. No modifications to the coating machine are required in this process, so it will not affect the basic functions of the coating machine.

[0040] First, the coating speed of the coating machine was set to 5 mm / s, and the distance H between the fiber optic probe and the thin film was adjusted to approximately 15 mm to obtain a suitable spot area (approximately 0.5 cm²). 2 After placing an empty substrate (a 25mm × 76mm glass slide) above the reflective surface of the coating machine, the light intensity at this time was read as the reference light source I0. A 0.75 M concentration of FAPbI3 perovskite ink was then dropped onto the glass substrate. The coating machine was then turned on to begin coating. Simultaneously with the start of perovskite ink coating, the reflectance spectrum R( of the thin film-reflective surface system) was measured. λ Continuous data acquisition was performed, and then, based on the experimental principle of the single-sided single-reflection method, the transmission spectrum T( of the perovskite ink during spin coating) was directly calculated. λ The relationship between the experimental results and the changes over time is as follows: Figure 6As shown in the figure, the transmission spectrum data for film coating times from 0 to 1.5 s represent the transmission spectra of the corresponding regions of the empty glass on the slide, so the transmission spectrum for different wavelengths is 1. The transmission spectrum data for film coating times from 1.5 to 10 s represent the transmission spectra of the perovskite ink immediately after being coated into a film by the wire rod at different locations. It can be seen that when the perovskite ink has just finished coating, the transmission spectrum intensity of the wet film at different wavelengths is close to 0.9. Based on this method, the uniformity of the film and the kinetic behavior of film formation during the ink coating process can be determined, thereby effectively optimizing important experimental parameters such as ink concentration and coating speed.

[0041] After coating, film 4 is subjected to heat annealing on the coating machine. The evolution of the transmission spectrum of film 4 in the annealed state after coating is measured in real time using the above method and device.

[0042] First, the coating machine temperature was set to the required experimental temperature (150 °C). After the coating machine was heated, the temperature of the sample stage was measured using a thermocouple thermometer, and it was found to be 150 °C. In the experiment, 0.75 M FAPbI3 perovskite ink was coated onto the glass substrate using the coating machine. After coating, the sample was transferred to a low-pressure auxiliary device to wait for the FAPbI3 perovskite crystal nuclei to precipitate. Then, the wet film sample was placed on the coating machine.

[0043] During wet film annealing, the reflectance spectrum R( of the thin film-transparent substrate-base plate system) is analyzed. λ Continuous data acquisition was performed, and then the transmission spectrum T( of film 4 during the annealing process was directly calculated.) λ The relationship between changes over time, such as Figure 7 As shown, during the annealing process of the FAPbI3 film from 0 to 4 s, the band edge of the transmission spectrum gradually forms. This phenomenon indicates that perovskite nuclei grow and form the film during this time period. From 5 to 14 s, the band edge of the film's transmission spectrum slowly red-shifts to 810 nm (the characteristic transmission band edge of FAPbI3), indicating that during this time, the organic solvent continuously evaporates under the action of heating and annealing, and the main component of the film transforms into FAPbI3 perovskite. From 15 to 1200 s (after heating and annealing is complete), the band edge of the film's transmission spectrum remains unchanged at 810 nm. Based on this method, the influence of annealing temperature and annealing time on the film morphology can be effectively adjusted, thereby achieving the goal of optimizing the film's performance.

[0044] This embodiment proposes integrating an optical fiber transmission measurement system and a free-space transmission measurement system onto a coating machine, achieving online in-situ spectral measurement during the coating process. No modifications to the coating machine are required, thus preserving its basic functionality. First, the transmission spectrum of the perovskite thin film was successfully and accurately measured, demonstrating the accuracy of the integrated measurement method. During coating, the optical fiber probe moves synchronously with the wire rod, enabling real-time in-situ monitoring of the optical properties of the thin film during coating and annealing. This achieves dynamic measurement of the thin film spectrum and seamless integration with the coating machine, showcasing online monitoring capabilities. This makes a significant contribution to the kinetics of thin film preparation using a coating machine and is crucial for optimizing the performance of such films.

[0045] The present invention provides an online thin film spectral measurement device integrated with a coating machine, comprising a base plate 1, the surface of which serves as a reflective surface; a light-transmitting substrate 2, which is placed above the base plate 1 and spaced apart from the base plate 1 by a predetermined distance; a coating head 3, which is used to prepare a thin film 4 on the light-transmitting substrate 2; and a spectral measurement system, which includes a light source 5, an incident light path structure, an outgoing light path structure, and a spectrometer; the light source provides an incident light beam, the incident light path structure guides the incident light beam to the upper surface of the thin film 4; the outgoing light path structure collects the reflected light beam after it has been reflected by the thin film 4, the light-transmitting substrate 2, and the base plate 1; and the spectrometer 6 receives the reflected light beam and performs spectral measurement and analysis; wherein the incident light path structure and the outgoing light path structure are fixedly connected to the coating head 3 and move synchronously with the coating head 3. Compared to existing technologies that suffer from difficulties in integration with coating equipment, optical path conflicts, and the inability to achieve millisecond-level measurements, this device enables online in-situ high-speed spectral measurement of thin films during the coating process.

Claims

1. A thin film spectral online measurement device integrated with a coating machine, characterized in that, include: The base plate (1) has a surface that serves as a reflective surface. A light-transmitting substrate (2) is placed above the base plate (1), and the light-transmitting substrate (2) and the base plate (1) are separated by a predetermined distance; The coating machine also includes a coating head (3), which is used to prepare a thin film (4) on the light-transmitting substrate (2). A spectral measurement system, comprising a light source (5), an incident light path structure, an outgoing light path structure, and a spectrometer (6). The light source (5) is used to provide an incident light beam, and the incident light path structure is used to guide the incident light beam to the upper surface of the thin film (4); The outgoing light path structure is used to collect the reflected light beam after the incident light beam has been reflected by the thin film (4), the light-transmitting substrate (2) and the base plate (1); The spectrometer (6) is used to receive the reflected beam and perform spectral measurement and analysis; The incident light path structure and the outgoing light path structure are fixedly connected to the coating head (3) and move synchronously with the coating head (3).

2. The apparatus according to claim 1, characterized in that, The spectral measurement system includes an optical fiber transmission system; The incident optical path structure includes an incident optical fiber (8) and an optical fiber probe, and the outgoing optical path structure includes an outgoing optical fiber (9) and the optical fiber probe; The fiber optic probe is fixed on the coating head (3), and the fiber optic probe forms a preset angle with the vertical direction, which is greater than the fiber divergence angle.

3. The apparatus according to claim 1, characterized in that, The spectral measurement system includes a free-space transmission system; The incident light path structure includes a first lens (10) and a beam splitter (11), and the outgoing light path structure includes a second lens (12) and the beam splitter (11). The beam splitter (11) is fixed on the coating head (3) and moves synchronously with the coating head (3).

4. The apparatus according to any one of claims 1 to 3, characterized in that, The surface of the base plate (1) is non-mirror. The base plate (1) is the original base plate of the coating machine or the base plate (1) is an additional base plate. The material of the additional base plate is metal, plastic, glass or paper.

5. The apparatus according to claim 1, characterized in that, The incident beam is a parallel beam or a diverging beam.

6. The apparatus according to claim 1, characterized in that, The spectrometer (6) is used to calculate the transmittance of the thin film (4) by measuring the reflectance of the system consisting of the thin film (4), the light-transmitting substrate (2) and the base plate (1).

7. The apparatus according to claim 1, characterized in that, The online spectral measurement device for the thin film is used to: measure in real time, in situ, the transmission and absorption spectra of the thin film (4) during the film-making process of the coating machine, and the spectral evolution during the annealing process.

8. The apparatus according to claim 1, characterized in that, The device also includes a distance adjustment mechanism for adjusting the preset distance between the light-transmitting substrate (2) and the base plate (1) online during the coating or annealing process, or adjusting the distance between the incident light path structure and the film to be tested.

9. The apparatus according to claim 1, characterized in that, The spectral measurement system also includes a synchronization triggering unit, which is connected to the coating machine and is used to trigger the spectrometer (6) to collect data at a preset position or preset time point on the coating head (3).

10. The apparatus according to claim 1, characterized in that, The coating head (3) is connected to the spectral measurement system via a quick-release mechanism (7).

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