A multi-channel near-infrared interferometric thickness measurement sensor based on optical switches

Abstract

The utility model discloses a kind of multi-channel near-infrared interferometric thickness measuring sensors based on optical switch.The sensor includes: near-infrared light source module, including near-infrared light emitting element;Optical fiber beam splitting module, including input single-mode optical fiber and multi-output single-mode optical fiber;Fast optical fiber optical switch module, including multiple bidirectional optical ports, common output port and optical switch;Multiple optical fiber interference probes, respectively configured at the end of each measurement channel, all by a single-mode optical fiber and miniature optical assembly component;Interferometric measurement detection module, including optical receiving interface, photoelectric detector and interference signal analysis processing unit;Central control and data processing module.In the utility model, a kind of multi-channel near-infrared interferometric thickness measuring sensors based on optical switch ingeniously utilizes single light source and single detection system to serve multiple measurement points, to realize the substantial reduction of system manufacturing cost, the fundamental enhancement of measurement result consistency and the significant improvement of overall measurement efficiency.

Description

Technical Field

[0001] This utility model relates to the field of optical measurement technology, and in particular to a multi-channel near-infrared interferometric thickness sensor based on an optical switch. Background Technology

[0002] As the requirements for material processing precision in industrial production increase, the inherent problems of traditional single-channel near-infrared interferometric thickness sensors, such as low measurement efficiency and difficulty in multi-point synchronous measurement, are becoming increasingly prominent. Currently, to achieve multi-channel thickness measurement, the industry generally adopts a solution of multiple independent detection systems operating in parallel. However, this solution not only leads to high initial system procurement costs, large overall equipment size, and heavy and complex subsequent maintenance, but more importantly, due to differences in components and environmental influences, inconsistencies in measurement results are easily introduced between detection systems in different physical channels, posing a severe challenge to quality control in precision manufacturing processes. Utility Model Content

[0003] To address the aforementioned issues, this invention provides a multi-channel near-infrared interferometric thickness sensor based on an optical switch. It cleverly utilizes a single light source and a single detection system to serve multiple measurement points, thereby significantly reducing system manufacturing costs, fundamentally enhancing the consistency of measurement results, and significantly improving overall measurement efficiency.

[0004] According to one aspect of this utility model, a multi-channel near-infrared interferometric thickness sensor based on an optical switch is provided, comprising:

[0005] A near-infrared light source module, including a near-infrared light-emitting element;

[0006] An optical fiber splitter module includes an input single-mode fiber and multiple output single-mode fibers;

[0007] A fast fiber optic switch module includes multiple bidirectional optical ports, a common output port, and an optical switch that can select and switch between the multiple bidirectional optical ports and the common output port.

[0008] Multiple fiber optic interferometers are configured at the end of each measurement channel. Each fiber optic interferometer consists of a section of single-mode fiber and a miniature optical component.

[0009] An interferometric detection module includes an optical receiving interface, a photodetector, and an interferometric signal analysis and processing unit;

[0010] A central control and data processing module;

[0011] Among them, the output end of the near-infrared light-emitting element of the near-infrared light source module is connected to the input end of the input single-mode fiber of the fiber optic bundle splitter module through an optical fiber.

[0012] Each output single-mode fiber of the fiber optic bundle splitter module is connected to each bidirectional optical port of the fast fiber optic switch module through multiple input fibers.

[0013] Each bidirectional optical port of the fast fiber optic switch module is connected to the single-mode fiber of each fiber optic interferometer probe via an optical fiber, and the miniature optical components of each fiber optic interferometer probe face the object being measured.

[0014] The common output port is connected to the optical receiving interface of the interferometric measurement detection module via optical fiber;

[0015] The central control and data processing module is connected to the fast fiber optic switch module and the interferometric measurement and detection module via control lines.

[0016] In some implementations, the near-infrared light source module is equipped with a precision drive circuit and a temperature controller. This is advantageous because it complements the specific structure of the near-infrared light source module.

[0017] In some embodiments, the near-infrared emitting element is a superluminescent diode with a center wavelength of 800 nm to 1700 nm. An advantage is that the specific selection of the near-infrared emitting element is further described.

[0018] In some implementations, the fiber optic bundle splitter module also includes a 1xN fused biconical or planar waveguide fiber coupler. Its advantage lies in complementing the specific structure of the fiber optic bundle splitter module.

[0019] In some implementations, the fast fiber optic switch module incorporates a high-precision positioning device, which is a microactuator and its closed-loop control system. The advantage of this is that the high-precision positioning device ensures high efficiency of optical path coupling and accurate repeatability of position after each switch.

[0020] In some implementations, each fiber optic interferometer probe is encapsulated within a protective sleeve. This has the advantage of allowing each fiber optic interferometer probe to be adapted to industrial environments.

[0021] In some embodiments, the photodetector is a miniature spectrometer that internally contains a dispersive element and a linear detector array. An advantage is that it describes the possible types of photodetectors.

[0022] In some implementations, the interference signal analysis and processing unit is an embedded processor. An advantage of this is that it describes the possible types of interference signal analysis and processing units.

[0023] In some implementations, the central control and data processing module employs an architecture combining a high-performance microcontroller, FPGA, and an industrial PC or embedded computer. The advantage lies in the description of the structure of the central control and data processing module.

[0024] In some implementations, the central control and data processing module is equipped with a communication interface, a large-capacity memory, and a user interface. Its advantage lies in further enhancing the configuration and functionality of the central control and data processing module. Attached Figure Description

[0025] Figure 1 This is a module structure diagram of a multi-channel near-infrared interferometric thickness sensor based on an optical switch, according to one embodiment of the present invention.

[0026] Figure 2 for Figure 1 The diagram shows a partial module structure of a multi-channel near-infrared interferometric thickness sensor based on an optical switch.

[0027] Figure 3 for Figure 1 The diagram shows the workflow of a multi-channel near-infrared interferometric thickness sensor based on an optical switch.

[0028] In the diagram: 1. Near-infrared light source module; 2. Fiber optic beam splitter module; 3. Fast fiber optic switch module; 4. Multiple fiber optic interferometer probes; 5. Interferometric measurement and detection module; 6. Central control and data processing module; 7. Object under test. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings.

[0030] like Figure 1 As shown, the sensor mainly includes a near-infrared light source module 1, an optical fiber beam splitter module 2, a fast optical fiber switch module 3, multiple optical fiber interference probes 4, an interferometric measurement and detection module 5, and a central control and data processing module 6.

[0031] The near-infrared light source module 1 mainly includes a near-infrared light-emitting element (such as a superluminescent diode with a center wavelength of 800nm ​​to 1700nm), and is equipped with a precision driving circuit and a temperature controller. The near-infrared light-emitting element includes an output terminal.

[0032] The near-infrared light source module 1 is mainly used to output stable, broadband near-infrared measurement light with power that can be precisely adjusted via the drive current, providing a high-quality light source for interferometric measurements. The broadband spectral characteristics help improve the axial resolution of the measurement.

[0033] The fiber optic bundle splitter module 2 mainly consists of an input single-mode fiber (including a 1xN fused tapered or planar waveguide fiber coupler and N output single-mode fibers, where N is the number of channels, which can be set to 2, 4, 8, 16, etc. The input end of the input single-mode fiber is connected to the output end of the near-infrared emitting element of the near-infrared light source module 1 via an optical fiber.

[0034] The fiber optic beam splitter module 2 is mainly used to distribute the infrared measurement light from the near-infrared light source module 1 relatively evenly into the channels of its N-way output single-mode fiber, and to provide optical input for the fast fiber optic switch module 3.

[0035] The fast fiber optic switch module 3 includes multiple bidirectional optical ports (designated C1...Cn), a common output port P0, and an optical switch (e.g., a MEMS optical switch based on microelectromechanical systems technology) capable of gating and switching between the bidirectional optical ports and the common output port. It also includes internal optical path switching elements (such as a micromirror array or a movable fiber collimator) driven by an electronic control unit. The optical fibers of each bidirectional optical port are connected to the output single-mode optical fibers of the beam splitter module 2 via multiple input optical fibers.

[0036] The fast fiber optic switch module 3 is mainly used to quickly select one of N bidirectional channel ports (e.g., Ci) within a microsecond-level response time (e.g., 1μs to hundreds of μs) according to the instructions issued by the central control and data processing module 6.

[0037] This gating operation enables the following dual optical path functions:

[0038] 1. The light from the corresponding channel of the fiber optic beam splitter module 2 is output through the selected bidirectional port Ci and transmitted to the fiber optic interference probe 4 (denoted as Di) connected thereto;

[0039] 2. The interference light signal returned from the fiber optic interferometer 4 is input through the same selected bidirectional port Ci and guided by the internal optical path to the common output port P0 of the optical switch, and then transmitted to the interferometric measurement and detection module 5.

[0040] In addition, the fast fiber optic switch module 3 also has a built-in high-precision positioning device, which is usually a micro-actuator and its closed-loop control system inside the MEMS optical switch used to accurately drive and stably maintain the position of the micro-mirror (or other switching element), which can ensure high efficiency of optical path coupling and accurate repeatability of position after each switch.

[0041] Multiple fiber optic interferometers 4 (designated as D1...Dn) are respectively configured at the end of each measurement channel. Each fiber optic interferometer 4 typically consists of a section of single-mode fiber, a miniature optical component (such as a gradient refractive index GRIN lens, a self-focusing lens, or a specific structure forming a Fabry-Perot interferometer cavity), and is encapsulated in a robust protective sleeve to adapt to industrial environments. The single-mode fiber of each fiber optic interferometer 4 is connected to the bidirectional optical ports of the fast fiber optic switch module 3 via optical fibers, and the miniature optical component of each fiber optic interferometer 4 faces the object under test 7.

[0042] The fiber optic interferometer probe 4 is primarily used to guide light transmitted from the bidirectional channel port selected by the fast fiber optic switch module 3 to a specific point on the surface of the object under test 7, and to collect the interference light signal carrying thickness information reflected from the object's surface (for thin film samples, this includes its upper and lower surfaces or internal interfaces). This interference light signal is then returned to the same bidirectional channel port (e.g., Ci) of the fast fiber optic switch module 3 via the probe's original path (or a return optical path designed internally within the probe). The probe's structural design allows it to effectively form the optical path required for interference with the surface under test.

[0043] The interferometric detection module 5 mainly includes an optical receiving interface, a photodetector, and an interferometric signal analysis and processing unit. The optical receiving interface is connected to the common output port P0 of the fiber optic switch module 3. The photodetector is preferably a miniature spectrometer, which typically contains dispersive elements such as gratings and a high-sensitivity InGaAs (or other suitable wavelength semiconductor materials) linear array detector. The interferometric signal analysis and processing unit is usually an embedded processor, such as a field-programmable gate array or a digital signal processor, running core algorithms such as Fourier transform.

[0044] In the interferometric measurement detection module 5, the optical receiving interface is used to receive the optical signal from the common output port P0, and the photodetector is used to receive the interference optical signal from a certain channel selected by the optical switch, expand it in the spectrum (dispersion), and convert it into an electrical signal representing the spectral intensity by the linear array detector array. The signal analysis and processing unit performs a fast Fourier transform on the acquired spectral interference signal to obtain the depth reflection profile (usually called A-scan). The distance between the reflection peaks of different interfaces on the depth reflection profile corresponds to the optical path difference. Combined with the refractive index of the material being measured, the thickness or related dimensions of the thin film can be accurately calculated.

[0045] The central control and data processing module 6 can adopt an architecture combining a high-performance microcontroller, FPGA, industrial PC (IPC), or embedded computer, and is equipped with necessary communication interfaces (such as Ethernet, USB, RS-485), large-capacity memory, and user interface (such as a touch screen or connection to an external display). The central control and data processing module 6 is connected to the fast fiber optic switch module 3 and the interferometric measurement and detection module 5 via control lines.

[0046] The central control and data processing module 6 mainly has the following functions:

[0047] 1. Synchronization control: Precisely control the channel switching action of the fast fiber optic switch module 3, and strictly synchronize it with the exposure and data acquisition process of the spectrometer in the interferometric measurement detection module 5 to ensure the accuracy of data acquisition;

[0048] 2. Data Acquisition and Processing: Obtain raw spectral data from the interferometric detection module 5, trigger or directly execute Fourier transform and subsequent thickness calculation algorithms;

[0049] 3. Data storage and display: Stores key data such as thickness values, measurement timestamps, and sample information for each measurement channel, and displays them graphically or digitally in real time on the user interface;

[0050] 4. System Management and Communication: Provides functions such as system parameter settings (e.g., number of channels, measurement frequency, calibration parameters), start / stop control, fault diagnosis, and user access control. It can also exchange data with a host computer or factory automation system through a communication interface.

[0051] The working process of the multi-channel near-infrared interferometric thickness sensor in this invention is as described in steps S1 to S9.

[0052] S1: System initialization and light source start-up: The central control and data processing module 6 starts the system, and the near-infrared light source module 1 emits stable, broadband near-infrared measurement light;

[0053] S2: Optical path distribution: The light emitted by the near-infrared light source module 1 enters the optical fiber splitting module 2 and is evenly distributed into N output single-mode optical fibers. These N output single-mode optical fibers are respectively connected to the N bidirectional optical ports (C1...Cn) of the fast fiber optic switch module 3.

[0054] S3: Channel selection: The central control and data processing module 6 sends a command to the fast fiber optic switch module 3 to select the first measurement channel (e.g., bidirectional optical port C1, which is connected to the fiber optic interferometer probe 4D1).

[0055] S4: Illumination, Interference and Signal Return: At this time, the light from the fiber optic beam splitter module 2 enters the fiber optic interference probe 4D1 through the selected bidirectional optical port C1 of the optical switch, illuminating the target point of the sample under test. The fiber optic interference probe 4D1 collects the interference signal formed at the sample and returns this interference signal to the fast fiber optic switch module 3 through the same bidirectional optical port C1.

[0056] S5: Signal routing and detection: The internal optical path of the fast fiber optic switch module 3 will guide the interference light signal returned from the selected bidirectional optical port C1 to its common output port P0, and transmit it to the spectrometer of the interferometric measurement and detection module 5.

[0057] S6: Spectral Acquisition and Thickness Calculation: The spectrometer acquires the spectral interferogram of this channel. The interference signal analysis and processing unit performs Fourier transform on the acquired spectral data to obtain the depth reflection profile, and then calculates the corresponding thickness value. The calculation result is transmitted to the central control and data processing module 6.

[0058] S7: Data recording and channel switching: The central control and data processing module 6 records the thickness data and related information of the first channel, and then instructs the fast fiber optic switch module 3 to switch to the second measurement channel (for example, select the bidirectional optical port C2, which is connected to the fiber optic interferometer probe 4D2), and repeats steps S4 to S6.

[0059] S8: Multi-channel polling measurement: In the above manner, all N configured measurement channels are polled sequentially and quickly to achieve continuous and rapid thickness data acquisition for multiple measurement points;

[0060] S9: Data Display and System Management: The central control and data processing module 6 updates and displays the thickness data of each channel in real time on the user interface, and can store data, perform statistical analysis or transmit data to the upper-level system according to presets. Operators can perform system parameter adjustment, start and stop control and other operations through the user interface.

[0061] This invention provides a multi-channel near-infrared interferometric thickness sensor based on an optical switch, which has the following advantages:

[0062] 1. Significantly reduced production costs and system maintenance difficulty: By using a fast fiber optic switch module to efficiently reuse a single light source and a single detection system, the number of multiple independent light sources and detection modules required in a traditional multi-channel thickness measurement system is significantly reduced, thereby directly and significantly reducing the overall production and manufacturing cost of the system. Furthermore, the reduced system complexity and number of components significantly reduce the difficulty and cost of subsequent maintenance.

[0063] 2. Significantly improves measurement efficiency: Through the microsecond-level switching capability of the fast fiber optic switch, real-time and rapid polling measurement of multiple measurement channels is realized, which can meet the urgent needs of industrial production sites for high-throughput and high-efficiency online detection;

[0064] 3. Fundamentally enhances the consistency of measurement results: Since all channel measurements are completed through the same set of near-infrared light source modules and the same set of interferometric measurement detection modules, the systematic error sources such as device differences and drift characteristics introduced by using different physical detection systems are fundamentally eliminated, ensuring a high degree of consistency and comparability among multi-channel measurement data;

[0065] 4. Compact structure and high integration: The design of a single light source, a single detector and an optical switch makes the entire sensor system structure simpler and more compact, greatly improving the system integration. This not only facilitates installation and deployment in space-constrained industrial sites, but also provides convenience for system relocation and maintenance.

[0066] The above descriptions are merely some embodiments of this utility model. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of this utility model, and all such modifications and improvements fall within the protection scope of this utility model.

Claims

1. A multi-channel near-infrared interferometric thickness sensor based on an optical switch, characterized in that: include A near-infrared light source module (1) includes a near-infrared light-emitting element; An optical fiber splitter module (2) includes an input single-mode fiber and multiple output single-mode fibers; A fast fiber optic switch module (3) includes multiple bidirectional optical ports, a common output port and an optical switch, the optical switch being able to select and switch between multiple bidirectional optical ports and the common output port; Multiple fiber optic interferometers (4) are respectively configured at the end of each measurement channel. Each fiber optic interferometer (4) consists of a single-mode fiber and a miniature optical component. An interferometric measurement detection module (5) includes an optical receiving interface, a photodetector, and an interferometric signal analysis and processing unit; A central control and data processing module (6); Among them, the output end of the near-infrared light-emitting element of the near-infrared light source module (1) is connected to the input end of the input single-mode fiber of the fiber optic splitter module (2) through an optical fiber. Each output single-mode fiber of the fiber optic bundle splitter module (2) is connected to each bidirectional optical port of the fast fiber optic switch module (3) through multiple input fibers. Each bidirectional optical port of the fast fiber optic switch module (3) is connected to the single-mode fiber of each fiber optic interference probe (4) via optical fiber, and the miniature optical components of each fiber optic interference probe (4) face the object under test (7). The common output port is connected to the optical receiving interface of the interferometric measurement detection module (5) via optical fiber; The central control and data processing module (6) is connected to the fast fiber optic switch module (3) and the interferometric measurement and detection module (5) respectively via control lines.

2. The multi-channel near-infrared interferometric thickness sensor based on an optical switch according to claim 1, characterized in that: The near-infrared light source module (1) is equipped with a precision drive circuit and a temperature controller.

3. The multi-channel near-infrared interferometric thickness sensor based on an optical switch according to claim 1, characterized in that: The near-infrared light-emitting element is a superluminescent light-emitting diode with a center wavelength of 800nm ​​to 1700nm.

4. The multi-channel near-infrared interferometric thickness sensor based on an optical switch according to claim 1, characterized in that: The fiber optic bundle splitter module (2) also includes a 1xN fused tapered or planar waveguide fiber coupler.

5. A multi-channel near-infrared interferometric thickness sensor based on an optical switch according to claim 1, characterized in that: The fast fiber optic switch module (3) has a built-in high-precision positioning device, which is a micro actuator and its closed-loop control system.

6. The multi-channel near-infrared interferometric thickness sensor based on an optical switch according to claim 1, characterized in that: Each fiber optic interferometer probe (4) is encapsulated in a protective sleeve.

7. A multi-channel near-infrared interferometric thickness sensor based on an optical switch according to claim 1, characterized in that: The photodetector is a miniature spectrometer, which contains a dispersive element and a linear detector array.

8. A multi-channel near-infrared interferometric thickness sensor based on an optical switch according to claim 1, characterized in that: The interference signal analysis and processing unit is an embedded processor.

9. A multi-channel near-infrared interferometric thickness sensor based on an optical switch according to claim 1, characterized in that: The central control and data processing module (6) adopts an architecture combining a high-performance microcontroller, FPGA, and an industrial PC or embedded computer.

10. A multi-channel near-infrared interferometric thickness sensor based on an optical switch according to claim 1, characterized in that: The central control and data processing module (6) is equipped with a communication interface, a large-capacity memory and a user interface.

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