Laser radar and gamma camera integrated detection system based on shared SiPM array

Abstract

The invention provides a laser radar and gamma camera integrated detection system based on a shared SiPM array, and belongs to the field of detector equipment. The system comprises a laser emission module, a gamma camera, an optical module, an SiPM array detection module, a signal processing module and a control module. Wherein the optical module controls high-frequency pulse laser of the laser emission module to scan a target scene, respectively guides a reflected laser beam and a scintillation light signal emitted by the gamma camera to the SIPM array detection module for photoelectric conversion to generate an electric signal, and performs gain and time gate adjustment according to a sensor working mode to obtain a first electric signal; the signal processing module receives the first electric signal and carries out laser radar ranging calculation and gamma camera imaging processing to obtain three-dimensional point cloud data and a radioactivity distribution image of the target scene. According to the invention, efficient fusion of functions of the laser radar and the gamma camera is realized, the size and weight of the system are greatly reduced, and the manufacturing and maintenance cost is also reduced.

Description

Technical Field

[0001] The present invention relates to the field of detector equipment, and in particular to an integrated detection system of a laser radar and a gamma camera based on a shared SiPM array. Background Art

[0002] With advances in sensor technology, multi-sensor fusion systems have gained increasing attention. These systems combine the strengths of different sensor types to improve environmental perception and target positioning accuracy. Existing multi-sensor fusion systems provide more comprehensive and accurate environmental information by integrating data from lidar, cameras, and other sensors. These systems fuse the three-dimensional point cloud generated by lidar with the two-dimensional images captured by cameras to achieve higher target detection and tracking performance. However, the lidar and gamma camera systems are independent, and the photodetectors and optical systems cannot be shared. This results in bulky devices and hinders the realization of compact, multifunctional integrated designs. Furthermore, existing photodetectors are limited to specific application scenarios and lack flexibility, making them difficult to use in a variety of sensing applications. Furthermore, because the detection systems in existing technologies are typically designed separately, they cannot share power and signal processing resources, resulting in low overall energy efficiency and increased system complexity and cost. Summary of the Invention

[0003] In view of this, an embodiment of the present invention provides an integrated detection system of a lidar and a gamma camera based on a shared SiPM array, so as to solve the problems of difficult integration and high system complexity of existing detection systems.

[0004] The technical solution adopted in the present invention is:

[0005] The present invention provides an integrated detection system of a laser radar and a gamma camera based on a shared SiPM array, comprising a laser emission module, a gamma camera, an optical module, a SiPM array detection module, a signal processing module and a control module; wherein,

[0006] The control module is electrically connected to the laser emission module, the optical module, the SiPM array detection module and the signal processing module respectively; the SiPM array detection module is connected to the signal processing module;

[0007] The optical module is arranged between the SIPM array detection module and the laser emission module and the gamma camera emission module, and is used to control the high-frequency pulse laser of the laser emission module to scan the target scene, and to guide the reflected laser beam and the scintillation light signal emitted by the gamma camera to the SIPM array detection module respectively;

[0008] The SIPM array detection module performs photoelectric conversion on the detected reflected laser beam and scintillation light signal to generate a corresponding electrical signal, and adjusts the gain and time gate of the electrical signal according to a preset sensor operating mode to obtain a first electrical signal; the sensor operating mode includes a lidar mode and a gamma camera mode;

[0009] The signal processing module receives the first electrical signal and performs laser radar ranging calculation and gamma camera imaging processing respectively to obtain three-dimensional point cloud data and radioactivity distribution image of the target scene.

[0010] Furthermore, the laser emission module includes a laser and a first optical collimator; the control module is electrically connected to the laser; the laser is used to transmit high-frequency pulsed laser, and adjust the pulsed laser to form a collimated beam through the first optical collimator.

[0011] Furthermore, the optical module includes a MEMS galvanometer, a dichroic mirror, a tunable filter and an optical coupler; wherein,

[0012] The MEMS galvanometer controls the high-frequency pulse laser to scan the target scene according to a preset scanning path, and refracts the scanned reflected laser beam into the dichroic mirror;

[0013] The dichroic mirror performs optical signal filtering on the reflected laser beam according to the wavelength of the optical signal, and transmits the filtered laser beam to the tunable filter;

[0014] The tunable filter performs filtering on the laser beam after filtering, and guides the filtered laser beam to the SiPM array detection module;

[0015] The optical coupler collects the scintillation light signal emitted by the gamma camera and reflects the scintillation light signal to the SiPM array detection module through the dichroic mirror.

[0016] Furthermore, the gamma camera module includes a scintillation crystal and a second optical collimator; the scintillation crystal generates scintillation light according to the gamma rays irradiated in the target scene, and the scintillation light is collimated by the second optical collimator to obtain a scintillation light signal.

[0017] Furthermore, the SiPM array detection module includes a SiPM array and a signal processing unit; wherein,

[0018] The SiPM array is used to capture the reflected laser beam and the scintillation light signal and perform photoelectric conversion processing to generate an electrical signal;

[0019] The signal processing unit is used to automatically adjust the gain and time gate of the electrical signal according to a preset sensor working mode to obtain a first electrical signal.

[0020] Furthermore, the signal processing module includes a distance calculation unit and an image generation unit;

[0021] The distance measurement calculation unit calculates the distance between the reflection point and the detection position in the target scene according to the first electrical signal, and generates three-dimensional point cloud data of the target scene according to the distance between the reflection point and the detection position;

[0022] The image generation unit performs energy spectrum analysis based on the first electrical signal, and reconstructs the spatial position of the gamma ray event using a maximum likelihood estimation algorithm based on the energy spectrum analysis result, maps the spatial position to an image plane, and generates a radioactivity distribution image.

[0023] Furthermore, the distance calculation unit includes:

[0024] A time-of-flight difference calculation subunit is used to record the time-of-flight difference (ToF) of each high-frequency pulse laser in the first electrical signal from the time it is emitted to the time it is captured by the SIPM array detection module and the reflected laser beam, and calculate the distance information between each reflection point in the target scene and the detection position based on the time-of-flight difference of the high-frequency pulse laser;

[0025] The 3D point cloud generation subunit is used to calculate the 3D coordinates of the target object in space based on the distance information between each reflection point and the detection position, combined with the detection position on the scanning path. After the scanning is completed, the 3D point cloud data of the entire target scene is generated;

[0026] The data optimization subunit is used to perform noise filtering and data optimization on the three-dimensional point cloud data of the target scene to obtain optimized three-dimensional point cloud data.

[0027] Furthermore, the image generation unit includes:

[0028] a photoelectric signal preprocessing subunit, configured to perform signal amplitude analysis and peak detection on the first photoelectric signal, distinguish single photon events based on the signal amplitude analysis results and the peak detection results, and filter out low-energy noise of the first photoelectric signal to obtain a preprocessed photoelectric signal;

[0029] An energy spectrum analysis subunit, used to calculate the signal amplitude of each photon event based on the preprocessed photoelectric signal and generate the energy spectrum of the gamma ray;

[0030] An event position reconstruction subunit is used to calculate a likelihood function value based on the energy spectrum of the gamma ray using a maximum likelihood estimation algorithm, and reconstruct the spatial position of the gamma ray event based on the likelihood function value;

[0031] An image generation and correction subunit is used to map the spatial position of the reconstructed gamma-ray event to the image plane to generate a preliminary radioactivity distribution image, and perform nonlinear correction, spatial resolution enhancement, and photon scattering correction on the preliminary radioactivity distribution image to obtain a target radioactivity distribution image;

[0032] The image construction output subunit is used to accumulate the frame data of the target radioactivity distribution image multiple times, finally generate a complete radioactivity distribution image, and output the complete radioactivity distribution image in pseudo color or grayscale form.

[0033] Furthermore, in the LiDAR operating mode, the control module coordinates and controls the laser emission module, optical module, SiPM array detection module, and signal processing module to detect the target scene and generate three-dimensional point cloud data of the target scene, specifically including:

[0034] The control module controls the laser emission module to emit high-frequency pulsed lasers and sends a galvanometer control signal to the MEMS galvanometer in the optical module. The MEMS galvanometer controls the motion trajectory of the high-frequency pulsed laser on a two-dimensional plane to form a Lissajous figure. The high-frequency pulsed laser is controlled to scan the target scene according to the preset Lissajous scanning path.

[0035] The high-frequency pulse laser is scanned in the target scene through the MEMS galvanometer, and the reflected laser beam is refracted and directed into the dichroic mirror. The reflected laser beam is filtered and filtered by the dichroic mirror and the tunable filter, and the reflected signal is output;

[0036] The SiPM array detection module receives the reflected signal in the target scene and transmits the reflected signal to the signal processing module;

[0037] The signal processing module records the time of flight (ToF) corresponding to each reflected signal and determines the distance between each reflection point and the current detection position through ToF calculation;

[0038] The signal processing module combines the distance information corresponding to each reflected signal with the current position on the Lissajous scanning path, and repeatedly calculates the three-dimensional coordinates of the target object in space until the scan is complete, generating three-dimensional point cloud data for the entire target scene.

[0039] Noise filtering and optimization processing are performed on the three-dimensional point cloud data to obtain optimized three-dimensional point cloud data.

[0040] Furthermore, in the gamma camera mode, the control module coordinates and controls the gamma camera, optical module, SiPM array detection module, and signal processing module to detect gamma rays in the target scene and generate a radioactivity distribution image of the target scene, specifically including:

[0041] Gamma cameras use scintillators to detect gamma rays in the target scene. Gamma rays interact with the scintillator to generate scintillation light, which is then collimated to form a scintillation light signal.

[0042] The scintillation light signal generated by the gamma camera is collected by an optical coupler and reflected to the SiPM array detection module by a dichroic mirror;

[0043] The scintillation light signal is detected by the SiPM array detection module, and the scintillation light signal is converted into an electrical signal and then input into the signal processing module;

[0044] The signal processing module performs amplitude analysis and peak detection on the electrical signal, distinguishes single photon events based on the amplitude analysis and peak detection results, and filters out low-energy noise in the electrical signal to obtain a pre-processed photoelectric signal;

[0045] Perform energy spectrum analysis on the pre-processed photoelectric signal, calculate the signal amplitude of each photon event, and generate the energy spectrum of the gamma ray;

[0046] The maximum likelihood estimation algorithm is used to perform maximum likelihood estimation on the preprocessed photoelectric signal, calculate the likelihood function value of the gamma ray event, and reconstruct the spatial position of the gamma ray event based on the likelihood function value;

[0047] The spatial position of the gamma ray time is mapped to the image plane to generate a preliminary radioactivity distribution image, and the preliminary radioactivity distribution image is processed with nonlinear correction, spatial resolution enhancement and photon scattering correction to obtain a target radioactivity distribution image;

[0048] The frame data of the target radioactivity distribution image are accumulated multiple times to finally generate a complete radioactivity distribution image.

[0049] In summary, the beneficial effects of the present invention are as follows:

[0050] This invention provides an integrated detection system for a LiDAR and gamma camera based on a shared SiPM array. By integrating multiple components, including a laser emission module, a gamma camera, an optical module, a SiPM array detection module, a signal processing module, and a control module, the system integrates the optical paths of a MEMS galvanometer-based LiDAR and a gamma camera, allowing them to share the same SiPM array for signal detection. This integration solution not only significantly reduces the system's size and weight, but also lowers manufacturing and maintenance costs by sharing the detector and control modules. It fully leverages the advantages of the SiPM array and achieves the efficient fusion of LiDAR and gamma camera functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work, and these are all within the scope of protection of the present invention.

[0052] Figure 1 This is an architecture diagram of an integrated detection system of a laser radar and a gamma camera based on a shared SiPM array according to the present invention;

[0053] Figure 2 Schematic diagram of the system working principle of the present invention. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. If there is no conflict, the various features of the present invention and the embodiments can be combined with each other and are all within the scope of protection of the present invention.

[0055] In recent years, MEMS (micro-electromechanical system) galvanometer LiDAR technology has made significant progress. MEMS galvanometer LiDAR uses tiny mechanical mirrors to control the direction of the laser beam, achieving high-precision three-dimensional scanning of the target environment. Compared to traditional mechanical LiDAR, MEMS galvanometer LiDAR offers the advantages of miniaturization, lightweight, high scanning speed, and high accuracy. These characteristics enable it to excel in real-time detection and detailed environmental modeling in dynamic environments, making it suitable for applications such as autonomous driving, robotic navigation, and drones.

[0056] Gamma camera technology continues to advance, becoming a vital tool in fields such as nuclear radiation monitoring, medical imaging, and industrial flaw detection. Modern gamma cameras utilize novel detector materials, such as cadmium zinc telluride (CZT) and high-purity germanium (HPGe), significantly improving detection sensitivity and energy resolution. Gamma cameras based on single-photon counting and time-projection techniques enable high-resolution radiation imaging, providing more detailed information about radiation sources. Furthermore, gamma cameras are becoming increasingly portable and intelligent, integrating automated radiation source location and analysis capabilities, significantly improving ease of use and efficiency.

[0057] Accurately locating and detecting radiation sources is crucial in fields such as environmental monitoring and nuclear safety. Traditional radiation detection methods rely primarily on single sensors, such as Geiger counters or gamma cameras, which are unable to achieve high-precision three-dimensional positioning. The introduction of laser ranging (LiDAR) technology can provide high-resolution spatial data, but it cannot detect radiation. Traditionally, these two sensors are independent, using different photodetectors and optical systems, resulting in bulky, costly, and difficult-to-integrate devices.

[0058] The main problems with existing technologies lie in the following areas: First, the LiDAR and gamma camera systems are independent, and the photodetectors and optical systems cannot be shared. This results in bulky devices and makes compact, multifunctional integrated designs difficult to achieve. Second, existing photodetectors are limited to specific application scenarios and lack flexibility, making them difficult to use in a variety of sensing applications. Furthermore, because existing systems are typically designed separately, they cannot share power and signal processing resources, resulting in overall low energy efficiency and increased system complexity and cost.

[0059] Limitations in data processing and fusion capabilities are also a major issue with existing radiation location technology. Gamma cameras primarily provide information on the intensity and location of radiation sources, but lack the ability to perceive surrounding structures. This makes comprehensive analysis and precise location of radiation sources difficult when used alone. In practical applications, data supplementation and fusion often require reliance on other types of sensors, which not only increases system complexity but also places higher demands on data synchronization and fusion algorithms.

[0060] Therefore, the present invention integrates the optical paths of MEMS galvanometer laser radar and gamma camera through innovative optical spectrometry and filtering system design, so that they can share the same SiPM array for signal detection. This integration solution not only greatly reduces the volume and weight of the system, but also reduces manufacturing and maintenance costs by sharing detectors and control modules. With the advancement of photoelectric detection technology, the performance of SiPM arrays has been continuously improved, and it has the advantages of high sensitivity, high temporal and spatial resolution, making it an ideal multifunctional detector. The present invention conforms to this development trend, fully utilizes the advantages of SiPM arrays, realizes the efficient integration of laser radar and gamma camera functions, fills the gap in the field of multi-sensor integration, and promotes the further application of related technologies in the fields of autonomous driving, intelligent manufacturing, and safety detection. The detailed implementation process of the present invention is shown in the following examples:

[0061] Example 1:

[0062] See Figure 1 , Figure 1This is an architecture diagram of an integrated detection system of a laser radar and a gamma camera based on a shared SiPM array in Example 1 of the present invention. Figure 1 As shown, the integrated detection system provided by the present invention includes: a laser emission module, a gamma camera, an optical module, a SiPM array detection module, a signal processing module, and a control module. The control module is electrically connected to the laser emission module, the optical module, the SiPM array detection module, and the signal processing module respectively; the SiPM array detection module is connected to the signal processing module.

[0063] The optical module is set between the SIPM array detection module and the laser emission module and the gamma camera emission module. It is used to control the high-frequency pulse laser of the laser emission module to scan the target scene, and to guide the reflected laser beam and the flash light signal emitted by the gamma camera to the SIPM array detection module respectively.

[0064] The SIPM array detection module performs photoelectric conversion on the detected reflected laser beam and scintillation light signal to generate a corresponding electrical signal, and adjusts the gain and time gate of the electrical signal according to the preset sensor working mode to obtain a first electrical signal; the sensor working mode includes lidar mode and gamma camera mode.

[0065] The signal processing module receives the first electrical signal and performs laser radar ranging calculation and gamma camera imaging processing respectively to obtain three-dimensional point cloud data and radioactivity distribution image of the target scene.

[0066] In some embodiments, the integrated detection system of the present invention further includes a power supply module, which supplies power to each module.

[0067] Further, in the embodiment of the present invention, referring to Figure 1 As shown, the laser emission module includes a laser and a first optical collimator. The control module is electrically connected to the laser. The laser is used to transmit high-frequency pulsed laser light, and the first optical collimator adjusts the pulsed laser light to form a collimated beam, thereby reducing the laser divergence angle and increasing the transmission distance of the beam.

[0068] Further, in the embodiment of the present invention, referring to Figure 1As shown, the optical module includes a MEMS galvanometer, a dichroic mirror, a tunable filter, and an optical coupler. The MEMS galvanometer controls the high-frequency pulse laser to scan the target scene according to a preset scanning path, and refracts the scanned reflected laser beam into the dichroic mirror. The dichroic mirror filters the reflected laser beam according to the wavelength of the optical signal and transmits the filtered laser beam to the tunable filter. The tunable filter filters the filtered laser beam and guides the filtered laser beam to the SiPM array detection module. The optical coupler collects the scintillation light signal emitted by the gamma camera and reflects the scintillation light signal to the SiPM array detection module through the dichroic mirror.

[0069] Specifically, in the embodiment of the present invention, refer to Figure 1 As shown, the optical module is primarily located between the laser emission module and the SIPM array detection module. A MEMS galvanometer controls the laser beam's scanning direction, scanning the laser beam across the target scene along a predetermined path. The reflected light from the beam scan is reflected by the galvanometer, passing through a dichroic mirror and a switchable filter before entering the SiPM array in the detection module. The dichroic mirror's primary function is to separate the light beams according to their wavelengths, directing the lidar laser signal and the gamma camera scintillation light signal onto their respective paths.

[0070] Among them, in the embodiment of the present invention, the tunable filter adopts a tunable liquid crystal filter (LTCF), which is a Lyot / Solc type tunable filter and a switchable filter that allows the user to switch from any wavelength between 420nm and 730nm. In addition to this wavelength tunability, this filter also allows the user to select a different half-height width at each center wavelength; selecting a wide half-height width can increase the transmittance of light from a broadband light source, while a narrow half-height width can only transmit a few wavelengths of light from a broadband light source. Through the tunable characteristics of LCTF, the present invention can dynamically adjust the response of the optical system in different working modes to adapt to different detection needs. This flexibility enables the system to switch quickly according to the actual application scenario, enhancing the applicability and practicality of the system.

[0071] In an embodiment of the present invention, dichroic mirrors, also known as two-color mirrors, are commonly used in laser technology. By using dichroic mirrors to distinguish optical signals, the probability of non-target signals entering the SiPM array is reduced during the initial differentiation of optical signals. When used in conjunction with a tunable liquid crystal filter (LCTF), the system's signal detection accuracy can be effectively improved, false detections and missed detections can be reduced, and system reliability can be enhanced.

[0072] In some embodiments, the present invention combines a MEMS galvanometer with a laser emission module to form a MEMS galvanometer LiDAR. MEMS galvanometer LiDAR uses tiny mechanical mirrors to control the direction of the laser beam, achieving high-precision three-dimensional scanning of the target environment. Compared to traditional mechanical LiDARs, MEMS galvanometer LiDARs offer the advantages of miniaturization, lightweightness, high scanning speed, and high precision. These characteristics enable them to excel in real-time detection and detailed environmental modeling in dynamic environments.

[0073] Furthermore, the gamma camera module includes a scintillation crystal and a second optical collimator; the scintillation crystal generates scintillation light according to the gamma rays irradiated in the target scene, and the scintillation light is collimated by the second optical collimator to obtain a scintillation light signal.

[0074] Specifically, gamma camera (also known as γ camera) technology is another type of technology widely used in radiation detection. It can efficiently detect gamma rays in the environment and provide information on the location and intensity of the radiation source. Modern gamma cameras use new detector materials such as high-purity germanium (HPGe) to significantly improve detection sensitivity and energy resolution. Gamma cameras use pinhole imaging technology or coded hole imaging technology to achieve high-resolution radiation imaging and can accurately locate the radiation source. However, the spatial resolution and imaging range of gamma cameras are relatively limited, making it difficult to provide comprehensive three-dimensional information about the environment. Gamma cameras perform well in high-precision radiation detection, but when used in complex environments, they cannot independently complete environmental modeling and precise positioning of radiation sources. Therefore, an embodiment of the present invention combines gamma camera technology with MEMS galvanometer laser radar technology, integrating the MEMS galvanometer laser radar and the gamma camera into the same device and sharing a set of SiPM arrays, thereby achieving efficient system integration and simplified signal processing.

[0075] Furthermore, the SiPM array detection module includes a SiPM array and a signal processing unit; wherein,

[0076] The SiPM array is used to capture the reflected laser beam and scintillation light signal and perform photoelectric conversion processing to generate electrical signals;

[0077] The signal processing unit is used to automatically adjust the gain and time gate of the electrical signal according to a preset sensor working mode to obtain a first electrical signal.

[0078] The SiPM array detection module directly detects the optical signal after processing by the optical system. The SiPM array is composed of multiple silicon photomultiplier tubes (SiPMTs). Featuring high sensitivity and fast response, the SiPM array can simultaneously capture signals from both the LiDAR and gamma camera. After passing through dichroic mirrors and filters, the different optical signals enter the SiPM array for photoelectric conversion, generating corresponding electrical signals. The signal processing unit in the SiPM array automatically adjusts the gain and time gate based on the sensor's operating mode to ensure optimal signal processing.

[0079] Furthermore, in an embodiment of the present invention, the signal processing module includes a distance measurement calculation unit and an image generation unit. The distance measurement calculation unit calculates the distance between the reflection point and the detection position in the target scene based on the first electrical signal, and generates three-dimensional point cloud data of the target scene based on the distance between the reflection point and the detection position.

[0080] The image generation unit performs energy spectrum analysis based on the first electrical signal, and reconstructs the spatial position of the gamma ray event using a maximum likelihood estimation algorithm based on the energy spectrum analysis result, maps the spatial position to an image plane, and generates a radioactivity distribution image.

[0081] Specifically, the ranging calculation unit in the embodiment of the present invention includes:

[0082] The time-of-flight difference calculation subunit is used to record the time-of-flight difference ToF of each high-frequency pulse laser in the first electrical signal from the time it is emitted to the time it is captured by the SIPM array detection module to the time it is reflected by the laser beam, and calculate the distance information between each reflection point in the target scene and the detection position based on the time-of-flight difference of the high-frequency pulse laser.

[0083] Among them, ToF (Time of Flight) means obtaining the distance information of the target object based on the propagation speed of light in the air by directly measuring the time difference between the emitted laser and the echo signal. It has the advantages of fast response speed and high detection accuracy.

[0084] The 3D point cloud generation subunit is used to calculate the 3D coordinates of the target object in space based on the distance information between each reflection point and the detection position, combined with the detection position on the scanning path. After the scanning is completed, the 3D point cloud data of the entire target scene is generated.

[0085] The data optimization subunit is used to perform noise filtering and data optimization on the three-dimensional point cloud data of the target scene to obtain optimized three-dimensional point cloud data.

[0086] Specifically, the image generation unit of the embodiment of the present invention includes:

[0087] The photoelectric signal preprocessing subunit is used to perform signal amplitude analysis and peak detection on the first photoelectric signal, distinguish single photon events based on the signal amplitude analysis results and the peak detection results, and filter out low-energy noise of the first photoelectric signal to obtain a preprocessed photoelectric signal.

[0088] The energy spectrum analysis subunit is used to calculate the signal amplitude of each photon event based on the pre-processed photoelectric signal and generate the energy spectrum of the gamma ray.

[0089] The event position reconstruction subunit is used to calculate the likelihood function value based on the energy spectrum of the gamma ray using the maximum likelihood estimation algorithm, and reconstruct the spatial position of the gamma ray event based on the likelihood function value.

[0090] The image generation and correction subunit is used to map the spatial position of the reconstructed gamma-ray event to the image plane, generate a preliminary radioactivity distribution image, and perform nonlinear correction, spatial resolution enhancement and photon scattering correction on the preliminary radioactivity distribution image to obtain the target radioactivity distribution image.

[0091] The image construction output subunit is used to accumulate the frame data of the target radioactivity distribution image multiple times, finally generate a complete radioactivity distribution image, and output the complete radioactivity distribution image in pseudo color or grayscale form.

[0092] In the embodiment of the present invention, the signal processing module mainly receives the electrical signal from the SiPM array and performs ranging calculation of the laser radar and imaging processing of the gamma camera respectively.

[0093] Specifically, in this embodiment of the present invention, the control module coordinates the operation of the entire system, including laser emission control, MEMS galvanometer scanning control, filter switching, and signal processing mode selection. Using pre-set scanning paths and detection modes, the control module automatically adjusts the operating state of various system components to accommodate different detection requirements.

[0094] In the LiDAR operating mode, the control module in the embodiment of the present invention coordinates and controls the laser emission module, the optical module, the SiPM array detection module, and the signal processing module to detect the target scene and generate three-dimensional point cloud data of the target scene, specifically including:

[0095] The control module controls the laser emission module to emit high-frequency pulsed lasers and sends a galvanometer control signal to the MEMS galvanometer in the optical module. The MEMS galvanometer controls the motion trajectory of the high-frequency pulsed laser on a two-dimensional plane to form a Lissajous figure. The high-frequency pulsed laser is controlled to scan the target scene according to the preset Lissajous scanning path.

[0096] The high-frequency pulse laser is scanned in the target scene through the MEMS galvanometer, and the reflected laser beam is refracted and directed into the dichroic mirror. The reflected laser beam is filtered and filtered by the dichroic mirror and the tunable filter, and the reflected signal is output;

[0097] The SiPM array detection module receives the reflected signal in the target scene and transmits the reflected signal to the signal processing module;

[0098] The signal processing module records the time of flight (ToF) corresponding to each reflected signal and determines the distance between each reflection point and the current detection position through ToF calculation;

[0099] The signal processing module combines the distance information corresponding to each reflected signal with the current position on the Lissajous scanning path, and repeatedly calculates the three-dimensional coordinates of the target object in space until the scan is complete, generating three-dimensional point cloud data for the entire target scene.

[0100] Noise filtering and optimization processing are performed on the three-dimensional point cloud data to obtain optimized three-dimensional point cloud data.

[0101] Furthermore, in the gamma camera mode, the control module in the embodiment of the present invention coordinates and controls the gamma camera, the optical module, the SiPM array detection module, and the signal processing module to detect gamma rays in the target scene and generate a radioactivity distribution image of the target scene, specifically including:

[0102] Gamma cameras use scintillators to detect gamma rays in the target scene. Gamma rays interact with the scintillator to generate scintillation light, which is then collimated to form a scintillation light signal.

[0103] The scintillation light signal generated by the gamma camera is collected by an optical coupler and reflected to the SiPM array detection module by a dichroic mirror;

[0104] The scintillation light signal is detected by the SiPM array detection module, and the scintillation light signal is converted into an electrical signal and then input into the signal processing module;

[0105] The signal processing module performs amplitude analysis and peak detection on the electrical signal, distinguishes single photon events based on the amplitude analysis and peak detection results, and filters out low-energy noise in the electrical signal to obtain a pre-processed photoelectric signal;

[0106] Perform energy spectrum analysis on the pre-processed photoelectric signal, calculate the signal amplitude of each photon event, and generate the energy spectrum of the gamma ray;

[0107] The maximum likelihood estimation algorithm is used to perform maximum likelihood estimation on the preprocessed photoelectric signal, calculate the likelihood function value of the gamma ray event, and reconstruct the spatial position of the gamma ray event based on the likelihood function value;

[0108] The spatial position of the gamma ray time is mapped to the image plane to generate a preliminary radioactivity distribution image, and the preliminary radioactivity distribution image is processed with nonlinear correction, spatial resolution enhancement and photon scattering correction to obtain a target radioactivity distribution image;

[0109] The frame data of the target radioactivity distribution image are accumulated multiple times to finally generate a complete radioactivity distribution image.

[0110] The embodiment of the present invention integrates a MEMS galvanometer laser radar and a gamma camera into the same device and shares a set of SiPM arrays, thereby achieving efficient system integration and simplified signal processing. This shared SiPM array design greatly reduces the complexity, volume and cost of the system, while optimizing the space utilization of the equipment. By combining a dichroic mirror with a liquid crystal tunable filter (LCTF), the present invention can effectively distinguish and optimize the different optical signals generated by the laser radar and the gamma camera. The dichroic mirror plays a preliminary wavelength differentiation role in the optical path, guiding signals of different wavelengths into their respective optical paths, while the LCTF further ensures the independence and purity of the signal in a specific mode through precise spectral selectivity. This combination of a dichroic mirror and an LCTF not only improves the signal processing accuracy of the system, but also enhances its reliability. In addition, the optical path design of the present invention has been optimized to minimize signal loss, and through a reasonable arrangement of optical components, efficient signal transmission and processing can be achieved. To ensure the system's flexibility in different application scenarios, the present invention introduces a dynamic operating mode switching mechanism. Through the tuning function of the LCTF, it can selectively transmit light signals of specific wavelengths in different time periods, thereby adapting to the different working requirements of lidar and gamma cameras.

[0111] Example 2:

[0112] Reference Figure 2 The figure is shown to further illustrate the process from the emission of laser and scintillation light to the SIPM array acquisition, to the final signal processing and output of the processing results. The embodiment of the present invention is explained based on the working mode of the sensor.

[0113] In LiDAR mode, the present invention uses Lissajous scanning to achieve comprehensive coverage and efficient scanning of the target scene. Lissajous scanning is a method that controls the biaxial vibration of the MEMS galvanometer to generate a complex scanning path at different frequencies and phases, thereby covering the entire detection area on a two-dimensional plane. The specific steps are as follows:

[0114] Galvanometer Control: The MEMS galvanometer is controlled by two pairs of actuators, one for X-axis and one for Y-axis vibration. These two actuators have slightly different frequencies and phases, resulting in the laser beam's trajectory in a two-dimensional plane exhibiting a Lissajous pattern. The complexity and coverage of this pattern depend on the frequency ratio of the two axes and the initial phase difference.

[0115] Scan Path Generation: During Lissajous scanning, the laser beam scans the scene along a path defined by a Lissajous curve. The non-repetitive nature and high coverage of this path ensures uniform distribution of the laser beam across the entire scanning area, enabling the acquisition of more comprehensive distance information. Lissajous curve parameters (such as frequency ratio and phase difference) can be adjusted to optimize scanning accuracy and speed based on specific application requirements.

[0116] Reflected Signal Reception and Time of Flight Calculation: When a laser beam encounters a target object along its scanning path, it reflects back a portion of the light signal. The SiPM array receives these reflected signals, and the signal processing module records the Time of Flight (ToF) corresponding to each reflected signal. Using ToF calculation, the distance to each reflection point is determined.

[0117] Data Processing and Point Cloud Generation: The signal processing module combines the distance information corresponding to each reflected signal with the current position along the Lissajous scanning path (i.e., the corresponding X- and Y-axis galvanometer angles) to calculate the target object's 3D coordinates in space. This process is repeated until the scan is complete, ultimately generating 3D point cloud data for the entire scene. Due to the high coverage of the Lissajous scanning path, the generated point cloud data has high resolution and integrity.

[0118] Point cloud optimization and output: The generated 3D point cloud data may contain noise points due to multipath reflections or other environmental factors. The signal processing module filters and optimizes the point cloud data to ensure high accuracy and clarity in the final output. The processed point cloud data can be directly used in subsequent applications such as 3D modeling, environmental perception, and navigation.

[0119] Specifically, in the gamma camera mode, the signal processing module performs energy spectrum analysis on the gamma ray signal to generate a radioactivity distribution image.

[0120] Gamma-ray detection and photoelectric conversion: Gamma cameras use scintillators to detect gamma rays. Gamma rays interact with the scintillator, generating photons. These photons are then detected by the SiPM array and converted into electrical signals that accurately reflect the energy of the gamma rays.

[0121] Photoelectric Signal Preprocessing: The electrical signal output from the SiPM array enters the signal processing module and undergoes preprocessing. This preprocessing includes signal amplitude analysis and peak detection to distinguish single photon events and filter out low-energy noise. This step ensures the purity of the input signal, providing high-quality data for subsequent energy spectrum analysis and position reconstruction.

[0122] Energy Spectrum Analysis: The preprocessed signal enters the energy spectrum analysis subunit. This subunit accurately calculates the signal amplitude of each photon event to generate the gamma ray energy spectrum. This step includes multi-peak separation and noise filtering to ensure accurate identification and differentiation of different gamma ray energy components.

[0123] Event Position Reconstruction: The signal processing module uses the Maximum Likelihood Estimation (MLE) algorithm to reconstruct the spatial position of the gamma-ray event. The MLE algorithm uses an iterative optimization process to find the event location that maximizes the probability of the observed data, based on the measured SiPM pixel signals. This approach considers the statistical characteristics of the detector system and the photon dispersion model, effectively improving the accuracy of position reconstruction. The MLE algorithm continuously adjusts the hypothesized value of the event position and calculates the corresponding likelihood function value to ultimately determine the most likely incidence position of the gamma-ray event within the scintillator.

[0124] Image Generation and Correction: After position reconstruction, the reconstructed event locations are mapped onto the image plane, generating a preliminary radioactivity distribution image. The signal processing module further performs nonlinear correction, spatial resolution enhancement, and photon scatter correction on the image. These corrections improve image quality, eliminate artifacts and errors, and ensure the accuracy and clarity of the output image.

[0125] Radioactivity distribution image construction and output: After multiple frames of data are accumulated, a complete radioactivity distribution image is generated. The output image is presented in pseudo-color or grayscale format, reflecting the spatial distribution characteristics of the gamma-ray source. These images can be viewed in real time on a display or stored for subsequent analysis and application.

[0126] In an embodiment of the present invention, based on the above laser and scintillation light processing process, the workflow of the integrated detection system of the lidar and gamma camera based on a shared SiPM array is as follows:

[0127] In LiDAR mode, after the system boots up, the control module first activates the laser, emitting high-frequency pulsed laser light. The laser beam is aligned by an optical collimator, ensuring it maintains excellent parallelism even after long distances, minimizing beam divergence and ensuring high-precision distance measurement. The laser beam is then directed to the MEMS galvanometer, whose motion gradually changes the direction of the laser beam according to a pre-set Lissajous scanning path, ensuring coverage of every detection point in the target area. At each detection point, the laser beam strikes the target object, partially reflecting back. This return light is then reflected again by the galvanometer and directed through the optical system to a dichroic mirror. In LiDAR mode, the dichroic mirror is designed to allow the laser wavelength to pass directly while filtering out light signals of other wavelengths. At this point, a switchable filter in the optical path is in a state that allows the laser wavelength to pass, further optimizing the optical signal and preventing interference from other light sources. Finally, the filtered, reflected laser beam is directed to the SiPM array, which rapidly converts the optical signal into an electrical signal, which is then transmitted in real time to the signal processing module. In the signal processing module, the system calculates the distance between each detection point and the LiDAR system by measuring the time between laser emission and return reflection. By scanning point by point, the system ultimately generates 3D point cloud data of the target area. This data can be used to reconstruct a 3D model of the target object or for tasks such as navigation and obstacle avoidance. The control module continuously monitors the scanning process, adjusting the scanning speed and path of the galvanometer as needed to ensure coverage of the entire target area and obtain highly accurate distance measurements.

[0128] In gamma camera mode, the system's workflow differs significantly from that in lidar mode. When the system switches to gamma camera mode, gamma rays first strike a scintillator crystal, stimulating it to emit scintillation light. This scintillation light is efficiently collected by an optical coupler and directed into the optical system. A dichroic mirror then reflects the scintillation light toward the SiPM array while blocking light of other wavelengths from entering the detection path. Simultaneously, the control module adjusts the switchable filter to the optimal wavelength for the scintillation light, ensuring optimal detection of the light entering the SiPM array. The SiPM array rapidly converts the received scintillation light signals into electrical signals, which are then transmitted to the signal processing module. The signal processing module performs energy spectrum analysis on the electrical signals. By analyzing the energy level of each signal, the system can identify and generate an image of the radioactivity distribution in the target area. This image can be used for medical diagnosis, nuclear facility monitoring, or other radioactivity detection applications. Since the system does not require the laser emitter and MEMS galvanometer in gamma camera mode, these components are turned off to conserve energy. During processing, the system adjusts the operating conditions of the filter and dichroic mirror in real time to ensure high-quality signal detection and accurate processing results. During the entire process, the control module automatically coordinates the switching between the lidar and gamma camera modes to ensure that the system can quickly and accurately complete its respective detection tasks in different application scenarios.

[0129] Specifically, the integrated detection system of the lidar and gamma camera based on a shared SiPM array according to an embodiment of the present invention has the following technical features:

[0130] 1. Improved signal separation and processing efficiency: By integrating a dichroic mirror with a liquid crystal tunable filter (LCTF), this invention effectively separates and optimizes the different optical signals from the lidar and gamma camera. This design eliminates the possibility of signal aliasing, improving signal separation accuracy and overall system processing efficiency.

[0131] 2. Improved system integration: By utilizing a shared SiPM array to process signals from two different sensors, the present invention significantly simplifies the system's hardware architecture, reduces the number of components and space occupancy, optimizes the layout of the optical system, and reduces the system's cost and size.

[0132] 3. Enhanced Signal Processing Flexibility: Through the tunable nature of the LCTF, the present invention can dynamically adjust the optical system's response in different operating modes to accommodate diverse detection requirements. This flexibility enables the system to rapidly adapt to specific application scenarios, enhancing its applicability and practicality.

[0133] 4. Improved reliability and accuracy of optical signals: During the initial differentiation of optical signals, the dichroic mirror reduces the probability of non-target signals entering the SiPM array. When used in conjunction with the LCTF, it can effectively improve the system's signal detection accuracy, reduce false detections and missed detections, and enhance system reliability.

[0134] 5.Optimized optical path design: Through a properly designed optical path, the signal can reach the SiPM array with minimal light loss and optimal path after passing through the dichroic mirror and LCTF, thereby improving the signal's photon detection efficiency and enhancing the performance of the entire system.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser radar and gamma camera integrated detection system based on a shared SiPM array, characterized in that: It includes laser emission module, gamma camera, optical module, SiPM array detection module, signal processing module and control module; among which, The control module is electrically connected to the laser emission module, the optical module, the SiPM array detection module and the signal processing module respectively; the SiPM array detection module is connected to the signal processing module; The optical module is arranged between the SIPM array detection module and the laser emission module and the gamma camera emission module, and is used to control the high-frequency pulse laser of the laser emission module to scan the target scene, and to guide the reflected laser beam and the flashing light signal emitted by the gamma camera to the SIPM array detection module respectively; The SIPM array detection module performs photoelectric conversion on the detected reflected laser beam and the flashing light signal to generate a corresponding electrical signal, and adjusts the gain and time gate of the electrical signal according to a preset sensor working mode to obtain a first electrical signal; the sensor working mode includes a laser radar mode and a gamma camera mode; The signal processing module receives the first electrical signal and performs laser radar ranging calculation and gamma camera imaging processing respectively to obtain three-dimensional point cloud data and radioactivity distribution image of the target scene.

2. The laser radar and gamma camera integrated detection system based on a shared SiPM array according to claim 1, characterized in that: The laser emission module comprises a laser and a first optical collimator; the control module is electrically connected to the laser; the laser is used to send high-frequency pulsed laser, and adjust the pulsed laser to form a collimated beam through the first optical collimator.

3. The laser radar and gamma camera integrated detection system based on a shared SiPM array according to claim 1, characterized in that: The optical module includes a MEMS galvanometer, a dichroic mirror, a tunable filter and an optical coupler; wherein, The MEMS galvanometer controls the high-frequency pulse laser to scan the target scene according to a preset scanning path, and refracts the laser beam reflected by the scanning into the dichroic mirror; The dichroic mirror performs optical signal filtering on the reflected laser beam according to the wavelength of the optical signal, and transmits the filtered laser beam to the tunable filter; The tunable filter performs filtering on the laser beam after filtering, and guides the laser beam after filtering to the SiPM array detection module; The optical coupler collects the scintillation light signal emitted by the gamma camera, and reflects the scintillation light signal to the SiPM array detection module through the dichroic mirror.

4. The laser radar and gamma camera integrated detection system based on a shared SiPM array according to claim 1, characterized in that: The gamma camera module comprises a scintillation crystal and a second optical collimator; the scintillation crystal generates scintillation light according to gamma rays irradiated in a target scene, and the scintillation light is collimated by the second optical collimator to obtain a scintillation light signal.

5. The laser radar and gamma camera integrated detection system based on a shared SiPM array according to claim 1, characterized in that: The SiPM array detection module includes a SiPM array and a signal processing unit; wherein, The SiPM array is used to capture the reflected laser beam and the flashing light signal and perform photoelectric conversion processing to generate an electrical signal; The signal processing unit is used to automatically adjust the gain and time gate of the electrical signal according to a preset sensor working mode to obtain a first electrical signal.

6. The laser radar and gamma camera integrated detection system based on a shared SiPM array according to claim 1, characterized in that: The signal processing module includes a distance measurement calculation unit and an image generation unit; The distance measurement calculation unit calculates the distance between the reflection point and the detection position in the target scene according to the first electrical signal, and generates three-dimensional point cloud data of the target scene according to the distance between the reflection point and the detection position; The image generation unit performs energy spectrum analysis based on the first electrical signal, and reconstructs the spatial position of the gamma ray event using a maximum likelihood estimation algorithm based on the energy spectrum analysis result, maps the spatial position to an image plane, and generates a radioactivity distribution image.

7. The laser radar and gamma camera integrated detection system based on a shared SiPM array according to claim 6, characterized in that: The distance measurement calculation unit comprises: A time flight difference calculation subunit is used to record the time flight difference ToF of each high-frequency pulse laser in the first electrical signal from the emission to the capture of the reflected laser beam by the SIPM array detection module, and calculate the distance information between each reflection point in the target scene and the detection position according to the time flight difference of the high-frequency pulse laser; The 3D point cloud generation subunit is used to calculate the 3D coordinates of the target object in space based on the distance information between each reflection point and the detection position, combined with the detection position on the scanning path, until the 3D point cloud data of the entire target scene is generated after the scanning is completed; The data optimization subunit is used to perform noise filtering and data optimization on the three-dimensional point cloud data of the target scene to obtain optimized three-dimensional point cloud data.

8. The laser radar and gamma camera integrated detection system based on a shared SiPM array according to claim 6, characterized in that: The image generating unit comprises: The photoelectric signal preprocessing subunit is used to perform signal amplitude analysis and peak detection on the first photoelectric signal, distinguish single photon events according to the signal amplitude analysis result and the peak detection result, and filter out low energy noise of the first photoelectric signal to obtain a preprocessed photoelectric signal; An energy spectrum analysis subunit, used to calculate the signal amplitude of each photon event based on the preprocessed photoelectric signal and generate the energy spectrum of the gamma ray; An event position reconstruction subunit is used to calculate a likelihood function value based on the energy spectrum of the gamma ray using a maximum likelihood estimation algorithm, and reconstruct the spatial position of the gamma ray event based on the likelihood function value; An image generation and correction subunit is used to map the spatial position of the reconstructed gamma-ray event to the image plane, generate a preliminary radioactivity distribution image, and perform nonlinear correction, spatial resolution enhancement and photon scattering correction on the preliminary radioactivity distribution image to obtain a target radioactivity distribution image; The image construction output subunit is used to accumulate frame data of the target radioactivity distribution image for multiple times, finally generate a complete radioactivity distribution image, and output the complete radioactivity distribution image in pseudo color or grayscale form.

9. The laser radar and gamma camera integrated detection system based on a shared SiPM array according to any one of claims 1 to 8, characterized in that: In the LiDAR working mode, the control module detects the target scene by coordinating and controlling the laser emission module, optical module, SiPM array detection module and signal processing module, and generates three-dimensional point cloud data of the target scene, including: The control module controls the laser emission module to emit high-frequency pulsed laser, and sends a galvanometer control signal to the MEMS galvanometer in the optical module. The MEMS galvanometer controls the motion trajectory of the high-frequency pulsed laser on the two-dimensional plane to present a Lissajous figure, and controls the high-frequency pulsed laser to scan in the target scene according to the preset Lissajous scanning path. The high-frequency pulse laser is scanned in the target scene through the MEMS galvanometer, and the reflected laser beam is refracted and introduced into the dichroic mirror. The reflected laser beam is filtered and filtered through the dichroic mirror and the tunable filter, and the reflected signal is output; The SiPM array detection module receives the reflected signal in the target scene and transmits the reflected signal to the signal processing module; The signal processing module records the time flight difference ToF corresponding to each reflected signal, and determines the distance information between each reflection point and the current detection position through ToF calculation; The signal processing module combines the distance information corresponding to each reflected signal with the current position on the Lissajous scanning path, and repeatedly calculates the three-dimensional coordinates of the target object in space until the scanning is completed, generating the three-dimensional point cloud data of the entire target scene; The three-dimensional point cloud data is subjected to noise filtering and optimization processing to obtain optimized three-dimensional point cloud data.

10. The laser radar and gamma camera integrated detection system based on a shared SiPM array according to any one of claims 1 to 8, characterized in that: In the gamma camera mode, the control module coordinates and controls the gamma camera, optical module, SiPM array detection module and signal processing module to detect gamma rays of the target scene and generate a radioactivity distribution image of the target scene, including: The gamma camera uses a scintillator to detect gamma rays in the target scene, generates scintillation light through the interaction between gamma rays and the scintillator, and collimates the scintillation light to form a scintillation light signal; The scintillation light signal generated by the gamma camera is collected through an optical coupler, and the scintillation light signal is reflected to the SiPM array detection module through a dichroic mirror; The scintillation light signal is detected by the SiPM array detection module, and the scintillation light signal is converted into an electrical signal and then input into the signal processing module; The signal processing module performs amplitude analysis and peak detection on the electrical signal, distinguishes single photon events and filters out low-energy noise in the electrical signal according to the amplitude analysis results and the peak detection results, and obtains a pre-processed photoelectric signal; Perform energy spectrum analysis on the pre-processed photoelectric signal, calculate the signal amplitude of each photon event, and generate the energy spectrum of gamma rays; The maximum likelihood estimation algorithm is used to perform maximum likelihood estimation on the preprocessed photoelectric signal, the likelihood function value of the gamma-ray event is calculated, and the spatial position of the gamma-ray event is reconstructed based on the likelihood function value; Mapping the spatial position of the gamma ray time to the image plane to generate a preliminary radioactivity distribution image, and performing nonlinear correction, spatial resolution enhancement and photon scattering correction processing on the preliminary radioactivity distribution image to obtain a target radioactivity distribution image; The frame data of the target radioactivity distribution image are accumulated multiple times to finally generate a complete radioactivity distribution image.

Images