A composite modulated excitation light source system for photomultiplier tube testing

Abstract

The application discloses a composite modulation excitation light source system for photomultiplier tube testing, comprising a control module, an analog light modulation module, a driving module, a switch module and a light source module. The control module outputs an analog light modulation setting signal and a pulse timing control signal; the analog light modulation module generates an analog reference voltage according to the analog light modulation setting signal; the driving module sets and stabilizes the driving current according to the analog reference voltage; the switch module is connected in parallel to the light source module and controls the on-off of the driving current path according to the pulse timing control signal to generate a pulsed current excitation; the light source module comprises at least two groups of light emitting elements with different wavelengths, which respectively output continuous light or pulsed light under the driving current or pulsed current excitation. The application realizes high-precision continuous light modulation, high-speed pulse modulation and multi-wavelength switching in the same system, and can meet the multi-parameter testing requirements of PMT gain calibration, linearity and time response.

Description

Technical Field

[0001] This application relates to the field of light source technology, and in particular to a composite modulation excitation light source system for photomultiplier tube testing. Background Technology

[0002] As a high-sensitivity photodetector, the performance testing of a photomultiplier tube (PMT) relies on a highly stable excitation light source to calibrate key parameters such as gain, linearity, and time response. Current testing light sources mostly employ lasers or ordinary LED driving schemes.

[0003] While lasers possess excellent timing characteristics, they also suffer from inherent drawbacks such as high cost, large size, and complex intensity regulation. LED-based driving solutions, despite their simple structure and low cost, face a core technological bottleneck: existing LED driving architectures struggle to simultaneously achieve wide dynamic range, high-precision continuous intensity regulation, nanosecond-level high-speed pulse response, and flexible multi-wavelength switching within the same system. This results in significant deficiencies in light intensity stability, pulse edge quality, and spectral adaptability, failing to fully meet the demands of multi-parameter, high-precision PMT testing. Summary of the Invention

[0004] To address the shortcomings mentioned above, this application provides a composite modulation excitation light source system for photomultiplier tube testing.

[0005] Firstly, to achieve the above objectives, this application provides a composite modulation excitation light source system for photomultiplier tube testing, comprising: The control module outputs analog dimming setting signals and pulse timing control signals; An analog dimming module is connected to the control module to receive the analog dimming setting signal and generate at least one analog reference voltage according to the analog dimming setting signal. A light source module comprising at least two sets of light-emitting elements with different emission wavelengths; A driving module is connected to the reference setting module to receive the analog reference voltage and set the driving current according to the analog reference voltage to output to the light-emitting element in the light source module, so as to stabilize the driving current of the light-emitting element. A switching module is connected in parallel across the two ends of the light source module. The switching module receives the pulse timing control signal and controls the on / off state of the driving current path according to the pulse timing control signal to generate pulsed current excitation. Each group of light-emitting elements outputs continuous light or pulsed light of the corresponding wavelength under the driving current or the pulsed current excitation.

[0006] Preferably, the analog dimming module is a multi-channel digital-to-analog converter, which receives data from the control module through a digital communication bus and outputs multiple independent analog reference voltages, which respectively control the driving current paths of each group of light-emitting elements.

[0007] Preferably, the driving module includes an operational amplifier, which acquires the current feedback signal in the driving current path of the light-emitting element, compares the current feedback signal with the analog reference voltage, and dynamically adjusts the driving current according to the comparison result.

[0008] Preferably, the switching module includes a driver chip and a power switch transistor. The driver chip performs level conversion and current amplification on the pulse timing control signal to drive the power switch transistor, thereby accelerating the turn-on and turn-off speed of the power switch transistor.

[0009] Preferably, the analog dimming setting signal and the pulse timing control signal output by the control module control different paths respectively. The analog dimming setting signal forms a stable DC drive current through the analog dimming module and the drive module. The pulse timing control signal controls the on / off state of the DC drive current through the switching module to form a pulsed current excitation on the light source module, thereby realizing the composite control of analog continuous dimming and digital pulse modulation.

[0010] Preferably, the control module controls the on / off timing of the switching module by adjusting the frequency, pulse width, and duty cycle of the pulse timing control signal, so that the light source module outputs single-pulse light, periodic pulse light, or variable-width pulse light.

[0011] Preferably, the control module switches between different channels of the light-emitting element and combines the analog dimming setting signal with the pulse timing control signal to enable the light source module to switch outputs between different wavelengths, and each wavelength channel has independent analog dimming and pulse modulation capabilities.

[0012] Preferably, the two sets of light-emitting elements with different emission wavelengths in the light-emitting module are violet LEDs and blue LEDs, respectively.

[0013] Preferably, the control module configures the analog dimming module via the SPI bus and outputs the pulse timing control signal via an independent pulse output interface.

[0014] Preferably, it also includes a power supply module, which is connected to an external power source and provides power to the control module, analog dimming module, drive module, switch module and light source module.

[0015] Compared with the prior art, the beneficial effects of this application are as follows: This application achieves wide dynamic range, high-precision continuous dimming, nanosecond-level high-speed pulse response, and flexible multi-wavelength switching through the coordinated operation of a control module, an analog dimming module, a drive module, a switching module, and a dual-wavelength light source module. It effectively solves the technical bottleneck of existing LED excitation light source systems that are difficult to balance light intensity stability, pulse edge quality, and spectral adaptability. It can fully meet the comprehensive testing requirements of multiple parameters such as PMT gain calibration, linearity testing, and time response characteristic testing. At the same time, the configuration of dual-wavelength light-emitting elements allows the system to adapt to the spectral response characteristics of different types of PMTs, further expanding the scope of testing applications. Attached Figure Description

[0016] Figure 1 This is a flowchart of the composite modulation excitation light source system for photomultiplier tube testing in this application; Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] This application provides a composite modulation excitation light source system for photomultiplier tube testing, including a control module 1, an analog dimming module 2, a drive module 3, a switch module 4, a light source module 5, and a power supply module.

[0019] Control module 1 is used to generate analog dimming setting signals and pulse timing control signals. The output terminals of control module 1 are connected to analog dimming module 2 and switch module 4 respectively. One output is the analog dimming setting signal to analog dimming module 2, and the other output is the pulse timing control signal to the control terminal of switch module 4.

[0020] In some implementations, control module 1 is implemented using an FPGA (Field-Programmable Gate Array). FPGAs have abundant programmable logic resources and flexible I / O interfaces, enabling them to simultaneously generate high-precision SPI control signals and high-speed PWM pulse signals. Through the FPGA's internal clock management unit, the pulse timing can be precisely controlled to meet the stringent time resolution requirements of PMT testing.

[0021] Control module 1 can also be implemented using MCU (microcontroller) or CPLD (complex programmable logic device), as long as it can generate analog dimming setting signal and pulse timing control signal at the same time.

[0022] The analog dimming module 2 is connected to the control module 1 and is used to receive the analog dimming setting signal and generate at least one analog reference voltage output to the drive module 3 based on the signal.

[0023] In some implementations, the analog dimming module 2 is implemented using a dual-channel high-precision digital-to-analog converter (DAC) chip, AD5689. This chip is connected to the control module 1 via an SPI bus, receives configuration data sent by the control module 1, and converts the digital setpoint into a high-precision analog voltage output. The AD5689 has two independent output channels, which can output two analog reference voltages respectively, corresponding to control the drive current paths of the two sets of light-emitting elements.

[0024] The analog dimming module 2 receives configuration data from the control module 1 via the SPI interface. The control signals include SDI, SCLK, SCS, LDAC, and reset signals, enabling precise configuration of the DAC output voltage. Because the DAC has high resolution (16-bit for AD5689), it can achieve fine-grained light intensity control.

[0025] In other embodiments, the analog dimming module 2 can also use other types of multi-channel DAC chips, as long as they have sufficient accuracy and number of channels.

[0026] The drive module 3 is connected to the analog dimming module 2 to receive the analog reference voltage, and sets the drive current according to the analog reference voltage to output to the light-emitting element in the light source module 5 to stabilize the drive current of the light-emitting element.

[0027] In some implementations, the drive module 3 employs a high-speed, low-noise operational amplifier ADA4807 to form a closed-loop constant current control structure. The non-inverting input of the operational amplifier receives an analog reference voltage from the analog dimming module 2, while the inverting input acquires the current feedback signal in the drive current path of the light-emitting element (typically achieved through a sampling resistor). The operational amplifier compares the analog reference voltage with the current feedback signal and dynamically adjusts the conduction level of the power transistor based on the comparison result, keeping the drive current constant at a set value.

[0028] Because of the closed-loop control method, even if the LED forward voltage drop, ambient temperature or power supply voltage changes, the driver module 3 can still maintain a stable driving current, thereby ensuring the consistency of the output light intensity.

[0029] The drive module 3 specifically includes an operational amplifier and a power regulation transistor (such as a MOSFET). The output of the operational amplifier is connected to the control terminal of the power regulation transistor, and the magnitude of the drive current is controlled by adjusting the conduction level of the power regulation transistor.

[0030] The control terminal of switch module 4 is connected to control module 1, and switch module 4 is connected in parallel across the two ends of light source module 5. Switch module 4 receives the pulse timing control signal output by control module 1, and controls the on / off state of the drive current path according to the signal to generate pulsed current excitation.

[0031] In some implementations, the switching module 4 includes a high-speed driver chip and a power switching transistor. The high-speed driver chip uses a UCC27511 to perform level conversion and current amplification on the PWM pulse timing control signal output by the control module 1, thereby improving the charging and discharging speed of the power switching transistor's gate. The high-speed switching signal after driving controls the power switching transistor (such as an N-channel MOSFET) to quickly turn on and off, causing the constant drive current to form a high-steep pulse current.

[0032] By changing the frequency, pulse width, and duty cycle of the PWM signal, single-pulse excitation, periodic pulse output, light pulses of different widths, and test light sources with different repetition frequencies can be achieved, meeting the needs of PMT time response testing and high-speed sampling testing.

[0033] The power switch can be a MOSFET, IGBT, or other semiconductor switching devices with high-speed switching characteristics. The driver chip is selected based on the type of power switch chosen.

[0034] The light source module 5 connects the drive module 3 and the switch module 4, and includes at least two sets of light-emitting elements with different emission wavelengths. Each set of light-emitting elements outputs continuous light or pulsed light of the corresponding wavelength under the excitation of drive current or pulsed current.

[0035] In some embodiments, the light source module 5 includes two sets of LEDs with different wavelengths: the first LED is a violet LED, and the second LED is a blue LED. The two sets of LEDs each have independent drive current paths and are respectively connected to the drive module 3 and the switch module 4.

[0036] Testers can select LEDs of corresponding wavelengths based on the spectral response characteristics of different PMTs, or switch wavelengths through the control system, thereby improving the adaptability of the test system. Each group of LEDs has independent analog dimming and pulse modulation control paths, allowing for independent parameter configuration.

[0037] The light-emitting element is not limited to LEDs; it can also be a laser diode (LD) or other electroluminescent device, as long as it can output a light signal of the corresponding wavelength under current drive. The wavelength of the light-emitting element is not limited to violet and blue light; other wavelengths, such as green and red light, can be selected according to actual testing requirements.

[0038] The power module connects to an external power source and provides power at different voltage levels to the control module 1, analog dimming module 2, drive module 3, switch module 4, and light source module 5.

[0039] In some implementations, the system uses a 12V DC power input, and the power module includes an input protection unit and a multi-stage voltage conversion unit.

[0040] The input protection unit is equipped with a fuse and a transient voltage suppressor (TVS) to achieve overcurrent protection and surge suppression, preventing damage to the system caused by abnormal external power supply.

[0041] The multi-stage voltage conversion unit includes a switching power supply conversion subunit and a linear regulator subunit. The switching power supply conversion subunit converts the 12V input voltage to 8V for LED driver-related circuits, while also generating 5.6V and 5V for subsequent analog and digital modules. The linear regulator subunit further generates 7.5V, 5.3V, and 3.3V through a low-noise linear regulator, providing low-noise power to high-speed analog circuits, DACs, and digital interfaces, respectively.

[0042] The multi-stage power supply method balances power conversion efficiency and low noise performance, reducing the impact of power supply ripple on LED light intensity stability. In one implementation, a 7.5V power supply powers the operational amplifier in driver module 3, while 5.3V and 3.3V power supplies power the DAC chip in analog dimming module 2.

[0043] The following is combined Figure 1 The overall working process of the system in the embodiments of this application will be described in detail.

[0044] First, the power module converts the external 12V DC input into multiple stable voltages to power the various modules of the system.

[0045] When the system needs to output continuous light, control module 1 generates an analog dimming setting signal and outputs it to analog dimming module 2. Analog dimming module 2 (such as DAC AD5689) converts this digital signal into an analog reference voltage and outputs it to driver module 3. The operational amplifier in driver module 3 (such as ADA4807) compares the analog reference voltage with the current feedback signal and adjusts the conduction level of the power transistor in a closed loop to form a stable DC drive current output to light source module 5. At this time, control module 1 controls switch module 4 to remain continuously closed, and the light-emitting element in light source module 5 outputs continuous light under the drive of the stable DC drive current.

[0046] When the system needs to output pulsed light, control module 1 generates two signals simultaneously: one is an analog dimming setting signal, which forms a stable DC drive current through analog dimming module 2 and drive module 3; the other is a pulse timing control signal (PWM), which is directly output to the control terminal of switch module 4. The high-speed drive chip (such as UCC27511) in switch module 4 performs level conversion and current amplification on the PWM signal to drive the power switch transistor, so that the drive current path quickly turns on and off according to the PWM timing, thereby forming a pulsed current excitation with fast rising and falling edges on the light source module 5, and the light-emitting element outputs corresponding pulsed light.

[0047] By adjusting the digital setpoint output from control module 1 to analog dimming module 2, the amplitude of the drive current can be changed, thereby achieving analog adjustment of the peak intensity of the light pulse. By adjusting the frequency, pulse width, and duty cycle of the PWM signal output from control module 1, output control of single pulse, periodic pulse, or variable width pulse can be achieved.

[0048] When it is necessary to switch wavelengths, the control module 1 selects the corresponding light-emitting element channel and outputs the corresponding analog reference voltage to the driving current path of the corresponding channel through the analog dimming module 2. At the same time, the switching module 4 controls the on / off of this path, so that different wavelength light signals can be output.

[0049] In a specific test embodiment, the above system was used to test a certain model of PMT. The system selected a violet LED (wavelength 415nm) and a blue LED (wavelength 465nm) as dual-wavelength light sources. The test results showed that in simulated dimming mode, the drive current stability was better than ±0.5%, and the light intensity modulation resolution reached more than 12 bits; in pulse modulation mode, the rise and fall times of the light pulse were both less than 10ns, the minimum pulse width reached 20ns, and the maximum repetition frequency reached 25MHz; the dual-wavelength switching response time was less than 1ms. The above indicators fully verified the effectiveness and superiority of the system in PMT performance testing.

[0050] In other embodiments, the number of light-emitting elements is three or more groups, each corresponding to three or more different emission wavelengths, to accommodate a wider range of spectral testing needs. Control module 1 selects the corresponding channel of analog dimming module 2 via a chip select signal, and achieves independent control of light-emitting elements of different wavelengths through channel selection by switching module 4.

[0051] In other implementations, the control module 1 connects to the host computer via communication interfaces such as Ethernet, USB, or RS232 to receive test commands and parameter configurations from the host computer, thereby enabling remote control and automated testing.

[0052] In other embodiments, the system may also include a temperature compensation module for detecting the ambient temperature and feeding it back to the control module 1. The control module 1 then corrects and compensates the analog dimming setting signal based on temperature changes, further reducing the impact of temperature drift on the output light intensity.

[0053] The composite modulation excitation light source system for photomultiplier tube testing provided in this application can be widely used in PMT production test lines, high-energy physics experiments, nuclear radiation detection equipment calibration, medical imaging equipment calibration, and fluorescence detection instruments, etc., and has significant industrial practical value and application prospects.

[0054] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A composite modulation excitation light source system for testing photomultiplier tubes, characterized in that, include: The control module outputs analog dimming setting signals and pulse timing control signals; An analog dimming module is connected to the control module to receive the analog dimming setting signal and generate at least one analog reference voltage based on the analog dimming setting signal. A light source module comprising at least two sets of light-emitting elements with different emission wavelengths; A driving module is connected to the reference setting module to receive the analog reference voltage and set the driving current according to the analog reference voltage to output to the light-emitting element in the light source module, so as to stabilize the driving current of the light-emitting element. A switching module is connected in parallel across the two ends of the light source module. The switching module receives the pulse timing control signal and controls the on / off state of the driving current path according to the pulse timing control signal to generate pulsed current excitation. Each group of light-emitting elements outputs continuous light or pulsed light of the corresponding wavelength under the driving current or the pulsed current excitation.

2. The composite modulation excitation light source system for photomultiplier tube testing according to claim 1, characterized in that, The analog dimming module is a multi-channel digital-to-analog converter. It receives data from the control module through a digital communication bus and outputs multiple independent analog reference voltages, which respectively control the driving current paths of each group of light-emitting elements.

3. The composite modulation excitation light source system for photomultiplier tube testing according to claim 1, characterized in that, The driving module includes an operational amplifier, which collects the current feedback signal in the driving current path of the light-emitting element, compares the current feedback signal with the analog reference voltage, and dynamically adjusts the driving current according to the comparison result.

4. The composite modulation excitation light source system for photomultiplier tube testing according to claim 1, characterized in that, The switching module includes a driver chip and a power switch. The driver chip performs level conversion and current amplification on the pulse timing control signal to drive the power switch, thereby accelerating the turn-on and turn-off speed of the power switch.

5. The composite modulation excitation light source system for photomultiplier tube testing according to claim 1, characterized in that, The analog dimming setting signal and the pulse timing control signal output by the control module control different paths respectively. The analog dimming setting signal forms a stable DC drive current through the analog dimming module and the drive module. The pulse timing control signal controls the on / off state of the DC drive current through the switching module to form a pulsed current excitation on the light source module, thereby realizing the composite control of analog continuous dimming and digital pulse modulation.

6. The composite modulation excitation light source system for photomultiplier tube testing according to claim 1, characterized in that, The control module controls the on / off timing of the switching module by adjusting the frequency, pulse width, and duty cycle of the pulse timing control signal, so that the light source module outputs single-pulse light, periodic pulse light, or variable-width pulse light.

7. The composite modulation excitation light source system for photomultiplier tube testing according to claim 1, characterized in that, The control module switches between different channels of the light-emitting element and combines the analog dimming setting signal with the pulse timing control signal to enable the light source module to switch outputs between different wavelengths, and each wavelength channel has independent analog dimming and pulse modulation capabilities.

8. The composite modulation excitation light source system for photomultiplier tube testing according to claim 1, characterized in that, The two sets of light-emitting elements with different emission wavelengths in the light-emitting module are violet LEDs and blue LEDs.

9. The composite modulation excitation light source system for photomultiplier tube testing according to claim 1, characterized in that, The control module configures the analog dimming module via the SPI bus and outputs the pulse timing control signal through an independent pulse output interface.

10. The composite modulation excitation light source system for photomultiplier tube testing according to claim 1, characterized in that, It also includes a power supply module, which is connected to an external power source and provides power to the control module, analog dimming module, drive module, switch module and light source module.

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