A VCSEL laser testing system

Abstract

This invention aims to provide a low-cost, flexible driving method, high test coverage, and rich test functions VCSEL laser testing system. This invention includes an MCU (1), a PWM drive circuit (2), a relay switching circuit (3), an analog switch circuit (4), and an AD acquisition circuit. The PWM drive circuit (2) is connected to an external constant current power supply (6). The PWM drive circuit (2) switches different channels to drive the output of the VCSEL laser product (8) through the relay switching circuit (3). The input terminal of the analog switch circuit (4) is connected to the VCSEL laser product, and the output terminal is connected to the AD acquisition circuit. The signal acquired by the AD acquisition circuit is input to the MCU (1). The MCU (1) communicates with an external host computer (7). The MCU (1) sends a feedback signal to the PWM drive circuit (2). This invention can be applied to the field of optoelectronic product testing.

Description

Technical Field

[0001] This utility model relates to the field of optoelectronic product testing, and in particular to a VCSEL laser testing system. Background Technology

[0002] VCSELs (Vertical-Cavity Surface-Emitting Lasers) are semiconductor lasers with advantages such as small size, low power consumption, and ease of integration, and are widely used in optical communication, optical storage, industrial processing, and lidar. As a novel type of semiconductor laser, VCSELs have many advantages and promising applications, and will play an increasingly important role in the future of optoelectronics. However, current technologies for testing VCSELs are costly, requiring expensive source meters; the laser driving method is fixed, mostly using constant current drive or PWM with fixed frequency and duty cycle; there are few test channels, resulting in low test coverage; and only one function can be tested at a time, leading to limited functional testing. Utility Model Content

[0003] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a VCSEL laser testing system with low cost, flexible driving mode, high test coverage and rich test functions.

[0004] The technical solution adopted in this utility model includes an MCU, a PWM drive circuit, a relay switching circuit, an analog switch circuit, and an AD acquisition circuit. The PWM drive circuit is connected to an external constant current power supply. The PWM drive circuit switches different channels to drive the output of the VCSEL laser product through the relay switching circuit. The input terminal of the analog switch circuit is connected to the VCSEL laser product, and the output terminal is connected to the AD acquisition circuit. The signal acquired by the AD acquisition circuit is input to the MCU. The MCU is connected to an external host computer for communication. The MCU sends a feedback signal to the PWM drive circuit.

[0005] As can be seen from the above scheme, the system, constructed using an MCU, PWM drive circuit, relay switching circuit, analog switch circuit, and AD acquisition circuit, is powered by an external constant current power supply. The PWM drive circuit drives the VCSEL laser product to light up, the relay switching circuit switches at least two channel drive outputs, the analog switch circuit switches the feedback acquisition channel, and the AD acquisition circuit acquires the forward voltage, open-circuit voltage, and open-circuit current of the VCSEL product. Compared with existing technologies, this invention does not require expensive equipment such as source meters, resulting in low cost. The PWM drive can set the frequency and duty cycle through a host computer, increasing its flexibility. In addition, the relay switching circuit can switch at least two channel drive outputs, and the number of channels can be set, improving the system's test coverage. Furthermore, this system can simultaneously perform forward voltage, open-circuit voltage, and open-circuit current tests on the VCSEL laser product, greatly enriching the testing functions.

[0006] Furthermore, the MCU acquires the forward voltage of the VCSEL laser product through a first operational amplifier, acquires the open-circuit and short-circuit voltage of the VCSEL laser product through a second operational amplifier and the analog switching circuit, and acquires the open-circuit and short-circuit current of the VCSEL laser product through a third operational amplifier, a sampling resistor, and the analog switching circuit. Thus, by setting up the AD sampling circuit, multiple functions of the VCSEL laser product can be tested, enriching the system's testing capabilities.

[0007] Furthermore, the MCU is selected from an STM32F103RCT6 embedded microcontroller, and the MCU is connected to the host computer via a UART serial port. Therefore, using an STM32F103RCT6 embedded microcontroller ensures the system's processing power while also guaranteeing low power consumption and reducing energy consumption.

[0008] Furthermore, the number of channels switched via the relay switching circuit is set to 26. Therefore, the multi-channel configuration can significantly improve the system's test coverage.

[0009] Furthermore, the PWM drive circuit uses the nineteenth and twenty-sixth field-effect transistors to switch and drive the output of the 26 channels, and the PWM drive circuit amplifies the current by setting a current sensing amplifier. Therefore, by using field-effect transistors to switch channels, and utilizing the fast response characteristics of field-effect transistors, rapid channel switching is achieved, improving the system's response speed.

[0010] Furthermore, the relay switching circuit consists of several relays. Using a circuit composed of relays to achieve channel switching improves the system's reliability and response speed.

[0011] Furthermore, the analog switch circuit includes an analog switch positive terminal selection circuit and an analog switch negative terminal selection circuit. The analog switch positive terminal selection circuit includes a positive terminal selection device, a sampling circuit amplification output circuit composed of two amplifiers, and a sampling resistor selection circuit composed of several field-effect transistors and several sampling resistors with different resistance values. The analog switch negative terminal selection circuit includes a negative terminal selection device controlled by a twentieth field-effect transistor and a positive and negative voltage circuit controlled by several field-effect transistors. Therefore, by using an analog switch to switch the feedback sampling channel, corresponding to the drive output channel, the system's anti-interference capability and signal processing speed are improved.

[0012] Furthermore, the AD acquisition circuit includes a forward voltage sampling circuit, an open-circuit and short-circuit voltage sampling circuit, and an open-circuit and short-circuit current sampling circuit, with the open-circuit and short-circuit current sampling circuit consisting of two amplifiers. The arrangement of these multiple circuits, integrated into the entire system, provides richer functional testing for VCSEL laser products.

[0013] Finally, the system also includes an open / short circuit switching circuit for grounding, composed of several field-effect transistors. This open / short circuit switching circuit works in conjunction with open / short circuit current and voltage tests to achieve effective testing of open / short circuit voltage and current, ensuring the safety and reliability of the system. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the principle of this utility model;

[0015] Figure 2 This is the circuit schematic of the PWM drive circuit.

[0016] Figure 3 This is the circuit schematic diagram of the MCU and its peripheral circuits;

[0017] Figure 4 This is the circuit schematic diagram of the DC power supply and UART serial communication.

[0018] Figure 5 This is the circuit diagram of the relay switching circuit.

[0019] Figure 6 This is the circuit schematic of the AD acquisition circuit.

[0020] Figure 7 This is the circuit schematic of the analog switch positive terminal selection circuit;

[0021] Figure 8 This is the circuit schematic of the analog switch negative terminal selection circuit;

[0022] Figure 9 This is the circuit schematic of the open / short circuit test ground switching circuit. Detailed Implementation

[0023] like Figures 1 to 9 As shown, this utility model is mounted on a drive test control board. This utility model includes an MCU 1, a PWM drive circuit 2, a relay switching circuit 3, an analog switch circuit 4, and an AD acquisition circuit. The PWM drive circuit 2 is externally connected to a constant current power supply 6. The PWM drive circuit 2 switches different channels to drive the output of the VCSEL laser product 8 through the relay switching circuit 3. The input terminal of the analog switch circuit 4 is connected to the VCSEL laser product 8, and the output terminal is connected to the AD acquisition circuit. The signal acquired by the AD acquisition circuit is input to the MCU 1. The MCU 1 communicates with an external host computer 7 through a UART port. The MCU 1 sends a feedback signal to the PWM drive circuit 2. The constant current power supply 6 powers the entire system. The PWM drive circuit 2 drives and illuminates the VCSEL laser product 8. The relay switching circuit 3 switches at least two channels for drive output. In this embodiment, the number of channels switched by the relay switching circuit 3 is set to 26. Different channels can be switched for drive output as needed. The analog switch circuit 4 switches the feedback acquisition channel, and the AD acquisition circuit acquires the forward voltage, open-circuit voltage, and open-circuit current of the VCSEL laser product 8. The MCU 1 acquires the forward voltage of the VCSEL laser product 8 through the first operational amplifier 9, acquires the open-circuit voltage of the VCSEL laser product 8 through the second operational amplifier 10 and the analog switch circuit 4, and acquires the open-circuit current of the VCSEL laser product 8 through the third operational amplifier 11, the sampling resistor 12, and the analog switch circuit 4.

[0024] Specifically, the MCU 1 is selected from an STM32F103RCT6 embedded microcontroller, and the MCU 1 is connected to the host computer 7 via a UART serial port. The PWM drive circuit 2 switches and drives the output of 26 channels through the source of the nineteenth field-effect transistor Q19 and the source of the twenty-sixth field-effect transistor Q26. The PWM drive circuit 2 amplifies the current by setting a current sensing amplifier U29. The host computer 7 sends frequency and duty cycle signals to the MCU as needed, the MCU sends signals to the PWM drive circuit 2, and the PWM drive circuit 2 receives the signals from the MCU and then adjusts the frequency and duty cycle to meet different test requirements.

[0025] The relay switching circuit 3 consists of several relays. In this embodiment, it includes relays K1 to K17, with one end of each relay connected to the PWM drive circuit and the other end connected to the VCSEL laser product 8.

[0026] The analog switch circuit 4 includes an analog switch positive terminal selection circuit and an analog switch negative terminal selection circuit. The analog switch positive terminal selection circuit includes a positive terminal selection device U8, a sampling circuit amplification output circuit composed of two amplifiers U7A and U7B, and a sampling resistor selection circuit composed of several field-effect transistors (Q3-Q6) and several sampling resistors with different resistance values ​​(R21-R24). Specifically, the resistance values ​​of the sampling resistor selection circuit are 1KΩ, 20KΩ, 100KΩ, or 1MΩ. The analog switch negative terminal selection circuit includes a negative terminal selection device U9 controlled by the twentieth field-effect transistor Q20 and a positive and negative voltage circuit controlled by several field-effect transistors (Q21-Q25). The AD acquisition circuit includes a forward voltage sampling circuit (such as...). Figure 6 As shown), open-short circuit voltage sampling circuit (such as...) Figure 6 (as shown) and open / short circuit current sampling circuit (such as) Figure 7 As shown in the figure, the open-short circuit current sampling circuit consists of two amplifiers, U7A and U7B. The system also includes an open-short circuit ground switching circuit composed of several field-effect transistors, which is used to switch the ground connection during the open-short circuit test.

[0027] The working process of this utility model is as follows:

[0028] The PWM drive circuit 2 drives the VCSEL laser product 8 to light up, the relay switching circuit 3 switches at least two channel drive outputs, the analog switch circuit 4 switches the feedback acquisition channel, and the AD acquisition circuit acquires the forward voltage, open-circuit voltage and open-circuit current of the VCSEL laser product 8.

[0029] Specifically, such as Figure 2 The circuit diagram shows the PWM drive circuit. VCT_4-10V_Row1-26 and VCT_4-10V_Row6_20 are external constant current source inputs. The two MCU I / O outputs of PWM drive Q16 and Q26 MOSFETs respectively via a push-pull circuit. The constant current power supply flows through the MOSFETs into a 0.1-ohm sampling resistor and a resettable fuse output. The sampling resistor is connected to a WS74199B current amplifier chip to sample the current.

[0030] Figure 3 This is the circuit schematic of the MCU and its peripheral circuits. The STM32F103RCT6 is used as the MCU processing chip. The MCU chip, reset circuit and crystal oscillator circuit form the minimum system of the microcontroller, and the SWD interface is reserved for programming and debugging.

[0031] Figure 4This is the circuit schematic for the DC power supply and UART serial communication. The external 24V power supply is output to 5V through the asynchronous step-down chip TD1688. The 5V is then output to -3.3V through the negative voltage generator chip TD1688, powering the operational amplifiers of the acquisition circuit. Simultaneously, the 5V is output to 3.3V through the LDO to power the MCU. The UART communicates with the host computer via the FTDI chip.

[0032] Figure 5 This is the circuit diagram of the relay switching circuit. Relays K1-K13, Q65, and Q66 form a 26-channel switching circuit, used to switch the acquisition of VCSEL laser positive voltage. Row1-Row26 are connected to the 26 VCSEL laser products through FPC respectively. Row_ComIn is the voltage acquisition point. Row_ComIn switches between different VCSEL lasers through an external analog switch.

[0033] Figure 6 This is the circuit schematic of the AD acquisition circuit; the open / short-circuit positive and negative terminal voltage sampling circuit automatically switches the amplification factor between 1x / 10x / 100x, using a CD4067 analog switch to switch different test points. The positive voltage sampling circuit reduces the voltage value to prevent exceeding the MCU's reference voltage; the voltage multiplier for Row_ComIn_ADC6 is 1 / 2, and the voltage multiplier for Row_ComIn_ADC7 is 1 / 4.

[0034] Figure 7 is a circuit diagram of the analog switch positive terminal selection circuit, which switches different resistance values ​​to collect open and short circuit currents.

[0035] Figure 8 is a circuit diagram of the analog switch negative terminal selection circuit.

[0036] Figure 9 is a circuit diagram of the open / short circuit test ground switching circuit.

[0037] Finally, it should be emphasized that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. For those skilled in the art, the present utility model can have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A VCSEL laser testing system, characterized in that, The system includes an MCU (1), a PWM drive circuit (2), a relay switching circuit (3), an analog switch circuit (4), and an AD acquisition circuit. The PWM drive circuit (2) is connected to an external constant current power supply (6). The PWM drive circuit (2) switches different channels to drive the output of the VCSEL laser product (8) through the relay switching circuit (3). The input terminal of the analog switch circuit (4) is connected to the VCSEL laser product (8), and the output terminal is connected to the AD acquisition circuit. The analog switch circuit (4) switches the feedback acquisition channel. The signal acquired by the AD acquisition circuit is input to the MCU (1). The MCU (1) is connected to the external host computer (7). The MCU (1) sends a feedback signal to the PWM drive circuit (2).

2. The VCSEL laser testing system according to claim 1, characterized in that, The MCU (1) acquires the forward voltage of the VCSEL laser product (8) through the first operational amplifier (9), the MCU (1) acquires the open and short circuit voltage of the VCSEL laser product (8) through the second operational amplifier (10) and the analog switch circuit (4), and the MCU (1) acquires the open and short circuit current of the VCSEL laser product (8) through the third operational amplifier (11), the sampling resistor (12) and the analog switch circuit (4).

3. The VCSEL laser testing system according to claim 1, characterized in that, The MCU (1) is selected from the embedded microcontroller model STM32F103RCT6. The MCU (1) is connected to the host computer (7) via UART serial port (13).

4. A VCSEL laser testing system according to any one of claims 1 to 3, characterized in that, The number of channels switched by the relay switching circuit (3) is set to 26.

5. A VCSEL laser testing system according to claim 4, characterized in that, The PWM drive circuit (2) uses the nineteenth field-effect transistor (Q19) and the twenty-sixth field-effect transistor (Q26) to switch and drive the output of 26 channels. The PWM drive circuit (2) amplifies the current by setting a current sensing amplifier (U29).

6. The VCSEL laser testing system according to claim 4, characterized in that, The relay switching circuit (3) consists of several relays.

7. The VCSEL laser testing system according to claim 4, characterized in that, The analog switch circuit (4) includes an analog switch positive terminal selection circuit (14) and an analog switch negative terminal selection circuit (15). The analog switch positive terminal selection circuit (14) includes an analog switch (U8) and a sampling resistor selection circuit composed of several field-effect transistors and several sampling resistors with different resistance values. The analog switch negative terminal selection circuit includes a negative terminal selection device (U9) controlled by the twentieth field-effect transistor (Q20) and a positive and negative voltage circuit controlled by several field-effect transistors.

8. A VCSEL laser testing system according to claim 4, characterized in that, The AD acquisition circuit includes a forward voltage sampling circuit, an open-circuit and short-circuit voltage sampling circuit, and an open-circuit and short-circuit current sampling circuit. The open-circuit and short-circuit current sampling circuit consists of two amplifiers (U7A and U7B).

9. A VCSEL laser testing system according to claim 8, characterized in that, The system also includes an open / short circuit switching circuit for grounding, consisting of several field-effect transistors.

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