A gain-adjustable four-quadrant photodetector

Abstract

The utility model belongs to photoelectric detection technical field, concretely relates to a gain adjustable four quadrant photoelectric detector, including four quadrant photodiode, first cross group amplifier TIA1, second cross group amplifier TIA2, third cross group amplifier TIA3 and fourth cross group amplifier TIA4, its characterized in that still includes: first resistance module, second resistance module, third resistance module, fourth resistance module, electric capacity C11, electric capacity C22, electric capacity C33, electric capacity C44, resistance RPA, resistance RPB, resistance RPC, resistance RPD and four-blade multi-pole switch, first resistance module, second resistance module, third resistance module and fourth resistance module structure are same, and all include at least two parallelly connected resistances. The utility model discloses a plurality of different resistance of resistance is set in each quadrant output end, utilizes four-blade multi-pole switch to realize gain adjustable, has improved the measurement range of four quadrant photoelectric detector.

Description

Technical Field

[0001] This utility model belongs to the field of photoelectric detection technology, specifically relating to a four-quadrant photoelectric detector with adjustable gain. Background Technology

[0002] Four-quadrant photodiode detectors measure spot offset. These devices consist of four identical photodiodes (or photosensitive regions) arranged in a Cartesian coordinate system, their photosensitive surfaces divided into four independent quadrants (A, B, C, D) by crosshairs, with the central intersection point serving as the detector origin. This structure allows for the calculation of the spot center offset relative to the origin by comparing the differences in light intensity received in the four quadrants. When a laser beam strikes the detector surface, the four quadrants convert the optical signal into a current signal, which is then amplified by a transimpedance amplifier to output a voltage signal. If the spot is centered, the light intensity is equal in all quadrants, and the output voltage offset is zero. If the spot is offset, for example, moving to the left, the light intensity received in quadrants A and B is greater than that in quadrant D. The system calculates the X-axis offset by measuring the output voltage difference, and the Y-axis offset is calculated similarly.

[0003] Currently, commercially available four-quadrant photodetectors convert received optical signals into electrical signals in quadrants A, B, C, and D. These signals are then amplified into voltage signals by four identical transimpedance amplifiers with fixed gains. The positional shift of the light spot is determined by the four output voltage signals. However, existing four-quadrant photodetectors all use fixed gain, which limits the power of the light spot. When the light spot power is high, the transimpedance amplifier may saturate prematurely; when the light spot power is low, the minute signal may be masked by noise, leading to measurement errors and making it impossible to accurately locate the positional shift of the light spot. For example, a transimpedance amplifier with a given power supply voltage has a maximum output voltage of 5 volts, while the transimpedance gain of a commercially available four-quadrant photodetector is typically 10 kV / A. Assuming a diode responsivity of 0.7 A / W, if the light spot power in any quadrant exceeds 0.72 mW, the transimpedance amplifier output will saturate. Therefore, fixed-gain four-quadrant photodetectors cannot flexibly switch the gain according to the light spot power, thus causing output saturation. Moreover, even if the same type of transimpedance amplifier and the same transimpedance gain are used, due to the limitations of the device's manufacturing process and its own precision, when the power of the light spot falling in the four quadrants is equal, the output voltage values ​​of the four channels may also differ, affecting the measurement accuracy.

[0004] Therefore, a fixed-gain four-quadrant photodetector cannot flexibly adjust the amplification factor according to the spot power. Moreover, even with the same amplification factor, it is easy to generate error interference due to differences in device precision, which will affect the final test results. Utility Model Content

[0005] This invention overcomes the shortcomings of the existing technology and aims to solve the following technical problem: provide a gain-adjustable four-quadrant photodetector to expand the power measurement range of the four-quadrant photodetector.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: a gain-adjustable four-quadrant photodetector, including a four-quadrant photodiode, a first cross-group amplifier TIA1, a second cross-group amplifier TIA2, a third cross-group amplifier TIA3 and a fourth cross-group amplifier TIA4, and further including: a first resistor module, a second resistor module, a third resistor module, a fourth resistor module, capacitors C11, C22, C33 and C44, resistors RPA, RPB, RPC, RPD and a four-pole multi-throw switch SW;

[0007] The first resistor module, the second resistor module, the third resistor module, and the fourth resistor module have the same structure and each includes at least two resistors connected in parallel.

[0008] The inverting input terminals of the first cross-group amplifier TIA1, the second cross-group amplifier TIA2, the third cross-group amplifier TIA3, and the fourth cross-group amplifier TIA4 are respectively connected to the output terminals of each quadrant of the four-quadrant photodiode, the non-inverting input terminal is grounded, and the output terminal is connected to its own inverting input terminal through capacitors C11, C22, C33, and C44 respectively.

[0009] In the first resistor module, one end of each resistor is connected to each of the sub-contacts of the first channel of the four-pole multi-throw switch SW, and the other end is connected to the output terminal of the first cross-group amplifier TIA1 through resistor RPA. The common contact ACOM of the first channel of the four-pole multi-throw switch SW is connected to the inverting input terminal of the first cross-group amplifier TIA1.

[0010] In the second resistor module, one end of each resistor is connected to the respective contact of the second channel of the four-pole multi-throw switch SW, and the other end is connected to the output terminal of the second cross-group amplifier TIA2 through resistor RPB. The common contact BCOM of the second channel of the four-pole multi-throw switch SW is connected to the inverting input terminal of the second cross-group amplifier TIA2.

[0011] In the third resistor module, one end of each resistor is connected to the individual contacts of the third channel of the four-pole multi-throw switch SW, and the other end is connected to the output terminal of the third cross-group amplifier TIA3 through resistor RPC. The common contact CCOM of the third channel of the four-pole multi-throw switch SW is connected to the inverting input terminal of the third cross-group amplifier TIA3.

[0012] In the fourth resistor module, one end of each resistor is connected to the respective contact of the fourth channel of the four-pole multi-throw switch SW, and the other end is connected to the output terminal of the fourth cross-group amplifier TIA4 through resistor RPD. The common contact DCOM of the fourth channel of the four-pole multi-throw switch SW is connected to the inverting input terminal of the fourth cross-group amplifier TIA4.

[0013] The first resistor module includes resistors R1, R2, and R3; the second resistor module includes resistors R4, R5, and R6; the third resistor module includes resistors R7, R8, and R9; and the fourth resistor module includes resistors R10, R11, and R12.

[0014] One end of resistors R1, R2, and R3 is connected to the first channel contacts A1, A2, and A3 of the four-pole multi-throw switch SW, respectively, and the other end is connected to the output terminal of the first cross-group amplifier TIA1 through resistor RPA.

[0015] One end of resistors R4, R5, and R6 is connected to the two contacts B1, B2, and B3 of the second channel of the four-pole multi-throw switch SW, respectively, and the other end is connected to the output terminal of the second cross-group amplifier TIA2 through resistor RPB.

[0016] One end of resistors R7, R8, and R9 is connected to the third channel contacts C1, C2, and C3 of the four-pole multi-throw switch SW, respectively, and the other end is connected to the output terminal of the third cross-group amplifier TIA3 through resistor RPC.

[0017] One end of resistors R10, R11, and R12 is connected to the four-pole multi-throw switch SW's fourth channel contacts D1, D2, and D3, respectively, and the other end is connected to the output of the fourth cross-group amplifier TIA4 via resistor RPD.

[0018] The four-pole multi-throw switch SW is a four-pole three-throw switch.

[0019] In each resistor module, the resistance values ​​of each resistor satisfy the following conditions: R1 > R2 > R3, R1 = R4 = R7 = R10, R2 = R5 = R8 = R11, R3 = R6 = R9 = R12.

[0020] In each resistor module, the resistance values ​​of each resistor satisfy the following conditions: R1=10R2=100R3, R4=10R5=100R6, R7=10R8=100R9, R10=10R11=100R12, and R1=R4=R7=R10.

[0021] The resistors RPA, RPB, RPC, and RPD are sliding rheostats.

[0022] The resistors RPA, RPB, RPC, and RPD are high-precision sliding rheostats with an accuracy higher than 0.5%.

[0023] The first cross-group amplifier TIA1, the second cross-group amplifier TIA2, the third cross-group amplifier TIA3, and the fourth cross-group amplifier TIA4 are all of model OPA182.

[0024] Compared with the prior art, this utility model has the following advantages: This utility model provides a four-quadrant photodetector with adjustable gain. By combining multiple gain levels with a four-pole multi-throw switch, the four signals can flexibly and synchronously switch levels according to the magnitude of optical power, and select the most suitable transimpedance gain. Therefore, this utility model effectively expands the power measurement range of the four-quadrant photodetector. Moreover, by setting a sliding rheostat to realize the calibration function, it can also eliminate the measurement error caused by the device accuracy and effectively eliminate the interference caused by the device accuracy error. Attached Figure Description

[0025] Figure 1 A circuit diagram of the first quadrant of a photodiode in a gain-adjustable four-quadrant photodetector provided for an embodiment of this utility model;

[0026] Figure 2 A circuit diagram of the second quadrant of a photodiode in a gain-adjustable four-quadrant photodetector provided for an embodiment of this utility model;

[0027] Figure 3 A circuit diagram of the third quadrant of a photodiode in a gain-adjustable four-quadrant photodetector provided for an embodiment of this utility model;

[0028] Figure 4 A circuit diagram of the fourth quadrant of a photodiode in a gain-adjustable four-quadrant photodetector provided for an embodiment of this utility model;

[0029] Figure 5 This is a circuit diagram of a four-quadrant photodiode in an embodiment of the present invention;

[0030] Figure 6 This is a circuit diagram of the four-pole multi-throw switch in an embodiment of this utility model. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are some embodiments of this utility model, but not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0032] like Figure 1-6 As shown, this utility model embodiment provides a gain-adjustable four-quadrant photodetector, including a four-quadrant photodiode D0, a first cross-group amplifier TIA1, a second cross-group amplifier TIA2, a third cross-group amplifier TIA3, and a fourth cross-group amplifier TIA4. It is characterized by further including: a first resistor module, a second resistor module, a third resistor module, a fourth resistor module, capacitors C11, C22, C33, and C44, resistors RPA, RPB, RPC, and RPD, and a four-pole multi-throw switch SW; wherein the first resistor module, the second resistor module, the third resistor module, and the fourth resistor module have the same structure and each includes at least two resistors connected in parallel.

[0033] Specifically, in this embodiment, the inverting input terminals of the first cross-group amplifier TIA1, the second cross-group amplifier TIA2, the third cross-group amplifier TIA3, and the fourth cross-group amplifier TIA4 are respectively connected to the output terminals of each quadrant of the four-quadrant photodiode, the non-inverting input terminal is grounded, and the output terminal is connected to its own inverting input terminal through capacitors C11, C22, C33, and C44 respectively.

[0034] Specifically, in this embodiment, one end of each resistor in the first resistor module is connected to each of the sub-contacts of the first channel of the four-pole multi-throw switch SW, and the other end is connected to the output terminal of the first cross-group amplifier TIA1 through resistor RPA. The common contact ACOM of the first channel of the four-pole multi-throw switch SW is connected to the inverting input terminal of the first cross-group amplifier TIA1.

[0035] Specifically, in this embodiment, one end of each resistor in the second resistor module is connected to each of the sub-contacts of the second channel of the four-pole multi-throw switch SW, and the other end is connected to the output terminal of the second cross-group amplifier TIA2 through resistor RPB. The common contact BCOM of the second channel of the four-pole multi-throw switch SW is connected to the inverting input terminal of the second cross-group amplifier TIA2.

[0036] Specifically, in this embodiment, one end of each resistor in the third resistor module is connected to each of the sub-contacts of the third channel of the four-pole multi-throw switch SW, and the other end is connected to the output terminal of the third cross-group amplifier TIA3 through resistor RPC. The common contact CCOM of the third channel of the four-pole multi-throw switch SW is connected to the inverting input terminal of the third cross-group amplifier TIA3.

[0037] Specifically, in this embodiment, one end of each resistor in the fourth resistor module is connected to each of the sub-contacts of the fourth channel of the four-pole multi-throw switch SW, and the other end is connected to the output terminal of the fourth cross-group amplifier TIA4 through resistor RPD. The common contact DCOM of the fourth channel of the four-pole multi-throw switch SW is connected to the inverting input terminal of the fourth cross-group amplifier TIA4.

[0038] Specifically, refer to Figure 1 In this embodiment, the first resistor module includes resistors R1, R2, and R3; the second resistor module includes resistors R4, R5, and R6; the third resistor module includes resistors R7, R8, and R9; and the fourth resistor module includes resistors R10, R11, and R12. One end of resistors R1, R2, and R3 is connected to the branch contacts A1, A2, and A3 of the first channel of the four-pole multi-throw switch SW, respectively, and the other end is connected to the output terminal of the first cross-group amplifier TIA1 through resistor RPA. One end of resistors R4, R5, and R6 is connected to the four-pole multi-throw switch. The second channel contacts B1, B2, and B3 of the SW are connected at one end to the output of the second cross-group amplifier TIA2 via resistor RPB; one end of resistors R7, R8, and R9 are connected to the third channel contacts C1, C2, and C3 of the four-pole multi-throw switch SW, respectively, and the other end is connected to the output of the third cross-group amplifier TIA3 via resistor RPC; one end of resistors R10, R11, and R12 are connected to the fourth channel contacts D1, D2, and D3 of the four-pole multi-throw switch SW, respectively, and the other end is connected to the output of the fourth cross-group amplifier TIA4 via resistor RPD.

[0039] Specifically, in this embodiment, the four-pole multi-throw switch SW is a four-pole three-throw switch.

[0040] Specifically, in this embodiment, the resistance values ​​of each resistor satisfy the following conditions: R1 > R2 > R3, R1 = R4 = R7 = R10, R2 = R5 = R8 = R11, R3 = R6 = R9 = R12. By setting different resistors in each quadrant of the four-quadrant photodiode and using a four-pole three-throw switch SW to switch the gain resistors, different gain levels can be achieved.

[0041] Furthermore, in this embodiment, the resistance values ​​of each resistor satisfy the following conditions: R1=10R2=100R3, R4=10R5=100R6, R7=10R8=100R9, R10=10R11=100R12, and R1=R4=R7=R10. Therefore, this embodiment achieves three gain adjustment levels, such as ×1K, ×10K, and ×100K, to adjust different spot power measurement levels.

[0042] In actual testing, even with the same spot power and transimpedance gain, the output voltages in the four quadrants still differed. This was mainly due to the manufacturing process and precision of the devices. To eliminate the influence of device precision on the results and ensure consistent response across the four outputs, in this embodiment, resistors RPA, RPB, RPC, and RPD were configured as sliding rheostats to adjust the gain of each channel. Since the difference in voltage output response among the four channels is not significant when the spot power and transimpedance gain are the same, in this embodiment, the resistance of the sliding rheostats should be much smaller than the gain resistors (R1, R2, R3), i.e., R13 << R3. Before testing, the standard spot was aligned with the center of the photodiode in each quadrant, and then the sliding rheostats in each quadrant were fine-tuned until the response of the four outputs was consistent.

[0043] Furthermore, in this embodiment, the resistors RPA, RPB, RPC, and RPD are high-precision sliding rheostats with an accuracy higher than 0.5%.

[0044] Specifically, in this embodiment, the first cross-group amplifier TIA1, the second cross-group amplifier TIA2, the third cross-group amplifier TIA3, and the fourth cross-group amplifier TIA4 are of model OPA182.

[0045] In this embodiment, the output voltage signals of the four signals of the four-quadrant photodetector have the following relationship with the power of the light spot:

[0046] (1)

[0047] in The output voltage signal is limited by the output voltage range of the transimpedance amplifier. The power of the light spot falling in a certain quadrant. The responsivity of a photodiode is a key performance parameter that measures its efficiency in converting incident light power into output photocurrent, measured in units of 1000 kilometres per second (kJ / m²). It is defined as how many amperes (A) of photocurrent can be generated for every watt (W) of light power incident on the photodiode. This is the transimpedance gain.

[0048] The working principle of this invention is as follows: To adapt to light spots of different power, this embodiment provides a gain-adjustable four-quadrant photodetector. It employs a multi-level manual switching method, where the transimpedance gain of the transimpedance amplifier in each quadrant ranges from low to high. When the light spot power is high, it switches to a low gain level; when the light spot power is low, it switches to a high gain level, ensuring the transimpedance amplifier always operates within its linear operating region and preventing output saturation when the light power is high. Furthermore, the gains of the four quadrants must switch synchronously to ensure that the gains of all four paths are always equal. Specifically, by setting multiple gain resistors with different resistance values ​​at the input and output terminals of the transimpedance amplifier and using a four-pole multi-throw switch to switch the gain resistors, synchronous switching of the transimpedance gain in the four quadrants can be achieved. In addition, this invention, by setting a sliding rheostat to adjust the resistance value, can also compensate for the insufficient device precision of the gain resistors, improving the detector's accuracy.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A gain-adjustable four-quadrant photodetector, comprising a four-quadrant photodiode, a first cross-group amplifier TIA1, a second cross-group amplifier TIA2, a third cross-group amplifier TIA3, and a fourth cross-group amplifier TIA4, characterized in that, Also includes: First resistor module, second resistor module, third resistor module, fourth resistor module, capacitor C11, capacitor C22, capacitor C33, capacitor C44, resistor RPA, resistor RPB, resistor RPC, resistor RPD and four-pole multi-throw switch SW; The first resistor module, the second resistor module, the third resistor module, and the fourth resistor module have the same structure and each includes at least two resistors connected in parallel. The inverting input terminals of the first cross-group amplifier TIA1, the second cross-group amplifier TIA2, the third cross-group amplifier TIA3, and the fourth cross-group amplifier TIA4 are respectively connected to the output terminals of each quadrant of the four-quadrant photodiode, the non-inverting input terminal is grounded, and the output terminal is connected to its own inverting input terminal through capacitors C11, C22, C33, and C44 respectively. In the first resistor module, one end of each resistor is connected to each of the sub-contacts of the first channel of the four-pole multi-throw switch SW, and the other end is connected to the output terminal of the first cross-group amplifier TIA1 through resistor RPA. The common contact ACOM of the first channel of the four-pole multi-throw switch SW is connected to the inverting input terminal of the first cross-group amplifier TIA1. In the second resistor module, one end of each resistor is connected to the respective contact of the second channel of the four-pole multi-throw switch SW, and the other end is connected to the output terminal of the second cross-group amplifier TIA2 through resistor RPB. The common contact BCOM of the second channel of the four-pole multi-throw switch SW is connected to the inverting input terminal of the second cross-group amplifier TIA2. In the third resistor module, one end of each resistor is connected to the individual contacts of the third channel of the four-pole multi-throw switch SW, and the other end is connected to the output terminal of the third cross-group amplifier TIA3 through resistor RPC. The common contact CCOM of the third channel of the four-pole multi-throw switch SW is connected to the inverting input terminal of the third cross-group amplifier TIA3. In the fourth resistor module, one end of each resistor is connected to the respective contact of the fourth channel of the four-pole multi-throw switch SW, and the other end is connected to the output terminal of the fourth cross-group amplifier TIA4 through resistor RPD. The common contact DCOM of the fourth channel of the four-pole multi-throw switch SW is connected to the inverting input terminal of the fourth cross-group amplifier TIA4.

2. The gain-adjustable four-quadrant photodetector according to claim 1, characterized in that, The first resistor module includes resistors R1, R2, and R3; the second resistor module includes resistors R4, R5, and R6; the third resistor module includes resistors R7, R8, and R9; and the fourth resistor module includes resistors R10, R11, and R12. One end of resistors R1, R2, and R3 is connected to the first channel contacts A1, A2, and A3 of the four-pole multi-throw switch SW, respectively, and the other end is connected to the output terminal of the first cross-group amplifier TIA1 through resistor RPA. One end of resistors R4, R5, and R6 is connected to the two contacts B1, B2, and B3 of the second channel of the four-pole multi-throw switch SW, respectively, and the other end is connected to the output terminal of the second cross-group amplifier TIA2 through resistor RPB. One end of resistors R7, R8, and R9 is connected to the third channel contacts C1, C2, and C3 of the four-pole multi-throw switch SW, respectively, and the other end is connected to the output terminal of the third cross-group amplifier TIA3 through resistor RPC. One end of resistors R10, R11, and R12 is connected to the four-pole multi-throw switch SW's fourth channel contacts D1, D2, and D3, respectively, and the other end is connected to the output of the fourth cross-group amplifier TIA4 via resistor RPD.

3. A gain-adjustable four-quadrant photodetector according to claim 2, characterized in that, The four-pole multi-throw switch SW is a four-pole three-throw switch.

4. A gain-adjustable four-quadrant photodetector according to claim 2, characterized in that, In each resistor module, the resistance values ​​of each resistor satisfy the following conditions: R1 > R2 > R3, R1 = R4 = R7 = R10, R2 = R5 = R8 = R11, R3 = R6 = R9 = R12.

5. A gain-adjustable four-quadrant photodetector according to claim 2, characterized in that, In each resistor module, the resistance values ​​of each resistor satisfy the following conditions: R1=10R2=100R3, R4=10R5=100R6, R7=10R8=100R9, R10=10R11=100R12, and R1=R4=R7=R10.

6. A gain-adjustable four-quadrant photodetector according to claim 1, characterized in that, The resistors RPA, RPB, RPC, and RPD are sliding rheostats.

7. A gain-adjustable four-quadrant photodetector according to claim 1, characterized in that, The resistors RPA, RPB, RPC, and RPD are high-precision sliding rheostats with an accuracy higher than 0.5%.

8. A gain-adjustable four-quadrant photodetector according to claim 1, characterized in that, The first cross-group amplifier TIA1, the second cross-group amplifier TIA2, the third cross-group amplifier TIA3, and the fourth cross-group amplifier TIA4 are all of model OPA182.

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