A standard light source

Abstract

The present application discloses a standard light source, including a first amplification module, a second amplification module, a differential ratio operation module, a drive control module, a light detection module, a light emitting diode and a photosensitive sensor. The differential input terminal of the first amplification module receives a voltage setting value, and the common mode input terminal is connected to a reference voltage source; the first input terminal and the second input terminal of the differential ratio operation module are respectively connected to the input terminal of the first amplification module and the output terminal of the photodetection module; the inverting input terminal of the photodetection module is connected to the photosensitive sensor, and the positive input terminal is connected to the reference voltage source. In the present application, the first amplification module and the photodetection module are both connected to a reference voltage source. The existence of the reference voltage source increases the voltage at the static operating point of the system, so that the voltage signal amplitude of each point is larger, avoiding the phenomenon that each component has a large noise at low voltage, improving the anti-interference ability of the circuit, and especially ensuring the good performance of weak light output.

Description

Technical Field

[0001] The invention relates to the field of weak light detection, and in particular to a standard light source. Background Art

[0002] Photon technology is a weak light detection instrument, and the photomultiplier tube is a key component. In order to make the photomultiplier tube work accurately and normally, it is necessary to provide a standard light source with stable luminous intensity as a reference calibration for the photomultiplier tube.

[0003] There are some standard light source design solutions in the current technology, such as the standard light sources disclosed in patents CN 105246190A and CN107343342A, which usually include an input module, a feedback control module, a light emitting diode and a detection module. However, the output of these standard light sources is not stable enough, especially when the light output is weak, the circuit noise is large, and the light emitting diode cannot accurately output a stable light source.

[0004] Therefore, how to provide a solution to the above technical problems is a problem that those skilled in the art need to solve. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a standard light source so as to output stable and accurate light sources in various situations. The specific scheme is as follows:

[0006] A standard light source includes a first amplification module, a second amplification module, a differential ratio operation module, a drive control module, a light detection module, a light emitting diode and a photosensitive sensor, wherein:

[0007] The differential input terminal of the first amplification module receives a voltage setting value, and the common mode input terminal is connected to a reference voltage source;

[0008] The first input terminal and the second input terminal of the differential ratio operation module are respectively connected to the input terminal of the first amplification module and the output terminal of the light detection module;

[0009] The first input terminal and the second input terminal of the driving control module are respectively connected to the output terminal of the differential ratio operation module and the output terminal of the second amplification module;

[0010] The output end of the driving control module is connected to the light emitting diode to drive the light emitting diode;

[0011] The second amplifying module performs current sampling on the light emitting diode;

[0012] The photosensitive sensor generates a photoelectric signal according to the light intensity of the light emitting diode;

[0013] The inverting input terminal of the light detection module is connected to the photosensor, and the non-inverting input terminal is connected to the reference voltage source.

[0014] Preferably, the standard light source further includes:

[0015] A neutral density filter is located between the light emitting diode and the photomultiplier tube.

[0016] Preferably, the photosensor and the light emitting diode are located on the same side of the neutral density filter.

[0017] Preferably, the optical detection module includes a TIA circuit and a first resistance matching circuit with adjustable resistance.

[0018] The second amplifying module includes an amplifier and a second resistance matching circuit with adjustable resistance.

[0019] Preferably, the first resistance matching circuit comprises a plurality of first resistance switch units connected in parallel, and each of the first resistance switch units comprises a first switch and a first resistor connected in series;

[0020] The second resistance matching circuit includes a plurality of second resistance switch units connected in parallel, and each of the second resistance switch units includes a second switch and a second resistor connected in series.

[0021] Preferably, the standard light source further includes:

[0022] An MCU receiving the voltage setting value via a computer;

[0023] A digital-to-analog converter whose input end is connected to the output end of the MCU and whose output end is connected to the differential input end of the first amplification module.

[0024] Preferably, the standard light source further includes:

[0025] The current of the light emitting diode and the photosensor is sampled and sent to a status detection module of a computer.

[0026] Preferably, the photosensor is a photodiode.

[0027] Preferably, the drive control module is specifically a constant current drive control module.

[0028] Preferably, the standard light source also includes a light-proof housing provided with a light-through hole, and the first amplification module, the second amplification module, the differential proportional operation module, the drive control module, the light detection module, the light-emitting diode and the photosensor are all placed inside the light-proof housing, and the light-emitting diode illuminates the photomultiplier tube through the light-through hole.

[0029] The present application discloses a standard light source, comprising a first amplifying module, a second amplifying module, a differential ratio operation module, a driving control module, a light detection module, a light emitting diode and a photosensor, wherein: the differential input terminal of the first amplifying module receives a voltage setting value, and the common mode input terminal is connected to a reference voltage source; the first input terminal and the second input terminal of the differential ratio operation module are respectively connected to the input terminal of the first amplifying module and the output terminal of the light detection module; the first input terminal and the second input terminal of the driving control module are respectively connected to the output terminal of the differential ratio operation module and the output terminal of the second amplifying module; the output terminal of the driving control module is connected to the light emitting diode to drive the light emitting diode; the second amplifying module performs current sampling on the light emitting diode; the photosensor generates a photoelectric signal according to the light intensity of the light emitting diode; the inverting input terminal of the light detection module is connected to the photosensor, and the non-inverting input terminal is connected to the reference voltage source. In the present application, the first amplification module and the light detection module are both connected to a reference voltage source. The presence of the reference voltage source increases the voltage of the static operating point of the system, so that the voltage signal amplitude of each point is larger, thereby avoiding the phenomenon that each component has large noise at low voltage, improving the anti-interference ability of the circuit, and especially ensuring good performance of weak light output. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0031] Figure 1 This is a structural distribution diagram of a standard light source in an embodiment of the present invention;

[0032] Figure 2 This is a structural distribution diagram of a specific standard light source in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] There are some standard light source design schemes in the current technology, such as the standard light sources disclosed in patents CN 105246190A and CN107343342A. The output of the standard light source is not stable enough, especially when the light output is weak, the circuit noise is large, and the light emitting diode cannot accurately output a stable light source.

[0035] In the present application, the first amplification module and the light detection module are both connected to a reference voltage source. The presence of the reference voltage source increases the voltage of the static operating point of the system, so that the voltage signal amplitude of each point is larger, thereby avoiding the phenomenon that each component has large noise at low voltage, improving the anti-interference ability of the circuit, and especially ensuring good performance of weak light output.

[0036] The embodiment of the present invention discloses a standard light source, see Figure 1 As shown, it includes a first amplification module 1, a second amplification module 2, a differential ratio operation module 3, a drive control module 4, a light detection module 5, a light emitting diode LED and a photosensitive sensor 6, wherein:

[0037] The differential input terminal of the first amplifying module 1 receives a voltage setting value, and the common mode input terminal is connected to a reference voltage source REF;

[0038] The first input terminal and the second input terminal of the differential ratio operation module 3 are respectively connected to the input terminal of the first amplification module 1 and the output terminal of the light detection module 5;

[0039] The first input terminal and the second input terminal of the driving control module 4 are respectively connected to the output terminal of the differential ratio operation module 3 and the output terminal of the second amplification module 2;

[0040] The output end of the driving control module 4 is connected to the light emitting diode LED to drive the light emitting diode LED;

[0041] The second amplifying module 2 performs current sampling on the light emitting diode LED;

[0042] The light sensor 6 generates a photoelectric signal according to the light intensity of the light emitting diode LED;

[0043] The inverting input terminal of the light detection module 5 is connected to the photosensor 6 , and the non-inverting input terminal is connected to the reference voltage source REF.

[0044] It is understandable that if Figure 1As shown, the first amplification module 1 is specifically an amplifier, which is marked as U1; similarly, the second amplification module 2 includes an amplifier and a related matching circuit, which is marked as U2; the differential ratio operation module 3 includes a differential ratio operational amplifier U3 and a related matching circuit; the drive control module 4 is used to drive the light emitting diode LED, which is marked as U4 in the figure, and a constant current drive control module can be specifically selected to improve the response speed of the entire standard light source; the light detection module 5 can specifically include a TIA (Trans-Impedance Amplifier) ​​circuit U5 and a related matching circuit, and the TIA circuit U5 converts the photoelectric signal in the form of current into a voltage value; the photosensor 6 is used to generate a corresponding electrical signal according to the luminous intensity of the light emitting diode LED, so a photosensitive diode can be specifically selected.

[0045] The working process of the entire standard light source includes the following: the differential input end of the first amplifying module 1 receives a voltage setting value, which determines the light intensity of the entire standard light source; the light detection module 5 receives the photoelectric signal generated by the photosensor 6; the differential proportional operation module 3 simultaneously receives the signals output by the first amplifying module 1 and the light detection module 5 and processes them; the second amplifying module 2 samples the current of the light emitting diode LED and outputs an electrical signal related thereto; the driving control module 4 simultaneously receives the output signals of the differential proportional operation module 3 and the second amplifying module 2, and outputs a driving signal for driving the light emitting diode LED. The process includes two feedback loops, one is the outer loop feedback from the light detection module 5 to the differential ratio operation module 3, which takes the light intensity change of the light emitting diode LED as the feedback basis, and can effectively suppress the light intensity fluctuation of the light emitting diode LED. The light intensity fluctuation may be caused by voltage fluctuation, temperature fluctuation or aging of the light emitting diode LED device, which can be suppressed by the outer loop feedback to ensure the stability of the light intensity of the light emitting diode LED; the other is the inner loop feedback from the second amplification module 2 to the drive control module 4, which takes the current change passing through the light emitting diode LED as the feedback basis, ensures the stability of the electrical signal driving the light emitting diode LED, suppresses the current fluctuation of the light emitting diode LED, and then obtains a stable light intensity corresponding to the voltage setting value.

[0046] It should be noted that, when the standard light source is required to output weak light, its voltage setting value and the voltage value output by the light detection module 5 are both relatively small. At this time, the influence of circuit noise and zero drift on its stability must be considered. In this embodiment, both the first amplification module 1 and the light detection module 5 are connected to the reference voltage source REF. The existence of the reference voltage source REF increases the static operating point voltage of the system and ensures that the standard light source has good performance when outputting weak light. For example Figure 1In the example, when the voltage setting value is 0V, the actual common-mode voltage of the first amplification module 1 is half the voltage of the reference voltage source REF, and the output voltage value of the amplifier U1 is the same as the reference voltage source REF. When the voltage setting value is not 0, the voltage of one path increases and the voltage of the other path decreases, and its differential mode voltage is the voltage setting value. The output value of the amplifier U1 is the sum of the voltage setting value and the voltage of the reference voltage source REF. The optical detection module 5 uses the TIA circuit to convert the photoelectric signal into a voltage value, and its positive input end is connected to the reference voltage source REF. Therefore, the output voltage of the optical detection module 5 is the sum of the converted voltage value and the voltage of the reference voltage source REF. When the output ends of the first amplification module 1 and the optical detection module 5 are both connected to the differential ratio operation module 3, the differential ratio operation module 3 outputs the difference between the two, and the voltage value of the reference voltage source REF is offset. In this process, the voltage signal at each point has a large amplitude, the static operating voltage point of the system is increased, and the anti-interference ability of the circuit is significantly improved.

[0047] Furthermore, considering that the standard light source is used in the photomultiplier tube, the photomultiplier tube is required to have a wide measurable range in practical applications, usually covering 10 2 to 10 9 Therefore, the standard light source should also have a wide range of variation. Considering the requirements of output accuracy and stability, a multi-level adjustment circuit can be selected. Specifically:

[0048] The light detection module 5 includes a TIA circuit and a first resistance matching circuit with adjustable resistance.

[0049] The second amplifying module 2 includes an amplifier and a second resistance matching circuit with adjustable resistance.

[0050] Furthermore, the first resistance matching circuit and the second resistance matching circuit may be in the form of an adjustable resistance unit or in the form of an adjustable resistance unit. Figure 1 The form of the single-pole multi-throw switch and multiple optional resistors shown in the figure can also be in the form of multiple parallel resistance switch units. Specifically, the first resistance matching circuit includes multiple parallel first resistance switch units, each first resistance switch unit includes a first switch and a first resistor connected in series; the second resistance matching circuit includes multiple parallel second resistance switch units, each second resistance switch unit includes a second resistor of a second switch connected in series.

[0051] In the present application, the first amplification module and the light detection module are both connected to a reference voltage source. The presence of the reference voltage source increases the voltage of the static operating point of the system, so that the voltage signal amplitude of each point is larger, thereby avoiding the phenomenon that each component has large noise at low voltage, improving the anti-interference ability of the circuit, and especially ensuring good performance of weak light output.

[0052] The embodiment of the present invention discloses a specific standard light source. Compared with the previous embodiment, this embodiment further illustrates and optimizes the technical solution. Figure 2 As shown, the standard light source also includes:

[0053] A neutral density filter 7 is located between the light emitting diode LED and the photomultiplier tube PMT.

[0054] It can be understood that the neutral density filter 7 attenuates the light intensity. When the light intensity irradiating the photomultiplier tube PMT remains unchanged, the stability and accuracy of the standard light source with the neutral density filter 7 are significantly higher. For example, by using a neutral density filter of 0D2.0, the light intensity of the light-emitting diode LED can be reduced to 1% of the original. At this time, the adjustment target of the light-emitting diode LED inside the standard light source is 100 times the received light intensity of the photomultiplier tube PMT. The standard light source is easier to adjust inside, and at the same time, the circuit signal-to-noise ratio is improved and the light source fluctuation is reduced.

[0055] Furthermore, the photosensor 6 and the light emitting diode LED are located on the same side of the neutral density filter 7 .

[0056] It can be understood that this arrangement reduces the complexity of the process and makes the space inside the standard light source more compact.

[0057] Furthermore, under normal circumstances, standard light sources also include:

[0058] MCU 8 that receives the voltage setting value through the computer;

[0059] A digital-to-analog converter 9 whose input end is connected to the output end of the MCU 8 and whose output end is connected to the differential input end of the first amplifying module 1 .

[0060] It is understandable that the MCU 8 can also be implemented by other programmable logic modules, and the digital-to-analog converter 9 can also be replaced by an adjustable potentiometer, which is not limited here. In addition, in order to cooperate with the MCU, an analog-to-digital converter ADC is usually provided.

[0061] Furthermore, the standard light source may also include:

[0062] Current sampling is performed on the light emitting diode LED and the photosensor 6 and the current is sent to the status detection module 10 of the computer.

[0063] Specifically, the status detection module 10 can reflect the current and voltage conditions inside the standard light source. After receiving the information, the computer can determine the working status of the standard light source and perform performance testing and function diagnosis.

[0064] Furthermore, the standard light source also includes a light-proof shell provided with a light-through hole, and the first amplification module 1, the second amplification module 2, the differential ratio operation module 3, the drive control module 4, the light detection module 5, the light-emitting diode LED and the photosensor 6 are all placed inside the light-proof shell, and the light-emitting diode LED illuminates the photomultiplier tube PMT through the light-through hole.

[0065] It is understandable that the light-proof housing can reduce the interference of the external environment on the light source and improve the stability of the standard light source.

[0066] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0067] The standard light source provided by the present invention is introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A standard light source, characterized in that: It includes a first amplification module, a second amplification module, a differential ratio operation module, a drive control module, a light detection module, a light emitting diode and a photosensitive sensor, wherein: The differential input terminal of the first amplification module receives a voltage setting value, and the common mode input terminal is connected to a reference voltage source; The first input terminal and the second input terminal of the differential ratio operation module are respectively connected to the output terminal of the first amplification module and the output terminal of the light detection module; The first input terminal and the second input terminal of the driving control module are respectively connected to the output terminal of the differential ratio operation module and the output terminal of the second amplification module; The output end of the driving control module is connected to the light emitting diode to drive the light emitting diode; The second amplifying module performs current sampling on the light emitting diode; The photosensitive sensor generates a photoelectric signal according to the light intensity of the light emitting diode; The inverting input terminal of the light detection module is connected to the photosensor, and the non-inverting input terminal is connected to the reference voltage source.

2. The standard light source according to claim 1, characterized in that: Also includes: A neutral density filter is located between the light emitting diode and the photomultiplier tube.

3. The standard light source according to claim 2, characterized in that: The photosensor and the light emitting diode are located on the same side of the neutral density filter.

4. The standard light source according to claim 1, characterized in that: The optical detection module includes a TIA circuit and a first resistance matching circuit with adjustable resistance; The second amplifying module includes an amplifier and a second resistance matching circuit with adjustable resistance.

5. The standard light source according to claim 4, characterized in that: The first resistance matching circuit includes a plurality of first resistance switch units connected in parallel, each of the first resistance switch units includes a first switch and a first resistor connected in series; The second resistance matching circuit includes a plurality of second resistance switch units connected in parallel, and each of the second resistance switch units includes a second switch and a second resistor connected in series.

6. The standard light source according to claim 1, characterized in that: Also includes: An MCU receiving the voltage setting value via a computer; A digital-to-analog converter whose input end is connected to the output end of the MCU and whose output end is connected to the differential input end of the first amplification module.

7. The standard light source according to claim 1, characterized in that: Also includes: The current of the light emitting diode and the photosensor is sampled and sent to a status detection module of a computer.

8. The standard light source according to claim 1, characterized in that: The photosensitive sensor is specifically a photosensitive diode.

9. The standard light source according to claim 1, characterized in that: The drive control module is specifically a constant current drive control module.

10. The standard light source according to any one of claims 1 to 9, characterized in that: It also includes a light-proof shell with a light-through hole, wherein the first amplification module, the second amplification module, the differential ratio operation module, the drive control module, the light detection module, the light-emitting diode and the photosensor are all placed inside the light-proof shell, and the light-emitting diode illuminates the photomultiplier tube through the light-through hole.

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