Handheld fluorescence detector

Abstract

The present invention relates to a handheld fluorescence detector, comprising a card slot, a first photoelectric switch, a second photoelectric switch, a light source, an optical path system, and a photoelectric sensor, a signal amplification circuit, a peak holding circuit, a microprocessor and an analog-to-digital converter connected in sequence. The first photoelectric switch and the second photoelectric switch are installed on the card slot to sequentially sense the reagent card inserted into the card slot. The optical path system comprises a first convex lens, a dichroic mirror, a second convex lens, a filter, and a third convex lens; the light emitted by the light source sequentially passes through the first convex lens, is reflected to the second convex lens by the dichroic mirror, passes through the second convex lens and forms a light spot on the reagent card being tested, and the excitation light sequentially passes through the second convex lens, the dichroic mirror, the filter and the third convex lens to the photoelectric sensor. The detector has a precise optical excitation and collection detection system, which can separately collect signals of the quality control line and the test line position of the reagent card, has a small amount of calculation, a fast speed, and the tester can be made smaller in size.

Description

Technical Field

[0001] The invention relates to the field of fluorescence analyzers, and in particular to a handheld fluorescence detector. Background Art

[0002] Immunoassay technology is an important medical testing method and an important part of the field of modern medical testing. Immunoassay technology is based on the specific binding phenomenon of antigen and antibody, and measures the content of another substance by labeling one substance in the antigen or antibody. Among various immunoassay technologies, immunofluorescence analysis technology has achieved rapid development in recent years due to its characteristics of simple marker preparation, multiple labels, and repeatable testing. Immunofluorescence analysis technology is divided into time resolved fluoroisnmunoassay (TRFIA), fluorescence polarization immunoassay (FPIA), and fluorometric enzyme immunoassay (FEIA), among which TRFIA has a broad application prospect. TRFIA technology is a newer ultra-micro analysis method that separates specific fluorescence from nonspecific fluorescence, greatly improving the accuracy of fluorescent immunoassay. At present, foreign TRFIA technology has entered the third era, basically realizing fully automated detection functions, and is widely used in clinical diagnosis, and emerging technologies are still developing. At present, there are many companies in China that are developing immunofluorescence analyzers, but there is a lack of standardization in related fields in China. Another current situation is that there are many large-scale time-resolved fluorescence immunoassay detection instruments for clinical testing, but there are relatively few lightweight instruments developed for POCT applications. Summary of the invention

[0003] The technical problem to be solved by the present invention is that there are few miniaturized immunofluorescence analyzer products in my country, and the equipment is basically desktop, with few handheld devices.

[0004] In order to solve the above technical problems, the present invention proposes a handheld fluorescence detector, which includes a card slot, a first photoelectric switch, a second photoelectric switch, a light source, an optical path system, and a photoelectric sensor, a signal amplification circuit, a peak holding circuit, a microprocessor and an analog-to-digital converter connected in sequence, wherein the first photoelectric switch and the second photoelectric switch are respectively connected to the microprocessor. The first photoelectric switch and the second photoelectric switch are installed on the card slot to sequentially sense the reagent card inserted into the card slot.

[0005] The optical path system includes a first convex lens, a dichroic mirror, a second convex lens, a filter, and a third convex lens. The light emitted by the light source sequentially passes through the first convex lens, is reflected to the second convex lens by the dichroic mirror, passes through the second convex lens and forms a light spot on the reagent card being tested, and the excitation light sequentially passes through the second convex lens, the dichroic mirror, the filter, and the third convex lens to the photoelectric sensor.

[0006] The distance from the first photoelectric switch to the light spot is equal to the distance from the front edge of the reagent card to the quality control line of the reagent card; the distance from the second photoelectric switch to the light spot is equal to the distance from the front edge of the reagent card to the detection line of the reagent card.

[0007] As a further improvement of the handheld fluorescence detector of the present invention, the light source is an ultraviolet lamp, and the fluorescence detector also includes a constant current LED drive circuit, and the constant current LED drive circuit is connected to the ultraviolet lamp.

[0008] As a further improvement of the handheld fluorescence detector of the present invention, the left side of the dichroic mirror inclined at 45° is the vertically arranged first convex lens, the bottom is the horizontally arranged second convex lens, and the top is the horizontally arranged filter; the light source is arranged on the left side of the first convex lens; the card slot is arranged below the second convex lens; the third convex lens is arranged above the filter; and the photoelectric sensor is arranged above the third convex lens.

[0009] As a further improvement of the handheld fluorescence detector of the present invention, the first convex lens, the second convex lens and the third convex lens are all plano-convex lenses; the convex surfaces of the first convex lens, the second convex lens and the third convex lens are all facing the dichroic mirror.

[0010] As a further improvement of the handheld fluorescence detector of the present invention, the light source is arranged at the left focus of the first convex lens, the card slot is arranged at the lower focus of the second convex lens; and the photoelectric sensor is arranged at the upper focus of the third convex lens.

[0011] As a further improvement of the handheld fluorescence detector of the present invention, the signal amplification circuit includes a connected charge-sensitive preamplifier circuit and a secondary amplifier circuit, the charge-sensitive preamplifier circuit is connected to the photoelectric sensor, and the secondary amplifier circuit is connected to the peak holding circuit; the charge-sensitive preamplifier circuit is provided with a first integrated operational amplifier; and the secondary amplifier circuit is provided with a second integrated operational amplifier.

[0012] As a further improvement of the handheld fluorescence detector of the present invention, the first integrated operational amplifier is grounded through one pin and connected to a dual capacitor through another pin; a first capacitor is provided in the charge-sensitive preamplifier circuit, and the two ends of the first capacitor are directly connected to the inverting input and output of the first integrated operational amplifier respectively; the non-inverting input of the first integrated operational amplifier is connected to a bias electrode.

[0013] As a further improvement of the handheld fluorescence detector of the present invention, a feedback resistor is also connected in parallel at both ends of the first capacitor; the inverting input end of the first integrated operational amplifier is also connected to the output end of the first resistor, and the input end of the first resistor is respectively connected to the photoelectric sensor, the first grounding capacitor and the secondary amplification circuit; the output end of the first integrated operational amplifier is also connected to the second resistor, and the second resistor is connected to the secondary amplification circuit.

[0014] As a further improvement of the handheld fluorescence detector of the present invention, the charge sensitive preamplifier circuit outputs a voltage signal which is in direct proportion to the photocurrent, and the simplified relationship between the output voltage and the input current is U out1 =R*I PD , where U out1 is the first-stage output voltage signal of the circuit, R is the resistance value of the feedback resistor, I PD is the current input to the photosensor.

[0015] As a further improvement of the handheld fluorescence detector of the present invention, the secondary amplifier circuit is a forward proportional amplifier circuit with an amplification factor of U out2 =2*U out1 -U bias1V , where U out2 is the second-stage output signal of the circuit, U bias1V is the bias voltage.

[0016] The present invention is based on indirect immunofluorescence detection method, combined with immunochromatography technology, time-resolved fluorescence immunoassay technology, and uses embedded microprocessor technology and photoelectric sensor technology to develop a miniaturized handheld fluorescence detector with rapid detection function, simple operation, and convenient on-site detection. The handheld fluorescence detector of the present invention uses time-resolved fluorescence analysis to quickly test the object to be tested, such as illicit drugs, based on the light beam emitted by fluorescence analysis. It has the characteristics of high signal-to-noise ratio, high resolution, high wavelength accuracy, etc., and can quickly complete the detection. It can be used for the detection of trace drugs in hair, and easily meets people's needs for qualitative and quantitative analysis and scientific research of illicit drugs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is an optical system diagram of the handheld fluorescence detector of the present invention.

[0018] Figure 2 4 is a circuit diagram of a constant current LED driving circuit of the present invention.

[0019] Figure 3 A structural diagram of the reagent card to be tested.

[0020] Figure 4 This is a waveform diagram of the fluorescence intensity signal focused on the photoelectric sensor, which is converted into a weak electrical signal and amplified.

[0021] Figure 5 and Figure 6 All of them are circuit diagrams of the signal amplifying circuit of the present invention.

[0022] Figure 7 This is a diagram of a photoelectric switch limit circuit provided in both the first photoelectric switch and the second photoelectric switch of the present invention.

[0023] Figure 8 This is a peak holding circuit diagram of the present invention.

[0024] Fig. 9 The following are waveform diagrams before and after peak hold.

[0025] Figure numerals: light source 1, photoelectric sensor 2, first convex lens 3, dichroic mirror 4, second convex lens 5, filter 6, third convex lens 7, reagent card 8, insertion front edge 80, charge-sensitive preamplifier circuit 9, secondary amplifier circuit 10. DETAILED DESCRIPTION

[0026] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0027] See also Figure 1 The present invention provides a handheld fluorescence detector, which includes a card slot, a first photoelectric switch, a second photoelectric switch, a light source 1, an optical path system, and a photoelectric sensor 2, a signal amplification circuit, a peak holding circuit, a microprocessor and an analog-to-digital converter connected in sequence. The first photoelectric switch and the second photoelectric switch are installed on the card slot to sequentially sense a reagent card 8 inserted into the card slot. The first photoelectric switch and the second photoelectric switch are connected to the microprocessor.

[0028] The optical path system includes a first convex lens 3, a dichroic mirror 4, a second convex lens 5, a filter 6, and a third convex lens 7. Figure 1 As shown, the left side of the dichroic mirror 4 inclined at 45° is a vertically arranged first convex lens 3, the bottom is a horizontally arranged second convex lens 5, and the top is a horizontally arranged filter 6; the light source 1 is arranged on the left side of the first convex lens 3; the card slot is arranged below the second convex lens 5; the third convex lens 7 is arranged above the filter 6; and the photoelectric sensor 2 is arranged above the third convex lens 7.

[0029] The first convex lens 3 , the second convex lens 5 and the third convex lens 7 are all plano-convex lenses; the convex surfaces of the first convex lens 3 , the second convex lens 5 and the third convex lens 7 are all facing the dichroic mirror 4 .

[0030] Specifically, the light source 1 is disposed at the left focus of the first convex lens 3 , the card slot is disposed at the lower focus of the second convex lens 5 ; and the photoelectric sensor 2 is disposed at the upper focus of the third convex lens 7 .

[0031] The light source 1 of the present invention is an ultraviolet lamp, and the fluorescence detector also includes a constant current LED drive circuit, which is connected to the ultraviolet lamp. The circuit diagram of the constant current LED drive circuit is as shown in FIG. Figure 2 As shown, it enables the UV lamp to emit controllable UV light.

[0032] The light emitted by the light source 1 passes through the first convex lens 3, forms parallel light and is projected onto the dichroic mirror 4, and is reflected by the dichroic mirror 4 to the second convex lens 5, and is converged on the reagent card 8 to form a light spot through the second convex lens 5. The fluorescent part excited on the reagent card 8 passes upward through the second convex lens 5 and becomes parallel light again. The parallel light passes through the dichroic mirror 4 and the filter 6. The filter 6 is mainly used to filter the light source of the unnecessary wavelength band, mainly the ultraviolet light source, leaving the fluorescent signal required for the test. The parallel light passing through the filter 6 continues to pass through the third convex lens and converges on the photoelectric sensor.

[0033] Please refer to Figure 3 , is a schematic diagram of the structure of the reagent card 8, which is also called an immunochromatographic reagent strip, and its rear end is a sample addition area for dripping the sample solution to be tested. After chromatography expansion, the expansion area has a detection line and a quality control line, and above the expansion area are multiple detection windows provided for the reagent card 8. As mentioned above, the first photoelectric switch and the second photoelectric switch are installed on the card slot, and sequentially sense the reagent card 8 inserted into the card slot. The specific design is that the distance from the first photoelectric switch to the light spot formed on the reagent card 8 is equal to the distance from the front edge 80 of the reagent card 8 to the quality control line (also called "C line") of the reagent card; the distance from the second photoelectric switch to the light spot formed on the reagent card 8 is equal to the distance from the front edge 80 of the reagent card 8 to the detection line (also called "T line") of the reagent card.

[0034] In the present invention, the optical system composed of the light source 1, the optical path system, and the photoelectric sensor 2 is the core part of the handheld fluorescence detector. The light source 1 generates monochromatic light close to the absorption wavelength of the fluorescent marker. After passing through the optical system, the monochromatic light is irradiated on a single scanning point (i.e., the detection window) of the reagent card 8. The fluorescent substance near the scanning point is stimulated to emit fluorescence, and the collection optical path collects the fluorescence and focuses it on the effective receiving target surface of the photoelectric sensor 2. In the process of measuring the reagent card 8, it is necessary to detect the fluorescence intensity distribution of the detection line and the quality control line of the reagent card 8. If a photodiode is used as a photoelectric conversion device alone, each conversion can only detect the fluorescence intensity within a single point. In order to be able to detect the entire reagent strip, it is necessary to detect the reagent card 8 in a scanning manner. During the process of manually inserting the reagent card 8 into the card slot of the detector, the light spot will move on the reagent card 8, that is, the reagent card 8 is detected in a scanning manner, and the fluorescence intensity signal focused on the photoelectric sensor 2 will be converted into a weak electrical signal, and then it will become a weak electrical signal after being amplified by the signal amplification circuit. Figure 4 The first photoelectric switch and the second photoelectric switch are used as trigger points to mark the positions of the T line and the C line. After the first photoelectric switch and the second photoelectric switch are triggered, the trigger signal is transmitted to the microprocessor, and the microprocessor starts the analog-to-digital converter to convert the amplified electrical signal into a digital signal and send it to the microprocessor for calculation and quantitative analysis.

[0035] The process of detecting the immunochromatographic reagent strip by the handheld fluorescence detector of the present invention is as follows:

[0036] (1) Place the sample to be tested into the sample loading area of ​​the chromatography reagent strip and wait for the chromatography and immune reaction processes to be fully completed; insert the reagent card 8 into the card slot;

[0037] (2) using the ultraviolet light source 1 and the optical path system to illuminate the first detection point in the detection window of the reagent card 8, so that the fluorescein-labeled conjugate to be detected in the detection point excites fluorescence;

[0038] (3) using a silicon photodiode (i.e., photoelectric sensor 2) to convert the optical signal into an electrical signal, which is then further amplified and converted into a digital signal and sent to a microprocessor;

[0039] (4) In order to detect the entire reagent strip, the system is manually inserted to allow the system to detect the reagent strip in a scanning manner;

[0040] (5) Two photoelectric switches are left in the device. When the reagent card 8 is inserted, the reagent card 8 blocks the first photoelectric switch and the second photoelectric switch in turn, which triggers a signal to the microprocessor. In this way, the positions of the C line and the T line are marked. At the same time, it can also be used as a detection signal for the insertion of the reagent strip. The microprocessor receives the signal from the photoelectric switch and turns on the analog-to-digital converter to convert the electrical signal of the fluorescence intensity value of the scanning point read by the photoelectric sensor into a digital signal for collection and recording. The values ​​of the C line and the T line are marked in sequence by the triggered photoelectric switches, and finally the values ​​are calculated by the microcontroller.

[0041] The photoelectric sensor 2 of the present invention is used to receive the fluorescent signal excited by the reagent card 8 to be tested and convert the fluorescent signal into a weak electrical signal.

[0042] In order to effectively measure the value of weak electrical signals, the handheld fluorescence detector is provided with a signal amplification circuit to amplify the electrical signals. Figure 5 and Figure 6 are circuit diagrams of signal amplification circuits, the signal amplification circuits including a connected charge sensitive preamplifier circuit 9 (such as Figure 5 ) and the secondary amplifier circuit 10 (such as Figure 6 ). The charge-sensitive preamplifier circuit 9 is connected to the photoelectric sensor 2, and the secondary amplifier circuit 10 is connected to the peak holding circuit. The charge-sensitive preamplifier circuit 9 is provided with a first integrated operational amplifier; and the secondary amplifier circuit 10 is provided with a second integrated operational amplifier.

[0043] The first integrated operational amplifier is grounded through one pin and connected to dual capacitors (C68 and C69 in parallel) through another pin; a first capacitor C65 is provided in the charge-sensitive preamplifier circuit 9, and the two ends of the first capacitor C65 are directly connected to the inverting input and output of the first integrated operational amplifier respectively; the non-inverting input of the first integrated operational amplifier is connected to the bias electrode.

[0044] The two ends of the first capacitor C65 are also connected in parallel with the first feedback resistor R28; the inverting input end of the first integrated operational amplifier is also connected to the output end of the first resistor R30, and the input end of the first resistor R30 is respectively connected to the photoelectric sensor PD, the first grounding capacitor C70 and the secondary amplifier circuit 10; the output end of the first integrated operational amplifier is also connected to the second resistor R61, and the second resistor R61 is connected to the secondary amplifier circuit 10.

[0045] The charge sensitive preamplifier circuit 9 has a fast response speed and is suitable for measurement systems for time and energy spectrum. The disadvantage is that the input impedance is small. The photodiode generates a photocurrent signal corresponding to the light intensity. The front end of the charge sensitive preamplifier circuit 9 is a current-voltage conversion circuit that can output a voltage signal that is proportional to the photocurrent. The simplified relationship between the output voltage and the input current is:

[0046] U out1 =R28*I PD ,

[0047] Among them U out1 is the first-stage output voltage signal of the circuit, R28 is the resistance value of the first feedback resistor, I PD is the current input to the photoelectric sensor. The capacitive reactance of the first capacitor C65 is ignored in the formula. The function of C65 is to make the circuit more stable and suppress the ringing phenomenon of the circuit. Of course, too large C65 will also cause the voltage to take too long to build up. In the circuit, resistor R28 is not only a DC feedback resistor, but also has the function of releasing the charge in capacitor C65.

[0048] The circuit diagram of the secondary amplifier circuit 10 is as follows Figure 6 As shown. In the secondary amplifier circuit 10, the in-phase input terminal of the second integrated operational amplifier is connected to the front end of the third resistor R33 and the second grounding capacitor C72, and the input terminal of the third resistor R33 is connected to the output terminal of the second resistor R61 and the input terminal of the second capacitor C71 and the input terminal of the first resistor R30; the inverting input terminal of the second integrated operational amplifier is respectively connected to the fourth resistor R55 and the second feedback resistor R56, and the other end of the fourth resistor R55 is connected to the third grounding capacitor C116 and a bias electrode. The output terminal of the second integrated operational amplifier is connected to the front end of the sixth resistor R31, and the output terminal of the sixth resistor R31 is respectively connected to the peak holding circuit and the output terminals of the second feedback resistor R56 and the second capacitor C71.

[0049] The secondary amplifier circuit 10 is a forward proportional amplifier circuit with an amplification factor of U out2 =2*U out1 -U bias1V , where U out2 is the second-stage output signal of the circuit, U bias1V is the bias voltage.

[0050] like Figure 7 As shown, the first photoelectric switch and the second photoelectric switch are both provided with a photoelectric switch limit circuit. Figure 7 The left half of the figure is the photoelectric switch limit circuit set by the first photoelectric switch. Figure 7 The right half of the figure is the photoelectric switch limit circuit set by the second photoelectric switch. During the test, the reagent card 8 is manually inserted to realize the test of the data of the reagent card 8 in a scanning manner. However, the test data of the reagent card 8 is mainly the C line and the T line. When the reagent card 8 is inserted, the reagent card 8 blocks the signal of the photoelectric switch. Figure 7 L_SW1 and L_SW2 in the circuit will trigger a high level to the microprocessor. After receiving the signal, the microprocessor will know to turn on the analog-to-digital converter to convert the electrical signal into a digital signal and collect and record it.

[0051] As mentioned above, the photoelectric switch is used to locate the position of the C line and the T line. However, there is also a problem. The placement of the photoelectric switch will be affected by the assembly and welding. If there is a deviation in the position, the test data of different equipment will likely deviate and the accuracy will be reduced. Therefore, this handheld fluorescence detector adds a peak hold circuit. The peak hold circuit diagram is as follows: Figure 8 The peak hold circuit is connected between the signal amplifier circuit and the microprocessor. Setting the peak hold circuit can hold the highest peak voltage value of the C line and the T line. In this way, as long as each photoelectric switch is behind the C line or T line to be measured, the accuracy of the photoelectric switch position positioning is not needed. The waveforms before and after the peak hold are shown in Fig. 9 As shown. Of course, after each test of the C line, the charge on the capacitor C73 in the peak holding circuit needs to be released (the C line is in front of the T line when the card is inserted, so each test will test C first and then T) to avoid affecting the data of the T line.

[0052] At present, most of the equipment uses a motor to drag the reagent strip so that the system records the spectrum waveform of the entire test in a scanning manner, and then uses a microprocessor to analyze and calculate the collected entire spectrum to obtain the data of the C line and T line. The whole system is complicated. This system triggers the photoelectric switch of the C line and T line by manual insertion. In this way, the position of the C line and T line can be easily identified, and the time of reagent card insertion can be determined. At the same time, the peak holding circuit is added to improve the test accuracy. The collected information does not need the entire spectrum, and only the signals of the C line and T line position are collected separately. The calculation amount is small, the speed is fast, the device and test method are simple, and the tester can be made smaller.

Claims

1. A handheld fluorescence detector, characterized in that: The device comprises a card slot, a first photoelectric switch, a second photoelectric switch, a light source, an optical path system, and a photoelectric sensor, a signal amplification circuit, a peak holding circuit, a microprocessor and an analog-to-digital converter connected in sequence, wherein the first photoelectric switch and the second photoelectric switch are respectively connected to the microprocessor; the first photoelectric switch and the second photoelectric switch are installed on the card slot to sequentially sense the reagent card inserted into the card slot; The optical path system includes a first convex lens, a dichroic mirror, a second convex lens, a filter, and a third convex lens; the light emitted by the light source sequentially passes through the first convex lens, is reflected by the dichroic mirror to the second convex lens, passes through the second convex lens and forms a light spot on the reagent card being tested, and the excitation light sequentially passes through the second convex lens, the dichroic mirror, the filter, and the third convex lens to the photoelectric sensor; The distance from the first photoelectric switch to the light spot is equal to the distance from the front edge of the reagent card to the quality control line of the reagent card; the distance from the second photoelectric switch to the light spot is equal to the distance from the front edge of the reagent card to the detection line of the reagent card; the signal amplification circuit includes a connected charge-sensitive preamplifier circuit and a secondary amplifier circuit, the charge-sensitive preamplifier circuit is connected to the photoelectric sensor, and the secondary amplifier circuit is connected to the peak holding circuit; the charge-sensitive preamplifier circuit is provided with a first integrated operational amplifier; the secondary amplifier circuit is provided with a second integrated operational amplifier; the first integrated operational amplifier is grounded through a pin, A dual capacitor is connected through another pin; a first capacitor is provided in the charge-sensitive preamplifier circuit, and the two ends of the first capacitor are directly connected to the inverting input and output of the first integrated operational amplifier respectively; the non-inverting input of the first integrated operational amplifier is connected to the bias electrode; a feedback resistor is also connected in parallel to the two ends of the first capacitor; the inverting input of the first integrated operational amplifier is also connected to the output of the first resistor, and the input of the first resistor is respectively connected to the photoelectric sensor, the first grounding capacitor and the secondary amplifier circuit; the output of the first integrated operational amplifier is also connected to the second resistor, and the second resistor is connected to the secondary amplifier circuit; The charge sensitive preamplifier circuit outputs a voltage signal that is proportional to the photocurrent. The simplified relationship between the output voltage and the input current is U out1 =R*I PD , where U out1 is the first-stage output voltage signal of the circuit, R is the resistance value of the feedback resistor, I PD is the current input to the photoelectric sensor; the secondary amplifier circuit is a forward proportional amplifier circuit with an amplification factor of U out2 =2*U out1 -U bias1V , where U out2 is the second-stage output signal of the circuit, U bias1V is a bias voltage; wherein, the handheld fluorescence detector detects the reagent strip in a scanning manner by manual insertion, and the first photoelectric switch and the second photoelectric switch are used as trigger points to mark the positions of the T line and the C line. After the first photoelectric switch and the second photoelectric switch are triggered, the trigger signal is transmitted to the microprocessor, and the microprocessor starts the analog-to-digital converter to convert the amplified electrical signal into a digital signal and sends it to the microprocessor for calculation and quantitative analysis.

2. The handheld fluorescence detector according to claim 1, characterized in that: The light source is an ultraviolet lamp, and the fluorescence detector also includes a constant current LED driving circuit, which is connected to the ultraviolet lamp.

3. The handheld fluorescence detector according to claim 1, characterized in that: The left side of the dichroic mirror inclined at 45° is the vertically arranged first convex lens, the bottom is the horizontally arranged second convex lens, and the top is the horizontally arranged filter; the light source is arranged on the left side of the first convex lens; the card slot is arranged below the second convex lens; the third convex lens is arranged above the filter; and the photoelectric sensor is arranged above the third convex lens.

4. The handheld fluorescence detector according to claim 3, characterized in that: The first convex lens, the second convex lens and the third convex lens are all plano-convex lenses; the convex surfaces of the first convex lens, the second convex lens and the third convex lens are all facing the dichroic mirror.

5. The handheld fluorescence detector according to claim 3, characterized in that: The light source is arranged at the left focus of the first convex lens, the card slot is arranged at the lower focus of the second convex lens; and the photoelectric sensor is arranged at the upper focus of the third convex lens.

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