A measuring system and method for amplifying and measuring the displacement of a light beam spot

Abstract

The present invention provides a beam spot displacement amplification measurement system and a measurement method. The focused beam to be measured is partially blocked by a diaphragm placed near the focusing focus. The beam to be measured partially blocked by the diaphragm is incident on the photosensitive surface of a position-sensitive photodetector, forming a defective spot. If the spatial position of the beam to be measured changes, the beam spot at the diaphragm blocking position will generate a displacement parallel to the blocked direction. d On the photosensitive surface of the position-sensitive photodetector, an amplified change amount of the spot defect will be generated. D = dL 2 / L 1, and the output spot displacement is amplified L 2 / L 1 times. L 1 is the distance between the diaphragm and the focusing focus in the light traveling direction. L 2 is the distance between the PSD and the focusing focus in the light traveling direction. The present invention enables the change in the position of the energy center of the spot on the position-sensitive photodetector to be amplified by the same multiple as the change in the spot size, which can greatly improve the measurement sensitivity of the beam spot displacement. The structure is simple and flexible, facilitating integration for different applications, and has a low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic detection, and particularly to a beam spot displacement amplification measurement system and a measurement method. Background Art

[0002] Due to its non-contact characteristics, optical measurement is increasingly widely used. Many optical measurement applications convert the change in the quantity to be measured into the change in the spatial position of the measurement beam, and then measure this position change through a position-sensitive detector, that is, measure the spot displacement formed by the beam on the photosensitive surface of the position-sensitive detector. The spot position detected by the position-sensitive detector is the position of the center of gravity of the spot energy. Currently, the basic usage mode of the position-sensitive detector is to make the beam form a complete spot on the photosensitive surface of the position-sensitive detector, and the position-sensitive detector detects and outputs the change in the position of the center of gravity of the spot energy caused by the overall movement of the complete spot. The position-sensitive detector in this usage mode has the advantages of a large detection range and good output linearity. However, in this usage mode of the position-sensitive detector, it is very difficult to physically amplify the spot displacement. Although a confocal double-lens structure similar to a telescopic system can be used, the magnification is not high and the system is complex, resulting in limited measurement accuracy for related applications.

[0003] The invention patent with the application number 202010704608.8 discloses an optoelectronic edge detection system and its detection method. By converting the object edge detection into the detection of the change in the position of the center of intensity of the measurement beam spot, non-contact and high-precision detection of the object edge is achieved. It can perform corresponding shaping on the measurement beam through a specific aperture according to the edge characteristics of different objects to be measured, greatly improving the sensitivity and stability of object edge detection; and the overall structure of the present invention is simple and flexible, can be adjusted for different materials with different optical properties, and is convenient for on-site measurement. However, this patent directly uses the output characteristic of the center of gravity position of the defective spot energy of the position-sensitive photodetector to identify and detect the edge of the object to be measured that blocks the measurement collimated beam, which is a kind of switch-type detection similar to determining the presence or absence. This patent is based on the output principle of the center of gravity position of the defective spot energy of the position-sensitive photodetector and its approximately linear output characteristic, combined with the optical structure of the focused beam size transformation, to achieve the displacement amplification measurement of the beam spot partially blocked by the aperture, which is a quantitative measurement. There are great differences in terms of application purpose, optical structure, and detection principle. Summary of the Invention

[0004] Aiming at the technical problems of the existing beam spot displacement detection method, such as difficult physical amplification of spot displacement, insufficient detection accuracy, complex system, and high cost, the present invention proposes a beam spot displacement amplification measurement system and a measurement method, so that the change in the position of the center of gravity of the spot energy on the position-sensitive photodetector is amplified by the same multiple as the change in the spot size, which can greatly improve the measurement sensitivity of the beam spot displacement.

[0005] In order to achieve the above object, the technical solution of the present invention is implemented as follows: a method for measuring the displacement of a beam spot by magnification, the steps of which are as follows:

[0006] Step S1: The focused light beam to be measured is partially blocked by an aperture placed near the focus point;

[0007] Step S2: the light beam to be measured that is partially blocked by the aperture is incident on the photosensitive surface of the position-sensitive photodetector, forming a defective light spot with a change in the energy center of gravity position;

[0008] Step S3: If the spatial position of the beam to be measured changes, causing the beam spot at the aperture blocking position to produce a displacement d parallel to the blocked direction, an amplified spot defect change D = dL will be generated on the photosensitive surface of the position sensitive photodetector 2 / L 1 , the spot displacement X(D) output by the position sensitive photodetector is magnified by L 2 / L 1 times; among them, L 1 L is the distance between the aperture and the focus in the direction of light travel; 2 is the distance between the position sensitive photodetector and the focusing point in the direction of light travel.

[0009] A rectangular coordinate system is established with the center of the photosensitive surface of the position-sensitive photodetector as the origin. The energy center position of the circular spot defect on the photosensitive surface is expressed as:

[0010] And d∈(0,2r), where X represents the position of the energy center of the light spot on the photosensitive surface of the position sensitive detector relative to the center of the photosensitive surface in the x-axis direction, d represents the defect width of the light spot on the photosensitive surface of the position sensitive photoelectric detector in the x-direction, r represents the spot radius when the light spot is not defective on the photosensitive surface of the position sensitive photoelectric detector, and I(x,y) represents the light intensity distribution function when the light spot is not defective on the photosensitive surface of the position sensitive photoelectric detector.

[0011] The light spot of the measured light beam incident on the photosensitive surface of the position sensitive photodetector is a circular Gaussian light spot, the center of which is located at the center of the photosensitive surface of the position sensitive photodetector. The light intensity distribution function of the Gaussian light spot is:

[0012]

[0013] Among them, I 0 is the maximum light intensity in the beam waist, and ω represents the time when the light intensity drops to the peak value. -2 The spot radius at that time, x and y represent the position coordinates on the photosensitive surface of the position sensitive photodetector.

[0014] The spot position output by the position-sensitive photodetector is as follows:

[0015]

[0016] In the formula, X represents the position of the center of gravity of the spot energy, Lx represents the length of the photosensitive surface of the position-sensitive photodetector in the x direction, and Ix+ and Ix- are the currents output by the two electrodes in the x direction respectively.

[0017] A beam spot displacement amplification measurement system includes a diaphragm and a position-sensitive photodetector. Both the diaphragm and the position-sensitive photodetector cooperate with the focused beam to be measured. The diaphragm partially blocks the focused beam to be measured. The beam to be measured is perpendicular to the photosensitive surface of the position-sensitive photodetector. The position-sensitive photodetector is located behind the focal point of the focused beam to be measured. The position-sensitive photodetector is used to receive the spot of the blocked beam to be measured. The spot of the blocked beam to be measured appears on the position-sensitive photodetector, causing a defect in the position of the center of gravity of the spot energy. The position-sensitive photodetector is connected to a signal processing unit.

[0018] The signal processing unit includes a signal processing circuit and a single-chip microcomputer / host computer. The photocurrent signal output by the position-sensitive photodetector is transmitted to the single-chip microcomputer or the host computer through the signal processing circuit.

[0019] It further includes a focusing lens. The focusing lens cooperates with the beam to be measured and is used to focus the beam to be measured. Both the diaphragm and the position-sensitive photodetector cooperate with the beam to be measured focused by the focusing lens.

[0020] When the beam to be measured is not partially blocked by the diaphragm, the size of the spot incident on the position-sensitive photodetector is smaller than the photosensitive surface of the position-sensitive photodetector.

[0021] The diaphragm is placed within a certain distance range before and after the focal point of the beam to be measured. The closer the diaphragm is to the focal point, the higher the spot displacement amplification factor.

[0022] The focusing lens can be any structure or device that converges the beam; the position-sensitive photodetector is one of a continuous position-sensitive detector PSD, a quadrant position-sensitive detector QD, a CMOS, or a CCD.

[0023] Compared with the prior art, the beneficial effects of the present invention:

[0024] 1. The present invention makes an innovative use of the physical action mechanism of a position-sensitive photodetector. By utilizing the spot position output characteristics of the position-sensitive photodetector in the spot defect mode and combining with the spot size transformation effect of a focused beam, the change in the position of the spot energy center of gravity on the position-sensitive photodetector is amplified by the same multiple as the change in the spot size, which can greatly improve the measurement sensitivity of the beam spot displacement and solve the problem of insufficient detection accuracy existing in the existing beam spot displacement detection methods.

[0025] 2. The optical structure of the measurement system of the present invention is simple and flexible, can be adjusted according to different optical path structures, is convenient for integration and integration of different applications, and has low cost, solving the problems of complex system and high cost existing in the existing beam spot displacement detection methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 It is a schematic structural diagram of the system of the present invention.

[0028] Figure 2 It is a schematic diagram of the spot position detection principle of the position-sensitive photodetector in the defective spot mode.

[0029] Figure 3 It is a characteristic curve graph of the spot position output of the position-sensitive photodetector in the defective spot mode.

[0030] In the figure: 1 is the beam to be measured, 2 is the focusing lens, 3 is the aperture, and 4 is the position-sensitive photodetector. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

[0032] Embodiment 1

[0033] As Figure 1As shown in the figure, a beam spot displacement amplification measurement system includes a focusing lens 2, a diaphragm 3 and a position-sensitive photodetector 4. The focusing lens 2 cooperates with the beam to be measured 1, and the focusing lens 2 is used to focus the beam to be measured 1. The smaller the focal length of the focusing lens 2, the more compact the optical path structure, which can be specifically selected according to needs. If the beam to be measured 1 is already focused, the focusing lens 2 can also be omitted. Both the diaphragm 3 and the position-sensitive photodetector 4 cooperate with the beam to be measured 1 focused by the focusing lens 2. The focusing lens 2, the diaphragm 3 and the position-sensitive photodetector 4 are arranged in sequence along the traveling direction of the beam to be measured 1. The axis of the focusing lens 2 is basically coincident with the beam to be measured 1 and is perpendicular to the photosensitive surface of the position-sensitive photodetector 4. The diaphragm 3 is placed near the focal point of the beam to be measured 1 after focusing to partially block the focused beam to be measured 1, so that the spot of the beam to be measured 1 on the position-sensitive photodetector 4 has a defect that causes the change of the energy center of gravity position of the spot. The diaphragm 3 can be placed within a certain distance range before and after the focal point of the beam to be measured 1. The closer it is to the focal point, the higher the spot displacement amplification factor, which can be specifically selected according to needs. The shape of the diaphragm 3 is not limited, and the degree of blocking of the beam to be measured 1 is not limited. As long as the energy center of gravity position of the spot on the photosensitive surface of the position-sensitive photodetector 4 changes after blocking, the shape of the diaphragm 3 and the degree of blocking of the beam to be measured 1 will affect the position detection sensitivity of the position-sensitive photodetector 4, and this influence is related to the shape and energy distribution of the corresponding spot of the beam to be measured 1 when it is not blocked. The shape of the diaphragm 3 and the degree of blocking of the beam to be measured 1 can be selected according to needs. The position-sensitive photodetector 4 is placed after the focal point of the beam to be measured 1. The farther it is from the focal point, the larger the area of the spot on the photosensitive surface of the position-sensitive photodetector 4, and the higher the spot displacement amplification factor. When the beam to be measured 1 is not partially blocked by the diaphragm 3, the size of the spot incident on the position-sensitive photodetector 4 should be smaller than the photosensitive surface of the position-sensitive photodetector 4. If the spatial position of the beam to be measured 1 changes, resulting in a displacement parallel to the blocked direction of the beam spot at the diaphragm blocking position, the position-sensitive photodetector 4 will output an amplified displacement of the energy center of gravity of the defective spot. The position-sensitive photodetector 4 is connected to a signal processing unit, and the signal processing unit includes a signal processing circuit and a single-chip microcomputer / host computer. The photocurrent signal output by the position-sensitive photodetector 4 is transmitted to the single-chip microcomputer or the host computer through the signal processing circuit. The signal processing circuit amplifies the weak photocurrent output by the position-sensitive photodetector, converts it into a voltage signal, and performs arithmetic operations such as addition and subtraction. The role of the single-chip microcomputer / host computer is to control the analog-to-digital conversion and data processing such as filtering and averaging of the voltage signal by writing a program, and finally give the spot position value.

[0034] Embodiment 2

[0035] A method for measuring beam spot displacement amplification includes the following steps:

[0036] S1. The focusing lens 2, the aperture 3, and the position-sensitive photodetector 4 are arranged in sequence along the traveling direction of the beam to be measured. The axis of the focusing lens 2 coincides basically with the beam to be measured 1 and is perpendicular to the photosensitive surface of the position-sensitive photodetector 4.

[0037] S2. The beam to be measured 1 is focused by the focusing lens 2. The smaller the focal length of the focusing lens, the more compact the optical path structure, which can be specifically selected according to needs. If the beam to be measured is already focused, the focusing lens can also be optionally omitted.

[0038] S3. The beam to be measured 1 is partially blocked by the aperture 3 placed near the focal point of the focusing lens 2.

[0039] S4. The beam to be measured partially blocked by the aperture 3 is perpendicularly incident on the photosensitive surface of the position-sensitive photodetector 4, forming a defective light spot. The shape of the aperture and the degree of blocking of the beam to be measured are not limited and can be selected according to needs. After the aperture 3 partially blocks, the energy center position of the light spot on the photosensitive surface of the position-sensitive photodetector 4 changes. According to the light spot position detection principle and output characteristics of the position-sensitive photodetector in the defective light spot mode, the shape of the aperture 3 and the degree of blocking of the beam to be measured 1 will affect the position detection sensitivity of the position-sensitive photodetector 4 and the displaceable range of the light spot of the beam to be measured that can be amplified, and this influence is related to the shape and energy distribution of the corresponding light spot of the beam to be measured when it is not blocked. The aperture 3 can be placed before or after the focal point of the beam to be measured 1, which can be specifically selected according to needs. Placing the aperture before or after the focal point has no impact on the principle and effect. It is mainly to consider the convenience of placement in the specific optical path structure. Sometimes, in order to make the structure compact, a plane mirror may be placed in the optical path for optical path turning, and the placement of the aperture should consider whether the space is sufficient. The position-sensitive photodetector 4 is placed after the focal point of the beam to be measured 1. The farther away from the focal point, the larger the area of the light spot on the photosensitive surface of the position-sensitive photodetector 4. When the beam to be measured 1 is not partially blocked by the aperture 3, the size of the light spot incident on the position-sensitive photodetector 4 should be smaller than the photosensitive surface of the position-sensitive photodetector 4.

[0040] The measurement method of the present invention is realized based on the light spot position detection principle and output characteristics of the position-sensitive photodetector operating in the defective light spot mode, as Figure 2 、 Figure 3 shown.

[0041] Suppose the light spot incident on the photosensitive surface of the position-sensitive photodetector 4 by the beam to be measured is a circular Gaussian light spot, and its center is located at the center of the photosensitive surface of the position-sensitive photodetector. Taking the center of the photosensitive surface of the position-sensitive photodetector as the origin, an xy rectangular coordinate system is established. The light intensity distribution of the Gaussian light spot can be expressed as:

[0042]

[0043] Where: I 0 is the maximum light intensity inside the waist, ω represents the spot radius when the light intensity drops to e -2 of the peak value. x and y represent the coordinate values of a certain point on the photosensitive surface of the position-sensitive photodetector.

[0044] As Figure 2 shown, let the spot radius when the spot on the photosensitive surface of the position-sensitive detector is intact be r, the defect is along the x direction, and the width of the defect of the spot on the photosensitive surface of the position-sensitive photodetector in the x direction is d. Then the functional relationship X(d) between the position change amount X of the energy centroid of the spot on the photosensitive surface of the position-sensitive detector relative to the center of the photosensitive surface and d can be expressed as:

[0045]

[0046] From the above formula, assuming the spot radius r is 0.5 mm, the relationship between the position change amount X of the energy centroid of the spot and the spot defect amount d was simulated using MATLAB, and the results are as shown in Figure 3 curve 1 in.

[0047] Taking the two-sided separated two-dimensional PSD as an example, the spot position output by it is calculated by the following formula:

[0048]

[0049] In the formula, X represents the position of the energy centroid of the spot in the x direction, Lx represents the length of the photosensitive surface of the position-sensitive photodetector PSD in the x direction, and Ix+ and Ix- are the currents output by the two electrodes in the x direction respectively. The position in the y direction can be obtained in the same way.

[0050] Based on formula (3), the spot position output characteristics of the PSD in the aforementioned spot defect process were experimentally verified. The experiment used a single-mode fiber-coupled semiconductor laser with a central wavelength of 635 nm and a power of 5 mw. After collimation, the diameter of the laser beam was about 1 mm. A rectangular baffle was used to gradually block the beam in the x direction, and the spot position was detected by a PSD (First senor, DL16-7-PCBA3) with a photosensitive area of 4*4 mm. The experimental results are as shown in Figure 3 curve 2.

[0051] From Figure 3 it can be seen that the experimental results are basically consistent with the simulation results. The parallel misalignment of the two curves is mainly due to the slight difference between the spot size set during the simulation and the actual spot. The latter part of curve 2 corresponds to the lower energy of the remaining spot on the photosensitive surface of the PSD, which is more affected by the background light. Therefore, the measured curve 2 is flatter than the end of the simulation curve 1.

[0052] Combining the above theoretical simulation and measured results, at the position where the spot defect is about halfway, the PSD has good position change detection sensitivity and stability, and has good linearity. The PSD was calibrated using a piezoelectric ceramic (PZT) with a resolution of 10nm to detect the displacement of the energy center of gravity of the defective spot at this position, and the position detection sensitivity was measured to be about 0.3μm. The detection sensitivity of the PSD for the position movement of a complete circular spot with a diameter of 1mm is about 0.16μm. From the perspective of directly detecting the position of the energy center of gravity of the spot, the detection sensitivity of the PSD in the defective spot mode is not as good as the conventional method based on the complete spot. However, the detection method based on the defective spot combined with a specific optical structure can bring new characteristics.

[0053] S5. If the spatial position of the light beam to be measured changes, causing the light spot of the light beam at the aperture blocking point to be displaced parallel to the blocked direction, an amplified light spot defect will be generated on the photosensitive surface of the position-sensitive photodetector, and the output light spot displacement will be amplified.

[0054] If the measured light beam 1 is blocked by the aperture 3 along the x direction, when the measured light beam 1 changes its spatial position, the focused light spot will be displaced, resulting in a defect change d of the light spot at the position of the aperture 3 along the x direction. Then, the defect change D of the light spot on the photosensitive surface of the position sensitive photodetector 4 along the x direction is:

[0055]

[0056] Among them, L 1 is the distance between the aperture and the focus in the direction of light travel; the position-sensitive photodetector 4 is located behind the focus of the light beam 1 to be measured, L 2 is the distance between the position sensitive photodetector 4 and the focus point in the direction of light travel. From the above formula and formula (2), it can be seen that as long as L 1 Small enough or L 2 If the position sensitive photodetector 4 outputs the amplified spot displacement X(D), the magnification factor of the beam spot displacement measured by the PSD will be extremely large. The root of this amplification characteristic is that the PSD can convert the spot size change factor into the spot energy center of gravity position change factor in the spot defect working mode. This characteristic has been experimentally verified. Based on the aforementioned experimental device, the sensitivity of beam spot displacement measurement is increased from 0.3μm to 10nm after adopting this structure.

[0057] Although the light beam spots of different shapes and energy distributions and the position sensitive photodetectors 4 of different structural types are slightly different in the forms of the energy distribution and energy center of gravity expression formulas (1) and (2) and the light spot position expression formula (3), the basic idea of ​​light spot position detection is the same and the same function can be achieved by the above method, which will not be elaborated one by one.

[0058] Embodiment 3

[0059] A beam spot displacement amplification measurement system, wherein the focusing lens can be any structure or device that converges light waves; if the beam to be measured is already focused, the focusing lens can be optionally omitted; the position-sensitive photodetector is a continuous position-sensitive detector PSD, a quadrant position-sensitive detector QD, a CMOS, or a CCD.

[0060] The remaining structures and measurement methods are the same as those in Embodiment 1.

[0061] In the above embodiments, the wavelength corresponding to the beam to be measured is not limited.

[0062] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for measuring the displacement amplification of a light beam spot, characterized in that, the steps are as follows: Step S1: A focusing lens, a diaphragm, and a position-sensitive photodetector are arranged in sequence along the traveling direction of the light beam to be measured. The axis of the focusing lens coincides with the light beam to be measured and is perpendicular to the photosensitive surface of the position-sensitive photodetector; Step S2: The light beam to be measured is focused by the focusing lens; Step S3: The focused light beam to be measured is partially blocked by the diaphragm placed near the focusing focus; Step S4: The light beam to be measured partially blocked by the diaphragm is incident on the photosensitive surface of the position-sensitive photodetector, forming a defective spot with a change in the energy centroid position; Step S5: If the spatial position of the beam to be measured changes, the light spot of the beam at the diaphragm occlusion will generate a displacement parallel to the occluded direction d , and an amplified change in the light spot defect will be generated on the photosensitive surface of the position-sensitive photodetector D = dL 2 / L 1 , and the light spot displacement output by the position-sensitive photodetector X ( D ) is amplified L 2 / L 1 times; Among them, L 1 is the distance between the diaphragm and the focusing focus in the light traveling direction; L 2 is the distance between the position-sensitive photodetector and the focusing focus in the light traveling direction.

2. The method for measuring the displacement amplification of a light beam spot according to claim 1, characterized in that, a rectangular coordinate system is established with the center of the photosensitive surface of the position-sensitive photodetector as the origin, and the energy centroid position of the defective circular spot on the photosensitive surface is expressed as: , and , where X represents the position of the center of gravity of the light spot energy on the photosensitive surface of the position-sensitive detector relative to the center of the photosensitive surface in the x axis direction, d represents the missing width of the light spot on the photosensitive surface of the position-sensitive photodetector in the x direction, r represents the radius of the light spot when there is no defect on the photosensitive surface of the position-sensitive detector, I ( x, y ) represents the light intensity distribution function when there is no defect on the photosensitive surface of the position-sensitive photodetector.

3. The method for measuring the displacement amplification of a light beam spot according to claim 2, characterized in that, the spot of the light beam to be measured incident on the photosensitive surface of the position-sensitive photodetector is a circular Gaussian spot, the center of which is located at the center of the photosensitive surface of the position-sensitive photodetector, and the light intensity distribution function of the Gaussian spot is: Among them, I 0 is the maximum light intensity inside the waist, ω represents the spot radius when the light intensity drops to e of the peak value -2 of the peak value, x and y represent the position coordinates on the photosensitive surface of the position-sensitive photodetector.

4. The method for measuring the displacement amplification of a light beam spot according to claim 2 or 3, characterized in that, the spot position output by the position-sensitive photodetector is: ； In the formula, X represents the position of the center of gravity of the spot energy, Lx represents the photosensitive surface of the position-sensitive photodetector x in the direction of the length, Ix+ and Ix- are respectively x the currents output from the two electrodes in the direction.

5. A measurement system using the method for measuring the displacement amplification of a light beam spot according to any one of claims 1-4, characterized in that, it includes a diaphragm (3) and a position-sensitive photodetector (4). The diaphragm (3) and the position-sensitive photodetector (4) are both matched with the focused light beam to be measured (1). The diaphragm (3) partially blocks the focused light beam to be measured (1). The light beam to be measured (1) is perpendicular to the photosensitive surface of the position-sensitive photodetector (4). The position-sensitive photodetector (4) is located after the focusing focus of the light beam to be measured (1). The position-sensitive photodetector (4) is used to receive the spot of the blocked light beam to be measured (1). The spot of the blocked light beam to be measured (1) appears on the position-sensitive photodetector (4) causing a defect in the spot energy centroid position change; the position-sensitive photodetector (4) is connected to a signal processing unit.

6. The measurement system of the method for measuring the displacement amplification of a light beam spot according to claim 5, characterized in that, the signal processing unit includes a signal processing circuit and a single-chip microcomputer / host computer. The photocurrent signal output by the position-sensitive photodetector (4) is transmitted to the single-chip microcomputer or the host computer through the signal processing circuit.

7. The measurement system of the method for measuring the displacement amplification of a light beam spot according to claim 6, characterized in that, it further includes a focusing lens (2). The focusing lens (2) is matched with the light beam to be measured (1). The focusing lens (2) is used to focus the light beam to be measured (1). The diaphragm (3) and the position-sensitive photodetector (4) are both matched with the light beam to be measured (1) focused by the focusing lens (2).

8. The measurement system of the method for measuring the displacement amplification of a light beam spot according to claim 6 or 7, characterized in that, When the beam to be measured (1) is not partially blocked by the diaphragm (3), the spot size incident on the position-sensitive photodetector (4) is smaller than the photosensitive surface of the position-sensitive photodetector (4).

9. The measurement system of the beam spot displacement amplification measurement method according to claim 7, characterized in that the diaphragm (3) is placed within a certain distance range before and after the focal point of the beam to be measured (1). The closer the diaphragm (3) is to the focal point, the higher the spot displacement amplification factor.

10. The measurement system of the beam spot displacement amplification measurement method according to claim 8, characterized in that the focusing lens can be any structure or device that converges the beam; the position-sensitive photodetector (4) is one of a continuous position-sensitive detector PSD, a quadrant position-sensitive detector QD, a CMOS, or a CCD.

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