CN112146851B - Method and device for measuring size and shape of light spot - Google Patents

Method and device for measuring size and shape of light spot Download PDF

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CN112146851B
CN112146851B CN202011034301.8A CN202011034301A CN112146851B CN 112146851 B CN112146851 B CN 112146851B CN 202011034301 A CN202011034301 A CN 202011034301A CN 112146851 B CN112146851 B CN 112146851B
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light
scanning
measured
slit
target
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CN112146851A (en
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尹志军
崔国新
叶志霖
许志城
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Nanjing Nanzhi Institute Of Advanced Optoelectronic Integration
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Nanjing Nanzhi Institute Of Advanced Optoelectronic Integration
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/02—Testing optical properties
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/02—Details
    • G01J1/04—Optical or mechanical part supplementary adjustable parts
    • G01J1/0403—Mechanical elements; Supports for optical elements; Scanning arrangements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/02—Details
    • G01J1/04—Optical or mechanical part supplementary adjustable parts
    • G01J1/0407—Optical elements not provided otherwise, e.g. manifolds, windows, holograms, gratings
    • G01J1/0462—Slit arrangements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J1/4257—Photometry, e.g. photographic exposure meter using electric radiation detectors applied to monitoring the characteristics of a beam, e.g. laser beam, headlamp beam
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J2001/4247—Photometry, e.g. photographic exposure meter using electric radiation detectors for testing lamps or other light sources

Abstract

The application provides a method and a device for measuring the size and the shape of a light spot. The method comprises the following steps: scanning light spots to be measured along a target scanning direction by utilizing a plurality of light-transmitting slits of which the widths are not integral multiple in a slit assembly, determining the light intensity of the light spots to be measured at the target scanning position according to the Fourier transform result of the target scanning light power and the Fourier transform result of the light power transmittance at the target scanning position, and finally determining the size and the shape of the light spots to be measured according to the light intensity distribution of the light spots to be measured in the target scanning direction and the other scanning direction. So, this application embodiment adopts a plurality of printing opacity slits that there is not integer multiple relation in width to scan the facula of awaiting measuring to the light intensity of the facula of awaiting measuring is confirmed according to the Fourier transform of scanning optical power and the Fourier transform of optical power transmissivity, measures and does not receive the influence of facula self size and printing opacity slit width, can measure the less facula of size more accurately.

Description

Method and device for measuring size and shape of light spot
Technical Field
The present disclosure relates to the field of photoelectric technology, and more particularly, to a method and an apparatus for measuring the size and shape of a light spot.
Background
Since the invention has been invented, laser has been widely used in many fields such as communication, industry, military, medical treatment, environmental protection, consumer electronics, etc., and the development speed is faster and faster. In practical applications, a laser is a key device for generating laser, and the spot size and shape of the generated laser are important parameters reflecting the performance of the laser, and also important parameters of the laser in applications, such as metal finishing in industrial fields, laser suture technology in medical fields, laser positioning in military fields, and the like.
The spot refers to a focal point of the laser focused on the irradiated object in a vertical state, and the size and the shape of the spot are generally reflected by measuring the light intensity distribution of the spot. The current commonly used method for measuring the size and the shape of the light spot is a slit method, which mainly adopts a slit with a certain size to scan the light spot, detects the light power penetrating through the slit, and directly reflects the light intensity distribution of the light spot according to a distribution curve of the detected light power changing along with the scanning displacement. Theoretically, the smaller the width of the slit used, the more accurate the measurement results. However, in practical applications, if the width of the slit is too small, the light power transmitted through the slit is very low, and when the measured spot power is low, the power is insufficient, which may cause difficulty in detection; meanwhile, the slit is limited by the existing manufacturing method, and the width is usually 50-100um, so the existing manufacturing method also restricts the further reduction of the slit width, and when a small (such as 20um diameter) light spot is measured, the difference between the slit width and the light spot size is large, so the deviation between the detected light power curve and the original light spot size is large, and the accuracy is low. For the above reasons, when the prior art is used to measure the size and shape of the light spot, the accuracy of measurement is greatly affected by the size of the light spot and the width of the slit, so that the light spot with small size cannot be measured accurately.
Based on this, there is a need for a method for measuring the size and shape of a light spot, which is used to solve the problem that the size and shape of the light spot cannot be measured accurately due to the influence of the size of the light spot and the width of the slit when the size and shape of the light spot are measured in the prior art.
Disclosure of Invention
The application provides a method and a device for measuring the size and the shape of a light spot, which can be used for solving the technical problem that the size of the light spot cannot be accurately measured due to the influence of the size of the light spot and the width of a slit when the size and the shape of the light spot are measured in the prior art.
In a first aspect, an embodiment of the present application provides a method for measuring a size and a shape of a light spot, where the method includes:
acquiring a light spot to be measured;
acquiring a pre-constructed slit group device; the slit group device is used for measuring the light spot to be measured and comprises an opaque substrate and a light-transmitting slit array processed on the opaque substrate at preset intervals; the light-transmitting slit array comprises a plurality of light-transmitting slits which are parallel to each other along the array direction; the height of the light-transmitting slit is greater than the maximum height of the light spot to be measured in two preset mutually orthogonal scanning directions; the widths of any two light-transmitting slits are not in integral multiple relation;
scanning the light spot to be measured along a target scanning direction by using the slit group device to obtain scanning light power penetrating through the slit group device at different scanning positions; the target scanning direction is any one of two mutually orthogonal scanning directions preset by the light spot to be measured;
aiming at the target scanning direction, acquiring the light power transmittance of a slit group device;
respectively carrying out Fourier transform on the scanning light power and the light power transmittance at a target scanning position to obtain a target scanning light power Fourier transform result and a light power transmittance Fourier transform result; the target scanning position is any one scanning position in the target scanning direction;
determining the light intensity of the light spot to be measured at the target scanning position according to the light power transmittance Fourier transform result and the target scanning light power Fourier transform result;
acquiring light intensity distribution of the light spot to be measured in each scanning direction; the light intensity distribution includes light intensities at all scanning positions;
and determining the size and the shape of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions.
In an implementation manner of the first aspect, the scanning the light spot to be measured along a target scanning direction by using the slit group apparatus to obtain scanning optical power transmitted through the slit group apparatus at different scanning positions includes:
determining the scanning initial position of the slit group device according to the target scanning direction, the preset initial distance between the slit group device and the light spot to be measured, the array direction of the plurality of light transmission slits and the height of the light transmission slits; the scanning initial position of the slit group device comprises the bottom edge center initial positions of a plurality of light-transmitting slits;
establishing a scanning coordinate system by taking the initial position of the bottom edge center of the target light-transmitting slit as an origin, the target scanning direction as a transverse axis and the direction vertical to the target scanning direction as a longitudinal axis; the target light-transmitting slit is any one of the light-transmitting slits;
and scanning the light spot to be measured along the target scanning direction from the scanning initial position by using the slit group device at a preset speed, and acquiring the scanning light power passing through the slit group device at different scanning positions.
In an implementation manner of the first aspect, the obtaining the optical power transmittance of the slit group apparatus includes:
and determining the optical power transmittance of the slit group device according to the width value of each light-transmitting slit, the abscissa value of the initial position of the bottom edge center of each light-transmitting slit and the abscissa value of any position of the plane where the slit group device is located.
In an implementation manner of the first aspect, the determining, according to the width value of each light-transmitting slit, an abscissa value of an initial position of a center of a bottom edge of each light-transmitting slit, and an abscissa value of any position of a plane where the slit group device is located, an optical power transmittance of the slit group device includes:
the optical power transmittance of the slit group device is determined by the following formula:
Figure BDA0002704729480000021
wherein g (x) is the optical power transmittance of the slit group device, rect represents a rectangular function, x is the abscissa value of any position of the plane where the slit group device is located, cjIs an abscissa value, w, of the initial position of the center of the bottom edge of the jth light-transmitting slitjThe width value of the jth light-transmitting slit is defined, j is an integer greater than or equal to 1 and less than or equal to N, and N is the number of light-transmitting slits in the slit assembly.
In an implementation manner of the first aspect, the determining, according to the optical power transmittance fourier transform result and the target scanning optical power fourier transform result, the light intensity of the light spot to be measured at the target scanning position includes:
determining the light intensity of the light spot to be measured at the target scanning position by the following formula:
Figure BDA0002704729480000022
wherein, b (x)0) For the light intensity, x, of the light spot to be measured at the target scanning position0Is the abscissa value, F (k), of the target scanning position0) For the target scanning optical power Fourier transform result, k0As spatial frequency, G (k)0) As a result of the optical power transmittance fourier transform,
Figure BDA0002704729480000031
is an inverse fourier transform.
In an implementation manner of the first aspect, the determining the size and the shape of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions includes:
determining the two-dimensional light intensity distribution of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions; the two-dimensional light intensity distribution is used for reflecting the size and the shape of the light spot to be measured.
In an implementation manner of the first aspect, the determining the two-dimensional light intensity distribution of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions includes:
determining the two-dimensional light intensity distribution of the light spot to be measured by the following formula:
S(x，y)＝b(x)×a(y)
wherein S (x, y) is a two-dimensional light intensity distribution of the light spot to be measured, b (x) is a light intensity distribution of the light spot to be measured in the target scanning direction, a (y) is a light intensity distribution of the light spot to be measured in another scanning direction orthogonal to the target scanning direction, x is an abscissa value of a scanning position of the slit group device in the target scanning direction, and y is an abscissa value of a scanning position of the slit group device in another scanning direction orthogonal to the target scanning direction.
In one implementation manner of the first aspect, the slit group apparatus further includes a laser power meter; the laser power meter is arranged on the light-tight substrate and used for acquiring scanning light power penetrating through the slit group device at different scanning positions.
In a second aspect, embodiments of the present application provide a device for measuring a size and a shape of a light spot, the device including:
the first acquisition unit is used for acquiring a light spot to be measured;
a second acquisition unit for acquiring a previously constructed slit group device; the slit group device is used for measuring the light spot to be measured and comprises an opaque substrate and a light-transmitting slit array processed on the opaque substrate at preset intervals; the light-transmitting slit array comprises a plurality of light-transmitting slits which are parallel to each other along the array direction; the height of the light-transmitting slit is greater than the maximum height of the light spot to be measured in two preset mutually orthogonal scanning directions; the widths of any two light-transmitting slits are not in integral multiple relation;
the scanning unit is used for scanning the light spot to be measured along a target scanning direction by using the slit group device and acquiring scanning light power penetrating through the slit group device at different scanning positions; the target scanning direction is any one of two mutually orthogonal scanning directions preset by the light spot to be measured;
a third obtaining unit, configured to obtain, for the target scanning direction, an optical power transmittance of the slit group apparatus;
the processing unit is used for respectively performing Fourier transform on the scanning light power and the light power transmittance at a target scanning position to obtain a target scanning light power Fourier transform result and a light power transmittance Fourier transform result; the target scanning position is any one scanning position in the target scanning direction; determining the light intensity of the light spot to be measured at the target scanning position according to the light power transmittance Fourier transform result and the target scanning light power Fourier transform result; acquiring light intensity distribution of the light spot to be measured in each scanning direction; the light intensity distribution includes light intensities at all scanning positions; and determining the size and the shape of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions.
In an implementable manner of the second aspect, the scanning unit is specifically configured to:
determining the scanning initial position of the slit group device according to the target scanning direction, the preset initial distance between the slit group device and the light spot to be measured, the array direction of the plurality of light transmission slits and the height of the light transmission slits; the scanning initial position of the slit group device comprises the bottom edge center initial positions of a plurality of light-transmitting slits;
establishing a scanning coordinate system by taking the initial position of the bottom edge center of the target light-transmitting slit as an origin, the target scanning direction as a transverse axis and the direction vertical to the target scanning direction as a longitudinal axis; the target light-transmitting slit is any one of the light-transmitting slits;
and scanning the light spot to be measured along the target scanning direction from the scanning initial position by using the slit group device at a preset speed, and acquiring the scanning light power passing through the slit group device at different scanning positions.
In an implementation manner of the second aspect, the third obtaining unit specifically includes:
and the optical power transmittance determining module is used for determining the optical power transmittance of the slit group device according to the width value of each light-transmitting slit, the abscissa value of the initial position of the center of the bottom edge of each light-transmitting slit and the abscissa value of any position of the plane where the slit group device is located.
In an implementation manner of the second aspect, the optical power transmittance determining module is specifically configured to:
determining the optical power transmittance of the slit group device by the following formula:
Figure BDA0002704729480000041
wherein g (x) is the optical power transmittance of the slit group device, rect represents a rectangular function, x is the abscissa value of any position of the plane where the slit group device is located, cjIs an abscissa value, w, of the initial position of the center of the bottom edge of the jth light-transmitting slitjThe width value of the jth light-transmitting slit is defined, j is an integer greater than or equal to 1 and less than or equal to N, and N is the number of light-transmitting slits in the slit assembly.
In an implementation manner of the second aspect, the processing unit specifically includes:
the light intensity determination module is used for determining the light intensity of the light spot to be measured at the target scanning position according to the following formula:
Figure BDA0002704729480000042
wherein, b (x)0) For the light intensity, x, of the light spot to be measured at the target scanning position0Is the abscissa value of the target scanning position,F(k0) For the target scanning optical power Fourier transform result, k0As spatial frequency, G (k)0) As a result of the optical power transmittance fourier transform,
Figure BDA0002704729480000043
is an inverse fourier transform.
In an implementation manner of the second aspect, the processing unit further includes:
the measurement result acquisition module is used for determining the two-dimensional light intensity distribution of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions; the two-dimensional light intensity distribution is used for reflecting the size and the shape of the light spot to be measured.
In an implementation manner of the second aspect, the measurement result obtaining module is specifically configured to:
determining the two-dimensional light intensity distribution of the light spot to be measured by the following formula:
S(x，y)＝b(x)×a(y)
wherein S (x, y) is a two-dimensional light intensity distribution of the light spot to be measured, b (x) is a light intensity distribution of the light spot to be measured in the target scanning direction, a (y) is a light intensity distribution of the light spot to be measured in another scanning direction orthogonal to the target scanning direction, x is an abscissa value of a scanning position of the slit group device in the target scanning direction, and y is an abscissa value of a scanning position of the slit group device in another scanning direction orthogonal to the target scanning direction.
In an implementation manner of the second aspect, the slit group apparatus acquired by the second acquiring unit further includes a laser power meter; the laser power meter is arranged on the light-tight substrate and used for acquiring scanning light power penetrating through the slit group device at different scanning positions.
Therefore, in the slit group device, the light transmission slits with the widths not having the integral multiple relation are used for scanning the light spots to be measured, the light intensity of the light spots to be measured in the target scanning position is determined according to the Fourier transform result of the target scanning light power and the Fourier transform result of the light power transmittance in the target scanning position, the light intensity distribution of the light spots to be measured in the target scanning direction and the other scanning direction orthogonal to the target scanning direction is further determined, and the size and the shape of the light spots to be measured are finally determined. The whole process determines the light intensity of the light spot to be measured according to the Fourier transform of the scanning light power and the Fourier transform of the light power transmittance, the measurement is not influenced by the size of the light spot and the width of the light transmission slit, and the measurement accuracy is higher even if the light spot with smaller size is measured; meanwhile, the widths of the plurality of light-transmitting slits are not in integral multiple relation, so that the situation that the light intensity cannot be solved in a Fourier transform mode is avoided, and the practicability is high.
Drawings
Fig. 1 is a schematic flow chart corresponding to a method for measuring a spot size and a spot shape according to an embodiment of the present disclosure;
fig. 2 is a schematic diagram of light intensity distribution of a light spot formed by a gaussian beam in a preset direction according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of a slit group apparatus according to an embodiment of the present disclosure;
fig. 4 is a schematic view of scanning optical power passing through a slit group device at different scanning positions according to an embodiment of the present disclosure;
FIG. 5 is a schematic diagram of transmittance of an exemplary slit group according to an embodiment of the present disclosure
Fig. 6 is a schematic diagram of light intensity distribution of an exemplary light spot in a target scanning direction in a specific example provided by the embodiment of the present application;
fig. 7 is a schematic diagram of scanning optical power passing through an exemplary slit group device at different scanning positions in a specific example provided by an embodiment of the present application;
FIG. 8a is a Fourier transform of scanned optical power in a specific example provided by an embodiment of the present application;
fig. 8b is a fourier transform result of optical power transmittance in a specific example provided by an embodiment of the present application;
fig. 8c is a fourier transform result of an exemplary light spot intensity distribution in a specific example provided by the embodiment of the present application;
fig. 9 is a schematic diagram illustrating the shape of an exemplary light spot in the target scanning direction in a specific example provided by the embodiment of the present application;
fig. 10 is a schematic structural diagram of a device for measuring the size and shape of a light spot according to an embodiment of the present application.
Detailed Description
To make the objects, technical solutions and advantages of the present application more clear, the following detailed description of the embodiments of the present application will be made with reference to the accompanying drawings.
In order to solve the prior art problem, the embodiment of the application provides a method for measuring the size and the shape of a light spot, and the method is particularly used for solving the problem that the size of the light spot cannot be accurately measured due to the influence of the size of the light spot and the width of a slit when the size and the shape of the light spot are measured in the prior art. Fig. 1 is a schematic flow chart corresponding to a method for measuring a spot size and a spot shape according to an embodiment of the present disclosure. The method specifically comprises the following steps:
step 101, obtaining a light spot to be measured.
Step 102, a pre-constructed slot group device is obtained.
And 103, scanning the light spot to be measured along the target scanning direction by using the slit group device, and acquiring the scanning light power which penetrates through the slit group device at different scanning positions.
And 104, acquiring the optical power transmittance of the slit group device according to the target scanning direction.
And 105, performing Fourier transform on the scanning light power and the light power transmittance at the target scanning position respectively to obtain a target scanning light power Fourier transform result and a light power transmittance Fourier transform result.
And 106, determining the light intensity of the light spot to be measured at the target scanning position according to the light power transmittance Fourier transform result and the target scanning light power Fourier transform result.
And step 107, acquiring the light intensity distribution of the light spot to be measured in each scanning direction.
And 108, determining the size and the shape of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions.
Specifically, in step 101, the light spot provided in the embodiment of the present application refers to a laser light spot, and the laser light spot is generally a gaussian beam and forms a light spot with a certain beam waist radius when being irradiated on an object to be irradiated. The shapes of the light spots are various, generally in a Laguerre-Gaussian shape, and the sizes and the shapes of the light spots are mainly reflected through the light intensity distribution condition. The light intensity of the light spot is in Gaussian distribution in the low-order mode, the light spot can form a plurality of split shapes in the high-order mode, and the shape of the light spot is more complex when a plurality of high-order modes are mixed. Fig. 2 schematically shows a light intensity distribution diagram of a light spot formed by a gaussian beam in a preset direction, provided by the embodiment of the present application. As shown in fig. 2, the spot radius is 10 μm, the horizontal axis represents the position in the preset direction, and the vertical axis represents the light intensity.
In step 102, fig. 3 schematically illustrates a structural schematic diagram of a slit group apparatus provided in an embodiment of the present application. As shown in fig. 3, the slit group apparatus 300 is used for measuring a light spot to be measured, and includes an opaque substrate 301, and a light-transmitting slit array 302 processed on the opaque substrate 301 at a predetermined interval Δ d. The light transmission slit array 302 comprises a plurality of light transmission slits 303 parallel to each other along the array direction, the height h of each light transmission slit 303 is greater than the maximum height of a light spot to be measured in two preset mutually orthogonal scanning directions, and the widths w of any two light transmission slits 303 are not in integral multiple. Specifically, three light transmission slits are exemplarily shown in fig. 3, w1, w2, and w3 are widths of the three light transmission slits, Δ d1 and Δ d2 are preset intervals between adjacent light transmission slits, and h is a height of the light transmission slit.
The slit group device provided by the embodiment of the application further comprises a laser power meter. The laser power meter is arranged on the opaque substrate and used for acquiring the scanning light power penetrating through the slit group device at different scanning positions. The laser power meter probe may be a photodiode, a thermal sensor, a pyroelectric sensor, or the like, and is not particularly limited.
The more the number of the light-transmitting slits in the slit assembly provided by the embodiment of the application is, the more accurate the scanned result is, but because the number is too much, the more difficult the subsequent calculation is caused, so that the skilled person in the art can determine the number of the light-transmitting slits in the slit assembly according to experience and actual requirements, and the specific limitation is not made.
The opaque substrate of the slit group device can be processed by a method of plating a metal reflecting film on the surface of glass, polymer or other transparent materials, and is not particularly limited; the light-transmitting slit array can be processed on the light-tight substrate by a method of laser cutting or etching by a photolithographic mask, and is not limited specifically.
Two mutually orthogonal scanning directions, such as a horizontal direction and a vertical direction, are preset for a light spot to be measured before measurement, and the size and the shape of the light spot can be determined by determining light intensity distribution in the two scanning directions. For two mutually orthogonal scanning directions to be selected, the height of the light-transmitting slit needs to be larger than the maximum height of the light spot to be measured in the two mutually orthogonal scanning directions, that is, the light-transmitting slit should be high enough to completely cover the whole light spot when scanning in any scanning direction.
The width of the light-transmitting slits is not particularly limited as long as there is no integral multiple relationship between the widths of any two light-transmitting slits. For example, three light-transmitting slits having widths of 70 μm, 100 μm and 170 μm, respectively.
The slit group device is adopted to scan the light spot to be measured, the size of the light transmission slit on the slit group device is determined flexibly, the width of the light transmission slit does not need to be reduced as much as possible when the size of the light spot is smaller, the processing difficulty of the light transmission slit is reduced, and the slit group device has higher practicability.
In step 103, the target scanning direction indicates any one of two mutually orthogonal scanning directions preset for the light spot to be measured. In practical application, when scanning the light spot to be measured, the slit group device can be kept still, and the light spot can be moved; the slit group device can also be moved while keeping the light spot still.
After the target scanning direction is determined, the slit group device is used for scanning the light spots to be measured along the target scanning direction, the scanning light power penetrating through the slit group device at different scanning positions is obtained, and the specific scanning process and the process of obtaining the scanning light power are as follows:
and determining the scanning initial position of the slit group device according to the target scanning direction, the initial distance between the preset slit group device and the light spot to be measured, the array direction of the plurality of light transmission slits and the height of the light transmission slits. The scanning initial position of the slit group device comprises the bottom edge center initial position of a plurality of light-transmitting slits.
And establishing a scanning coordinate system by taking the initial position of the bottom edge center of the target light-transmitting slit as an origin, the target scanning direction as a horizontal axis and the direction vertical to the target scanning direction as a vertical axis. Wherein, the target light-transmitting slit is any one of the light-transmitting slits.
And scanning the light spot to be measured along the target scanning direction from the scanning initial position by using the slit group device according to a preset speed, and acquiring the scanning light power passing through the slit group device at different scanning positions.
Specifically, when the scanning initial position of the slit group device is determined, firstly, the direction of the slit group device needs to be adjusted according to the target scanning direction, so that the array direction of the plurality of light-transmitting slits is parallel to the target scanning direction; and secondly, determining the scanning initial position of the slit group device according to the preset initial distance between the slit group device and the light spot to be measured and the height of the light-transmitting slit. That is to say, the target scanning direction determines the direction of the light-transmitting slit array, the initial distance between the preset slit group device and the light spot to be measured determines the approximate position of the slit group device, the height of the light-transmitting slit needs to completely cover the light spot during scanning, so that the candidate range of the initial position of the slit group device is further narrowed, and under the condition that the light spot can be completely covered during scanning of the light-transmitting slit, one position of the slit group device can be selected as the initial scanning position within an appropriate height range. When the initial scanning position of the slit group device is determined, the initial positions of the centers of the bottom sides of the plurality of light-transmitting slits are also determined simultaneously. Regarding the initial distance between the slit group device and the light spot to be measured, in one example, the distance between the center of the bottom edge of any one of the light transmission slits and the center of the bottom edge of the light spot to be measured may be used as the preset initial distance between the slit group device and the light spot to be measured, and in other possible examples, the distance between the center of any one of the light transmission slits and the center of the light spot to be measured may also be used as the preset initial distance between the slit group device and the light spot to be measured, which is not limited specifically.
After the initial scanning position of the slit group device is determined, any one of the plurality of light transmitting slits is used as a target light transmitting slit, the initial position of the center of the bottom edge of the target light transmitting slit is used as an origin, the target scanning direction is used as a horizontal axis, the direction perpendicular to the target scanning direction is used as a vertical axis, a scanning coordinate system is established, the slit group device is used for scanning a light spot to be measured along the target scanning direction from the scanning initial position according to a preset speed, and the scanning light power which penetrates through the slit group device at different scanning positions is obtained. A laser power meter mounted on the slot group apparatus may be employed to detect the scanning position as well as the scanning optical power. Assuming that the widths of the three light-transmitting slits in the slit group device are 70 μm, 100 μm and 170 μm, respectively, the scanning optical power obtained after scanning a spot with a radius of 10 μm as shown in fig. 2 by using the slit group device is shown in fig. 4. Fig. 4 schematically shows a scanning optical power diagram of the slit group device at different scanning positions according to the embodiment of the present application. As can be seen from fig. 4, when scanning is performed with only a single slit having a width larger than the diameter of the spot in the prior art, for example, scanning a spot having a diameter of 20 μm with a slit of 70 μm, the measurement result obtained is much larger than the true value.
In step 104, any light-transmitting slit in the slit assembly is rectangular, and light in the light-transmitting slit can completely transmit, that is, the optical power transmittance is 1; the light outside the light-transmitting slit is completely blocked, i.e. the optical power transmittance is 0. Specifically, the transmittance of a single rectangular slit can be expressed by formula (1):
Figure BDA0002704729480000071
in the formula (1), g (x) represents the transmittance of the rectangular slit, x is the abscissa value of any position on the plane where the rectangular slit is located, c is the center position of the rectangular slit, rect represents a rectangular function, and w is the width of the rectangular slit.
In combination with the principle of transmittance of rectangular slits, for a slit group device formed by combining a plurality of rectangular slits, the optical power transmittance of the slit group device can be specifically obtained in the following manner:
and determining the optical power transmittance of the slit group device according to the width value of each light-transmitting slit, the abscissa value of the initial position of the bottom edge center of each light-transmitting slit and the abscissa value of any position of the plane where the slit group device is located.
Specifically, the optical power transmittance of the slit group device can be determined by the formula (2):
Figure BDA0002704729480000072
in the formula (2), g (x) is the optical power transmittance of the slit group device, rect represents a rectangular function, x is the abscissa value of any position of the plane where the slit group device is located, and cjIs an abscissa value, w, of the initial position of the center of the bottom edge of the jth light-transmitting slitjIs the width value of the jth light-transmitting slit, j is an integer which is more than or equal to 1 and less than or equal to N, and N is the number of the light-transmitting slits in the slit assembly.
Assuming that the widths of the three light-transmitting slits in the example slit group set are 70 μm, 100 μm, and 170 μm, respectively, the transmittance of the example slit group set is schematically shown in fig. 5.
It should be noted that, since the ordinate does not change during scanning, the change in the scanning position is represented by a change in the abscissa value, and the ordinate is not described in detail.
In step 105, the target scanning position indicates any scanning position in the target scanning direction.
In step 106, the light intensity of the light spot to be measured at the target scanning position is determined according to the light power transmittance Fourier transform result and the target scanning light power Fourier transform result. After the light intensity of the light spot to be measured at the target scanning position is determined, the light intensity of the light spot to be measured at each scanning position can be determined similarly, and further the light intensity distribution of the light spot to be measured in the whole target scanning direction is correspondingly determined. The light intensity of the light spot to be measured at the target scanning position can be determined by formula (3):
Figure BDA0002704729480000081
in the formula (3), b (x)0) For measuring the intensity, x, of the light spot at the target scanning position0Is the abscissa value, F (k), of the target scanning position0) For the target scanning optical power Fourier transform result, k0As spatial frequency, G (k)0) As a result of the optical power transmittance fourier transform,
Figure BDA0002704729480000082
is an inverse fourier transform.
The method for determining the light intensity of the light spot to be measured according to the Fourier transform of the scanning light power and the Fourier transform of the light power transmittance provided by the embodiment of the application is mainly determined based on the following ideas:
when the light transmission slit scans the light spot along the target scanning direction, the scanning light power transmitted through the slit group device at different scanning positions can be represented by formula (4):
Figure BDA0002704729480000083
in the formula (4), f (x) is the scanning light power transmitted through the slit group device, and represents the convolution of the light intensity distribution of the light spot in the target scanning direction and the transmittance function of the slit group device; t is an abscissa value of any position of the plane of the slit group device, b (t) is the light intensity of any position of the plane of the slit group device, g (t-x) is the transmittance function of the slit group device at different scanning positions, b (x) is the light intensity distribution of the light spot in the target scanning direction, and g (x) is the transmittance function of the slit group device.
It can be concluded from equation (4) that when the slit is infinitely narrow, the result of the scan is equal to the intensity distribution of the spot; as the slit gets wider and wider, the result of the scan will get wider and wider, which also corroborates the scan result in fig. 4. In order to recover the light intensity distribution result, a recovery algorithm is performed in the spatial frequency domain. Fourier transform is performed on both sides of equation (4) to obtain a spatial frequency function, which is expressed by equation (5):
f (k) ═ b (k) · g (k) formula (5)
In the formula (5), f (k) is the fourier transform of the scanning light power f (x) transmitted through the slit group device, b (k) is the fourier transform of the light intensity distribution b (x) of the light spot in the target scanning direction, g (k) is the fourier transform of the transmittance function g (x) of the slit group device, and k is the spatial frequency.
The original convolution operation in the formula (4) is changed into the product operation in the formula (5) after being subjected to Fourier transform, and the Fourier transform result of the light intensity distribution of the light spot in the target scanning direction is represented by a formula (6):
Figure BDA0002704729480000084
in formula (6), b (k) is a fourier transform result of the light intensity distribution of the light spot in the target scanning direction, f (k) is a fourier transform result of the scanning light power transmitted through the slit group device, and g (k) is a fourier transform result of the transmittance function of the slit group device.
And (5) performing inverse Fourier transform on the formula (6) to obtain a result of the formula (3).
From the formula (3), the optical power transmittance fourier transform result G (k) can be found0) At the denominator, if G (k)0) Equal to zero, equation (3) cannot be calculated, while the fourier transform of the rectangular function is a Sinc function, with multiple zeros, so to avoid this, multiple width slit combinations can be usedThe way (1) excludes the zero point from the valid calculation data. The optical power transmittance of the slit group device is fourier-transformed, and the obtained fourier transform result can be represented by formula (7):
Figure BDA0002704729480000091
in the formula (7), G (k) is the result of Fourier transform of optical power transmittance of the slit group device, k is spatial frequency, cjIs an abscissa value, w, of the initial position of the center of the bottom edge of the jth light-transmitting slitjIs the width value of the jth light-transmitting slit, j is an integer greater than or equal to 1 and less than or equal to N, N is the number of the light-transmitting slits in the slit assembly, and i is an imaginary unit.
Since sinc (k) in equation (7) is equal to sin (π k) divided by π k, where k is the spatial frequency, a single sinc function has a null at k 2 π/w. The width of the light-transmitting slit is selected to have no integral multiple relation, so that the added position is not zero, and the problem that dividend is zero is avoided. For example, the zero point of the 70 μm, 100 μm, and 170 μm slits will be at a factor of 10 × 17 to 170 times the zero point of the 70 μm slits, and ignoring these very far frequency values will not affect the calculation result.
Based on the above principle, the slit group device provided in the embodiment of the present application needs to include a plurality of light-transmitting slits, and there is no integer multiple relationship between the widths of any two light-transmitting slits, so that the subsequent space recovery algorithm does not have the situation that it cannot be solved.
By adopting the method for determining the light intensity of the light spot to be measured according to the Fourier transform of the scanning light power and the Fourier transform of the light power transmittance, the measurement can be free from the influence of the size of the light spot and the width of the light transmission slit, and the measurement accuracy is higher even when the light spot with smaller size is measured.
In step 107, the light intensity distribution of the light spot to be measured in each scanning direction refers to the light intensity of the light spot to be measured at all scanning positions in each scanning direction. That is, the light intensity distribution includes the light intensity at all the scanning positions. The light intensity distribution in the target scanning direction and the light intensity distribution in another scanning direction orthogonal to the target scanning direction are acquired. The light intensity distributions in both scanning directions are determined in accordance with steps 103 to 106, respectively.
In step 108, the size and shape of the light spot to be measured are determined according to the light intensity distribution of the light spot to be measured in all scanning directions. When the size and the shape of the light spot to be measured are determined, the two-dimensional light intensity distribution of the light spot to be measured can be determined according to the light intensity distribution of the light spot to be measured in all scanning directions; the two-dimensional intensity distribution can be used to reflect the size and shape of the spot to be measured.
Specifically, the two-dimensional light intensity distribution of the light spot to be measured can be determined by equation (8):
s (x, y) ═ b (x) x a (y) formula (8)
In formula (8), S (x, y) is a two-dimensional light intensity distribution of the light spot to be measured, b (x) is a light intensity distribution of the light spot to be measured in the target scanning direction, a (y) is a light intensity distribution of the light spot to be measured in another scanning direction orthogonal to the target scanning direction, x is an abscissa value of a scanning position of the slit group device in the target scanning direction, and y is an abscissa value of a scanning position of the slit group device in another scanning direction orthogonal to the target scanning direction.
Therefore, in the slit group device, the light transmission slits with the widths not having the integral multiple relation are used for scanning the light spots to be measured, the light intensity of the light spots to be measured in the target scanning position is determined according to the Fourier transform result of the target scanning light power and the Fourier transform result of the light power transmittance in the target scanning position, the light intensity distribution of the light spots to be measured in the target scanning direction and the other scanning direction orthogonal to the target scanning direction is further determined, and the size and the shape of the light spots to be measured are finally determined. The whole process determines the light intensity of the light spot to be measured according to the Fourier transform of the scanning light power and the Fourier transform of the light power transmittance, the measurement is not influenced by the size of the light spot and the width of the light transmission slit, and the measurement accuracy is higher even if the light spot with smaller size is measured; meanwhile, the widths of the plurality of light-transmitting slits are not in integral multiple relation, so that the situation that the light intensity cannot be solved in a Fourier transform mode is avoided, and the practicability is high.
In order to more clearly explain step 101 to step 108, the following description is given by way of specific examples.
The detailed description will be given assuming that two scanning directions, horizontal and vertical, are preset for the exemplary light spot, and the horizontal scanning direction is set as the target scanning direction. Fig. 6 is a schematic diagram illustrating an intensity distribution of an exemplary light spot in a target scanning direction in a specific example provided by the embodiment of the application. As shown in fig. 6, the exemplary light spot is divided into two lobes, a small plot showing the cross-sectional intensity of the light spot and a large plot showing the intensity distribution of the light spot in the target scanning direction, wherein the widths of the two peaks of the light spot are 10 μm and 20 μm, respectively.
Assuming that the exemplary slit set apparatus includes three light-transmitting slits with widths of 70 μm, 100 μm and 170 μm, respectively, the scanning optical power obtained after scanning the exemplary light spot with the exemplary slit set apparatus is as shown in fig. 7. Fig. 7 is a schematic diagram illustrating scanning optical power passing through an example slit group device at different scanning positions in a specific example provided by an embodiment of the present application. While obtaining the optical power transmittance of the example slot set arrangement.
A fourier transform result of the scanning optical power obtained by performing fourier transform on the scanning optical power is shown in fig. 8a, and fig. 8a exemplarily shows the fourier transform result of the scanning optical power in the specific example provided by the embodiment of the present application. The fourier transform result of the optical power transmittance obtained by performing fourier transform on the optical power transmittance is shown in fig. 8b, and fig. 8b exemplarily shows the fourier transform result of the optical power transmittance in the specific example provided in the embodiment of the present application. The fourier transform result of the exemplary light spot intensity distribution calculated according to the formula (6) is shown in fig. 8c, and fig. 8c illustrates the fourier transform result of the exemplary light spot intensity distribution in the specific example provided in the embodiment of the present application. The fourier transform result of the light intensity distribution of the exemplary light spot is subjected to inverse fourier transform, and the shape of the obtained exemplary light spot in the target scanning direction is shown in fig. 9, and fig. 9 exemplarily shows a schematic diagram of the shape of the exemplary light spot in the target scanning direction in the specific example provided by the embodiment of the present application.
And rotating the example slit group device by 90 degrees, scanning along the other scanning direction, namely the vertical direction, and repeating the measurement process to obtain the light intensity distribution of the example light spots in the other scanning direction. And multiplying the light intensity distribution in the horizontal scanning direction and the light intensity distribution in the vertical scanning direction of the sample light spots to obtain the two-dimensional distribution condition of the sample light spots.
The following are embodiments of the apparatus of the present application that may be used to perform embodiments of the method of the present application. For details which are not disclosed in the embodiments of the apparatus of the present application, reference is made to the embodiments of the method of the present application.
Fig. 10 schematically illustrates a structure of a device for measuring a spot size and a spot shape according to an embodiment of the present application. As shown in fig. 10, the apparatus has a function of implementing the above-described measurement method of the spot size and shape, and the function may be implemented by hardware or by hardware executing corresponding software. The measuring device may include: a first acquisition unit 1001, a second acquisition unit 1002, a scanning unit 1003, a third acquisition unit 1004, and a processing unit 1005.
A first acquiring unit 1001 is configured to acquire a light spot to be measured.
A second acquiring unit 1002, configured to acquire a pre-constructed slit group apparatus. The slit group device is used for measuring the light spot to be measured and comprises a light-tight substrate and a light-transmitting slit array processed on the light-tight substrate at preset intervals; the light-transmitting slit array comprises a plurality of light-transmitting slits which are parallel to each other along the array direction; the height of the light transmission slit is greater than the maximum height of the light spot to be measured in two preset mutually orthogonal scanning directions; the widths of any two light-transmitting slits do not have integral multiple relation.
And a scanning unit 1003, configured to scan the light spot to be measured along a target scanning direction by using the slit group device, and acquire scanning optical power transmitted through the slit group device at different scanning positions. The target scanning direction is any one of two mutually orthogonal scanning directions preset by the light spot to be measured.
A third acquiring unit 1004 for acquiring the optical power transmittance of the slit group apparatus with respect to the target scanning direction.
The processing unit 1005 is configured to perform fourier transform on the scanning optical power and the optical power transmittance at the target scanning position, respectively, to obtain a target scanning optical power fourier transform result and an optical power transmittance fourier transform result. The target scanning position is any scanning position in the target scanning direction. And determining the light intensity of the light spot to be measured at the target scanning position according to the light power transmittance Fourier transform result and the target scanning light power Fourier transform result. And acquiring the light intensity distribution of the light spot to be measured in each scanning direction. The light intensity distribution includes light intensities at all scanning positions. And determining the size and the shape of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions.
In one implementation, the scanning unit 1003 is specifically configured to:
determining the scanning initial position of the slit group device according to the target scanning direction, the initial distance between the preset slit group device and the light spot to be measured, the array direction of the plurality of light transmission slits and the height of the light transmission slits; the scanning initial position of the slit group device comprises a bottom edge center initial position of a plurality of light-transmitting slits.
Establishing a scanning coordinate system by taking the initial position of the bottom edge center of the target light-transmitting slit as an origin, the target scanning direction as a transverse axis and the direction vertical to the target scanning direction as a longitudinal axis; the target light-transmitting slit is any one of the plurality of light-transmitting slits.
And scanning the light spot to be measured along the target scanning direction from the scanning initial position by using the slit group device according to a preset speed, and acquiring the scanning light power passing through the slit group device at different scanning positions.
In an implementation manner, the third obtaining unit 1004 specifically includes:
and the optical power transmittance determining module is used for determining the optical power transmittance of the slit group device according to the width value of each light-transmitting slit, the abscissa value of the initial position of the center of the bottom edge of each light-transmitting slit and the abscissa value of any position of the plane where the slit group device is located.
In one implementation, the optical power transmittance determination module is specifically configured to:
the optical power transmittance of the slit group device is determined by the following formula:
Figure BDA0002704729480000111
wherein g (x) is the optical power transmittance of the slit group device, rect represents a rectangular function, x is the abscissa value of any position of the plane where the slit group device is located, cjIs an abscissa value, w, of the initial position of the center of the bottom edge of the jth light-transmitting slitjIs the width value of the jth light-transmitting slit, j is an integer which is more than or equal to 1 and less than or equal to N, and N is the number of the light-transmitting slits in the slit assembly.
In an implementation manner, the processing unit 1005 specifically includes:
the light intensity determination module is used for determining the light intensity of the light spot to be measured at the target scanning position according to the following formula:
Figure BDA0002704729480000112
wherein, b (x)0) For measuring the intensity, x, of the light spot at the target scanning position0Is the abscissa value, F (k), of the target scanning position0) For the target scanned optical power Fourier transform result, k0As spatial frequency, G (k)0) As a result of the optical power transmittance fourier transform,
Figure BDA0002704729480000113
is an inverse fourier transform.
In an implementation manner, the processing unit 1005 specifically further includes:
the measurement result acquisition module is used for determining the two-dimensional light intensity distribution of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions; the two-dimensional light intensity distribution is used for reflecting the size and the shape of the light spot to be measured.
In an implementation manner, the measurement result obtaining module is specifically configured to:
determining the two-dimensional light intensity distribution of the light spot to be measured by the following formula:
S(x，y)＝b(x)×a(y)
wherein, S (x, y) is the two-dimensional light intensity distribution of the light spot to be measured, b (x) is the light intensity distribution of the light spot to be measured in the target scanning direction, a (y) is the light intensity distribution of the light spot to be measured in another scanning direction orthogonal to the target scanning direction, x is the abscissa value of the scanning position of the slit group device in the target scanning direction, and y is the abscissa value of the scanning position of the slit group device in another scanning direction orthogonal to the target scanning direction.
In an implementation manner, the slit group apparatus acquired by the second acquiring unit 1002 further includes a laser power meter; the laser power meter is arranged on the opaque substrate and used for acquiring the scanning light power penetrating through the slit group device at different scanning positions.
Therefore, in the slit group device, the light transmission slits with the widths not having the integral multiple relation are used for scanning the light spots to be measured, the light intensity of the light spots to be measured in the target scanning position is determined according to the Fourier transform result of the target scanning light power and the Fourier transform result of the light power transmittance in the target scanning position, the light intensity distribution of the light spots to be measured in the target scanning direction and the other scanning direction orthogonal to the target scanning direction is further determined, and the size and the shape of the light spots to be measured are finally determined. The whole process determines the light intensity of the light spot to be measured according to the Fourier transform of the scanning light power and the Fourier transform of the light power transmittance, the measurement is not influenced by the size of the light spot and the width of the light transmission slit, and the measurement accuracy is higher even if the light spot with smaller size is measured; meanwhile, the widths of the plurality of light-transmitting slits are not in integral multiple relation, so that the situation that the light intensity cannot be solved in a Fourier transform mode is avoided, and the practicability is high.
In an exemplary embodiment, a computer-readable storage medium is further provided, in which a computer program or an intelligent contract is stored, and the computer program or the intelligent contract is loaded and executed by a node to implement the transaction processing method provided by the above-described embodiment. Alternatively, the computer-readable storage medium may be a Read-Only Memory (ROM), a Random Access Memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.
Those skilled in the art will clearly understand that the techniques in the embodiments of the present application may be implemented by way of software plus a required general hardware platform. Based on such understanding, the technical solutions in the embodiments of the present application may be essentially implemented or a part contributing to the prior art may be embodied in the form of a software product, which may be stored in a storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, etc., and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method described in the embodiments or some parts of the embodiments of the present application.
Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice in the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
It will be understood that the present disclosure is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims (9)

1. A method of measuring spot size and shape, the method comprising:
acquiring a light spot to be measured;
acquiring a pre-constructed slit group device; the slit group device is used for measuring the light spots to be measured and comprises a light-tight substrate and a light-transmitting slit array processed on the light-tight substrate at preset intervals; the light-transmitting slit array comprises a plurality of light-transmitting slits which are parallel to each other along the array direction; the height of the light-transmitting slit is greater than the maximum height of the light spot to be measured in two preset mutually orthogonal scanning directions; the widths of any two light-transmitting slits are not in integral multiple relation;
scanning the light spot to be measured along a target scanning direction by using the slit group device to obtain scanning light power penetrating through the slit group device at different scanning positions; the target scanning direction is any one of two mutually orthogonal scanning directions preset by the light spot to be measured;
aiming at the target scanning direction, acquiring the optical power transmittance of the slit group device;
respectively carrying out Fourier transform on the scanning light power and the light power transmittance at a target scanning position to obtain a target scanning light power Fourier transform result and a light power transmittance Fourier transform result; the target scanning position is any one scanning position in the target scanning direction;
determining the light intensity of the light spot to be measured at the target scanning position according to the light power transmittance Fourier transform result and the target scanning light power Fourier transform result;
acquiring light intensity distribution of the light spot to be measured in each scanning direction; the light intensity distribution includes light intensities at all scanning positions;
determining the size and the shape of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions;
wherein, the determining the light intensity of the light spot to be measured at the target scanning position according to the optical power transmittance fourier transform result and the target scanning optical power fourier transform result comprises:
determining the light intensity of the light spot to be measured at the target scanning position by the following formula:
Figure FDA0003586136870000011
wherein, b (x)0) For the light intensity, x, of the light spot to be measured at the target scanning position0Is the abscissa value, F (k), of the target scanning position0) For the target scanning optical power Fourier transform result, k0As spatial frequency, G (k)0) As a result of the optical power transmittance fourier transform,
Figure FDA0003586136870000012
is an inverse Fourier transform;
the abscissa value of the target scanning position is obtained from a scanning coordinate system which is established in advance, wherein the scanning coordinate system is established by taking the initial position of the center of the bottom edge of a target light-transmitting slit as an origin, the target scanning direction as a horizontal axis and the direction perpendicular to the target scanning direction as a vertical axis, and the target light-transmitting slit is any one of a plurality of light-transmitting slits.
2. The method for measuring the size and shape of the light spot according to claim 1, wherein the scanning the light spot to be measured along a target scanning direction by using the slit group device to obtain the scanning optical power transmitted through the slit group device at different scanning positions comprises:
determining the scanning initial position of the slit group device according to the target scanning direction, the preset initial distance between the slit group device and the light spot to be measured, the array direction of the plurality of light transmission slits and the height of the light transmission slits; the scanning initial position of the slit group device comprises the bottom edge center initial positions of a plurality of light-transmitting slits;
and under the scanning coordinate system, scanning the light spot to be measured along the target scanning direction from the scanning initial position by using the slit group device according to a preset speed, and acquiring the scanning light power passing through the slit group device at different scanning positions.
3. The method of claim 2, wherein the obtaining the optical power transmittance of the slit group device comprises:
and determining the optical power transmittance of the slit group device according to the width value of each light-transmitting slit, the abscissa value of the initial position of the bottom edge center of each light-transmitting slit and the abscissa value of any position of the plane where the slit group device is located.
4. The method according to claim 3, wherein the determining the optical power transmittance of the slit group device according to the width of each light-transmitting slit, the abscissa value of the initial position of the center of the bottom edge of each light-transmitting slit, and the abscissa value of any position of the plane of the slit group device comprises:
the optical power transmittance of the slit group device is determined by the following formula:
Figure FDA0003586136870000021
wherein g (x) is the optical power transmittance of the slit group device, rect represents a rectangular function, x is the abscissa value of any position of the plane where the slit group device is located, cjIs an abscissa value, w, of the initial position of the center of the bottom edge of the jth light-transmitting slitjThe width value of the jth light-transmitting slit is defined, j is an integer greater than or equal to 1 and less than or equal to N, and N is the number of light-transmitting slits in the slit assembly.
5. The method for measuring the size and shape of the light spot according to claim 1, wherein the determining the size and shape of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions comprises:
determining the two-dimensional light intensity distribution of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions; the two-dimensional light intensity distribution is used for reflecting the size and the shape of the light spot to be measured.
6. The method for measuring the size and shape of the light spot according to claim 5, wherein the determining the two-dimensional light intensity distribution of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions comprises:
determining the two-dimensional light intensity distribution of the light spot to be measured by the following formula:
S(x,y)＝b(x)×a(y)
wherein S (x, y) is a two-dimensional light intensity distribution of the light spot to be measured, b (x) is a light intensity distribution of the light spot to be measured in the target scanning direction, a (y) is a light intensity distribution of the light spot to be measured in another scanning direction orthogonal to the target scanning direction, x is an abscissa value of a scanning position of the slit group device in the target scanning direction, and y is an abscissa value of a scanning position of the slit group device in another scanning direction orthogonal to the target scanning direction.
7. The method of claim 1, wherein the slit group apparatus further comprises a laser power meter; the laser power meter is arranged on the light-tight substrate and used for acquiring scanning light power penetrating through the slit group device at different scanning positions.
8. A device for measuring spot size and shape, the device comprising:
the first acquisition unit is used for acquiring a light spot to be measured;
a second acquisition unit for acquiring a previously constructed slit group device; the slit group device is used for measuring the light spot to be measured and comprises an opaque substrate and a light-transmitting slit array processed on the opaque substrate at preset intervals; the light-transmitting slit array comprises a plurality of light-transmitting slits which are parallel to each other along the array direction; the height of the light-transmitting slit is greater than the maximum height of the light spot to be measured in two preset mutually orthogonal scanning directions; the widths of any two light-transmitting slits are not in integral multiple relation;
the scanning unit is used for scanning the light spots to be measured along a target scanning direction by using the slit group device and acquiring scanning light power penetrating through the slit group device at different scanning positions; the target scanning direction is any one of two mutually orthogonal scanning directions preset by the light spot to be measured;
a third obtaining unit, configured to obtain, for the target scanning direction, an optical power transmittance of the slit group apparatus;
the processing unit is used for respectively performing Fourier transform on the scanning light power and the light power transmittance at a target scanning position to obtain a target scanning light power Fourier transform result and a light power transmittance Fourier transform result; the target scanning position is any one scanning position in the target scanning direction; determining the light intensity of the light spot to be measured at the target scanning position according to the light power transmittance Fourier transform result and the target scanning light power Fourier transform result; acquiring light intensity distribution of the light spot to be measured in each scanning direction; the light intensity distribution includes light intensities at all scanning positions; determining the size and the shape of the light spot to be measured according to the light intensity distribution of the light spot to be measured in all scanning directions; wherein, the processing unit specifically includes:
the light intensity determination module is used for determining the light intensity of the light spot to be measured at the target scanning position according to the following formula:
Figure FDA0003586136870000031
wherein, b (x)0) For measuring the intensity, x, of the light spot at the target scanning position0Is the abscissa value, F (k), of the target scanning position0) For the target scanning optical power Fourier transform result, k0As spatial frequency, G (k)0) As a result of the optical power transmittance fourier transform,
Figure FDA0003586136870000032
is an inverse Fourier transform;
the abscissa value of the target scanning position is obtained from a scanning coordinate system which is established in advance, wherein the scanning coordinate system is established by taking the initial position of the center of the bottom edge of a target light-transmitting slit as an origin, the target scanning direction as a horizontal axis and the direction perpendicular to the target scanning direction as a vertical axis, and the target light-transmitting slit is any one of a plurality of light-transmitting slits.
9. The apparatus for measuring spot size and shape according to claim 8, wherein the scanning unit is specifically configured to:
determining the scanning initial position of the slit group device according to the target scanning direction, the preset initial distance between the slit group device and the light spot to be measured, the array direction of the plurality of light transmission slits and the height of the light transmission slits; the scanning initial position of the slit group device comprises the bottom edge center initial positions of a plurality of light-transmitting slits;
and under the scanning coordinate system, scanning the light spot to be measured along the target scanning direction from the scanning initial position by using the slit group device according to a preset speed, and acquiring the scanning light power passing through the slit group device at different scanning positions.
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