CN115200839A - Laser beam quality measuring device and method - Google Patents
Laser beam quality measuring device and method Download PDFInfo
- Publication number
- CN115200839A CN115200839A CN202210740993.0A CN202210740993A CN115200839A CN 115200839 A CN115200839 A CN 115200839A CN 202210740993 A CN202210740993 A CN 202210740993A CN 115200839 A CN115200839 A CN 115200839A
- Authority
- CN
- China
- Prior art keywords
- laser beam
- laser
- incident
- imaging lens
- dove prism
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- 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
- 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
- G01M11/0207—Details of measuring devices
Landscapes
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Abstract
The invention discloses a laser beam quality measuring device and method, belonging to the technical field of laser beam quality measurement, wherein the device comprises: the system comprises a spectroscope, a first imaging lens, a first observation camera, a dove prism, a laser focusing lens, a laser scattering medium, a second imaging lens and a second observation camera. The incident laser beam is divided into two beams by the spectroscope, wherein the reflected laser beam irradiates the first observation camera through the first imaging lens, so that the light intensity distribution on the cross section of the incident laser beam is observed; the transmission laser beam firstly enters the dove prism, is focused into a laser scattering medium through the laser focusing lens after being emitted from the dove prism, is scattered through the scattering medium, the scattering profile of the focusing beam near the focus is imaged on the second observation camera through the second imaging lens, and the beam quality of the incident beam can be measured by measuring the profile of the focusing beam. Therefore, the measuring structure is optimized, fewer CCD cameras are used, the structure is simple, the cost is low, and the measuring time is shortened.
Description
Technical Field
The invention belongs to the technical field of laser beam quality measurement, and particularly relates to a laser beam quality measurement device and method.
Background
The laser is widely applied to the development and application of various high-tech products by virtue of the characteristics of good monochromaticity, coherence, directivity and high strengthThe laser beam quality is an important parameter for measuring the laser performance, and the accurate laser beam quality can be measured in time, so that the laser has high reference value for the design, manufacture and use of the laser. At present, a plurality of methods for evaluating the quality of laser beams comprise BPP parameters, M 2 Factor, beta factor, sterlb method, etc., wherein the BPP parameter and M 2 Factors are widely used.
(1) The BPP parameter is defined as the product between the beam waist radius ω of an actual laser beam and its far field divergence half angle θ, i.e.:
BPP＝ω·θ
the BPP parameters for an ideal fundamental mode gaussian beam are:
BPP 0 ＝ω 0 ·θ 0 ＝λ/π
wherein, ω is 0 Is the beam waist radius, θ, of an ideal fundamental mode Gaussian beam 0 Lambda is the wavelength of the incident laser beam, which is the divergence half-angle of an ideal fundamental mode gaussian beam.
For the actual laser beam there are:
BPP≥BPP 0 ＝λ/π
the larger the BPP parameter of the actual laser beam, the worse the laser beam quality, the closer the BPP parameter is to lambda/pi, the better the laser beam quality.
(2)M 2 The factor is that the product of the beam waist radius omega of the actual beam and the far field divergence half angle theta is equal to the beam waist radius omega of the ideal fundamental mode Gaussian beam 0 Divergence angle theta from far field 0 The ratio of the products, namely:
M 2 the factor is used to characterize the degree to which the actual beam deviates from the fundamental mode Gaussian beam, M 2 The factor is greater than or equal to 1.M 2 The larger the factor value, the faster the beam diffraction diverges and the worse the quality. When M is 2 When the factor value is closer to 1, the closer the laser beam to be measured is to the fundamental mode Gaussian beam, and the better the beam quality is.
From BPP parameters and M 2 Factor meterAs can be seen by the calculation formula, the BPP parameter or M can be calculated by measuring the beam waist radius and the far field divergence half angle of the incident laser beam and knowing the wavelength of the incident laser beam 2 A factor.
BPP parameters and M 2 The laser beam quality analysis method of the factor is mature, and comprises a two-point method, a three-point method, a hyperbolic curve fitting method and the like. The hyperbolic fitting method has higher precision because the hyperbolic fitting is carried out by measuring multiple points, but the realization mode is complex, a laser beam needs to be focused by a lens, the sizes of light spots of the laser beam at a plurality of positions near the beam waist are measured by utilizing a CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) camera, then the hyperbolic fitting is carried out in a computer to obtain the beam waist radius and the far-field divergence half angle of the laser beam near a focusing point, and finally the beam quality BPP (band-to-beam power) parameter or M of the laser is obtained by calculation 2 A factor.
At present, products in the market can better evaluate the quality of laser beams, but some problems still remain to be solved. Firstly, the camera can only obtain the spot image at one position at a time, and in order to measure the laser beam quality, the image of multiple points needs to be obtained, firstly, the position of the camera (or a focusing lens) is continuously changed by adopting a manual or electric mechanical platform to obtain the spot sizes at multiple positions (see Chinese patent ZL 201615402.2 and ZL 201610723333.6), and when the position of a device is changed by adopting a mechanical translation platform, time adjustment equipment is needed, so that the laser beam quality cannot be measured in real time, and the measurement time is long. Secondly, a plurality of cameras are adopted to measure the sizes of the light spots at different positions respectively (see the Chinese invention patent application 202011231540.2), but the structure of the light beam quality measuring device becomes complicated, and the device cost is high.
Disclosure of Invention
Aiming at the defects and improvement requirements of the prior art, the invention provides a laser beam quality measuring device and a laser beam quality measuring method, and aims to solve the technical problems that the existing laser beam quality measuring device cannot measure the quality of a laser beam in real time, the measuring time is long, and the measuring device is complex in structure and high in cost.
To achieve the above object, in a first aspect, the present invention provides a laser beam quality measuring apparatus, including: the device comprises a dove prism, a laser focusing lens, a laser scattering medium, a first imaging lens and a first observation camera;
the dove prism, the laser focusing lens and the laser scattering medium are sequentially arranged along an optical axis of an incident laser beam, the first imaging lens and the first observation camera are sequentially arranged along a direction perpendicular to the optical axis, so that the incident laser beam enters the dove prism, is focused into the laser scattering medium through the laser focusing lens after being emitted from the dove prism, and after being scattered, a scattering profile of a focused beam near a focus is imaged on the first observation camera through the first imaging lens, and the beam quality of the incident laser beam is obtained by measuring the scattering profile of the focused beam; the focal point is located inside the laser scattering medium.
Further, the apparatus further comprises: a spectroscope, a second imaging lens and a second observation camera;
the spectroscope, the dove prism, the laser focusing lens and the laser scattering medium are sequentially arranged along an optical axis, and the second imaging lens and the second observation camera are sequentially arranged along a direction vertical to the optical axis;
the incident laser beam is divided into two beams by the spectroscope, wherein the reflected laser beam is imaged on the second observation camera through the second imaging lens, and the transmitted laser beam is incident to the dove prism.
Further, the apparatus also includes an attenuation sheet located between the second imaging lens and the second viewing camera.
Further, the power of the reflected laser beam does not exceed 1% of the power of the incident laser beam.
Further, the second observation camera may be moved along the optical axis of the reflected laser beam to observe the laser light intensity distribution on the cross section at different positions after focusing.
Further, the dove prism can be manually or electrically controlled to rotate around the optical axis, so that the transmission laser beam is driven to rotate around the optical axis, and the rotation angle of the transmission laser beam around the optical axis is 2 times that of the dove prism.
Further, the laser scattering medium is air containing fine dust or water vapor generated by an ultrasonic atomizer.
Further, the wavelength of the incident laser beam is in the range of 340nm to 1500nm.
Further, the incident laser beam is femtosecond, picosecond, nanosecond, millisecond pulse or continuous laser.
In a second aspect, the present invention provides a method for measuring a laser beam quality, which is characterized in that the laser beam quality measuring apparatus according to the first aspect is used to obtain a scattering profile of a focused beam, and hyperbolic fitting is performed through spot radii at different positions before and after a beam waist of the focused beam to obtain a beam waist radius and a far-field divergence half-angle of the laser beam, so as to obtain a BPP parameter or M of an incident laser beam 2 A factor.
Generally, by the above technical solution conceived by the present invention, the following beneficial effects can be obtained:
(1) Compared with the prior art that the position of a camera (or a focusing lens) needs to be continuously changed by a mechanical platform to obtain the spot sizes at a plurality of positions or a plurality of cameras are adopted to measure the spot sizes at different positions respectively, the invention does not measure the beam quality by measuring the spot size any more, but adopts a new idea that the scattering profile of a focusing beam is directly obtained by introducing a laser scattering medium so as to measure the beam quality. Meanwhile, the dove prism can rotate around the optical axis, and the transmitted light beam rotates around the optical axis, so that focused light beam profiles in different directions can be observed on the first observation camera, and the light beam quality of the light beams in different directions can be measured. Therefore, the measuring structure is optimized, fewer CCD cameras are used, the structure is simple, and the cost is low; the measuring time is shortened, the light beam quality can be calculated by only one picture, and the position of a camera does not need to be changed.
(2) The invention can realize the measurement of the laser beam quality BPP parameter or M by introducing the spectroscope, the second imaging lens and the second observation camera 2 And meanwhile, the light intensity distribution on the cross section of the laser beam is observed, and the position of a CCD camera is not required to be adjusted in the measuring process.
(3) The invention has little influence on the transmitted light beam of the main light path,the lens beam of the main light path can be guided into a subsequent laser processing system, so that the measurement of the BPP parameter or M of the quality of the laser beam can be realized 2 And the factor does not influence the subsequent laser processing.
(4) When the laser beam quality measurement is carried out, the laser beam in the transmission light path can not directly enter the observation camera, and the observation camera can not be damaged, so that the measurable laser beam power range is large.
(5) The laser beam quality measuring device has compact integral size, simple mechanical structure, convenient adjustment and short required measuring time, and is particularly suitable for industrial application.
Drawings
Fig. 1 is a structural diagram of a laser beam quality measuring apparatus according to an embodiment of the present invention;
FIG. 2 is a partial diagram of beam transmission near the beam waist of a focused spot inside a scattering medium provided by an embodiment of the invention;
the same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein: 1 is an incident laser beam, 2 is a reflected laser beam, 3 is a second imaging lens, 4 is a second observation camera, 5 is a spectroscope, 6 is a transmission laser beam, 7 is a dove prism, 8 is a transmission laser beam after passing through the dove prism for rotation, 9 is a laser focusing lens, 10 is a laser scattering medium, 11 is a local area near a focused laser beam waist, 12 is a first imaging lens, 13 is a first observation camera, 14 is an optical axis, and 111-117 are 7 cross-sectional positions before and after the focused laser beam waist.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
In the present application, the terms "first," "second," and the like (if any) in the description and the drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
Referring to fig. 1, the present invention provides a laser beam quality measuring apparatus, including: a spectroscope 5, a second imaging lens 3, a second observation camera 4, a dove prism 7, a laser focusing lens 9, a laser scattering medium 10, a first imaging lens 12 and a first observation camera 13.
The front surface of the spectroscope 5 is coated with a partial reflection film (45-degree incident angle), and the rear surface is coated with an antireflection film (45-degree incident angle). An incident laser beam 1 output from a laser light source is split into two paths by a spectroscope 5 after being incident on the spectroscope 5, wherein one path is a reflected laser beam 2, and the other path is a transmitted laser beam 6. Wherein the power of the reflected laser beam 2 only accounts for a very small part, typically around 1%, of the power of the incident laser beam 1, and the optical axis of the reflected laser beam 2 is perpendicular to the optical axis 14. The reflected laser beam 2 is used for measuring the light intensity distribution on the cross section of the incident laser beam 1, and the transmitted laser beam 6 is used for measuring the BPP parameter or M of the incident laser beam 2 A factor.
The second imaging lens 3 and the second observation camera 4 are on the optical axis of the reflected laser beam 2. The reflected laser beam 2 is imaged on a second observation camera 4 through a second imaging lens 3, and the light intensity distribution of the laser on the cross section of the reflected laser beam 2 can be displayed on a display screen after the light intensity distribution is processed by a computer. If the intensity of the laser beam to be measured is high, an attenuation sheet needs to be added in the light path to protect the second observation camera 4. The spot intensity and the spot shape in the cross section of the reflected laser beam 2, i.e. the incident laser beam 1, can be measured by the second observation camera 4. Meanwhile, the second observation camera 4 can move along the optical axis of the reflected laser beam 2, observe the laser intensity distribution on the cross section at different positions after focusing, and the focusing characteristics of the reflected laser beam 2.
The transmission laser beam 6 passes through a dove prism 7 and is focused by a laser focusing lens 9, and the focusing focus is positioned in a local area 11 near the beam waist of the focusing laser beam in a laser scattering medium 10. The optical axes of the dove prism 7, the laser focusing lens 9 and the laser scattering medium 10 coincide with the optical axis 14.
The optical axes of the first imaging lens 12 and the first observation camera 13 are perpendicular to the optical axis 14, and can image the local region 11 near the beam waist of the focused laser beam of the laser scattering medium 10.
When the transmitted laser beam 8 which is rotated by the dove prism is focused into the laser scattering medium 10, a small part of the laser is scattered by the laser scattering medium 10, the scattered light can be received by the first imaging lens 12 and the first observation camera 13 and imaged in the first observation camera 13, so that the profile of the focused beam can be recorded by the first observation camera 13, and the transverse spot diameters of several different positions (111-117) before and after the beam waist of the focused beam can be measured, as shown in fig. 2.
Substituting the transverse spot diameters at the positions of 111-117 into a computer to perform hyperbolic fitting, and calculating to obtain the beam waist radius and the far field divergence half angle of the laser beam so as to obtain the BPP parameter or M of the laser beam 2 A factor.
The dove prism 7 can be manually or electrically controlled to rotate around the optical axis 14 to drive the transmission laser beam 6 to rotate around the optical axis 14, and according to the characteristics of the dove prism, the rotation angle of the transmission laser beam 6 around the optical axis 14 is 2 times of that of the dove prism 7, namely the dove prism 7 rotates 45 degrees, and the transmission laser beam 6 rotates 90 degrees. Therefore, by rotating the angle of the dove prism 7, the beam quality parameters BPP or M in the X direction and the Y direction can be rapidly measured at the same position 2 A factor.
It will be understood by those skilled in the art that the foregoing is only an exemplary embodiment of the present invention, and is not intended to limit the invention to the particular forms disclosed, since various modifications, substitutions and improvements within the spirit and scope of the invention are possible and within the scope of the appended claims.
Claims (10)
1. A laser beam quality measuring apparatus, comprising: the device comprises a dove prism (7), a laser focusing lens (9), a laser scattering medium (10), a first imaging lens (12) and a first observation camera (13);
the dove prism (7), the laser focusing lens (9) and the laser scattering medium (10) are sequentially arranged along an optical axis (14) of an incident laser beam (1), the first imaging lens (12) and the first observation camera (13) are sequentially arranged along a direction perpendicular to the optical axis (14), so that the incident laser beam (1) enters the dove prism (7), is focused into the laser scattering medium (10) through the laser focusing lens (9) after being emitted from the dove prism (7), a scattering profile of a focused beam near a focus point is imaged on the first observation camera (13) through the first imaging lens (12) after being scattered, and the beam quality of the incident laser beam (1) is obtained by measuring the scattering profile of the focused beam; the focal point is located inside the laser light scattering medium (10).
2. The laser beam quality measurement apparatus of claim 1, further comprising: a spectroscope (5), a second imaging lens (3) and a second observation camera (4);
the spectroscope (5), the dove prism (7), the laser focusing lens (9) and the laser scattering medium (10) are sequentially arranged along an optical axis (14), and the second imaging lens (3) and the second observation camera (4) are sequentially arranged along a direction perpendicular to the optical axis (14);
the incident laser beam (1) is divided into two beams by a spectroscope (5), wherein the reflected laser beam (2) is imaged on a second observation camera (4) through a second imaging lens (3), and the transmitted laser beam (6) is incident on a dove prism (7).
3. Laser beam quality measuring device according to claim 2, characterized in that the device further comprises an attenuation sheet located between the second imaging lens (3) and the second viewing camera (4).
4. A laser beam quality measuring device according to claim 2 or 3, characterized in that the power of the reflected laser beam (2) does not exceed 1% of the power of the incident laser beam (1).
5. A laser beam quality measuring apparatus according to claim 2 or 3, characterized in that the second observation camera (4) is movable along the optical axis of the reflected laser beam (2) to observe the laser intensity distribution over the cross-section at different positions after focusing.
6. A laser beam quality measuring apparatus according to claim 2 or 3, wherein the dove prism (7) is rotatable about the optical axis (14) either manually or electronically, the transmitted laser beam (6) is caused to rotate about the optical axis (14) therewith, and the angle of rotation of the transmitted laser beam (6) about the optical axis (14) is 2 times that of the dove prism (7).
7. The laser beam quality measuring apparatus according to claim 1, wherein the laser scattering medium (10) is air containing fine dust or water vapor generated by an ultrasonic atomizer.
8. The laser beam quality measuring device according to claim 1, wherein the wavelength of the incident laser beam (1) is in the range of 340nm to 1500nm.
9. The laser beam quality measuring device according to claim 1, characterized in that the incident laser beam (1) is a femtosecond, picosecond, nanosecond, millisecond pulse or continuous laser.
10. A laser beam quality measuring method, characterized in that a laser beam quality measuring apparatus according to any one of claims 1 to 9 is used to obtain a scattering profile of a focused beam, and a hyperbolic fitting is performed by using spot radii at different positions before and after a beam waist of the focused beam to obtain a beam waist radius and a far field divergence half angle of the laser beam, thereby obtaining a BPP parameter or M of an incident laser beam 2 A factor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210740993.0A CN115200839A (en) | 2022-06-27 | 2022-06-27 | Laser beam quality measuring device and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210740993.0A CN115200839A (en) | 2022-06-27 | 2022-06-27 | Laser beam quality measuring device and method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115200839A true CN115200839A (en) | 2022-10-18 |
Family
ID=83577242
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210740993.0A Pending CN115200839A (en) | 2022-06-27 | 2022-06-27 | Laser beam quality measuring device and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115200839A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117830392A (en) * | 2024-03-05 | 2024-04-05 | 季华实验室 | Environmental object identification method and imaging system |
-
2022
- 2022-06-27 CN CN202210740993.0A patent/CN115200839A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117830392A (en) * | 2024-03-05 | 2024-04-05 | 季华实验室 | Environmental object identification method and imaging system |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103098319B (en) | Laser beam analytical equipment | |
| EP2929558B1 (en) | Semiconductor inspection and metrology system using laser pulse multiplier | |
| CN109099859B (en) | Device and method for measuring surface defect three-dimensional morphology of large-caliber optical element | |
| US9610729B2 (en) | Device and method for performing and monitoring a plastic laser transmission welding process | |
| CN111650695A (en) | Space light-optical fiber coupling alignment method for optical fiber transmission characteristic measurement | |
| CN113092070B (en) | Beam quality factor M 2 Quick measuring device and method | |
| DE112014004139B4 (en) | Low-noise, high-stability, deep-ultraviolet cw laser, inspection system using such a laser, and method for generating deep-ultraviolet cw light in a laser | |
| CN110186653B (en) | Optical axis consistency calibration and split image fixed focus adjustment device and method for non-imaging system | |
| CN108563034B (en) | Reflective spatial filter debugging device and method | |
| CN113568153B (en) | Microscopic imaging equipment and nanoscale three-dimensional shape measurement system | |
| CN104597476A (en) | Real-time diagnosis system for section of accelerator particle beam | |
| CN115200839A (en) | Laser beam quality measuring device and method | |
| CN104501946B (en) | System and method for measuring high-strength beam | |
| CN108723012A (en) | A kind of integrated laser cleaning electro-optical system | |
| CN105353516B (en) | Single detector synthesizes sensor to the dual-beam of pupil optical axis subregion domain imaging | |
| CN104764593B (en) | Horizontal dual-port plane Fizeau interference test device | |
| CN115900598A (en) | Device for measuring included angle between normal line of light passing surface of electro-optical crystal and optical axis of crystal | |
| CN113634877A (en) | Laser processing device and method | |
| CN115839826B (en) | Detection device and detection method for optical fiber transmittance and numerical aperture | |
| CN117030012A (en) | Laser cleaning energy density real-time monitoring system, method and device | |
| CN116773147A (en) | Laser output light spot characteristic measuring device and method | |
| CN208156292U (en) | A kind of optical component body scattering imperfection detection device | |
| CN116184679A (en) | Terahertz imaging light path, adjustment system and method, and imaging light path construction method | |
| CN105892068A (en) | High-frequency pulse laser beam combining device for thomson scattering diagnostic | |
| CN116067628B (en) | Method and system for measuring angle of incidence space |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |