CN113092070A - Light beam quality factor M2Rapid measuring device and method - Google Patents
Light beam quality factor M2Rapid measuring device and method Download PDFInfo
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Abstract
The invention belongs to a beam quality factor M2The technical field of measurement and particularly discloses a light beam quality factor M2A rapid measurement device and method. The device comprises a to-be-sampled device, a zooming device, a light spot measuring device and a data processing device, and the light beam quality factor M of the to-be-measured laser source is calculated according to the focal length of the zooming device and the size of the light spot acquired and measured by the zooming device in real time under different focal lengths2. The method comprises the following steps: the laser source to be detected emits laser, and the laser is attenuated; focusing the attenuated laser, acquiring and measuring the size of a laser spot at a focus in real time in the continuous zooming process, and calculating a beam quality factor M of the laser source to be measured2. The invention overcomes the defect of the traditional M2The measuring equipment needs to drive the reflector group to carry out large-stroke displacement, so that the measuring speed is low, the measuring equipment has the advantages of clear principle, high adjusting speed, simplicity and convenience in operation and the like, and the beam quality factor M can be greatly improved2The measured speed of (2).
Description
Technical Field
The invention belongs to a beam quality factor M2The field of measurement, more specifically, to a beam quality factor M2A rapid measurement device and method.
Background
Beam quality has received widespread attention from researchers and users as a core indicator of lasers. In order to accurately evaluate the beam quality of the laser, researchers at home and abroad propose various beam quality evaluation factors from the aspects of theory and practice, and the most common beam quality factor M2A diffraction limit power factor β, a Power In Bucket (PIB), a power in bucket ratio (BQ), a Snell Ratio (SR), and the like. For unifying the criteria for evaluating the quality of the laser output beam, the International organization for standardization (ISO) proposed M2The proposal of the factor characterization light beam quality is generally accepted at home and abroad.
According to ISO 11146-1:2005 standard, M2The factor is defined as:
in the formula:
d0-girdling width or girdling diameter;
theta-far field beam divergence angle.
Due to M2The factor is calculated by using a second moment method to calculate the diameter of the cross section of the beam. Based on beam width measurement M2The factor method has been studied in many ways, specifically, a two-point focusing method, a three-point method, a multi-point fitting method, and the like. In principle, M can be calculated using the beam widths of three different positions2Factor, the measurements of more positions are used to check against each otherThe error is reduced. Measuring the beam width d of the beam at different positions along the propagation axis z, determining the transmission profile of the beam by hyperbolic fitting, and finally determining M2A factor. According to the relevant standards of ISO, at least 10 measurements, at least 5 within the rayleigh length of the beam are necessary to ensure the accuracy of the measurement. The fit equation for the beam width is as follows:
d2＝A+B·z+C·z2
the waist position z can be obtained by obtaining coefficients A, B and C of the hyperbola according to the knowledge of mathematical statistics0And diameter d0Far field divergence angles theta and M2Factor, as shown in the following equation:
common M2The operation principle of the factor measuring device is shown in FIG. 4, wherein a high-power light source to be measured enters M after passing through a reflector, a sampling device and an attenuation sheet2In the analyzer, a control system controls a servo motor connected with a movable guide rail to scan near a beam waist, so that the beam width d of a light beam at different positions along a propagation axis z can be obtained, a transmission profile of the light beam is determined after hyperbolic fitting processing, and M is finally determined2A factor. According to the ISO standard, at least 10 measurements, at least 5 within the rayleigh length of the beam are necessary to ensure accuracy of the measurement. Existing M2The movement of the measuring position is controlled by mechanical displacement of the distance-adjusting structure, requiring the test equipmentThe shift-measurement-fitting-shift process is carried out more than 10 times, and the measurement time is about 1min-2 min. The working time of the high-power laser is generally short, and the long-time operation of the laser and optical components can cause the degradation of the beam quality, so that the M measured for a long time2The value does not truly reflect the beam quality of the laser beam, but is an average over a period of time.
Disclosure of Invention
In response to the above-identified deficiencies in the art or needs for improvement, the present invention provides a beam quality factor M2Fast measuring apparatus and method, in which a beam quality factor M is combined2The characteristics of the self characteristic and the measuring and calculating method thereof correspondingly design a light beam quality factor M2The rapid measuring device and method, and the research and design of the structure and the specific setting mode of the key components, such as the device to be sampled, the zooming device, the electric control adjusting device and the data processing device, can effectively solve the problem of the traditional M2The measuring equipment needs to drive the reflector group to carry out large-stroke displacement, so that the measuring speed is low, the device has the advantages of clear principle, high adjusting speed, simplicity and convenience in operation and the like, and the beam quality factor M can be greatly improved2The measured speed of (2).
To achieve the above object, according to one aspect of the present invention, a beam quality factor M is provided2A rapid measurement device, comprising:
the device to be sampled is used for inputting the collimated laser emitted by the laser source to be tested and attenuating the collimated laser;
the zooming device is used for changing the focal length of the collimated laser under the control of the electric control adjusting device and focusing the attenuated collimated laser under different focal lengths;
the light spot measuring device is used for acquiring and measuring the light spot size of the collimated laser focused by the zooming device in real time;
a data processing device for calculating the beam quality factor M of the laser source to be measured according to the focal length of the zoom device and the spot size acquired and measured by the spot measuring device under different focal lengths2。
Further preferably, the apparatus further comprises an optical path folding device, which is disposed between the zoom device and the light spot measuring device, and is used for folding the optical path between the zoom device and the light spot measuring device.
As a further preferred, the zoom device is a zoom lens, a zoom mirror or a zoom multi-piece lens and mirror combination driven by a micro-electro-mechanical system, and the typical focal length of the zoom device ranges from 1 mm to 1000 mm. .
Preferably, the electrically controlled adjusting device is connected to a zoom device through an electrically controlled interface, and the electrically controlled adjusting device drives a movable unit or acousto-optic characteristics or electromagnetic characteristics in the zoom device by changing a current or voltage signal input to the zoom device, so as to control the change of the focal length of the zoom device.
Preferably, the detector built in the light spot measuring device is a CCD camera or a CMOS, the response wavelength range of the detector covers the central wavelength of the light source to be measured, and the distance between the light spot measuring device and the zoom device is fixed to the median of the focal length variation range of the zoom device.
Preferably, the data processing device calculates the beam quality factor M of the laser source to be measured by constructing a spot radius calculation model at the spot measuring device2；
The spot radius calculation model is as follows:
wherein the content of the first and second substances,
the beam waist radius of the collimated laser beam focused by the zoom device with the focal length f,
is the Rayleigh length, z, of the collimated laser beam focused by a zoom device having a focal length ffThe distance between the beam waist of the collimated laser beam focused by the zooming device with the focal length f and the detection surface of the light spot measuring device is obtained;
z is the same as the zoom means and the spot measuring means remain the samef＝f-f0And expressing the spot radius calculation model as:
wherein the content of the first and second substances,
B＝ω2，C＝-2ω2f0，D＝ω2f0 2so as to derive a beam quality factor M for calculating the laser source to be measured2The calculation model of (a) is:
wherein f is the focal length of the zoom device, pi and lambda are constants, M2Is the beam quality factor of the laser source to be measured, omega is the beam waist radius of the laser source to be measured, f0The initial focal length value of the zooming device (2) is set as the default value of the middle value of the focusing range.
According to another aspect of the invention, the invention also provides a beam quality factor M2The rapid measurement method comprises the following steps:
(11) emitting collimated laser by a laser source to be detected, and attenuating the collimated laser;
(12) carrying out primary focusing on the attenuated collimated laser, and collecting and measuring the size of a collimated laser spot at the focal point of the primary focusing of the laser;
(13) changing the focal length of the collimated laser focus, and acquiring and measuring the size of a collimated laser spot at the primary focused focal point in real time in the continuous zooming process;
(14) calculating a beam quality factor M of the laser source to be measured according to the size of the collimated laser spot obtained by the primary focusing measurement, the primary focusing focal length and the size of the collimated laser spot at the primary focusing focal point under different focal lengths2。
Further preferably, in the step (12) and the step (13), when the laser light is focused, the optical path folding device is further used to fold the optical path during the focusing process.
Preferably, the focal length of the collimated laser is changed by a zoom device, and the size of the collimated laser spot at the focus of the primary focusing is collected and measured in real time by a spot measuring device, wherein the distance between the zoom device and the spot measuring device is kept constant.
As a further preferred, the step (14) specifically includes the steps of:
(141) constructing a calculation model of the size of the laser spot at the focus of the primary focusing:
wherein the content of the first and second substances,
the beam waist radius of the collimated laser beam focused by the zoom device with the focal length f,
is the Rayleigh length, z, of the collimated laser beam focused by a zoom device having a focal length ffThe distance between the beam waist of the collimated laser beam focused by the zooming device with the focal length f and the detection surface of the light spot measuring device is obtained;
(142) z is the same as the zoom means and the spot measuring means remain the samef＝f-f0And expressing the spot radius calculation model as:
wherein the content of the first and second substances,
B＝ω2，C＝-2ω2f0，D＝ω2f0 2，
(143) deriving a beam quality factor M for calculating the laser source to be measured according to step (142)2The calculation model of (a) is:
wherein f is the focal length of the zoom device, pi and lambda are constants, M2Is the beam quality factor of the laser source to be measured, omega is the beam waist radius of the laser source to be measured, f0The initial focal length value of the zooming device (2) is set as the default value of the middle value of the focusing range.
Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
1. the invention combines a beam quality factor M2The characteristics of the self-body and the measuring and calculating method characteristics thereof, and researches and designs the structures and the specific arrangement modes of key components of the self-body, such as a device to be sampled, a zooming device, an electric control adjusting device and a data processing device, and accordingly, the traditional M can be effectively solved2The measuring equipment needs to drive the reflector group to carry out large-stroke displacement, so that the measuring speed is low, the device has the advantages of clear principle, high adjusting speed, simplicity and convenience in operation and the like, and the beam quality factor M can be greatly improved2The measured speed of (2).
2. According to the invention, the focal length of the zooming device is changed through the electric control adjusting device, and the light spot measuring device keeps the axial position unchanged, so that the light spot sizes under different focal lengths can be obtained. Due to the size of the light spot and the beam quality factor M of the light beam to be measured2Initial spot size, system focal length and the like are closely related, and the light beam to be measured can be obtained through theoretical derivation and data fittingBeam quality factor M of2。
3. The light path folding device adopts the reflection-type light path to fold the light path between the zooming device and the light spot measuring device so as to reduce the size of the whole device.
4. The zoom lens has extremely high focal length change speed, and the bottleneck of measurement lies in the frame frequency of the CCD camera and the data processing speed. The CCD camera needs 50ms to acquire a single-frame image, the radius of a calculated light spot is less than 1ms, so that the time for completing 11 times of measurement is less than 600ms, the data fitting can be controlled within 50ms, the whole measurement process can be completed within 700ms, and the measurement is far higher than the traditional M2And (6) testing the speed.
5. The invention adopts a zooming device to replace the traditional fixed-focus lens or a liquid crystal spatial light modulator, the detector is fixedly arranged without electric regulation, and the M of the light source to be measured is obtained by adopting a new fitting equation2The system deduces the corresponding relation between the spot radius and the focal length under the constraint of collimated light, and only 2 coefficients are needed to obtain M through function fitting in a specific form2The numerical value of (c).
Drawings
Fig. 1 is a schematic structural diagram of a beam quality factor rapid measurement apparatus according to a preferred embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a beam quality factor rapid measurement apparatus according to another preferred embodiment of the present invention;
FIG. 3 is a beam quality factor M calculated by the beam quality factor rapid measurement device in FIG. 22The result of (1);
FIG. 4 is a conventional beam quality factor M2The structure of the measuring device is shown schematically.
In all the figures, the same reference numerals denote the same features, in particular: 1-a device to be sampled, 2-a zooming device, 3-an electronic control adjusting device, 4-a light path folding device, 5-a light spot measuring device, 6-a data processing device, 7-a light source to be measured, 8-a first reflector, 9-a wedge mirror, 10-an electric attenuation sheet, 11-a variable focus lens, 12-a controller, 13-a second reflector and 15-a silicon-based CCD camera.
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.
As shown in FIG. 1, the present invention provided by the embodiment of the present invention provides a beam quality factor M2The device comprises a sampling device, a zooming device, an electric control adjusting device, a light path folding device, a light spot measuring device and a data processing device, wherein the zooming device and the light spot measuring device are coaxial, and the light spot measuring device is positioned at an initial focal plane of the zooming device. And the laser beam to be measured enters along the direction of the optical axis of the system, and the light spot size of the focal plane is obtained through the light spot measuring device. The focal length of the zooming device is changed through the electric control adjusting device, and the light spot measuring device keeps the axial position unchanged, so that the light spot sizes under different focal lengths can be obtained. Due to the size of the light spot and the beam quality factor M of the light beam to be measured2The initial spot size, the system focal length and the like are closely related, and the beam quality factor M of the light beam to be measured can be obtained through theoretical derivation and data fitting2。
Specifically, the invention provides a beam quality factor M2The rapid measuring device includes: the device to be sampled 1 is used for inputting the collimated laser emitted by the laser source to be tested, the Rayleigh length of the collimated laser is far longer than the distance from the light source to the zooming device 2, and the laser is attenuated. The zooming device 2 is used for changing the focal length under the control of the electric control adjusting device 3 and focusing the attenuated collimated laser under different focal lengths; the light spot measuring device 5 is used for collecting and measuring the light spot size of the laser focused by the zooming device 2 in real time; a data processing device 6 for calculating the size of the light spot acquired and measured by the light spot measuring device 5 in real time according to the focal length of the zooming device 2 and the size of the light spot acquired and measured by the zooming device 2 under different focal lengthsBeam quality factor M of the source2. The device comprises a laser source to be detected, a collimating laser input device 1 to be detected, a zooming device 2, a light spot measuring device 4, a data processing device 6 and a data processing device, wherein the collimating laser emitted by the laser source to be detected is input into the sampling device 1 to be detected, attenuated into weak light and focused by the zooming device 2, the light spot measuring device 4 is used for collecting and measuring the size of a light spot of the collimated laser focused by the zooming device 2 in real time, the data processing device 6 is used for calculating a light beam quality factor M of the laser source to be detected according to the focal length of the zooming device 2 and the size of the light spot collected2。
In the invention, the device further comprises an optical path folding device 4, wherein the optical path folding device 4 is arranged between the zooming device 2 and the light spot measuring device 5 and is used for folding the optical path between the zooming device 2 and the light spot measuring device 5. The optical path folding device 4 folds the optical path between the zoom device 2 and the light spot measuring device 5 by using a reflection-type optical path to reduce the size of the entire device.
In the invention, the laser source to be measured can enter the subsequent measuring device only after being attenuated into weak light without distortion greatly through the sampling device 1.
In the invention, the zoom device 2 is a zoom lens, a zoom reflector or a zoom multi-piece lens group combined by the lens and the reflector driven by a micro-electro-mechanical system, the focal length change of the zoom device 2 does not depend on the characteristics of the light source to be measured, and the typical value of the focal length ranges from 1 mm to 1000 mm. The focal length of the zoom apparatus 2 may be rapidly varied in real time and may be of a transmissive or reflective construction, such as a variable focus lens/mirror or multi-piece mirror arrangement, with a focal length typically in the range of tens to hundreds of millimetres.
In the invention, the electrically controlled adjusting device 3 is connected with the zooming device 2 through an electrically controlled interface, and the electrically controlled adjusting device 3 drives a movable unit or acousto-optic characteristics or electromagnetic characteristics in the zooming device 2 by changing a current or voltage signal input into the zooming device 2 so as to control the change of the focal length of the zooming device 2.
In the present invention, the detector built in the light spot measuring device 5 is a CCD camera or a CMOS, the response wavelength range of the detector covers the central wavelength of the light source to be measured, and the distance (calculated by the actual optical path) from the zoom device is fixed to the median of the focal length variation range of the zoom device. The light spot measuring device 5 is located at a certain focal plane of the zooming device 2, the built-in detector is a photoelectric device such as a CCD camera and a CMOS, the response wavelength range covers the central wavelength of the light source to be measured, and the light spot which is incident to the detection surface can be responded.
The data processing device 6 communicates with the electric control adjusting device 3 and the light spot measuring device 5 through a universal data interface to obtain the current focal length of the zooming device 3 and the light spot size currently measured by the light spot measuring device 5. When the focal length of the zooming device 3 changes, a plurality of groups of focal lengths and light spot sizes are recorded, and data are processed through a built-in algorithm to obtain a beam quality factor M of the laser to be measured2And other relevant measurements.
In the invention, the data processing device 6 calculates the beam quality factor M of the laser source to be measured by constructing a light spot radius calculation model at the light spot measuring device 52。
The spot radius calculation model is as follows:
wherein the content of the first and second substances,
the beam waist radius of the collimated laser beam focused by the zoom apparatus 2 with the focal length f,
is the Rayleigh length, z, of the beam focused by the zoom means 2 having a focal length ffThe distance between the beam waist of the light beam focused by the zooming device 2 with the focal length f and the detection surface of the light spot measuring device 5 is shown;
z is the same as the zoom apparatus 2 and the spot measuring apparatus 5 are the samef＝f-f0And expressing the spot radius calculation model as:
wherein the content of the first and second substances,
B＝ω2，C＝-2ω2f0，D＝ω2f0 2so as to derive a beam quality factor M for calculating the laser source to be measured2The calculation model of (a) is:
wherein f is the focal length of the zoom device 2, pi and lambda are constants, M2Is the beam quality factor of the laser source to be measured, omega is the beam waist radius of the laser source to be measured, f0Is the initial focal length value of the zooming device (2) (default is the focal length median value of the zooming device 2).
The invention overcomes the defect of the traditional M2The measuring equipment needs to drive the reflector group to carry out large-stroke displacement, so that the measuring speed is low, the measuring equipment has the advantages of clear principle, high adjusting speed, simplicity and convenience in operation and the like, and the beam quality factor M can be greatly improved2The measured speed of (2).
According to another aspect of the present invention, there is also provided a beam quality factor M2The rapid measurement method comprises the following steps:
(11) the laser source to be measured emits collimated laser, and the collimated laser is attenuated.
(12) And carrying out primary focusing on the attenuated collimated laser, and collecting and measuring the size of a collimated laser spot at the primary focusing point of the collimated laser.
(13) And changing the focal length of laser focusing, and acquiring and measuring the size of the collimated laser spot at the primarily focused focal point in real time in the continuous zooming process.
In the step (12) and the step (13), when the straight laser is focused, the optical path folding device 4 is further adopted to fold the optical path in the focusing process. The focal length of the collimated laser focus is changed by adopting the zooming device 2, the size of the collimated laser spot at the focus of the primary focus is collected and measured in real time by adopting the spot measuring device 5, wherein the distance between the zooming device 2 and the spot measuring device 5 is kept unchanged.
(14) Calculating a beam quality factor M of the laser source to be measured according to the size of the collimated laser spot obtained by the primary focusing measurement, the primary focusing focal length and the size of the collimated laser spot at the primary focusing focal point under different focal lengths2。
The step (14) specifically includes the steps of:
(141) constructing a calculation model of the size of the collimated laser spot at the focus of the primary focusing:
wherein the content of the first and second substances,
for the beam waist radius of the beam focused by the zoom apparatus 2 having the focal length f,
is the Rayleigh length, z, of the beam focused by the zoom means 2 having a focal length ffThe distance between the beam waist of the light beam focused by the zooming device 2 with the focal length f and the detection surface of the light spot measuring device 5 is shown;
(142) z is the same as the zoom apparatus 2 and the spot measuring apparatus 5 are the samef＝f-f0And expressing the spot radius calculation model as:
wherein the content of the first and second substances,
B＝ω2，C＝-2ω2f0，D＝ω2f0 2；
(143) deriving a beam quality factor M for calculating the laser source to be measured according to step (142)2The calculation model of (a) is:
wherein f is the focal length of the zooming device (2), pi and lambda are constants, M2Is the beam quality factor of the laser source to be measured, omega is the beam waist radius of the laser source to be measured, f0Is the initial focal length value of the zooming device (2).
The invention adopts a zooming device to replace the traditional fixed focus lens or a liquid crystal spatial light modulator, the zooming device is a zooming multi-piece type lens group which adopts a zooming lens and a zooming reflector driven by a micro-electro-mechanical system or a lens and reflector combination, the focal length change of the zooming device does not depend on the characteristics of a light source to be measured, and the typical value of the focal length ranges from 1 mm to 1000 mm. In the aspect of specific implementation, the detector is a CCD camera or a CMOS, more importantly, the distance between the detector and the zooming device is specially designed, namely the middle value of the focusing range of the zooming device, the implementation of the device is more definite and operable due to the limitation, and the problem that the light spot measurement is inaccurate due to the fact that the position of the detector is not matched with the focal length of the zooming device is solved. Furthermore, the new fitting equation adopted in the invention obtains the M of the light source to be measured2. The traditional measuring method is to obtain M through 3 coefficients after hyperbolic curve fitting is carried out on the diameter and the position2The numerical value of (c). The system deduces the corresponding relation between the spot radius and the focal length under the constraint of collimated light, and only 2 coefficients can be used for obtaining M through function fitting in a specific form2The numerical value of (c).
FIG. 2 and FIG. 3 show the quality factor M of the laser beam2Quick measuring device and measuring knot thereofAn example of a fruit. The device comprises a device to be sampled 1, a zooming device 2, an electric control adjusting device 3, a light path folding device 4, a light spot measuring device 5 and a data processing device 6, wherein the device to be sampled 1 comprises a light source to be measured 7, a first reflector 8, a wedge mirror 9 and an electric attenuation sheet 10. The laser to be detected is output from the light source 7 to be detected, and the output laser sequentially passes through the first reflector 8, the wedge mirror 9 and the electric attenuation sheet 10, is attenuated in the electric attenuation sheet 10 and then enters the zooming device 2. The zoom device 2 is a variable focus lens 11 for changing the focus of the attenuated laser light. The electrically controlled adjusting means 3 is a controller for changing the focus of the variable focus lens 11. The optical path folding device 4 is two second reflecting mirrors 13 correspondingly arranged and used for changing the path of the laser focused by the variable-focus lens 11 so as to fold the laser path. The light spot measuring device 5 is a silicon-based CCD camera. A laser beam to be measured is quasi-Gaussian collimated, the output power of which is 1kW, the peak wavelength of which is 1064nm and the beam radius of which is 5mm, is sampled by a piece of coated wedge mirror, the wedge mirror is coated with a high-transmittance film, the residual reflectivity is less than 2 per thousand, and then the laser beam enters a beam quality tester through an electric attenuation sheet set. The zoom device of the light beam quality tester adopts an ultra-fast acousto-optic variable focus lens, the focal length change range of the variable focus lens is 300mm-400mm, and the focal length change speed reaches the sub-microsecond level. The two second reflectors which are arranged at an angle of 45 degrees fold the light path passing through the lens, the horizontal distance between the second reflectors and the zoom lens is 150mm, the vertical distance between the second reflectors is 50mm, the light spot measuring device 5 adopts a silicon-based CCD camera, the response wavelength range of the silicon-based CCD camera is 400nm-1100nm, the caliber is 5.12mm multiplied by 5.12mm, 1024 multiplied by 1024 pixels, the size of a single pixel is 5 mu m multiplied by 5 mu m, the frame frequency of the light spot measuring device is 20Hz, and the optical path between the light spot measuring device 5 and the zoom lens is 350 mm.
In the light emitting process, the focal length of the zoom lens is increased from 340mm to 360mm, and the step length is 2 mm. Since the zoom lens has a very fast focal length variation speed, the bottleneck of measurement is the frame rate of the CCD camera and the speed of data processing. The CCD camera needs 50ms to acquire a single-frame image, the radius of a calculated light spot is less than 1ms, so that the time for completing 11 times of measurement is less than 600ms, the data fitting can be controlled within 50ms, and the whole measurement process can be carried outFinished within 700ms, which is far higher than the traditional M2And (6) testing the speed. Table 1 gives the experimental results and the fitting of the simulation.
TABLE 1 input parameters and simulation results
Therefore, there are:
substantially consistent with the simulation input.
The embodiment shows that the invention can effectively, correctly and quickly process the beam quality factor M2And (6) carrying out testing.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. Light beam quality factor M2Quick measuring device, its characterized in that includes:
the device to be sampled (1) is used for inputting the collimated laser emitted by the laser source to be sampled and attenuating the collimated laser;
the zooming device (2) is used for changing the focal length under the control of the electric control adjusting device (3) and focusing the attenuated collimated laser under different focal lengths;
the light spot measuring device (5) is used for acquiring and measuring the light spot size of the collimated laser focused by the zooming device (2) in real time;
data processing means (6) for processing data according to said zooming means (c)2) The focal length of the zoom device (2) and the spot size acquired and measured by the spot measuring device (5) in real time under different focal lengths calculate the beam quality factor M of the laser source to be measured2：
Wherein the position distance between the zooming device (2) and the light spot measuring device (5) is kept unchanged.
2. A beam quality factor M according to claim 12The rapid measuring device is characterized by further comprising an optical path folding device (4), wherein the optical path folding device (4) is arranged between the zooming device (2) and the light spot measuring device (5) and is used for folding an optical path between the zooming device (2) and the light spot measuring device (5).
3. A beam quality factor M according to claim 12The rapid measuring device is characterized in that the zooming device (2) is a zooming multi-piece type lens group which adopts a zooming lens, a zooming reflector or a lens and reflector combination driven by a micro-electro-mechanical system, and the typical value of the focal length of the zooming device (2) ranges from 1 mm to 1000 mm.
4. A beam quality factor M according to claim 12The rapid measuring device is characterized in that the electric control adjusting device (3) is connected with the zooming device (2) through an electric control interface, and the electric control adjusting device (3) drives a movable unit in the zooming device (2) or acousto-optic characteristics or electromagnetic characteristics by changing current or voltage signals input into the zooming device (2) so as to control the change of the focal length of the zooming device (2).
5. A beam quality factor M according to claim 12The rapid measuring device is characterized in that a detector arranged in the light spot measuring device (5) is a CCD camera or a CMOS, the response wavelength range of the detector covers the central wavelength of a light source to be measured, and the distance between the light spot measuring device (5) and the zooming device (2) is fixed to be the median of the focal length variation range of the zooming device (2).
6. A beam quality factor M according to claim 12The rapid measuring device is characterized in that the data processing device (6) calculates the beam quality factor M of the laser source to be measured by constructing a light spot radius calculation model at the light spot measuring device (5)2；
The spot radius calculation model is as follows:
wherein the content of the first and second substances,
the beam waist radius of the collimated laser beam after being focused by the zoom device (2) with the focal length f,
is the Rayleigh length, z, of the collimated laser beam focused by a zoom device (2) having a focal length ffThe distance between the beam waist of the collimated laser beam focused by the zooming device (2) with the focal length of f and the detection surface of the light spot measuring device (5);
z is determined by the fact that the zoom device (2) and the spot measuring device (5) remain unchangedf＝f-f0And expressing the spot radius calculation model as:
wherein the content of the first and second substances,
B＝ω2，C＝-2ω2f0，
thereby to obtainConstructing a beam quality factor M for calculating a laser source to be measured2The calculation model of (2):
wherein f is the focal length of the zooming device (2), pi and lambda are constants, M2Is the beam quality factor of the laser source to be measured, omega is the beam waist radius of the laser source to be measured, f0Is the initial focal length value of the zooming device (2).
7. Light beam quality factor M2The rapid measurement method is characterized by comprising the following steps:
(11) emitting collimated laser by a laser source to be detected, and attenuating the collimated laser;
(12) primarily focusing the attenuated collimated laser, and collecting and measuring the size of a collimated laser spot at the primarily focused focal point of the collimated laser;
(13) changing the focal length of the collimated laser focus, and acquiring and measuring the size of a collimated laser spot at the primary focused focal point in real time in the continuous zooming process;
(14) calculating a beam quality factor M of the laser source to be measured according to the size of the collimated laser spot obtained by the primary focusing measurement, the primary focusing focal length and the size of the collimated laser spot at the primary focusing focal point under different focal lengths2。
8. A beam quality factor M according to claim 72The rapid measurement method is characterized in that in the step (12) and the step (13), when the straight laser is focused, an optical path folding device (4) is further adopted to fold an optical path in the focusing process.
9. A beam quality factor M according to claim 72The rapid measurement method is characterized in that a focal length of a collimated laser focus is changed by adopting a zooming device (2), and a light spot measurement device (5) is adopted to collect and measure a primary focus in real timeWherein the distance between the zoom means (2) and the spot measuring means (5) is kept constant.
10. A beam quality factor M according to claim 92The rapid measurement method is characterized in that the step (14) specifically comprises the following steps:
(141) constructing a calculation model of the size of the collimated laser spot at the focus of the primary focusing:
wherein the content of the first and second substances,
the beam waist radius of the collimated laser beam after being focused by the zoom device (2) with the focal length f,
is the Rayleigh length, z, of the collimated laser beam focused by a zoom device (2) having a focal length ffThe distance between the beam waist of the collimated laser beam focused by the zooming device (2) with the focal length of f and the detection surface of the light spot measuring device (5);
(142) z is determined by the fact that the zoom device (2) and the spot measuring device (5) remain unchangedf＝f-f0And expressing the spot radius calculation model as:
wherein the content of the first and second substances,
B＝ω2，C＝-2ω2f0，
(143) deriving a beam quality factor M for calculating the laser source to be measured according to step (142)2The calculation model of (a) is:
wherein f is the focal length of the zooming device (2), pi and lambda are constants, M2Is the beam quality factor of the laser source to be measured, omega is the beam waist radius of the laser source to be measured, f0Is the initial focal length value of the zooming device (2).
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