CN111487042A - Measuring system and measuring method for parallelism and uniformity of collimated light beams - Google Patents
Measuring system and measuring method for parallelism and uniformity of collimated light beams Download PDFInfo
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- CN111487042A CN111487042A CN202010367628.0A CN202010367628A CN111487042A CN 111487042 A CN111487042 A CN 111487042A CN 202010367628 A CN202010367628 A CN 202010367628A CN 111487042 A CN111487042 A CN 111487042A
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
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- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
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Abstract
The invention discloses a system and a method for measuring the parallelism and the uniformity of a collimated light beam, wherein the measuring method comprises the following steps: s1, placing the measuring system in front of the collimated light beam to be measured; s2, controlling the measurement system to scan along the horizontal direction and the vertical direction; s3, identifying the light spot of the collimated light beam to be detected, searching the edge position of the effective imaging area of the collimated light beam to be detected, and fitting the imaging cross section area of the collimated light beam to be detected; s4, selecting a data scanning point in the imaging cross section area of the collimated light beam to be detected, and determining a path plan; s5, traversing each data scanning point in the path planning, identifying the light spot of the collimated light beam to be detected at each data scanning point position, and calculating the image gray level mean value and the image centroid coordinate of the light spot; and S6, calculating the parallelism and uniformity of the collimated light beam to be detected according to the image gray average value and the image centroid coordinates of the light spots. The invention can realize the simultaneous measurement of the uniformity and the parallelism and can also measure the uniformity of the large-size light beam.
Description
Technical Field
The invention relates to the technical field of collimated light measurement, in particular to a system and a method for measuring parallelism and uniformity of a collimated light beam.
Background
The existing method for testing the uniformity and the parallelism of the collimated light beam needs to carry out scanning twice, and respectively collects parameters required by calculating the uniformity and the parallelism, so that the uniformity and the parallelism cannot be tested simultaneously.
In the method for testing the uniformity and the parallelism independently, the uniformity testing method generally images the whole light spot, and the uniformity is further calculated by judging the energy distribution or the gray distribution of the imaged light spot, so that the method has great limitation, namely, the uniformity of the light beam with small size can be tested only, the precision of judging the energy distribution or the gray distribution of the light spot is not high, and the testing precision of the uniformity is influenced finally; the parallelism testing method adopts a one-dimensional scanning mode to scan the light beam, can not test the cross section of the whole light beam, and has lower testing precision.
Disclosure of Invention
The invention aims to solve the technical problems and provides a system and a method for measuring the parallelism and the uniformity of a collimated light beam, so as to solve the problems that the existing method for measuring the uniformity and the parallelism of the collimated light beam cannot realize simultaneous measurement, and the uniformity test only aims at small-size light beams and has lower parallelism test precision.
In order to achieve the purpose, the invention adopts the following specific technical scheme:
a method for measuring the parallelism and uniformity of a collimated light beam comprises the following steps:
s1, two-dimensional scanning is carried out on the collimated light beam to be detected, the edge position of the effective imaging area of the collimated light beam to be detected is searched, and the imaging cross section area of the collimated light beam to be detected is fitted;
s2, selecting a data scanning point in the imaging cross section area of the collimated light beam to be detected, and determining a path plan;
s3, traversing each data scanning point in the path planning, identifying the light spot of the collimated light beam to be detected at each data scanning point position, and calculating the image gray level mean value and the image centroid coordinate of the light spot;
s4, calculating the parallelism and the uniformity of the collimated light beam to be detected according to the image gray average value and the image centroid coordinates of the light spots; wherein the content of the first and second substances,
the formula for calculating the uniformity of the collimated light beam to be measured according to the image gray level mean value of the light spots is as follows:
wherein U is the uniformity of the collimated light beam to be measured, VavgImage gray level mean value, V, of light spots for all data scanning pointsiIs the image gray average value, V, of the ith data scanning pointmnThe gray values of the pixel points of the mth row and the nth column in one frame of image are W, H, which are the width and the height of the image respectively, and L is the number of data scanning points;
the formula for calculating the parallelism of the collimated light beam to be detected according to the image centroid coordinates of the light spots is as follows:
wherein, PiFor the parallelism of each data scanning point relative to the center of the imaging cross-sectional area of the collimated light beam to be measured, (X)i，Yi) For scanning the points for each dataImage centroid coordinates (X)0，Y0) The image centroid coordinate of the central point of the cross section of the light beam imaging area is shown, F is the focal length of the collimated light beam to be detected, and S is the pixel size of the image acquisition unit.
Preferably, in step S1, the process of finding the edge position of the effective imaging area of the collimated measured light beam and fitting out the imaging cross-sectional area of the collimated measured light beam includes the following steps:
s110, horizontal direction scanning: the electric control unit controls the two-dimensional moving device to scan along the horizontal direction;
when the two-dimensional moving device moves to SXi-1The spot is not identified in position, and moves to SXiLight spots are identified and recorded as horizontal edge A points SXA＝SXi；
When the two-dimensional moving device moves to SXi-1The spot is identified and moved to SXiNo light spot is identified at the position and is recorded as a horizontal edge B point SXB＝SXi(ii) a Then
In the horizontal direction, the horizontal coordinate of the central point of the imaging area of the detected collimated light beam is as follows:
CX＝0.5*(SXA+SXB)；
s120, scanning in the vertical direction: the electric control unit controls the two-dimensional mobile device to move to a central point horizontal coordinate CX which is recorded as a vertical edge A point SYAThen scanning is carried out along the vertical direction;
when the two-dimensional mobile device moves to SYi-1The position recognizes a light spot and moves to SYiNo light spot is identified in position and is marked as a vertical edge B point SYB＝SYi(ii) a Then
The radius of the imaging area of the collimated light beam to be measured is:
in the vertical direction, the vertical coordinate of the central point of the imaging area of the detected collimated light beam is as follows:
CY＝SYA+(|SYA-SYB|-R)，
and finally fitting the imaging cross-sectional area of the measured collimated light beam with the central point of (CX, CY) and the radius of R.
Preferably, coordinate points equidistant from the central point (CX, CY) are selected as data scanning points within the imaging cross-sectional area of the collimated light beam to be measured.
Preferably, in step S1, the image acquisition unit identifies the light spot of the collimated light beam to be detected using OTSU algorithm.
A collimated beam parallelism and uniformity measurement system, comprising:
the prism is used for refracting and converting the collimated light beam to be detected;
the image acquisition unit is used for receiving the collimated light beam to be detected, which is converted by the prism, and imaging the collimated light beam;
the two-dimensional moving device is used for driving the image acquisition unit and the prism to move;
the electric control unit is used for controlling the two-dimensional moving device to move in two dimensions;
the imaging area fitting unit is used for searching the edge position of the effective imaging area of the collimated light beam to be measured and fitting the imaging cross section area of the collimated light beam to be measured;
the path planning establishing unit is used for establishing path planning according to the data scanning points selected in the imaging cross section area of the collimated light beam to be detected;
the light spot identification unit is used for traversing each data scanning point in the path planning and identifying the light spot of the collimated light beam to be detected at each data scanning point;
the image gray level mean value calculating unit is used for calculating the image gray level mean value of the light spot through the following formula:
wherein, ViThe average value of the gray scales of the image at the ith data scanning point is W, H, which are the width and height of the image, VmnThe gray values of the pixel points of the mth row and the nth column in the frame image are obtained;
the image centroid coordinate calculating unit is used for calculating the image centroid coordinate of the light spot through the following formula:
wherein (X)i，Yi) Scanning the image centroid coordinates of the points for each data;
the uniformity calculation unit is used for calculating the uniformity of the collimated light beam to be measured according to the image gray level mean value of the light spots, and the calculation formula is as follows:
wherein U is the uniformity of the collimated light beam to be measured, VavgThe average of the image gradations of the light spots for all the data scanning points, L the number of the data scanning points
The parallelism calculating unit is used for calculating the parallelism of the collimated light beam to be measured according to the image centroid coordinates of the light spots, and the calculation formula is as follows:
wherein, PiFor the parallelism of each data scanning point relative to the center of the imaging cross-sectional area of the collimated light beam to be measured, (X)0，Y0) The image centroid coordinate of the central point of the cross section of the light beam imaging area is shown, F is the focal length of the collimated light beam to be detected, and S is the pixel size of the image acquisition unit.
Preferably, the two-dimensional moving device comprises a fixed frame, a horizontal moving mechanism and a longitudinal moving mechanism; the longitudinal moving mechanism comprises a longitudinal driving motor, a longitudinal guide rail, a sliding block, a rack, a longitudinal moving mechanism mounting plate and a horizontal moving mechanism mounting plate, the longitudinal driving motor is fixed on the longitudinal moving mechanism mounting plate, and a longitudinal gear is sleeved on the longitudinal driving motor; the number of the longitudinal guide rails is two, and the longitudinal guide rails are fixed on the fixed frame at intervals; the number of the sliding blocks is two, one surfaces of the two sliding blocks are respectively connected with the longitudinal guide rail in a sliding manner, and the other surfaces of the two sliding blocks are respectively fixedly connected with the longitudinal moving mechanism mounting plate and the horizontal moving mechanism mounting plate; the rack is fixed on the fixed frame and is in meshing transmission with the longitudinal gear; the horizontal moving mechanism comprises a horizontal driving motor, a synchronous belt, a driving synchronous gear and a driven synchronous gear, the horizontal driving motor is fixed on the longitudinal moving mechanism mounting plate, the driving synchronous gear is sleeved on an output shaft of the horizontal driving motor, the driven synchronous gear is mounted on the horizontal moving mechanism mounting plate through a gear shaft, the synchronous belt is meshed between the driving synchronous gear and the driven synchronous gear, a prism is fixed on the synchronous belt through a fixing block, and an image acquisition unit is fixed on the horizontal moving mechanism mounting plate.
Preferably, the longitudinal moving mechanism further comprises a guide shaft connected between the longitudinal moving mechanism mounting plate and the horizontal moving mechanism mounting plate, and the fixed block is sleeved on the guide shaft.
Preferably, an adjusting foot is installed at the bottom of the fixed frame.
The invention can obtain the following technical effects:
1. the invention drives the prism to perform two-dimensional scanning on the collimated light beam to be tested through the two-dimensional moving device, can test the section of the whole light beam, and improves the testing precision of the parallelism.
2. The invention can obtain the parameters for calculating the parallelism and the uniformity through one-time scanning, and realizes the simultaneous test of the parallelism and the uniformity.
3. The invention adopts the mode of selecting the data scanning points to traverse the section area of the whole light spot, can test the uniformity of the large-size light beam, and can improve the judgment precision of the energy distribution or the gray distribution of the light spot by taking all error factors into account in the uniformity test method, thereby improving the test precision of the uniformity.
Drawings
FIG. 1 is a schematic diagram of a first view angle of a collimated beam parallelism and uniformity measurement system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a second view angle of the collimated light beam parallelism and uniformity measurement system according to the embodiment of the present invention.
Fig. 3 is a schematic flow chart of a method for measuring parallelism and uniformity of a collimated light beam according to an embodiment of the present invention.
Wherein the reference numerals include: the device comprises a prism 1, an image acquisition unit 2, an electronic control unit 3, a fixed frame 410, a horizontal support 411, a vertical support 412, an oblique support 413, an auxiliary support 414, an adjusting anchor 415, a longitudinal driving motor 420, a longitudinal guide rail 421, a sliding block 422, a rack 423, a longitudinal moving mechanism mounting plate 424, a horizontal moving mechanism mounting plate 425, a longitudinal gear 426, a horizontal driving motor 431, a synchronous belt 432, a driving synchronous gear 433, a driven synchronous gear 434, a guide shaft 435 and a fixed block 5.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention.
Noun interpretation
Parallelism: refers to the parallelism between the beams in the outgoing direction of the collimated beam.
Uniformity: refers to the uniformity of the light intensity distribution across the cross-section of the collimated beam.
The two-dimensional scanning device drives the prism to perform two-dimensional scanning on the measured collimated light beam in the horizontal direction and the vertical direction through the two-dimensional moving device, the image scanning unit receives the light beam converted by the prism and images, the uniformity and the parallelism of the measured collimated light beam are calculated by calculating the image gray level mean value of the imaging light spot and the image centroid coordinate of the light spot, different positions of the light beam can be scanned according to needs in the scanning process, the precision is controllable, and the uniformity and the parallelism of the whole light beam can be measured simultaneously according to the calculated image gray level mean value and the image centroid coordinate of the imaging light spot.
The collimated light beam parallelism and uniformity structure provided by the embodiment of the invention comprises:
the prism is used for refracting and converting the collimated light beam to be detected;
the image acquisition unit is used for receiving the collimated light beam to be detected which is converted by the prism and imaging the collimated light beam;
the two-dimensional moving device is used for driving the image acquisition unit and the prism to move;
the electric control unit is used for controlling the two-dimensional moving device to move in two dimensions;
the imaging area fitting unit is used for searching the edge position of the effective imaging area of the collimated light beam to be measured and fitting the imaging cross section area of the collimated light beam to be measured;
the path planning establishing unit is used for establishing path planning according to the data scanning points selected in the imaging cross section area of the collimated light beam to be detected;
the light spot identification unit is used for traversing each data scanning point in the path planning and identifying the light spot of the collimated light beam to be detected at each data scanning point;
the image gray level mean value calculating unit is used for calculating the image gray level mean value of the light spot through the following formula:
wherein, ViThe average value of the gray scales of the image at the ith data scanning point is W, H, which are the width and height of the image, VmnThe gray values of the pixel points of the mth row and the nth column in the frame image are obtained;
the image centroid coordinate calculating unit is used for calculating the image centroid coordinate of the light spot through the following formula:
wherein (X)i，Yi) Scanning the image centroid coordinates of the points for each data;
the uniformity calculation unit is used for calculating the uniformity of the collimated light beam to be measured according to the image gray level mean value of the light spots, and the calculation formula is as follows:
wherein U is the uniformity of the collimated light beam to be measured, VavgThe average of the image gradations of the light spots for all the data scanning points, L the number of the data scanning points
The parallelism calculating unit is used for calculating the parallelism of the collimated light beam to be measured according to the image centroid coordinates of the light spots, and the calculation formula is as follows:
wherein, PiFor the parallelism of each data scanning point relative to the center of the imaging cross-sectional area of the collimated light beam to be measured, (X)0，Y0) The image centroid coordinate of the central point of the cross section of the light beam imaging area is shown, F is the focal length of the collimated light beam to be detected, and S is the pixel size of the image acquisition unit.
The structures of a prism, an image acquisition unit, a two-dimensional moving device and an electric control unit in the collimated light beam parallelism and uniformity measuring system are shown in fig. 1 and fig. 2, the prism 1 is used for converting the collimated light beam to be measured and converting the collimated light beam to be measured to the image acquisition unit 2, the prism 1 can be a triangular prism or a pentaprism, preferably a pentaprism, and the converted image is a positive image; the image acquisition unit 2 is a high-resolution camera and is used for receiving the collimated light beam after being converted by the prism 1 and imaging the collimated light beam; the prism 1 and the image acquisition unit 2 are respectively fixed on the two-dimensional moving device, and the two-dimensional moving device drives the prism 1 and the image acquisition unit 2 to move; the electronic control unit 3 is used for controlling the two-dimensional moving device, and the electronic control unit 3 is prior art and therefore will not be described herein again.
The two-dimensional moving device includes: the device comprises a fixed frame 410, a longitudinal moving mechanism and a horizontal moving mechanism, wherein the fixed frame 410 is used for supporting and fixing the longitudinal moving mechanism and the horizontal moving mechanism, the longitudinal moving mechanism is used for driving the prism 1 and the image acquisition unit 2 to move in the vertical direction, and the horizontal moving mechanism is used for driving the prism 1 to move horizontally.
The fixed frame 410 includes four horizontal brackets 411, two vertical brackets 412 and two inclined brackets 413, the four horizontal brackets 411 enclose a rectangular structure, the two vertical brackets 412 are vertically fixed at two right angles on the same side of the rectangular structure, one ends of the two inclined brackets 413 are respectively fixed at the tops of the two vertical brackets 412, the other ends of the two inclined brackets 413 are respectively fixed at the other two right angles of the rectangular structure, the horizontal brackets 411, the vertical brackets 412 and the inclined brackets 413 enclose a triangle, and the fixed frame 410 with the structure is the most stable.
In order to further improve the stability of the fixing frame 410, an auxiliary bracket 414 is connected between the top ends of the two vertical brackets 412, and the auxiliary bracket 414 plays a role of assisting in stabilizing the fixing frame 410.
The longitudinal movement mechanism includes: a longitudinal driving motor 420, a longitudinal guide rail 421, a slider 422, a rack 423, a longitudinal moving mechanism mounting plate 424, a horizontal moving mechanism mounting plate 425, and a longitudinal gear 426; wherein, the number of the longitudinal guide rails 421 is two, and the two longitudinal guide rails are respectively fixed on the two vertical brackets 412; the rack 423 is fixed on a vertical bracket 412 and is positioned at one side of the longitudinal guide rail 421; the number of the sliding blocks 422 is two, and the two sliding blocks 422 are respectively connected to the two longitudinal guide rails 402 in a sliding manner; the longitudinal moving mechanism mounting plate 424 is fixedly connected with one sliding block 422, the horizontal moving mechanism mounting plate 425 is fixedly connected with the other sliding block 422, the longitudinal driving motor 420 is fixed on the longitudinal moving mechanism mounting plate 424, the longitudinal gear 426 is sleeved on an output shaft of the longitudinal driving motor 420 and meshed with the rack 423, and the longitudinal gear 426 rotates synchronously along with the output shaft of the longitudinal driving motor 420 and is meshed with the rack 423 for transmission to drive the sliding block 422 fixed with the longitudinal moving mechanism mounting plate 424 to slide on the corresponding longitudinal guide rail 421.
The horizontal movement mechanism includes: a horizontal driving motor 431, a synchronous belt 432, a driving synchronous gear 433 and a driven synchronous gear 434; wherein, the horizontal driving motor 431 is fixed on the longitudinal moving mechanism mounting plate 424, the driving synchronous gear 433 is sleeved on the output shaft of the horizontal driving motor 431 and rotates synchronously with the output shaft of the horizontal driving motor 431; the driven synchronizing gear 434 is mounted on the horizontal movement mechanism mounting plate 425 through a gear shaft, the timing belt 432 is engaged between the driving synchronizing gear 433 and the driven synchronizing gear 434, and the prism 1 is fixed to the timing belt 432 through the fixed block 5.
When the sliding block 422 fixed to the longitudinal moving mechanism mounting plate 424 slides on the corresponding longitudinal guide rail 420, the horizontal moving mechanism and the image collecting unit 2 are driven to move in the vertical direction, and the other sliding block 422 is driven to slide on the other longitudinal guide rail 420 through the synchronous belt 432, the horizontal moving mechanism drives the prism 1 to move in the vertical direction, and the prism 1 and the image collecting unit 2 synchronously move in the vertical direction, so that the image collecting unit 2 can receive the collimated light beam refracted by the prism 1.
The image capturing unit 2 is fixed on the horizontal movement mechanism mounting plate 425, and moves in the vertical direction synchronously with the horizontal movement mechanism mounting plate 425 under the driving of the sliding block 422.
When the horizontal driving motor 431 drives the driving synchronous gear 433 to rotate, the synchronous belt 432 is driven to transmit, so that the prism 1 is driven to move in the horizontal direction. Since the image pickup unit 2 is fixed to the horizontal movement mechanism mounting plate 425, the image pickup unit 2 does not move in the horizontal direction along with the belt 432.
The invention fixes a horizontal moving mechanism on a longitudinal moving mechanism, fixes a prism 1 on the horizontal moving mechanism, and fixes an image acquisition unit 2 on the longitudinal moving mechanism. The longitudinal moving mechanism can drive the prism 1 and the image acquisition unit 2 to synchronously lift, and the horizontal moving mechanism can drive the prism 1 to move in the horizontal direction.
In order to guide the prism 1, a guide shaft 435 is provided between the longitudinal moving mechanism mounting plate 424 and the horizontal moving mechanism mounting plate 425, a guide hole is provided at a position of the fixed block 5 corresponding to the guide shaft 435, so that the fixed block 5 is fitted over the guide shaft 435, and when the prism 1 moves along with the belt 432, the prism 1 moves under the guide of the guide shaft 435.
The invention realizes the two-dimensional movement of the prism 1 through the longitudinal moving mechanism and the transverse moving mechanism so as to enlarge the scanning range.
The prism 1 needs to be perpendicular to the optical axis of the collimated light beam to be measured, in order to adjust the verticality of the prism 1 and the optical axis of the collimated light beam to be measured, an adjusting ground pin 415 is arranged at the position, below the prism 1, of the bottom of the horizontal support 411, and the verticality of the prism 1 and the optical axis of the collimated light beam is adjusted by adjusting the height of the adjusting ground pin 415.
The image acquisition unit 2 is provided with a focusing lens, and when the prism 1 refracts the collimated light beam to the focusing lens, the collimated light beam is converged by the focusing lens, and then is subjected to analog-to-digital conversion and subsequent processing.
The above details describe the structure of the collimated beam parallelism and uniformity measurement system provided by the embodiments of the present invention, which corresponds to the collimated beam parallelism and uniformity measurement system, and the present invention further provides a method for measuring parallelism and uniformity of a collimated beam by using the measurement system.
Fig. 3 shows a flow chart of a method for measuring the parallelism and uniformity of a collimated light beam provided by the embodiment of the invention.
As shown in fig. 3, the method for measuring the parallelism and the uniformity of the collimated light beam according to the embodiment of the present invention includes the following steps:
and S1, placing the collimated light beam parallelism and uniformity measuring system in front of the collimated light beam to be measured, and enabling the prism to be perpendicular to the optical axis of the collimated light beam to be measured.
And adjusting the height of the feet to make the prism perpendicular to the optical axis of the collimated light beam to be measured.
The prism is arranged to be perpendicular to the optical axis of the collimated light beam to be measured so as to realize the folding of the collimated light beam to be received by the image acquisition unit.
And S2, inputting the basic parameters of the collimated light beam to be detected into an electric control unit, and controlling the two-dimensional moving device to scan along the horizontal direction and the vertical direction.
After the basic parameters of the collimated light beam to be detected are input into the electric control unit, the electric control unit controls the horizontal driving motor and the longitudinal driving motor to rotate, and the prism is driven to perform two-dimensional scanning.
S3, the image acquisition unit identifies the light spot of the collimated light beam to be detected, the edge position of the effective imaging area of the collimated light beam to be detected is searched, and the imaging cross-section area of the collimated light beam to be detected is fitted.
The image acquisition unit adopts OTSU algorithm to identify the light spot of the collimated light beam to be detected, and the specific steps are as follows:
s310, calculating an adaptive threshold T of the image by adopting the Otsu method (OTSU);
s320, if the Gray value Gray of the pixels in the image is greater than T, the point is considered to be a point in the light spot, otherwise, the point is considered to be a background pixel;
and S330, counting the number N of light spots in the image, identifying the light spots if N is greater than 0, and identifying no light spot at the current scanning position if N is 0.
The process that the image acquisition unit searches the edge position of the effective imaging area of the collimated light beam to be detected and fits the imaging cross section area of the collimated light beam to be detected comprises the following steps:
s340, horizontal direction scanning: the electric control unit controls the two-dimensional moving device to scan along the horizontal direction;
when the two-dimensional moving device moves to SXi-1The spot is not identified in position, and moves to SXiLight spots are identified and recorded as horizontal edge A points SXA＝SXi；
When the two-dimensional moving device moves to SXi-1The spot is identified and moved to SXiNo light spot is identified at the position and is recorded as a horizontal edge B point SXB＝SXi(ii) a Then
In the horizontal direction, the horizontal coordinate of the central point of the imaging area of the detected collimated light beam is as follows:
CX＝0.5*(SXA+SXB)；
s350, scanning in the vertical direction: the electric control unit controls the two-dimensional mobile device to move to a central point horizontal coordinate CX which is recorded as a vertical edge A point SYAThen sweeping in the vertical directionDrawing;
when the two-dimensional mobile device moves to SYi-1The position recognizes a light spot and moves to SYiNo light spot is identified in position and is marked as a vertical edge B point SYB＝SYi(ii) a Then
The radius of the imaging area of the collimated light beam to be measured is:
in the vertical direction, the vertical coordinate of the central point of the imaging area of the detected collimated light beam is as follows:
CY＝SYA+(|SYA-SYB|-R)，
and finally fitting the imaging cross-sectional area of the measured collimated light beam with the central point of (CX, CY) and the radius of R.
In the present invention, the scanning in the vertical direction may be performed first, and then the scanning in the horizontal direction may be performed.
And S4, selecting a data scanning point in the imaging cross section area of the detected collimated light beam, and determining a path plan.
In the imaging cross section area of the collimated light beam to be detected, coordinate points with equal distance to the central points (CX, CY) are selected as data scanning points, the data scanning points are coordinate points of positions to be traversed, and path planning is established by the data scanning points.
And S5, driving the two-dimensional mobile device to traverse each data scanning point in the path planning by the electric control unit, identifying the light spot of the collimated light beam to be detected at each data scanning point position by the image acquisition unit, and calculating the image gray level mean value and the image centroid coordinate of each light spot.
The calculation formula of the image gray level mean value of each light spot is as follows:
wherein, ViThe average value of the gray scales of the image at the ith data scanning point is W, H, which are the width and height of the image, VmnThe gray values of the pixel points of the mth row and the nth column in the frame image are obtained.
The calculation formula of the image centroid coordinate of each light spot is as follows:
wherein (X)i，Yi) The image centroid coordinates of the points are scanned for each data.
The invention adopts a mode of selecting data scanning points to traverse the cross section area of the whole light spot, and can test the uniformity of the large-size light beam.
And S6, calculating the parallelism and uniformity of the collimated light beam to be detected according to the image gray average value and the image centroid coordinates of the light spots.
The formula for calculating the uniformity of the collimated light beam to be measured according to the image gray level mean value of the light spots is as follows:
wherein U is the uniformity of the collimated light beam to be measured, VavgThe average of the image gradations of the light spots for all the data scanning points, L is the number of the data scanning points.
The uniformity measuring method provided by the invention considers various error factors (such as the accuracy error of adjustment and the like), and can improve the judgment accuracy of the energy distribution or the gray distribution of the light spots, thereby improving the uniformity measuring accuracy.
The formula for calculating the parallelism of the collimated light beam to be detected according to the image centroid coordinates of the light spots is as follows:
wherein, PiImaging cross-sectional area of each data scanning point relative to the collimated beam to be measuredParallelism of domain centers, (X)0，Y0) The image centroid coordinate of the central point of the cross section of the light beam imaging area is shown, F is the focal length of the collimated light beam to be detected, and S is the pixel size of the image acquisition unit.
The invention can obtain the data of calculating the parallelism and the uniformity of the collimated light beam to be measured in the process of one-time scanning, and can realize the simultaneous measurement of the parallelism and the uniformity.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
The above embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.
Claims (8)
1. A method for measuring the parallelism and the uniformity of a collimated light beam is characterized by comprising the following steps:
s1, two-dimensional scanning is carried out on the collimated light beam to be detected, the edge position of the effective imaging area of the collimated light beam to be detected is searched, and the imaging cross section area of the collimated light beam to be detected is fitted;
s2, selecting a data scanning point in the imaging cross section area of the collimated light beam to be detected, and determining a path plan;
s3, traversing each data scanning point in the path planning, identifying the light spot of the collimated light beam to be detected at each data scanning point position, and calculating the image gray level mean value and the image centroid coordinate of the light spot;
s4, calculating the parallelism and the uniformity of the collimated light beam to be detected according to the image gray average value and the image centroid coordinates of the light spots; wherein the content of the first and second substances,
the formula for calculating the uniformity of the collimated light beam to be measured according to the image gray level mean value of the light spots is as follows:
wherein U is the uniformity of the collimated light beam to be measured, VavgImage gray level mean value, V, of light spots for all data scanning pointsiIs the image gray average value, V, of the ith data scanning pointmnThe gray values of the pixel points of the mth row and the nth column in one frame of image are W, H, which are the width and the height of the image respectively, and L is the number of data scanning points;
the formula for calculating the parallelism of the collimated light beam to be detected according to the image centroid coordinates of the light spots is as follows:
wherein, PiFor the parallelism of each data scanning point relative to the center of the imaging cross-sectional area of the collimated light beam to be measured, (X)i，Yi) Scanning the image centroid coordinates of the points for each data, (X)0，Y0) The image centroid coordinate of the central point of the cross section of the light beam imaging area is shown, F is the focal length of the collimated light beam to be detected, and S is the pixel size of the image acquisition unit.
2. The method for measuring the parallelism and uniformity of a collimated light beam according to claim 1, wherein in step S1, the process of finding the edge position of the effective imaging area of the collimated light beam to fit the imaging cross-sectional area of the collimated light beam comprises the following steps:
s110, horizontal direction scanning: the electric control unit controls the two-dimensional moving device to scan along the horizontal direction;
when the two-dimensional moving device moves to SXi-1The spot is not identified in position, and moves to SXiLight spots are identified and recorded as horizontal edge A points SXA＝SXi；
When the two-dimensional moving device moves to SXi-1The spot is identified and moved to SXiNo light spot is identified at the position and is recorded as a horizontal edge B point SXB＝SXi(ii) a Then
In the horizontal direction, the horizontal coordinate of the central point of the imaging area of the detected collimated light beam is as follows:
CX＝0.5*(SXA+SXB)；
s120, scanning in the vertical direction: the electric control unit controls the two-dimensional mobile device to move to the central point horizontal coordinate CX which is recorded as a vertical edge A point SYAThen scanning is carried out along the vertical direction;
when the two-dimensional mobile device moves to SYi-1The position recognizes a light spot and moves to SYiNo light spot is identified in position and is marked as a vertical edge B point SYB＝SYi(ii) a Then
The radius of the imaging area of the collimated light beam to be measured is:
in the vertical direction, the vertical coordinate of the central point of the imaging area of the detected collimated light beam is as follows:
CY＝SYA+(|SYA-SYB|-R)，
and finally fitting the imaging cross-sectional area of the measured collimated light beam with the central point of (CX, CY) and the radius of R.
3. A method for measuring parallelism and uniformity of a collimated light beam according to claim 2, wherein coordinate points equidistant from said central point (CX, CY) are selected as data scanning points within the image cross-sectional area of the collimated light beam to be measured.
4. The method for measuring the parallelism and uniformity of a collimated light beam according to claim 1, wherein in step S1, the image capturing unit uses OTSU algorithm to identify the spot of the collimated light beam to be measured.
5. A collimated beam parallelism and uniformity measurement system, comprising:
the prism is used for refracting and converting the collimated light beam to be detected;
the image acquisition unit is used for receiving the collimated light beam to be detected which is converted by the prism and imaging the collimated light beam;
characterized in that, this measurement system still includes:
the two-dimensional moving device is used for driving the image acquisition unit and the prism to move;
the electric control unit is used for controlling the two-dimensional moving device to move in two dimensions;
the imaging area fitting unit is used for searching the edge position of the effective imaging area of the collimated light beam to be measured and fitting the imaging cross section area of the collimated light beam to be measured;
the path planning establishing unit is used for establishing path planning according to the data scanning points selected in the imaging cross section area of the collimated light beam to be detected;
the light spot identification unit is used for traversing each data scanning point in the path planning and identifying the light spot of the collimated light beam to be detected at each data scanning point;
the image gray level mean value calculating unit is used for calculating the image gray level mean value of the light spot through the following formula:
wherein, ViThe average value of the gray scales of the image at the ith data scanning point is W, H, which are the width and height of the image, VmnThe gray values of the pixel points of the mth row and the nth column in the frame image are obtained;
the image centroid coordinate calculating unit is used for calculating the image centroid coordinate of the light spot through the following formula:
wherein (X)i，Yi) Scanning the image centroid coordinates of the points for each data;
the uniformity calculation unit is used for calculating the uniformity of the collimated light beam to be measured according to the image gray level mean value of the light spots, and the calculation formula is as follows:
wherein U is the uniformity of the collimated light beam to be measured, VavgThe average of the image gradations of the light spots for all the data scanning points, L the number of the data scanning points
The parallelism calculating unit is used for calculating the parallelism of the collimated light beam to be measured according to the image centroid coordinates of the light spots, and the calculation formula is as follows:
wherein, PiFor the parallelism of each data scanning point relative to the center of the imaging cross-sectional area of the collimated light beam to be measured, (X)0，Y0) The image centroid coordinate of the central point of the cross section of the light beam imaging area is shown, F is the focal length of the collimated light beam to be detected, and S is the pixel size of the image acquisition unit.
6. The collimated light beam parallelism and uniformity measurement system of claim 5, wherein the two-dimensional movement device comprises a fixed frame, a horizontal movement mechanism, a longitudinal movement mechanism; wherein the content of the first and second substances,
the longitudinal moving mechanism comprises a longitudinal driving motor, a longitudinal guide rail, a sliding block, a rack, a longitudinal moving mechanism mounting plate and a horizontal moving mechanism mounting plate, the longitudinal driving motor is fixed on the longitudinal moving mechanism mounting plate, and a longitudinal gear is sleeved on the longitudinal driving motor; the number of the longitudinal guide rails is two, and the longitudinal guide rails are fixed on the fixed frame at intervals; the number of the sliding blocks is two, one surfaces of the two sliding blocks are respectively connected with the longitudinal guide rail in a sliding manner, and the other surfaces of the two sliding blocks are respectively fixedly connected with the longitudinal moving mechanism mounting plate and the horizontal moving mechanism mounting plate; the rack is fixed on the fixed frame and is in meshed transmission with the longitudinal gear;
horizontal migration mechanism includes horizontal drive motor, hold-in range, initiative synchronizing gear and driven synchronizing gear, horizontal drive motor fixes on the vertical migration mechanism mounting panel, initiative synchronizing gear suit is in on horizontal drive motor's the output shaft, driven synchronizing gear passes through the gear shaft and installs on the horizontal migration mechanism mounting panel, the hold-in range meshing is in initiative synchronizing gear with between the driven synchronizing gear, the prism passes through the fixed block to be fixed on the hold-in range, the image acquisition unit is fixed on the horizontal migration mechanism mounting panel.
7. The collimated light beam parallelism and uniformity measurement system of claim 5, wherein the longitudinal movement mechanism further comprises a guide shaft connected between the longitudinal movement mechanism mounting plate and the horizontal movement mechanism mounting plate, and the fixed block is sleeved on the guide shaft.
8. The collimated beam parallelism and uniformity measuring system of claim 5, wherein an adjustment foot is mounted to the bottom of the fixed frame.
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