CN106204535A - A kind of scaling method of high energy beam spot - Google Patents

Abstract

The present invention relates to a kind of scaling method, disclose the scaling method of a kind of high energy beam spot, including: at regulation beam spot to preset coordinate, making beam spot be in preset state, record beam spot is in circularity during preset state；In the case of keeping beam spot astigmatism constant, change the focus value of beam spot at least one times；Generate the functional relationship between beam spot location parameter and focus value.The present invention is by generating the functional relationship between beam spot location parameter and focus value, and it is in circularity during preset state according to this functional relationship and beam spot, it is capable of the calibration of the demarcation to beam spot position, and the impact focused on beam spot position can be demarcated, beam spot is carried out timing signal to be affected by pattern distortion, it is not necessary to solve imaging device relative to the complicated position orientation relation between the plane of beam spot place.

Description

A Calibration Method of High Energy Beam Spot

technical field

The invention relates to a calibration method, in particular to a calibration method for a high-energy beam spot.

Background technique

Calibration, also known as calibration, correction. Even if the size, shape and position of the beam spot reach the preset state, let the system remember this state.

In the field of high-energy beam processing such as additive manufacturing (3D printing), the size, shape and position of the high-energy beam spot will directly affect the quality of the processing process. For example, the size of the beam spot should be kept at a minimum to make the energy more concentrated; if the beam spot size is too large, the energy will not be concentrated, resulting in processing defects. The shape of the beam spot should remain circular, and the distorted beam spot will lead to a decrease in processing accuracy. The position of the beam spot should be accurate, and a beam spot with a deviation in position will lead to a decrease in processing accuracy. Therefore, before high-energy beam processing, it is necessary to calibrate the beam spot.

One of the current beam spot calibration methods is manual calibration, that is, to manually adjust the size, shape and position of the beam spot to reach a preset state. The manual calibration method generally uses some standard parts, such as marking points on the standard parts in advance, and the positions of the marking points are precisely positioned. Adjust the beam spot so that it coincides with the marking point, and adjust the beam spot to make it the smallest in size and most round in shape. The number of marker points is generally greater than 1 and distributed in an array. The main disadvantage of the manual calibration method is that it relies on human experience, lacks reliability, and is time-consuming and labor-intensive.

Another calibration method for the beam spot is automatic calibration, which relies on computers and sensors to adjust the size, shape and position of the beam spot to achieve a preset state. Commonly used is the visual sensing method, which captures images through imaging devices and extracts beam spot size, shape, and position information. However, due to the distortion of the captured image, the difficulty of solving the pose relationship of the imaging device relative to the plane where the beam spot is located, and the inability to eliminate the influence of focusing on the position of the beam spot, this calibration method makes it difficult to extract the position information of the beam spot and cannot be completed quickly and effectively. calibration.

Contents of the invention

The purpose of the present invention is to provide a high-energy beam spot calibration method to solve the problems of insufficient reliability existing in the existing calibration method and difficulty in extracting beam spot position information and unable to quickly and effectively complete the calibration.

For reaching this purpose, the present invention adopts following technical scheme:

A calibration method for a high-energy beam spot, characterized in that it comprises the following steps:

adjusting the beam spot to the preset coordinates so that the beam spot is in the preset state, and recording the circularity of the beam spot in the preset state;

changing the focus value of the beam spot at least once while keeping the astigmatism of the beam spot unchanged;

Generate a functional relationship between the beam spot position parameter and the focus value;

Adjusting the astigmatism of the current beam spot so that the absolute value of the difference between the circularity of the beam spot and the circularity in the preset state is smaller than the preset value, and determining the position parameter of the current beam spot according to the functional relationship.

Preferably, the making the beam spot in a preset state includes:

adjusting the focus value of the beam spot so that the size of the beam spot reaches a preset minimum value;

The astigmatism of the beam spot is adjusted so that the circularity of the beam spot is at a preset circularity.

Preferably, changing the focus value of the beam spot at least once while keeping the astigmatism of the beam spot unchanged includes:

keeping the astigmatism of the beam spot unchanged, so that the absolute value of the difference between the circularity of the beam spot and the circularity in a preset state is smaller than a preset value;

Changing the focus value of the beam spot so that the changed focus of the beam spot is higher/lower than the focus of the beam spot when it is in a preset state.

Preferably, after changing the focus value of the beam spot so that the changed focus of the beam spot is higher/lower than the focus of the beam spot when it is in a preset state, it further includes:

The focus value of the beam spot is changed again, so that the changed focus point of the beam spot is lower/higher than the focus point when the beam spot is in a preset state.

Preferably, the functional relationship between the generated beam spot position parameter and the focus value includes:

Record the focus value and position parameters of the beam spot in the preset state;

Record the focus value of the beam spot after the focus value is changed, change the position parameter until the beam spot moves to the preset coordinate, and record the new position parameter;

According to the focus value and position parameter of the beam spot in the preset state, the focus value of the beam spot after the focus value is changed, and the new position parameter, a functional relationship between the position parameter of the beam spot and the focus value is generated.

Preferably, the functional relationship between the beam spot position parameter and the focus value is as well as or (X,Y)=f(F), where:

X is a coordinate control parameter of the beam spot position in the X direction, Y is a coordinate control parameter of the beam spot position in the Y direction, and F is a focus value.

Preferably, before adjusting the beam spot to the preset coordinates, it also includes:

Set at least one marking point on the standard plate;

taking an image of the standard plate by an imaging device;

The corresponding preset coordinates are generated according to each marker point in the image.

Preferably, the imaging device is a CCD camera, a CMOS camera, an infrared camera, a near-infrared camera or a far-infrared camera.

As preferred, also include:

When the preset coordinates are greater than or equal to two, the beam spot corresponding to the first preset coordinate is calibrated;

After the beam spot corresponding to the first preset coordinate is calibrated, the beam spot corresponding to the next preset coordinate is calibrated.

As preferred, also include:

When the preset coordinates are greater than or equal to two, adjust each beam spot to the preset coordinates corresponding to the beam spot, and make each beam spot in a preset state, and record the time when each beam spot is in a preset state circularity;

After all the beam spots are adjusted to the corresponding preset coordinates and are in the preset state, while keeping the astigmatism of each beam spot unchanged, changing the focus value of the beam spot at least once;

A functional relationship between each beam spot position parameter and the focus value is generated.

The present invention generates a functional relationship between the beam spot position parameter and the focus value, and according to the functional relationship and the circularity of the beam spot in a preset state, can realize the calibration and calibration of the beam spot position, and can calibrate the focus value The influence of the position of the beam spot will not be affected by image distortion when calibrating the beam spot, and there is no need to solve the complex pose relationship between the imaging device and the plane where the beam spot is located. It has the advantages of fast, convenient and reliable.

Description of drawings

Fig. 1 is the structural representation of calibration device of the present invention;

Fig. 2 is a flow chart of the calibration method of the high-energy beam spot of the present invention;

Fig. 3 is the structural representation of standard panel among the present invention;

Fig. 4 is the schematic diagram of the image of the standard plate taken by the imaging device in the present invention;

Fig. 5 is the positional relationship between the beam spot and the preset coordinates when the beam spot is not adjusted in the present invention;

Fig. 6 shows the positional relationship between the beam spot and the preset coordinates when the beam spot is adjusted to the preset coordinates in the present invention;

Fig. 7 is the positional relationship between the beam spot and the preset coordinates when the focus value of the beam spot is changed for the first time in the present invention;

Fig. 8 shows the positional relationship between the beam spot and the preset coordinates when the focus value of the beam spot is changed for the second time in the present invention.

In the picture:

1. Ray generating device; 2. Working plane; 3. Imaging device; 4. Computer; 5. Ray beam; 6. Standard plate; 7. Mark point; 8. Coordinate; 9. Beam spot.

detailed description

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

The present invention provides a high-energy beam spot calibration method, which is used to calibrate the position of the high-energy beam spot in the field of high-energy beam processing such as additive manufacturing, which is completed by a calibration device, as shown in Figure 1, the calibration device Including a ray generating device 1, a working plane 2, an imaging device 3 and a computer 4, wherein the ray generating device 1 is used to generate a ray beam 5, the ray beam 5 can be a laser or an electron beam, and the ray beam 5 in this embodiment is an electron beam, The accelerating voltage of the above-mentioned ray generating device 1 is 60kV, the power is 0-10kW, and the above-mentioned electron beam is used in a high vacuum environment formed under the action of pumps and valves.

The above-mentioned ray beam 5 leaves a beam spot on the working plane 2, the imaging device 3 is used to photograph the beam spot on the working plane 2, and acquires an image, the computer 4 receives the image taken by the imaging device 3, and processes the image, simultaneously The computer 4 can also control the ray generating device 1 to adjust the size, shape and position of the ray beam spot on the working plane 2, thereby realizing the calibration of the position of the beam spot.

In the present invention, the aforementioned imaging device 3 may be a CCD (Charged Coupled Device) camera, a CMOS (Complementary Metal Oxide Semiconductor) camera, an infrared camera, a near-infrared camera or a far-infrared camera.

In the present invention, the above-mentioned calibration device is mainly used in an additive manufacturing device, which is used for calibration of high-energy beam spots in the additive manufacturing process.

As shown in Figure 2, the calibration method of the high-energy beam spot of the present invention specifically includes the following steps:

S100. Adjust the beam spot to a preset coordinate, make the beam spot in a preset state, and record the circularity of the beam spot in the preset state.

In this embodiment, the above-mentioned preset coordinates are preset before calibration. Specifically, the method for obtaining the above-mentioned preset coordinates is as follows:

First, with reference to Fig. 3, a standard board 6 is provided first, the standard board 6 is in the shape of a plane plate, and at least one marking point 7 is set on the standard board 6, and the marking points 7 can be arranged in an array when there are a plurality of them. , for example, may be a circular array, or an N×N array arrangement (such as 5×5, or 7×7, etc.), or other arrangements. The above-mentioned marking points 7 can be holes, laser marking patterns, spray paint, or polishing points, as long as the marking points 7 have a strong contrast with other parts of the standard plate 6 and are easy to identify. The shape of the marker point 7 can be a regular pattern such as a circle, a square, or a regular polygon. Since the marking point 7 is set on the standard plate 6, the relative position of the marking point 7 on the standard plate 6 is accurate and unique.

Subsequently, the standard plate 6 is placed on the working plane 2 of the calibration device, and the upper surface of the standard plate 6 is photographed by the imaging device 3. Since the image taken by the imaging device 3 is distorted, the captured image As shown in Figure 4, the standard plate 6 and the mark point 7 on it taken are different from the actual standard plate 6 and the shape of the mark point 7, and the coordinates 8 of the mark point 7 in the image are calculated by the computer 4 , the coordinate 8 is the above-mentioned preset coordinate of the present invention, since at least one marker point 7 is set, so the preset coordinate corresponds to at least one.

In the present invention, the above preset coordinates are stored in the computer 4, as long as the relative pose between the imaging device 3 and the working plane 2 remains unchanged, the preset coordinates do not need to be updated.

In the image taken by the imaging device 3 , both the marker point 7 and the beam spot exist in the form of pixels, and the coordinates of the center of the marker point 7 or the beam spot can be used to represent the coordinates of the marker point 7 or the beam spot. The coordinates are in pixels, and the resolution can be lower than 1 pixel.

After setting the above-mentioned preset coordinates, the image of the beam spot at a certain focus value is taken by the shaping device 3. At this time, the positional relationship between the beam spot 9 and the preset coordinates is shown in Figure 5, where the X represents preset coordinates, at this time, the size, shape and position of the beam spot are in a random state, and then the size, shape and position of the beam spot 9 are calculated by the computer 4 .

Afterwards, the beam spot shown in FIG. 5 needs to be adjusted so that it is placed at the preset coordinates and is in a preset state (as shown in FIG. 6 ). In this embodiment, the above-mentioned preset state specifically refers to:

adjusting the focus value of the beam spot so that the size of the beam spot reaches a preset minimum value;

adjusting the astigmatism of the beam spot so that the circularity of the beam spot is at a preset circularity;

Adjust the position parameters of the beam spot so that the distance between the center of the beam spot and the center of the preset coordinates is less than a preset value, which depends on the shooting range and resolution of the imaging device 3 and the calculation method of the computer 4 , in this embodiment, the imaging device 3 has a resolution exceeding 20 million pixels, and the preset value can be selected as 0.2mm, 0.1mm or 0.05mm.

After the beam spot is adjusted to the preset state, the computer 4 records the astigmatism, focus value and position parameters when the beam spot is in the preset state. In this embodiment, the position parameter of the beam spot refers to the position corresponding to the above-mentioned preset coordinates The formed position parameters are embodied in the form of coordinate control parameters in the X and Y directions.

S110. Under the condition of keeping the astigmatism of the beam spot unchanged, change the focus value of the beam spot at least once.

That is, keep the astigmatism of the beam spot unchanged in step S100, make the absolute value of the difference between the circularity of the beam spot and the circularity in the preset state smaller than the preset value, and then change the focus value of the beam spot , at this time, due to the change of the focus value of the beam spot, not only the size of the beam spot will be changed, but also its position parameters will be changed accordingly.

In this embodiment, the focus value of the beam spot can be changed only once. At this time, changing the focus value of the beam spot can make the focus point after the change of the beam spot higher/lower than the focus point when the beam spot is in a preset state, such as Figure 7 shows.

Of course, it can also be changed several times as needed to improve the calibration accuracy. In this embodiment, it is preferable to change twice, and at this time, the focus value of the beam spot is changed for the first time, so that the focus point after the beam spot change is higher than the focus point when the beam spot is in a preset state (as shown in FIG. 7 ), The focus value of the beam spot is changed for the second time, and the changed focus point is lower than the focus point when the beam spot is in a preset state (as shown in FIG. 8 ).

S120. Generate a functional relationship between a beam spot position parameter and a focus value.

That is, when adjusting the beam spot to be in the preset state, record the focus value and position parameters of the beam spot in the preset state;

After changing the focus value of the beam spot, record the focus value of the beam spot after the focus value has been changed, and change the position parameter until the beam spot moves to the preset coordinates, and record the new position parameter;

Then according to the focus value and the position parameter of the beam spot in the preset state, the focus value of the beam spot after the focus value has been changed, and the new position parameter, a functional relationship between the position parameter of the beam spot and the focus value is generated.

In this embodiment, the above-mentioned position is reflected in the form of coordinates in the image, so it includes parameters in the X and Y directions. The above-mentioned functional relationship can be the functional relationship between the focus value F and the X-direction coordinates and the focus value F and Y The functional relationship formed between the direction coordinates can be expressed as as well as Where X is a coordinate control parameter of the beam spot position in the X direction, Y is a coordinate control parameter of the beam spot position in the Y direction, F is a focus value, k is a coefficient, and b is a constant. It can also be the functional relationship between the coordinates in the X and Y directions and the focus value F, that is, (X, Y)=f(F), where X is the coordinate of the beam spot position in the X direction Control parameter, Y is the coordinate control parameter of the beam spot position in the Y direction, F is the focus value.

In this embodiment, after the above functional relationship is generated, the position parameter of the beam spot with a certain focus value used in the actual manufacturing process can be determined according to the functional relationship, that is, the current coordinate control of the beam spot can be calculated according to the functional relationship parameter. Under the control of the coordinate control parameters, the error between the actual coordinates of the beam spot on the working plane and the given coordinates is very small, so as to achieve the purpose of improving the machining accuracy of the beam spot.

In this embodiment, in the above-mentioned calibration method, the ray beam 5 emitted by the ray emitting device 1 used is an electron beam, therefore, the focusing value of the beam spot can be adjusted by changing the current in the focusing coil, and can be adjusted by changing the current in the astigmatic coil. Beam spot shape, the position of the beam spot is adjusted by changing the current in the deflection yoke.

In this embodiment, the above-mentioned preset coordinates may be one. At this time, it is only necessary to complete the calibration of one beam spot, and there may be multiple preset coordinates. At this time, the beam spot calibration methods of the present invention can be divided into Two types, of which:

The first method: the beam spot corresponding to the first preset coordinate is first calibrated until the calibration is completed, that is, the operations of step S100 to step S130 are first performed on the beam spot corresponding to the first preset coordinate.

After the calibration of the beam spot corresponding to the first preset coordinate is completed, the beam spot corresponding to the next preset coordinate is calibrated, and the operations of step S100 to step S130 are also performed on the beam spot corresponding to the preset coordinate.

By analogy, the calibration of all beam spots is completed.

The second method is to first perform the operation of step S100 on all beam spots, that is, adjust the beam spots to the preset coordinates corresponding to the beam spots, and make each beam spot in a preset state, and record that each beam spot is in a preset state. The circularity of the state.

After all the beam spots are adjusted to the corresponding preset coordinates and are in the preset state, while keeping the astigmatism of each beam spot unchanged, change the focus value of each beam spot, and the focus value of each beam spot Value changed at least once.

A functional relationship between each beam spot position parameter and a focus value is generated, that is, each beam spot corresponds to a functional relationship.

Apparently, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. All modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (10)

1. A calibration method of high-energy beam spot, is characterized in that, comprises the following steps: adjusting the beam spot to the preset coordinates so that the beam spot is in the preset state, and recording the circularity of the beam spot in the preset state; changing the focus value of the beam spot at least once while keeping the astigmatism of the beam spot unchanged; A functional relationship between the beam spot position parameter and the focus value is generated. 2. The calibration method according to claim 1, wherein said making the beam spot in a preset state comprises: adjusting the focus value of the beam spot so that the size of the beam spot reaches a preset minimum value; adjusting the astigmatism of the beam spot so that the circularity of the beam spot is at a preset circularity; The position parameter of the beam spot is adjusted so that the distance between the center of the beam spot and the center of the preset coordinates is smaller than a preset value. 3. The calibration method according to claim 2, wherein the changing the focus value of the beam spot at least once while keeping the astigmatism of the beam spot unchanged comprises: keeping the astigmatism of the beam spot unchanged, so that the absolute value of the difference between the circularity of the beam spot and the circularity in a preset state is smaller than a preset value; Changing the focus value of the beam spot so that the changed focus of the beam spot is higher/lower than the focus of the beam spot when it is in a preset state. 4. The calibration method according to claim 3, wherein the change of the focus value of the beam spot makes the changed focus of the beam spot higher/lower than the beam spot in a preset state After Focus Focus also includes: The focus value of the beam spot is changed again, so that the changed focus point of the beam spot is lower/higher than the focus point when the beam spot is in a preset state. 5. The calibration method according to claim 4, wherein said generating a functional relationship between the beam spot position parameter and the focus value comprises: Record the focus value and position parameters of the beam spot in the preset state; Record the focus value of the beam spot after the focus value is changed, change the position parameter until the beam spot moves to the preset coordinate, and record the new position parameter; According to the focus value and position parameter of the beam spot in the preset state, the focus value of the beam spot after the focus value is changed, and the new position parameter, a functional relationship between the position parameter of the beam spot and the focus value is generated. 6. The calibration method according to claim 5, wherein the functional relationship between the beam spot position parameter and the focus value is as well as or (X,Y)=f(F), where: X is a coordinate control parameter of the beam spot position in the X direction, Y is a coordinate control parameter of the beam spot position in the Y direction, and F is a focus value. 7. The calibration method according to any one of claims 1-6, characterized in that before adjusting the beam spot to the preset coordinates, it also includes: Set at least one marking point on the standard plate; taking an image of the standard plate by an imaging device; Corresponding preset coordinates are generated according to each marker point in the image. 8. The calibration method according to claim 7, wherein the imaging device is a CCD camera, a CMOS camera, an infrared camera, a near-infrared camera or a far-infrared camera. 9. The calibration method according to claim 8, further comprising: When the preset coordinates are greater than or equal to two, the beam spot corresponding to the first preset coordinate is calibrated; After the beam spot corresponding to the first preset coordinate is calibrated, the beam spot corresponding to the next preset coordinate is calibrated. 10. The calibration method according to claim 8, further comprising: When the preset coordinates are greater than or equal to two, adjust each beam spot to the preset coordinates corresponding to the beam spot, and make each beam spot in a preset state, and record the time when each beam spot is in a preset state circularity; After all the beam spots are adjusted to the corresponding preset coordinates and are in the preset state, while keeping the astigmatism of each beam spot unchanged, changing the focus value of the beam spot at least once; A functional relationship between each beam spot position parameter and the focus value is generated.