CN115236863A - Laser beam collimation method - Google Patents
Laser beam collimation method Download PDFInfo
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- CN115236863A CN115236863A CN202110441146.XA CN202110441146A CN115236863A CN 115236863 A CN115236863 A CN 115236863A CN 202110441146 A CN202110441146 A CN 202110441146A CN 115236863 A CN115236863 A CN 115236863A
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- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
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Abstract
The invention relates to a laser beam collimation method. The collimation method comprises the following steps: the method comprises the steps of obtaining the spot diameter of a laser beam emitted by a laser, selecting a diaphragm with a proper light through hole aperture according to the spot diameter, wherein the aperture of the light through hole satisfies the condition that a diffraction ring can be formed after the laser beam passes through. And installing a laser, a diaphragm and a photosensitive device, enabling the laser to emit laser beams by taking a target on the photosensitive device as a target, and enabling the laser beams to form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm. And adjusting the distance between the photosensitive device and the light through hole to adjust the annular degree of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold. And adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the target on the photosensitive device. The method can effectively improve the convenience of the laser beam collimation degree and can keep good collimation effect.
Description
Technical Field
The invention relates to the technical field of laser, in particular to a laser beam collimation method.
Background
In the application of laser, such as laser cutting, the degree of collimation of the beam is one of the necessary prerequisites for achieving high quality processing. In the actual production process, the laser beam is usually collimated and then processed. The traditional collimation method often needs to use more complicated collimation equipment, such as a collimation cavity with complicated matching and the like. Although these methods have a certain collimation effect on the laser beam, the investment of complex equipment also brings certain inconvenience to the collimation of the laser beam.
Disclosure of Invention
Accordingly, there is a need for a laser beam collimation method that can effectively improve the convenience of collimation and effectively maintain the collimation effect.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a method of laser beam collimation comprising the steps of:
acquiring the spot diameter of a laser beam emitted by a laser, and selecting a diaphragm with a proper light through hole aperture according to the spot diameter, wherein the aperture of the light through hole satisfies the condition that a diffraction ring can be formed after the laser beam passes through;
installing the laser, the diaphragm and the photosensitive device, enabling the laser to emit laser beams by taking a target on the photosensitive device as a target, and enabling the laser beams to form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm;
adjusting the distance between the photosensitive device and the light through hole to adjust the annular degree of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold;
and adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the target on the photosensitive device.
In one embodiment, the number of diffraction rings is no less than 4.
In one embodiment, the aperture of the light-passing hole is not more than 2/3 of the diameter of the light spot.
In one embodiment, the aperture of the light through hole is not less than 1/3 of the diameter of the light spot.
In one embodiment, the aperture of the light through hole is not less than 1/2 of the diameter of the light spot.
In one embodiment, the preset absolute value threshold is exposure for 999ms with a gain of no more than 5.0.
In one embodiment, after the offset of the laser beam is adjusted, the offset of the laser beam is not more than 20 μm.
In one embodiment, the laser beam is a gaussian beam.
In one embodiment, the radial distribution of the light intensity on the optical path of the laser beam is:
In one embodiment, the photosensitive device is a spot analyzer.
The laser beam collimation method comprises the following steps: the method comprises the steps of obtaining the spot diameter of a laser beam emitted by a laser, selecting a diaphragm with a proper light through hole aperture according to the spot diameter, wherein the aperture of the light through hole satisfies the condition that a diffraction ring can be formed after the laser beam passes through. And installing a laser, a diaphragm and a photosensitive device, enabling the laser to emit laser beams by taking a target on the photosensitive device as a target, and enabling the laser beams to form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm. And adjusting the distance between the photosensitive device and the light through hole to adjust the circularity of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold. And adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the target on the photosensitive device. In the collimation method, the diaphragm with the proper clear aperture diameter is selected according to the spot diameter of the laser beam, the distance between the photosensitive device and the clear aperture of the diaphragm is adjusted, a plurality of concentric diffraction rings are formed, the diffraction rings have good circularity and exposure uniformity, the collimation degree of the laser beam can be preliminarily adjusted, and the collimation accuracy of the laser beam can be effectively ensured. Then, the offset of the laser beam is adjusted to enable the circle center of the diffraction ring to coincide with the target on the photosensitive device, and at the moment, the laser beam can have good collimation degree. When the method is adopted to carry out collimation adjustment on the laser beam, good collimation degree can be obtained without depending on complex equipment, the convenience of the collimation degree of the laser beam can be effectively improved, and meanwhile, a good collimation effect can be kept.
Drawings
FIG. 1 is a flow chart of a laser beam alignment method according to an embodiment of the present invention;
FIG. 2 is a schematic view of a diffraction ring in examples 1 to 3;
FIG. 3 is a schematic view of the diffraction ring in examples 4 to 6;
FIG. 4 is a schematic diagram of the diffraction rings of examples 7 to 9.
Detailed Description
The present invention will be described in detail with reference to the following embodiments in order to make the aforementioned objects, features and advantages of the invention more comprehensible. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, an embodiment of the invention provides a laser beam collimating method. The laser beam collimation method comprises the following steps:
s101: the method comprises the steps of obtaining the spot diameter of a laser beam emitted by a laser, selecting a diaphragm with a proper light through hole aperture according to the spot diameter, wherein the aperture of the light through hole satisfies the condition that a diffraction ring can be formed after the laser beam passes through.
S102: and installing a laser, a diaphragm and a photosensitive device, enabling the laser to emit laser beams by taking a target on the photosensitive device as a target, and enabling the laser beams to form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm.
S103: and adjusting the distance between the photosensitive device and the light through hole to adjust the circularity of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold.
S104: and adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the target on the photosensitive device.
In the collimation method of the embodiment, the diaphragm with the proper light through hole aperture is selected according to the spot diameter of the laser beam, the distance between the photosensitive device and the light through hole of the diaphragm is adjusted, a plurality of concentric diffraction rings are formed, and the plurality of diffraction rings have good circularity and exposure uniformity, so that the collimation degree of the laser beam can be preliminarily adjusted, and the collimation accuracy of the laser beam can be effectively ensured. Then, the offset of the laser beam is adjusted to enable the circle center of the diffraction ring to coincide with the target on the photosensitive device, and the laser beam can have good collimation. When the method is adopted to carry out collimation adjustment on the laser beam, good collimation degree can be obtained without depending on complex equipment, the convenience of the collimation degree of the laser beam can be effectively improved, and meanwhile, a good collimation effect can be kept.
It is understood that, in the laser beam collimation process, the selection of the diaphragm, the installation of the laser, the installation of the diaphragm and the installation sequence of the photosensitive device can be adjusted according to actual conditions. For example, a diaphragm having a clear aperture may be selected, and then the laser, the diaphragm, and the photosensitive device may be mounted in this order. The laser and the photosensitive device can be installed at first, the installation position of the diaphragm is reserved, then the diaphragm with the aperture of the light through hole is selected according to the diameter of a light spot of a laser beam emitted by the laser, and then the diaphragm is installed at the installation position of the diaphragm.
It can also be understood that, when the laser, the diaphragm and the photosensitive device are installed, the light through hole of the diaphragm is positioned on the light path of the laser beam emitted by the laser, and the photosensitive device is further away from the emitting end of the laser than the light through hole. Therefore, laser beams emitted by the laser can form a plurality of concentric diffraction rings on the photosensitive device after passing through the light-transmitting holes.
It will also be appreciated that the target on the photosensitive means may appear as a given mark on the photosensitive means. The laser emits laser beams by taking the target on the photosensitive device as a target, and the center of a light spot of the laser beam emitted by the laser coincides with the target on the photosensitive device under an ideal state. However, during the actual emission of the laser, the center of the laser beam may deviate from the target on the photosensitive device to some extent. The target on the photosensitive device can be the center of a cross cursor, a preset mark point and the like.
It should be noted that, when the laser emits laser light, the spot diameter of the laser beam may be obtained according to the predetermined emission parameters of the laser. Under the corresponding emission parameters, the spot diameter of the laser beam emitted by the laser can be acquired. When laser beams are collimated, the spot diameter of the laser beams emitted by the laser can be firstly obtained according to emission parameters of the laser, after the spot diameter of the laser beams is obtained, a diaphragm with a proper light through hole aperture is selected according to the spot diameter, and the diaphragm is matched with the laser and a photosensitive device to perform collimation and debugging on the laser beams. The aperture of the clear hole of the diaphragm indicates the diameter of the clear hole.
In one particular example, the circularity of the diffraction ring is expressed in terms of the degree of circularity and the degree of completeness of the diffraction ring. The better the circularity of the diffraction ring, the more circular the diffraction ring tends to. The better the integrity of the diffraction ring, the more complete the diffraction ring, and no deletions in the diffraction ring. When laser beams are collimated, the distance between the photosensitive device and the light through hole is adjusted to adjust the annular degree of the diffraction ring, so that the diffraction ring shows better annular degree, the diffraction ring tends to be circular, and the diffraction ring is not lost. Therefore, the real situation of laser beam diffraction can be reflected more accurately, and the accuracy of laser beam collimation is improved.
In another specific example, the laser beam collimation method comprises the following steps: the method comprises the steps of obtaining the spot diameter of a laser beam emitted by a laser, selecting a diaphragm with a proper light through hole aperture according to the spot diameter, wherein the aperture of the light through hole satisfies the condition that a diffraction ring can be formed after the laser beam passes through. And installing a laser, a diaphragm and a photosensitive device, enabling the laser to emit laser beams by taking a target on the photosensitive device as a target, and enabling the laser beams to form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm. And adjusting the distance between the photosensitive device and the light through hole to adjust the circularity of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold. And adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the target on the photosensitive device. In this example, the laser beam can be accurately collimated without additional steps in the collimation process, except for the listed steps, so that the laser beam has good collimation.
In a preferred embodiment, there are no fewer than 4 diffraction rings. Regarding the accuracy of the laser beam collimation, the inventors found in experiments that the number of diffraction rings can represent the accuracy of the laser beam collimation. On the basis that can form clear complete diffraction ring, when the diffraction ring is no less than 4, can effectively get rid of the influence of the accidental factor among the collimation process, improve the degree of accuracy of collimation. As an alternative number of diffraction rings, the number of diffraction rings may be, but is not limited to, 4, 5, 6, 7, 8, etc. At this time, on the basis of being able to form a clear and complete diffraction ring, the greater the number of diffraction rings, the higher the accuracy of collimation.
As the selection basis of the aperture of the light through hole of the diaphragm, the aperture of the light through hole of the diaphragm does not exceed the diameter of the facula. In this case, the laser beam can be made to pass through the light-passing hole and then form a diffraction ring that is easily recognized on the light-receiving device. When the aperture of the light through hole exceeds the diameter of the light spot, the problem that the diffraction ring is difficult to identify or even cannot be formed may occur.
Further, the aperture of the clear hole is not more than 2/3 of the diameter of the light spot. When the aperture of the light through hole does not exceed 2/3 of the diameter of the light spot, a clear diffraction ring which is easy to identify can be formed on the photosensitive device after the laser beam passes through the light through hole.
Further, when the aperture of the clear hole is selected in accordance with the spot diameter of the laser beam, the aperture of the clear hole is not less than 1/3 of the spot diameter. In the collimation process of laser beams, when the aperture of the light through hole is too small, the problem of aberration is easy to occur, even the problem that a diffraction ring cannot be displayed is caused, so that a clear and complete diffraction ring is difficult to obtain. Therefore, when the aperture of the diaphragm clear hole is selected, the aperture of the diaphragm clear hole is controlled not to be less than 1/3 of the diameter of the light spot. Preferably, when the aperture of the clear hole is selected in accordance with the spot diameter of the laser beam, the aperture of the clear hole is not less than 1/2 of the spot diameter.
When the laser beam is collimated, the distance between the photosensitive device and the light through hole of the diaphragm is adjusted, so that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed the preset absolute value threshold. As an example of an alternative to the preset absolute value threshold, the preset absolute value threshold is such that the 999ms exposure gain does not exceed 5.0. At the moment, the diffraction ring can show uniform brightness, and the diffraction ring can also show uniform brightness on the basis of good circularity, shape approaching to a circle and no loss. This may further improve the accuracy of the laser beam collimation.
After the distance between the photosensitive device and the light through hole is adjusted, the offset of the laser beam is adjusted, so that the circle center of the diffraction ring is coincided with the light spot center of the laser beam. The offset amount of the laser beam indicates a perpendicular distance between the laser beam and the optical axis. Preferably, the amount of shift of the laser beam is not more than 20 μm after the amount of shift of the laser beam is adjusted. For example, the amount of shift of the laser beam is not more than 18 μm, 15 μm, 13 μm, 12 μm, 10 μm, 8 μm, 5 μm, or the like. By controlling the offset of the adjusted laser beam to be not more than 20 μm, the diffraction condition of the laser beam can be more accurately reflected, and the accuracy of collimation can be improved.
In one particular example, the laser beam is a gaussian beam. Further, the radial distribution of the light intensity on the optical path of the laser beam is:
wherein I is the light intensity, r is the radial position of the section light spot, omega 0 At the center position of the cross section, r =0, i (0) =1, which is the spot radius of the gaussian beam when the intensity drops from the maximum value to 13%. It will be appreciated that the ideal gaussian beam energy is distributed axisymmetrically about its propagation axis.
As a preferable embodiment of the photosensitive device, the photosensitive device is a spot analyzer. At the moment, the diffraction ring can be visually displayed and accurately analyzed through the light spot analyzer, and the exposure value of each point on the diffraction ring is measured. Specifically, when the laser beam is collimated, the center of the cross cursor on the spot analyzer is used as a target, and in the collimation process, the centers of the plurality of diffraction rings are coincided with the center of the cross cursor by adjusting the distance between the photosensitive device and the light through hole and the offset of the laser beam.
It will be appreciated that the photosensitive device may be white paper when the laser emits a laser beam of visible light. When the white paper is used, the laser beams pass through the light through holes in the diaphragm and then form a plurality of concentric diffraction rings on the white paper, the circularity and the uniform brightness of the diffraction rings can be observed by naked eyes, and a good laser beam collimation effect can be achieved. When the laser emits a laser beam of invisible light, the photosensitive device can be a visible light conversion sheet. When the visible light conversion sheet is used, after the laser beam passes through the light through hole in the diaphragm, the laser beam of the invisible light is displayed as the visible light under the action of the visible light conversion sheet, and at the moment, the circularity and the brightness uniformity of the diffraction ring can be observed, so that a good laser beam collimation effect is achieved. As an alternative to the visible light conversion sheet, the visible light conversion sheet may be a frequency doubling sheet.
The following are specific examples.
Example 1
In this embodiment, the laser beam emitted by the laser is green light, the diameter of the light spot is 4.3mm, and the aperture of the light-transmitting hole is 2.0mm according to the diameter of the light spot. The light sensing device in this embodiment is a spot analyzer.
The laser beam collimation method in the embodiment comprises the following steps:
(1) The emission parameters of the laser are controlled so that the laser emits green light with the spot diameter of 4.3 mm. A diaphragm having a clear aperture of 2.0mm was selected according to the spot diameter.
(2) And installing a laser, a diaphragm and a light spot analyzer, so that the laser emits laser beams by taking the center of a cross cursor on the light spot analyzer as a target, and the laser beams form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm.
(3) And adjusting the distance between the light spot analyzer and the light through hole to adjust the annular degree of the diffraction ring, and enabling the absolute value of the difference value of the exposure values of any two points on the diffraction ring not to exceed a preset absolute value threshold. The distance between the light spot analyzer and the light through hole is adjusted to be 270mm. The absolute threshold was preset at 999ms exposure with a gain of 4.5.
(4) And adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the center of the cross cursor. After the laser beam shift amount was adjusted, the laser beam shift amount was 20 μm.
A schematic diagram of the diffraction ring on the spot analyzer in this example is shown in FIG. 2 (a). In FIG. 2 (a), there are 3 diffraction rings.
Example 2
In this embodiment, the laser beam emitted by the laser is green light, the diameter of the light spot is 4.3mm, and the aperture of the light-transmitting hole is 2.25mm according to the diameter of the light spot. The light sensing device in this embodiment is a spot analyzer.
The laser beam collimation method in the embodiment comprises the following steps:
(1) The emission parameters of the laser are controlled so that the laser emits green light with the spot diameter of 4.3 mm. A diaphragm having a clear aperture of 2.25mm was selected according to the spot diameter.
(2) And installing a laser, a diaphragm and a light spot analyzer, enabling the laser to emit laser beams by taking the center of a cross cursor on the light spot analyzer as a target, and enabling the laser beams to form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm.
(3) And adjusting the distance between the light spot analyzer and the light through hole to adjust the circularity of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold. The distance between the light spot analyzer and the light through hole is adjusted to be 270mm. The absolute value threshold is preset to be exposure 999ms with a gain of 4.5.
(4) And adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the center of the cross cursor. After the laser beam shift amount was adjusted, the laser beam shift amount was 20 μm.
A schematic diagram of the diffraction ring on the spot analyzer in this example is shown in FIG. 2 (b). In FIG. 2 (b), there are 4 diffraction rings.
Example 3
In the embodiment, the laser beam emitted by the laser is green light, the diameter of the light spot is 4.3mm, and the diaphragm with the aperture of the light through hole being 2.5mm is selected according to the diameter of the light spot. The light sensing device in this embodiment is a spot analyzer.
The laser beam collimation method in the embodiment comprises the following steps:
(1) The emission parameters of the laser are controlled so that the laser emits green light with the spot diameter of 4.3 mm. A diaphragm having a clear aperture of 2.5mm was selected according to the spot diameter.
(2) And installing a laser, a diaphragm and a light spot analyzer, enabling the laser to emit laser beams by taking the center of a cross cursor on the light spot analyzer as a target, and enabling the laser beams to form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm.
(3) And adjusting the distance between the light spot analyzer and the light through hole to adjust the circularity of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold. And adjusting the distance between the light spot analyzer and the light through hole to be 270mm. The absolute threshold was preset at 999ms exposure with a gain of 4.5.
(4) And adjusting the offset of the laser beam to ensure that the circle center of the diffraction ring is superposed with the center of the cross cursor. After the laser beam shift amount was adjusted, the laser beam shift amount was 20 μm.
A schematic diagram of the diffraction ring on the spot analyzer in this example is shown in FIG. 2 (c). In FIG. 2 (c) there are 5 diffraction rings.
Example 4
In this embodiment, the laser beam emitted by the laser is green light, the diameter of the light spot is 4.3mm, and the aperture of the light-transmitting hole is 2.0mm according to the diameter of the light spot. The light sensing device in this embodiment is a spot analyzer.
The laser beam collimation method in the embodiment comprises the following steps:
(1) The emission parameters of the laser are controlled so that the laser emits green light with the spot diameter of 4.3 mm. A diaphragm having a clear aperture of 2.0mm was selected according to the spot diameter.
(2) And installing a laser, a diaphragm and a light spot analyzer, so that the laser emits laser beams by taking the center of a cross cursor on the light spot analyzer as a target, and the laser beams form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm.
(3) And adjusting the distance between the light spot analyzer and the light through hole to adjust the circularity of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold. And adjusting the distance between the light spot analyzer and the light through hole to be 150mm. The absolute value threshold is preset to be exposure 999ms with a gain of 4.5.
(4) And adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the center of the cross cursor. After the laser beam shift amount was adjusted, the laser beam shift amount was 20 μm.
A schematic diagram of the diffraction ring on the spot analyzer in this example is shown in FIG. 3 (a). There are 6 diffraction rings in FIG. 3 (a).
Example 5
In this embodiment, the laser beam emitted by the laser is green light, the diameter of the light spot is 4.3mm, and the aperture of the light-transmitting hole is 2.0mm according to the diameter of the light spot. The light sensing device in this embodiment is a spot analyzer.
The laser beam collimation method in the embodiment comprises the following steps:
(1) The emission parameters of the laser are controlled so that the laser emits green light with the spot diameter of 4.3 mm. A diaphragm having a clear aperture of 2.0mm was selected according to the spot diameter.
(2) And installing a laser, a diaphragm and a light spot analyzer, so that the laser emits laser beams by taking the center of a cross cursor on the light spot analyzer as a target, and the laser beams form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm.
(3) And adjusting the distance between the light spot analyzer and the light through hole to adjust the circularity of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold. And adjusting the distance between the light spot analyzer and the light through hole to be 190mm. The absolute value threshold is preset to be exposure 999ms with a gain of 4.5.
(4) And adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the center of the cross cursor. After the laser beam shift amount was adjusted, the laser beam shift amount was 20 μm.
A schematic diagram of the diffraction ring on the spot analyzer in this example is shown in FIG. 3 (b). In FIG. 3 (b), there are 5 diffraction rings.
Example 6
In the embodiment, the laser beam emitted by the laser is green light, the diameter of the light spot is 4.3mm, and the diaphragm with the aperture of the light through hole being 2.0mm is selected according to the diameter of the light spot. The light sensing device in this embodiment is a spot analyzer.
The laser beam collimation method in the embodiment comprises the following steps:
(1) The emission parameters of the laser are controlled so that the laser emits green light with the spot diameter of 4.3 mm. A diaphragm having a clear aperture of 2.0mm was selected according to the spot diameter.
(2) And installing a laser, a diaphragm and a light spot analyzer, so that the laser emits laser beams by taking the center of a cross cursor on the light spot analyzer as a target, and the laser beams form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm.
(3) And adjusting the distance between the light spot analyzer and the light through hole to adjust the circularity of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold. The distance between the light spot analyzer and the light through hole is adjusted to be 230mm. The absolute value threshold is preset to be exposure 999ms with a gain of 4.5.
(4) And adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the center of the cross cursor. After the laser beam shift amount was adjusted, the laser beam shift amount was 20 μm.
A schematic diagram of the diffraction ring on the spot analyzer in this example is shown in FIG. 3 (c). In fig. 3 (a), there are 4 diffraction rings.
As can be seen from fig. 2, the smaller the aperture of the diaphragm clear aperture, the larger the number of diffraction rings. At this time, as the number of diffraction rings increases, the accuracy of laser beam collimation becomes higher.
As can be seen from fig. 3, the smaller the distance between the spot analyzer and the light-passing hole, the larger the number of diffraction rings. At this time, as the distance between the spot analyzer and the light-passing hole is reduced, the accuracy of the laser beam collimation is higher.
Example 7
In this embodiment, the laser beam emitted by the laser is green light, the diameter of the light spot is 4.3mm, and the aperture of the light-transmitting hole is 2.0mm according to the diameter of the light spot. The light sensing device in this embodiment is a spot analyzer.
The laser beam collimation method in the embodiment comprises the following steps:
(1) The emission parameters of the laser are controlled so that the laser emits green light with the spot diameter of 4.3 mm. A diaphragm having a clear aperture of 2.0mm was selected according to the spot diameter.
(2) And installing a laser, a diaphragm and a light spot analyzer, enabling the laser to emit laser beams by taking the center of a cross cursor on the light spot analyzer as a target, and enabling the laser beams to form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm.
(3) And adjusting the distance between the light spot analyzer and the light through hole to adjust the circularity of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold. And adjusting the distance between the light spot analyzer and the light through hole to be 270mm. The absolute value threshold is preset to be exposure 999ms with a gain of 4.5.
(4) And adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the center of the cross cursor. After the laser beam shift amount was adjusted, the laser beam shift amount was 200 μm.
A schematic diagram of the diffraction ring on the spot analyzer in this example is shown in FIG. 4 (a). In FIG. 4 (a), there are 3 diffraction rings.
Example 8
In the embodiment, the laser beam emitted by the laser is green light, the diameter of the light spot is 4.3mm, and the diaphragm with the aperture of the light through hole being 2.25mm is selected according to the diameter of the light spot. The light sensing device in this embodiment is a spot analyzer.
The laser beam collimation method in the embodiment comprises the following steps:
(1) The emission parameters of the laser are controlled so that the laser emits green light with the spot diameter of 4.3 mm. A diaphragm having a clear aperture of 2.25mm was selected according to the spot diameter.
(2) And installing a laser, a diaphragm and a light spot analyzer, enabling the laser to emit laser beams by taking the center of a cross cursor on the light spot analyzer as a target, and enabling the laser beams to form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm.
(3) And adjusting the distance between the light spot analyzer and the light through hole to adjust the circularity of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold. And adjusting the distance between the light spot analyzer and the light through hole to be 270mm. The absolute threshold was preset at 999ms exposure with a gain of 4.5.
(4) And adjusting the offset of the laser beam to ensure that the circle center of the diffraction ring is superposed with the center of the cross cursor. After the laser beam shift amount was adjusted, the laser beam shift amount was 200 μm.
A schematic diagram of the diffraction ring on the spot analyzer in this example is shown in FIG. 4 (b). In FIG. 4 (b), there are 4 diffraction rings.
Example 9
In the embodiment, the laser beam emitted by the laser is green light, the diameter of the light spot is 4.3mm, and the diaphragm with the aperture of the light through hole being 2.5mm is selected according to the diameter of the light spot. The light sensing device in this embodiment is a spot analyzer.
The laser beam collimation method in the embodiment comprises the following steps:
(1) The emission parameters of the laser are controlled, so that the laser emits green light with the spot diameter of 4.3 mm. A diaphragm having a clear aperture of 2.5mm was selected according to the spot diameter.
(2) And installing a laser, a diaphragm and a light spot analyzer, enabling the laser to emit laser beams by taking the center of a cross cursor on the light spot analyzer as a target, and enabling the laser beams to form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm.
(3) And adjusting the distance between the light spot analyzer and the light through hole to adjust the circularity of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold. The distance between the light spot analyzer and the light through hole is adjusted to be 270mm. The absolute value threshold is preset to be exposure 999ms with a gain of 4.5.
(4) And adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the center of the cross cursor. After the laser beam shift amount was adjusted, the laser beam shift amount was 200 μm.
A schematic diagram of the diffraction ring on the spot analyzer in this example is shown in FIG. 4 (c). In FIG. 4 (c), there are 5 diffraction rings.
In fig. 4, in the color pictures displayed on the actual spot analyzer, the brightness uniformity of the diffraction rings in fig. 4 (a), 4 (b), and 4 (c) is poor, and the brightness of the diffraction ring on the left half is obviously lower than that of the diffraction ring on the right half, especially the brightness of the diffraction ring on the upper left part is the lowest, with reference to the cross-shaped cursor. Compared to fig. 2 and 3, fig. 4 is lower in degree of uniformity of brightness than fig. 2 and 3. The light and shade uniformity degree of the diffraction ring is reduced when the offset of the laser beam is too large, and the collimation accuracy of the laser beam is reduced.
All possible combinations of the technical features of the above embodiments may not be described for the sake of brevity, but should be considered as within the scope of the present disclosure as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A laser beam collimation method is characterized by comprising the following steps:
acquiring the spot diameter of a laser beam emitted by a laser, and selecting a diaphragm with a proper light through hole aperture according to the spot diameter, wherein the aperture of the light through hole satisfies the condition that a diffraction ring can be formed after the laser beam passes through;
installing the laser, the diaphragm and the photosensitive device, enabling the laser to emit laser beams by taking a target on the photosensitive device as a target, and enabling the laser beams to form a plurality of concentric diffraction rings on the photosensitive device after passing through a light through hole of the diaphragm;
adjusting the distance between the photosensitive device and the light through hole to adjust the annular degree of the diffraction ring, and ensuring that the absolute value of the difference value of the exposure values of any two points on the diffraction ring does not exceed a preset absolute value threshold;
and adjusting the offset of the laser beam to enable the circle center of the diffraction ring to coincide with the target on the photosensitive device.
2. The laser beam collimation method of claim 1, wherein the number of diffraction rings is not less than 4.
3. The method of claim 1, wherein the aperture of the clear hole is not more than 2/3 of the spot diameter.
4. The laser beam collimation method of claim 1, wherein an aperture of the light-passing hole is not less than 1/3 of the spot diameter.
5. The laser beam collimation method of claim 4, wherein an aperture of the light passing hole is not less than 1/2 of the spot diameter.
6. The method of claim 1, wherein the predetermined absolute threshold is exposure 999ms gain not exceeding 5.0.
7. The laser beam collimation method as recited in claim 1, wherein the offset of the laser beam is adjusted to be not more than 20 μm.
8. The method of any of claims 1-7, wherein the laser beam is a Gaussian beam.
9. The laser beam collimation method of claim 8, wherein a radial distribution of light intensity on the optical path of the laser beam is:
10. The laser beam collimation method of any of claims 1-7, wherein said light sensing device is a spot analyzer.
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