Optical path correction method for magneto-optical Kerr detection device

Abstract

The invention provides a magneto-optical Kerr detection device optical path correction method, the magneto-optical Kerr detection device comprises at least two light sources, light emitted by the light sources passes through a polarizer and an objective lens and then converges at a detection position, and light reflected by the detection position can enter a camera through the objective lens and an analyzer; a calibration card is arranged at a position which is a preset interval away from the detection position, and the at least two light sources are turned on at the same time, so that light emitted by the light sources forms corresponding light spots on the calibration card; the light source is adjusted according to at least one of the position and the shape of the light spot, the light source is adjusted by means of the position of the light spot, the light path can be integrally corrected, and the use and efficiency of equipment are greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic detection, and relates to the calibration of a magneto-optical Kerr detection device, and in particular to a method for calibrating the optical path of a magneto-optical Kerr detection device. Background Art

[0002] When a beam of linearly polarized light is reflected by a magnetic medium, the polarization plane of the reflected light is deflected at an angle relative to the polarization plane of the incident light, which is called the Kerr rotation angle. This phenomenon is called the magneto-optical Kerr effect. This effect is combined with microscopic imaging technology to form a magneto-optical Kerr microscope, which is widely used in magnetic material magnetic measurement, magnetic domain observation, etc.

[0003] In some magneto-optical Kerr microscopes, in order to achieve multiple detections of the object to be measured, multiple light sources are set up to generate multiple beams of detection light and detect the object to be measured respectively. However, when multiple light sources are set up, the difficulty of adjusting the optical path is greatly increased. At the same time, since the detection spot is usually small, such as a micron-sized spot, the difficulty of adjusting the position of the light source, the light emission direction and other states is further increased.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0005] In view of the problem of difficulty in adjusting the optical path of a multi-light source magneto-optical Kerr detection device in the prior art, the present application provides a method for correcting the optical path of a magneto-optical Kerr detection device, wherein the magneto-optical Kerr detection device comprises at least two light sources, so that the light emitted by the light sources converges at a detection position after passing through a polarizer and an objective lens, and the light reflected at the detection position can enter a camera through the objective lens and an analyzer; a calibration card is arranged at a position with a preset interval from the detection position, and at least two of the light sources are turned on at the same time, so that the light emitted by the light sources forms a corresponding light spot on the calibration card; and the position of the light source is adjusted with reference to the position of the light spot.

[0006] According to a specific implementation of the present invention, a reference line is provided on the calibration card, and the posture of the light source is adjusted according to the relative position of the light spot and the reference line.

[0007] According to a specific embodiment of the present invention, the ideal light spot position is indicated by the reference line, and the position of the light source is adjusted according to the difference between the light spot position and the ideal light spot position until the difference between the light spot position and the ideal light spot position meets a preset threshold.

[0008] According to a specific embodiment of the present invention, the light emitted by the light source is at least partially transmitted through an optical fiber, and when the shape of the light spot is irregular, the end face of the optical fiber is adjusted or repaired.

[0009] According to a specific implementation of the present invention, the calibration card is arranged on a side of the detection position away from the objective lens.

[0010] According to a specific implementation of the present invention, the luminous intensity of the light source is corrected according to the brightness of the light spot.

[0011] According to a specific embodiment of the present invention, at least three light sources are provided, the three light sources are turned on to form three light spots on the calibration card, and the turned-on light sources are not arranged in a collinear manner.

[0012] According to a specific embodiment of the present invention, the three light sources arranged in an L shape are turned on, and three light spots arranged along the L shape are formed on the calibration card; all the light sources are moved as a whole so that the light spots at the corners of the L shape reach preset positions, and all the light sources are rotated as a whole so that the remaining two light spots are close to the corresponding preset positions.

[0013] According to a specific embodiment of the present invention, adjusting the posture of the light source includes adjusting at least one of the position and the light emitting direction of the light source.

[0014] According to a specific embodiment of the present invention, a calibration surface is provided on the calibration card, and the light emitted by the light source is at least diffusely reflected on the calibration surface to form a light spot.

[0015] The present invention has at least the following beneficial effects: by setting a calibration card and judging the position characteristics of the current light source such as the position and light emitting direction according to the position and shape of the light spot on the calibration card, the position of the light source can be adjusted with the help of the position of the light spot, and the optical path can be corrected as a whole; according to the position characteristics of multiple light spots, multiple light sources can be calibrated, which is suitable for a multi-light source magneto-optical Kerr detection device, and the calibration process is simple and easy to operate; after the calibration is completed, the corresponding detection can be directly carried out, which greatly improves the use and efficiency of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of an embodiment of the present invention.

[0017] Figure 2 It is a schematic diagram of another embodiment of the present invention.

[0018] Figure 3 It is a schematic diagram of an embodiment of a light source involved in the present invention.

[0019] Figure 4 It is a schematic diagram of an embodiment of the calibration card involved in the present invention.

[0020] Figure 5 It is a schematic diagram of an implementation method of the position setting method of the calibration card involved in the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. It should be noted that the drawings are all in a very simplified form and use inaccurate ratios, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0022] The present invention provides a method for correcting the optical path of a magneto-optical Kerr detection device. In a magneto-optical Kerr detection device with multiple light sources, multiple light sources 110 are provided, but there is usually only one detection position F, and it is necessary to make the light emitted by the multiple light sources 110 converge at the detection position F. Since the optical devices through which the light emitted by the multiple light sources 110 passes are substantially the same, the present application considers adjusting the light source 110 to achieve the correction of the entire optical path.

[0023] The magneto-optical Kerr detection device involved in the optical path correction method of the present invention includes at least two light sources 110, so that the light emitted by the light source 110 becomes linearly polarized light after passing through the polarizer 200, and the linearly polarized light converges at the detection position F after passing through the objective lens 400. When the detection position F is provided with the object to be measured 800, the linearly polarized light converges at the detection position F on the object to be measured 800; when the object to be measured 800 is provided, the linearly polarized light at the detection position F can be reflected by the object to be measured 800, and the position of the corresponding optical device is set so that the light reflected by the object to be measured 800 can enter the camera 600 through the objective lens 400 and the analyzer 500 to form a reflected light path. It should be noted that when using the optical path correction method provided by the present invention, the object to be measured 800 can be removed. Accordingly, except for the object to be measured 800, each optical element is set at the proper position, and the aforementioned reflected light path only constitutes an optical path for light to pass. When the object to be measured 800 re-enters the optical path and reaches the detection position F to be measured, the aforementioned reflected light path will be able to play a role.

[0024] The detection position F may be located at the focus of the objective lens 400, for example, the linear polarized light entering the objective lens 400 enters the objective lens 400 in a direction parallel to the optical axis of the objective lens 400; or may not be located at the focus of the objective lens 400, for example, the linear polarized light entering the objective lens 400 enters the objective lens 400 in a direction forming an angle with the optical axis of the objective lens 400. The detection position F may be adjusted or set accordingly as needed, and usually, the detection position F is located at the focal plane of the objective lens 400.

[0025] As for the light source 110, the light source 110 can be set on the corresponding optical bracket 100 for corresponding installation. The light source 110 mainly refers to a device that can provide light for magneto-optical Kerr detection, which can be in the form of a light emitting device directly set on the optical bracket 100, or in the form of a light emitting end face 120 of an optical fiber 140 set on the optical bracket 100, and the optical fiber 140 is connected to a light emitting device 130. The light emitting devices 110 and 130 can be lasers, LED lights and other devices.

[0026] See also Figure 1 , Figure 2 , Figure 3 When a light emitting device is directly used as the light source 110, the light emitting device can be fixed to the optical bracket 100 according to the detection requirements. Figure 3 When the light source 110 is in the form shown, it can be Figure 3 The light source 110 is arranged in the manner shown, and a corresponding light emitting device is set; when the light 140 is used to connect other light emitting devices 130 as the light source 110, the optical fiber 140 can be connected to the light emitting device 130, and the light emitting end face of the optical fiber 140 can be fixed to the optical bracket 100 according to the detection requirements, for example, when it is necessary to Figure 3 When the light source 110 is in the form shown, it can be Figure 3 In the arrangement of the light source 110 shown, the light emitting end surface 120 of the optical fiber 140 is disposed on the optical bracket 100 .

[0027] A calibration card 700 is set at a preset distance from the detection position F, and at least two light sources 110 are turned on at the same time, so that the light emitted by the light source 110 forms a corresponding light spot on the calibration card 700. The calibration card 700 is mainly used to observe the light spot, and usually a form that can at least partially diffusely reflect the light irradiated thereon can be selected. For example, frosted glass, paint surface, plastic sheet, surface-treated metal, paper, acrylic plate, etc. can be used, as long as the surface can diffusely reflect. When the light spot is observed, the position of the light spot can be referred to to adjust the posture of the light source 110 to adjust the entire light path until the detection requirements are met. Specifically, the posture of the light source 110 includes the position and angle of the light source 110, and specifically, it can include at least one of the position of the light source 110 and the light emitting direction.

[0028] See also Figure 5 The position of the light spot on the calibration card 700 is obviously affected by the light source 110, specifically, the position and light emission direction of the light source 110. Therefore, the position of the light spot can be used to determine the current position and light emission direction of the light source 110, and the light source can be adjusted based on the position of the light spot.

[0029] For example, in a detection requirement, it is necessary to make the light emitted by multiple light sources 110 substantially parallel and incident on the objective lens 400 in a direction parallel to the optical axis of the objective lens 400. At the same time, the two beams of linear polarized light do not overlap and are at the same distance from the optical axis of the objective lens 400, so that the incident angles of the detection light incident on the object 800 are the same and the incident surfaces are different, which is used for the detection of the corresponding magneto-optical Kerr effect. At this time, according to the characteristics of the optical path, it can be known that when the optical path meets the detection requirements, the light spot will be distributed at the same distance around the optical axis of the objective lens 400. In this case, the position of the light source 110, the light emitting direction, etc. can be adjusted until the light spot reaches the aforementioned distribution state. When the light spot reaches the preset situation, it indicates that both the light source 110 and the optical path meet the required detection requirements.

[0030] See also Figure 5 The calibration surface 710 of the calibration card 700 is arranged close to the objective lens 400, so that the light emitted by the light source 110 is irradiated on the calibration surface 710 and forms a corresponding light spot. In some cases, when the thickness of the calibration card 700 is small, or when part of the calibration card 700 is transparent, the side of the calibration card 700 away from the objective lens 400 can also be used as the calibration surface 710, and the calibration surface 710 can be observed as a light spot when it is illuminated. In addition, in order to observe the light spot more clearly, the light emitted by the light source 110 can also be at least diffusely reflected on the calibration surface 710. Specifically, the calibration surface 710 can be formed by frosted glass, paint surface, plastic sheet, surface-treated metal, paper, acrylic plate, etc.

[0031] See also Figure 4 , the ideal spot positions are L1a and L2a. When the adjustment is not completed, the spots L1 and L2 may not reach the ideal spot positions. At this time, the light source is adjusted to make the spot L1 close to the ideal spot position L1a and the spot L2 close to the ideal spot position L2a. It should be noted that the ideal spot position mainly refers to the position of the spot. When adjusting, the size of the spot can be ignored, and the center of the spot can be moved to the corresponding ideal spot position.

[0032] For setting the position of the ideal light spot, reference may be made to the specific arrangement of the light source 110 and the detection requirements, so that the position of the ideal light spot and the position of the light source 110 may be substantially the same or proportional.

[0033] In addition, the components in the optical path can be detected and the correction of the optical path can be assisted according to the shape of the light spot. For example, in some cases, the light emitted by the light source 110 is at least partially transmitted through the optical fiber. When the shape of the light spot is irregular, it indicates that there is an abnormality in the light output end face of the optical fiber. In this case, the light output end face of the optical fiber can be adjusted or repaired, and then the entire optical path can be adjusted to correct the light output state of the light source or equivalent light source.

[0034] In addition, in some cases, the brightness and differences between the light spots can be used as a reference to compare and adjust the luminous intensity of the light source so that the luminous intensity of the light source is roughly similar and forms light spots with similar brightness. This can reduce the difference in image brightness caused by light brightness when detecting the object being tested, thereby facilitating comparative analysis and interpretation of the magnetic domain image and facilitating the use of the detection equipment.

[0035] See also Figure 4 , a reference line 720 may be further provided on the calibration card 700, and the light source 110 may be adjusted according to the relative position of each light spot and the reference line 720. For the convenience of observation, the reference line 720 may be provided on the calibration surface 710. For example, see Figure 3 , Figure 4 When the light source 112 located at the center of the multiple light sources 110 is lit, a light spot L2 is generated accordingly. When a reference line 720 is provided, the light spot L2 can be moved to a specific position of the reference line, for example, the light spots L2 on both sides of the reference line are made substantially the same; when the reference line 720 is provided in the form of a rectangular coordinate system, the light source 112 can be adjusted so that the light spot L2 is substantially located at the origin of the rectangular coordinate system; after completing the adjustment of the light source 112 located at the center of the multiple light sources 110, the multiple light sources 110 can be quickly positioned and adjusted as a whole, so that the light spots generated by the other light sources 110 are closer to the ideal light spot position, which is convenient for the subsequent adjustment process.

[0036] See also Figure 3 , Figure 4 When the light source 113 located on one side of the multiple light sources 110 is turned on, a light spot L3 is generated accordingly. When a reference line 720 is provided, the light spot L3 can be moved to a specific position of the reference line. For example, the ideal light spot position L3a is determined according to the reference line 720, and the light source 113 is adjusted so that the light spot L3 is close to L3a.

[0037] The reference line 720 can be set in various forms, for example, Figure 4The rectangular coordinate system shown can also be set in the form of a polar coordinate system, and matching reference lines can be set according to the positional relationship of the light sources 110. For example, when multiple light sources 110 are distributed along a straight line, a straight reference line 720 is set; when multiple light sources 110 are distributed along multiple straight lines at an angle, corresponding angled straight reference lines 720 are set.

[0038] In addition, a scale line 721 may be further added on the basis of the reference line 720 to further measure the size of the light spot so as to facilitate adjustment of the light source 110 .

[0039] According to the foregoing, the ideal light spot position can be indicated by the reference line 720. More specifically, the position of the ideal light spot can be directly marked on the calibration card 700 using the reference line 720. When the position of the calibration card 700 is set to be roughly fixed during calibration, the size of the ideal light spot can be further marked to further facilitate determination of the optical path adjustment effect.

[0040] When comparing the position difference between the light spot and the ideal light spot, the center of the light spot can be calculated and the distance between the center of the ideal light spot and the center of the light spot can be compared to determine whether the light spot meets the adjustment requirements. For example, when the distance between the center of the light spot and the center of the ideal light spot is no more than 5% of the diameter of the light spot, the position of the light spot is considered to meet the threshold with the ideal light spot position. Of course, the corresponding threshold can also be determined according to the actual needs of the detection. For example, when the requirements for the accuracy of the light path are low, the threshold can be set to the distance between the center of the light spot and the center of the ideal light spot is no more than 10% of the diameter of the light spot; when the requirements for the accuracy of the light path are high, the threshold can be set to the distance between the center of the light spot and the center of the ideal light spot is no more than 1% of the diameter of the light spot; or other ranges. When the difference between the position of the light spot and the preset ideal light spot position meets the threshold, the adjustment of the light path is terminated.

[0041] See also Figure 5 , the calibration card 700 can be arranged at the side of the detection position F away from the objective lens 400, so that the light source 110 forms a clear light spot on the calibration card 700. Of course, in some cases, the calibration card 700 can be arranged between the detection position F and the objective lens 400 to form a corresponding light spot, but usually the light spot will be relatively blurred, and when adjusting the light source 110 according to the light spot, it is difficult to determine whether it is adjusted in place, and the adjustment difficulty is relatively large.

[0042] The light source 110 can be arranged according to actual needs. For example, when the polar Kerr effect and the in-plane Kerr effect are used to detect the object 800, at least three light sources 110 can be arranged. At least three light sources 110 are arranged non-collinearly so that the polarized light can be irradiated to the detection position F at the corresponding incident angle and incident plane. For example, please refer to Figure 3The light source 110 may be provided with at least three light sources 111, 112, 113. Figure 4 , three light spots L1, L2, L3 can be formed on the calibration card 700, according to Figure 5 It can be seen from the optical path shown that when the light sources 111, 112, 113 can form light spots L1, L2, L3, when the light spots L1a, L2a, L3a are adjusted to the ideal light spot positions L1a, L2a, L3a respectively, the light spot L2 near the center can be irradiated to the detection position F along the direction perpendicular to the object under test 800 to detect the polar Kerr effect; the light spots L1 and L3 near the central light spot L2 can be irradiated to the detection position F along different incident angles and incident planes to detect the in-plane Kerr effect in two directions. Of course, it is also possible to further set a larger number of light sources, for example, Figure 3 The five light sources shown may be used, or other numbers of light sources may be used to meet corresponding detection requirements.

[0043] According to the above content, the three light sources 111, 112, 113 arranged in an L shape can be turned on, and three light spots L1, L2, L3 arranged along the L shape can be formed on the calibration card. By using the light source 110 and the optical path form in this form, the polar Kerr effect and the in-plane Kerr effect can be used to detect the object 800. On this basis, when the optical path is calibrated, all the light sources 110 can be moved as a whole so that the light spot L2 at the corner of the L shape reaches the preset position L2a, and all the light sources 110 can be rotated as a whole so that the remaining two light spots L1 and L3 are close to the corresponding preset positions L1a and L3a respectively.

[0044] It is understandable that when performing optical path correction, it is not required that all light sources are turned on, and the light sources to be turned on need to be determined based on actual needs. For example, when the light emission direction of the light source 110 on the optical bracket 100 has been corrected, only the overall orientation of the light source 110 needs to be corrected. At this time, only two light sources can be turned on; when at least one of the directions and positions of each light source 110 needs to be corrected, the light source 110 to be corrected needs to be turned on; when only part of the light sources 110 needs to be corrected, only the light sources 110 to be corrected can be turned on.

[0045] When performing optical path correction, since the light emitted by the light source 110 can pass through most of the optical elements in the optical path, adjusting the light source 110 can significantly adjust the optical path; as a feasible optical path adjustment method, the position of the light source 110 and at least one of the light emitting directions can be adjusted until the light spot reaches a preset position. In addition, at least one of the position of the light source 110 and the light emitting direction can be adjusted until the light spots reach a preset position relationship. In other words, the aforementioned preset position, as a basis for judging the final effect of the adjustment, can be either the specific position of each light spot or the positional relationship between the light spots, and can be adjusted and selected as needed.

[0046] In some cases, when the position of the light source 110 is fixed, the light emission direction of the light source 110 can be adjusted so that the positional relationship between the light spots is the same as or proportional to the positional relationship between the light sources 110 to ensure that the light emitted by the light source 110 is substantially parallel.

[0047] See also Figure 1 , Figure 2 , corresponding optical elements may be provided according to actual needs, for example, a beam splitter 300 may be provided to adjust the shape of the light path.

[0048] In addition, regarding the aforementioned light sources 111, 112, 113, when the optical fiber 140 and the corresponding light source 130 are used, the light-emitting end faces 121, 122, 123 of the optical fiber 140 can also be used as the light sources 111, 112, 113, and the corresponding calibration process mainly calibrates the light path from the light-emitting end faces 121, 122, 123 to the calibration card 700, rather than the light path between the optical fiber 140 and the light source 130.

[0049] After completing the optical path calibration of the multi-light source magneto-optical Kerr detection device using the aforementioned optical path calibration method, please refer to Figure 5 In some cases, the object to be tested 800 can be directly placed in and the corresponding test can be carried out, or the calibration card 700 can be removed and the object to be tested 800 can be placed in. By using the optical path correction method provided by the present invention, it is possible to quickly switch between the correction state and the use state. The correction process is simple and easy to operate, which greatly improves the use and efficiency of the equipment.

[0050] The above shows and describes the basic principles, main features and advantages of the present invention, so the above is only an embodiment of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above embodiments, and the above embodiments and descriptions only describe the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention also includes various equivalent changes and improvements, which will fall within the scope of the present invention to be protected.

Claims

1. A method for correcting the optical path of a magneto-optical Kerr detection device, characterized in that: The magneto-optical Kerr detection device comprises at least two light sources, so that the light emitted by the light sources converges at the detection position after passing through the polarizer and the objective lens, and the light reflected from the detection position can enter the camera through the objective lens and the analyzer; A calibration card is set at a position preset interval from the detection position, and at least two of the light sources are turned on at the same time, so that the light emitted by the light sources forms a corresponding light spot on the calibration card; and the position of the light source is adjusted with reference to the position of the light spot.

2. A method for correcting the optical path of a magneto-optical Kerr detection device as claimed in claim 1, characterized in that: A reference line is provided on the calibration card, and the position of the light source is adjusted according to the relative position of the light spot and the reference line.

3. A method for correcting the optical path of a magneto-optical Kerr detection device as claimed in claim 2, characterized in that: The ideal light spot position is indicated by the reference line, and the position of the light source is adjusted according to the difference between the light spot position and the ideal light spot position until the difference between the light spot position and the ideal light spot position meets a preset threshold.

4. A method for correcting the optical path of a magneto-optical Kerr detection device as claimed in claim 1, characterized in that: The light emitted by the light source is at least partially transmitted through the optical fiber, and when the shape of the light spot is irregular, the end face of the optical fiber is adjusted or repaired.

5. A method for calibrating an optical path of a magneto-optical Kerr detection device as claimed in claim 1, characterized in that: The calibration card is arranged at a side of the detection position away from the objective lens.

6. A method for calibrating an optical path of a magneto-optical Kerr detection device as claimed in claim 1, characterized in that: The luminous intensity of the light source is corrected according to the brightness of the light spot.

7. A method for correcting the optical path of a magneto-optical Kerr detection device as claimed in claim 1, characterized in that: At least three light sources are provided, and the three light sources are turned on to form three light spots on the calibration card, and the turned-on light sources are not arranged in a collinear manner.

8. A method for correcting the optical path of a magneto-optical Kerr detection device according to any one of claims 6 or 7, characterized in that: The three light sources arranged in an L shape are turned on, and three light spots arranged along the L shape are formed on the calibration card; all the light sources are moved as a whole so that the light spots at the corners of the L shape reach the preset positions, and all the light sources are rotated as a whole so that the remaining two light spots are close to the corresponding preset positions.

9. A method for calibrating an optical path of a magneto-optical Kerr detection device as claimed in claim 1, characterized in that: Adjusting the posture of the light source includes adjusting at least one of the position and the light emitting direction of the light source.

10. The optical path correction method of a magneto-optical Kerr detection device according to claim 1, characterized in that: The calibration card is provided with a calibration surface, and the light emitted by the light source is at least diffusely reflected on the calibration surface to form a light spot.

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