A uniform line laser generator with large depth of field

Abstract

The application belongs to the field of laser, and relates to a large-depth uniform linear laser generator, the main structure of which comprises N light-emitting sources and a Powell prism or a cylindrical lens combination, N>=2, N being a positive integer; a collimating lens and a mirror combination are arranged in the light path direction of each light-emitting source, so that different light-emitting sources reach the same Powell prism or cylindrical lens combination after collimation, reflection or transmission, and uniform linear laser with different focusing positions is obtained, the depth of the focusing position is expanded, and the purpose of expanding the depth of field is achieved; the multiple light sources change the linear focal point position, the original position can be kept unchanged, so that the repeatability is better and the precision is higher; the application is mainly applied to machine vision light sources, and has great application value in aspects of depth measurement of complex structures, high-precision device flaw detection of large depth, high-precision micro 3D modeling and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of laser, and relates to a large-depth-of-field uniform linear laser generator, the light source of which is composed of multiple coaxial and coplanar linear laser light sources and is focused at different positions to obtain a super large depth of field. BACKGROUND

[0002] Linear laser light source refers to a laser light source that converts a laser point into a linear laser. The uniform linear laser light source mainly refers to a point-to-linear laser light source obtained by a Powell prism. The uniform linear light source is widely used and is often used in machine vision, such as railway scratch detection, mobile phone size measurement, electronic component height measurement, etc. For example, Chinese patent application CN200710099445.X discloses a laser three-dimensional depth acquisition active mechanism, which comprises a two-dimensional laser range finder as a first light source unit, a second light source unit, a third light source unit, a mirror rotating unit and a base; the first light source unit, the second light source unit and the third light source unit are respectively installed on three supports with an equilateral triangle layout, and the mirror rotating unit is installed on a rotating shaft arranged at the center of gravity G of the equilateral triangle. The laser three-dimensional depth acquisition active mechanism adopts a two-dimensional laser range finder, and the two plane mirrors of the second light source unit and the third light source unit perform pitching motion, so as to form three light planes with the same exit angle. Through the rotation of the rotating shaft, the three light planes form three light regions, thereby increasing the collection of three-dimensional depth information. Chinese patent application CN201710087592.9 discloses a mobile phone shell quality online detection device and method based on linear laser scanning; the device comprises a conveying device, an acquisition device and a computer; the conveying device comprises a conveying guide rail, a motor, a motion control card, a photoelectric sensor and a base; the acquisition device comprises a light source controller, a linear laser generator, a CCD camera and an image acquisition card, and the image acquisition card is used to acquire images from the CCD camera; the computer is connected with the sensor, the image acquisition card and the motion control card through data lines to complete the control of the detection device and the realization of the detection algorithm; the three-dimensional profile of the mobile phone shell is reconstructed online, and is compared with the standard mobile phone shell profile to determine whether there is a defect; the defects such as concave, convex and profile deformation of the mobile phone shell are detected in real time, and the device has the characteristics of rapidness, high efficiency, stability and intelligence.

[0003] But the uniform line laser light source on the market, basically all single laser light source forms line laser, by the basic principle of laser transmission and basic optical principle limit, its depth of field exists a maximum, under certain conditions, its depth of field size can't meet the actual application demand. For example, the wavelength of laser is λ, the beam waist size is less than ω at a distance of l, the depth of field size is basically around ±Z, but the actual application demand is to achieve more than ±Z. For example, Chinese patent application CN202010281988.9 discloses a kind of super large depth of field 3D line structured light source module, including shell and LD seat, its characterized in that: still include aspheric mirror seat, aspheric lens, one character mirror seat, power prism, laser diode, lock ring, locking top screw, power prism is located in the right side of aspheric lens, and aspheric lens is located in the right side of laser diode, LD seat is fixedly connected with the inner wall of shell by adhesive, the present application relates to 3D machine vision technical field.The super large depth of field 3D line structured light source module, 4 locking top screws are all connected with LD seat by thread hole and are all in contact with the surface of laser diode, the customized power prism scheme meets the height uniformity of laser line, by adjusting laser tube locking top screw, ensure that laser tube and aspheric lens are precisely matched, guarantee beam directivity, make full use of the output characteristics of laser diode in different directions and optimize the focusing characteristics of light, obtain the large depth of field of laser line.

[0004] Even if there is single light source line laser through adjusting focus to obtain different positions of focusing effect, due to the error of focusing mechanism, it will lead to inaccurate focusing or deviation. SUMMARY

[0005] The purpose of the present application is to solve the shortcomings of the prior art, provide a kind of large depth of field uniform line laser generator, the light source of the uniform line laser generator is composed of multiple coaxial, coplanar laser line light sources, and focuses at different positions, so as to obtain super large depth of field.

[0006] In order to achieve the above purpose, the present application provides a kind of large depth of field uniform line laser generator, its main structure includes N light sources and a power prism or cylindrical lens combination, N≥2, N is positive integer;In the light path direction of each light source, collimating lens and mirror combination are arranged, specifically: M mirrors are arranged between 1 light source and power prism or cylindrical lens combination, M≥1, M is positive integer;Light source is arranged on the left side or right side of at least one mirror;Collimating lens is arranged between each light source and adjacent mirror, so that different light sources reach the same power prism or cylindrical lens combination after collimation, reflection or transmission.N light sources emit laser, and the beam waist of the line laser obtained after passing through the power prism or cylindrical lens combination is at different positions.

[0007] The light-emitting light source is a laser light source such as a semiconductor laser diode, an F-packaged semiconductor laser, a semiconductor-pumped solid-state laser, a semiconductor-coupled fiber output laser, or a fiber laser.

[0008] The N light-emitting light sources are different in position and light path.

[0009] The collimating lens is a single aspheric plano-convex lens, a combined lens composed of one negative lens and one positive lens, a cemented lens composed of one negative lens and one positive lens, or a combination of multiple cylindrical lenses for collimating the fast and slow axes of the light source.

[0010] The Powell prism or the cylindrical lens combination is used to convert the point laser into a uniform linear laser.

[0011] The cylindrical lens combination is a combination of a plano-concave cylindrical lens and a plano-convex cylindrical lens, the plane of the plano-concave cylindrical lens is a light receiving surface, the convex surface of the plano-convex cylindrical lens faces the concave surface of the plano-concave cylindrical lens and is a light receiving surface, or one plano-convex cylindrical lens, the plane faces one side of the exit pupil and the cylindrical surface faces one side of the light source, or a combination of two plano-convex cylindrical lenses, the two cylindrical surfaces are opposite and the planes face outward, or a combination of a biconcave cylindrical lens and a plano-convex cylindrical lens, etc.

[0012] Compared with the prior art, the uniform linear laser generator provided by the application is composed of multiple different light sources through the same Powell prism, and the light source has different focusing positions at the same time. Since multiple linear lasers with different focusing positions are obtained at the same time, the depth of the focusing position is expanded when the different light sources are turned on to obtain linear lasers, thereby achieving the purpose of expanding the depth of field, and further obtaining a linear laser generator with a large depth of field. Compared with a single laser light source with adjustable focal length, multiple laser light sources can change the focal point position in real time, thereby achieving a faster speed than the focal length adjustment, and the focusing mechanism has a gap due to the thread or mechanical structure, which can easily cause deviation or inaccuracy of the focusing position. Therefore, the multiple light source changing linear focal point position of the application can keep the original position unchanged, thereby achieving better repeatability and higher precision. At the same time, by adjusting the included angle of the different focusing beams, a linear laser with a certain included angle and focused on the same position can be obtained, thereby expanding the area of simultaneous measurement compared with a single laser light source obtaining a laser line. The application is mainly applied to machine vision light sources, and has great application value in depth measurement of complex structures, device flaw detection of large depth and high precision, high-precision micro 3D modeling, etc. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The figure shows the overall structure and optical path principle of the uniform linear laser generator of embodiment 1.

[0014] Figure 2The schematic diagram of the overall structure principle of the Powell prism involved in the present application.

[0015] Figure 3 The schematic diagram of the light path principle when the three light sources in Example 1 are separately lighted.

[0016] Figure 4 The schematic diagram of the light path principle in the fan angle direction of the uniform linear laser generator involved in the present application.

[0017] Figure 5 The schematic diagram of the overall structure principle of the uniform linear laser generator in Example 5 involved in the present application.

[0018] Figure 6 The schematic diagram of the position principle of the reflection angle involved in the present application. DETAILED DESCRIPTION

[0019] The present application will be further described below through specific examples and in conjunction with the drawings.

[0020] Example 1

[0021] The present example relates to a uniform linear laser generator with large depth of field, the main structure of which comprises a first light source 1, a first collimating lens 2, a first reflecting mirror 3, a second reflecting mirror 4, a Powell prism 5, a second light source 6, a second collimating lens 7, a third light source 8 and a third collimating lens 9. The first light source 1 emits a laser beam, and the first collimating lens 2, the first reflecting mirror 3, the second reflecting mirror 4 and the Powell prism 5 are sequentially arranged along the direction of the beam. The laser beam emitted by the first light source 1 is first focused by the first collimating lens, then passes through the first reflecting mirror and the second reflecting mirror to reach the Powell prism 5, and forms a uniform linear laser through the Powell prism. The second light source 6 and the second collimating lens 7 are located on one side (left or right) of the first reflecting mirror 3. The second light source 6 emits a laser beam, which is focused by the second collimating lens 7, then reflected by the first reflecting mirror 3, and the reflected light passes through the second reflecting mirror 4 to reach the Powell prism 5, and forms a uniform linear laser through the Powell prism. The third light source 8 and the third collimating lens 9 are located on one side (left or right) of the second reflecting mirror 4. The third light source 8 emits a laser beam, which is focused by the third collimating lens 9, then reflected by the second reflecting mirror 4, and the reflected light reaches the Powell prism 5, and forms a uniform linear laser through the Powell prism.

[0022] The Powell prism is an optical element capable of converting a Gaussian point laser into a uniform linear laser. The material thereof can be glass, quartz, plastic or other transparent materials, and is preferably K9 glass. The ridge surface 51 and the slope surface 52 of the Powell prism are light receiving surfaces.

[0023] The first light source 1, the second light source 6 and the third light source 8 are semiconductor laser diodes.

[0024] The first collimating lens 2, the second collimating lens 7 and the third collimating lens 9 are all aspheric plano-convex lenses, and the three collimating lenses focus different laser light sources respectively, and make the beam waist of the linear laser obtained after the laser emitted by the three laser light sources passes through the Powell prism at different positions.

[0025] The first mirror 3 and the second mirror 4 are half-transparent mirrors or special coated mirrors. When the wavelengths of the laser light sources are the same, the first mirror 3 and the second mirror 4 are both half-transparent mirrors, and the reflectivity is 20%-60%, which can both transmit a part of the laser and reflect a part of the laser; when the wavelengths of the laser light sources are different, the first mirror 3 and the second mirror 4 are both special coated mirrors, that is, the reflectivity of a certain specific wavelength range of light beam is high, >93%, and the transmittance of other wavelengths of light beam is high, >93%.

[0026] The reflection angles of the first mirror 3 and the second mirror 4 are adjustable, preferably 45°, which facilitates the process debugging of the coaxial multi-beam.

[0027] In order to keep the linear laser power density at the Powell conversion position the same or similar, so as to keep the consistency and accuracy of the machine vision lens in identifying the laser line, the power of different laser beams reaching the Powell prism needs to be the same or similar.

[0028] The large-depth uniform linear laser generator in the embodiment needs to obtain linear laser beams focused at different positions on the same plane, so the three laser beams need to be adjusted coaxially before reaching the Powell, so as to obtain linear laser beams in the same plane. The adjustment mode is to adjust the positions of the light source, or the collimating lens, or the mirror, or some combination of the three, which can achieve the purpose of adjusting the position or inclination angle of the final laser line. For example, taking the light beam focused by the third light source as a reference, fixing the light beam systems focused by the first light source and the second light source, adjusting the first mirror and the second mirror to make the light beams emitted by the first light source and the second light source coaxial with the light beam focused by the third light source; or fixing the first mirror and the second mirror, taking the light beam focused by the first light source as a reference, adjusting the positions of the second light source and the third light source and the collimating lens (or taking the light beam focused by the second light source or the third light source as a reference, adjusting the positions of the other two light sources).

[0029] When the three light sources in the embodiment are turned on at the same time, uniform linear laser beams with different focusing positions can be obtained, and there are three beam waists. The light path principle in the linear width direction is as shown in Figure 1 , and the light path in the fan angle direction is as shown in Figure 4 .

[0030] The working principle of the large depth of field uniform linear laser generator relates to three laser light sources. The three laser light sources are generally not turned on at the same time, but are turned on at least once, respectively. When dealing with different depths of the object to be tested, or the depth of the same object is large, different laser light sources are turned on to test the data, respectively, and then the test data is spliced to obtain the final test data of the object (the beam waist position of multiple light sources is different, the beam waist is thinner, and the data is more accurate). The laser generator with one light source can more accurately measure the object data. For example, when the 3D scanning instrument with a fixed probe tests objects with different heights, the depth of field of one light source is limited, and cannot simultaneously adapt to different objects with a height difference larger than the depth of field of a single light source (i.e., when h1-h2>Z, one light source cannot measure the two objects at the same time). The combination of three or more light sources can obtain 3D data of the object with the height by turning on the light sources respectively, comparing the data by algorithm, and splicing the data. For another example, when testing a complex object with a height greater than the depth of field, a single light source cannot accurately measure the part beyond the depth of field (the beam width is smaller at the beam waist, and the test accuracy is higher after visual calculation). The present application can accurately measure different depths by using multiple light sources and splicing the data. The traditional single light source focusing can also achieve the effect of measuring the characteristics of objects at different positions, but the focusing requires a certain time, and the focusing mechanism is not easy to maintain coaxial, or errors may occur during the focusing process due to the thread gap, which is not as good as the effect of measuring data by multiple light sources in the present application.

[0031] The embodiment can obtain linear laser focused at the same horizontal line position with a certain interval between the beam waist and the main beam by adjusting the focusing position of the light beam by adjusting the angle of the reflector and the distance between the collimating lens and the LD. Compared with a single laser light source and a linear laser, the present application can simultaneously measure multiple linear positions of an object, thereby expanding the area of simultaneous measurement.

[0032] The uniform linear laser light source can obtain linear laser focused at different positions on the same plane, and can also obtain linear laser focused at the same position on different planes. When obtaining linear laser on different planes, the horizontal position and the reflection angle of the two reflectors are adjusted according to the included angle of the linear laser on the different planes required.

[0033] Embodiment 2:

[0034] The embodiment is different from embodiment 1 in that only the first light source and the second light source are provided, and the third light source is not provided.

[0035] Embodiment 3:

[0036] The embodiment is different from the embodiment 1 in that only the first light emitting source and the third light emitting source are provided without the second light emitting source.

[0037] Embodiment 4

[0038] The embodiment is different from the embodiment 1 in that the fourth light emitting source and the fourth collimating lens are further provided, and the third reflecting mirror is located between the second reflecting mirror and the Powell prism; the fourth light emitting source and the fourth collimating lens are located at one side of the third reflecting mirror, the fourth light emitting source emits a laser beam, the laser beam is focused by the fourth collimating lens, and then is reflected by the third reflecting mirror, the reflected light reaches the Powell prism, and uniform linear laser is formed by the Powell prism.

[0039] Embodiment 5

[0040] The embodiment relates to a uniform linear laser generator with a large depth of field, which uses a cylindrical lens combination (for example, a combination of a plano-concave cylindrical lens 10 and a plano-convex cylindrical lens 11 given in the following formula (1) of the embodiment 1, a plane of the plano-concave cylindrical lens 10 is a light receiving surface, a convex surface of the plano-convex cylindrical lens 11 faces a concave surface of the plano-concave cylindrical lens 10, and the convex surface is a light receiving surface; or a plano-convex cylindrical lens can be used, a plane faces one side of an exit pupil, and a cylindrical surface faces one side of a light source; or two plano-convex cylindrical lenses can be combined, two cylindrical surfaces face each other, and planes face outward; or other combinations such as a biconcave cylindrical lens + a plano-convex cylindrical lens combination) instead of the Powell prism in the embodiment 1, and uniform linear laser with a large depth of field can be obtained. Figure 5 ​

Claims

1. A uniform line laser generator with large depth of field, characterized in that, The main body structure comprises N light emitting sources and a Powell prism or a cylindrical lens combination, N≥2, N being a positive integer; a collimating lens and a mirror combination are arranged in the light path direction of each light emitting source, so that different light emitting sources reach the same Powell prism or cylindrical lens combination after collimation, reflection or transmission, and N beams of laser emitted by the N light emitting sources need to be adjusted coaxially before reaching the Powell prism or cylindrical lens combination, and the beam waist of the linear laser obtained after passing through the Powell prism or cylindrical lens combination is at different positions, so as to obtain linear laser at different focusing positions in the same plane, thereby expanding the depth of the focusing position; The working principle of the large-depth uniform linear laser generator is that the N light emitting sources are generally not turned on at the same time, but are turned on at least once respectively; when a to-be-tested object with different depths or a same object with a large depth is encountered, different laser sources are turned on respectively for data testing, and then the test data are spliced to obtain the final test data of the object.

2. The uniform line laser generator with large depth of field according to claim 1, characterized in that, M mirrors are arranged between one light emitting source and the Powell prism or cylindrical lens combination, M≥1, M being a positive integer; the light emitting source is arranged on the left side or the right side of at least one mirror; a collimating lens is arranged between each light emitting source and the adjacent mirror.

3. The uniform line laser generator with large depth of field according to claim 1, characterized in that, The light emitting source is a semiconductor laser diode, an F-packaged semiconductor laser, a semiconductor-pumped solid-state laser, a semiconductor-coupled fiber output laser or a fiber laser.

4. The uniform line laser generator with large depth of field according to claim 1, characterized in that, The collimating lens is a single aspheric plano-convex lens, or a combination lens composed of one negative lens and one positive lens, or a cemented lens composed of one negative lens and one positive lens, or a combination of multiple cylindrical lenses for collimating the fast and slow axes of the light source.

5. The uniform line laser generator with large depth of field according to claim 1, characterized in that, The cylindrical lens combination is a combination of a plano-concave cylindrical lens and a plano-convex cylindrical lens, the plane of the plano-concave cylindrical lens is a light receiving surface, and the convex surface of the plano-convex cylindrical lens faces the concave surface of the plano-concave cylindrical lens and is a light receiving surface; or one plano-convex cylindrical lens, the plane faces one side of the exit pupil, and the cylindrical surface faces one side of the light source; or two plano-convex cylindrical lenses combined, the two cylindrical surfaces are opposite, and the planes face outward; or a double-concave cylindrical lens and a plano-convex cylindrical lens combination.

6. The uniform line laser generator with large depth of field according to claim 1, characterized in that, The reflection angle of the mirror is adjustable.

7. The uniform line laser generator with large depth of field according to claim 1, characterized in that, The reflection angle of the mirror is 45°.

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