CN106773025A - Focusing lens and lens vibrating type laser scanning system - Google Patents

Abstract

The invention discloses a kind of focusing lens and lens vibrating type laser scanning system, the focusing lens include the plano-concave mirror and convex lens that are coaxially disposed, the plano-concave mirror includes the plane and the concave surface that are oppositely arranged, the convex lens include the first convex surface and the second convex surface that are oppositely arranged, the convex lens are fixedly installed, plano-concave mirror is movably arranged on axis, and light is incident from the plane of plano-concave mirror, sequentially passes through the second convex surface outgoing from convex lens behind the concave surface of plano-concave mirror, the first convex surface of convex lens.Focusing lens simple structure of the present invention, and alignment error is small；Focusing lens enable that focusing lens keep relative low temperature without real focus；When incoming laser beam waist radius is more than 7.5mm, laser does not influence focusing effect to lens vibrating type laser scanning system apart from the distance between focusing lens.

Description

Focusing lens and galvanometer laser scanning system

technical field

The invention relates to the technical field of optical engineering, in particular to a focusing lens and a galvanometer laser scanning system.

Background technique

Laser scanning technology is a technology that can precisely control the pointing of laser beams. It has been widely used in optoelectronic medical treatment, laser processing, space laser communication, laser radar, remote sensing and measurement, adaptive optics and other fields. In the field of laser processing and laser compliance, galvanometer laser scanning technology has been used. In order to ensure the accuracy of laser processing, the laser needs to be focused before reaching the processing surface to ensure good focusing characteristics on the working surface. According to the position of the focusing system, it can be divided into two types of focusing: the front focus of the galvanometer and the focus after the galvanometer. Way.

Patent CN101419336B in the prior art proposes a galvanometer rear focusing method. The galvanometer laser three-dimensional scanning system includes a laser, a beam expander, an x-axis scanning galvanometer, a y-axis scanning galvanometer, a scanning focusing lens, and a z-axis moving mechanism and control system. The vibrating mirror laser scanning system separates the xy two-dimensional scanning vibrating mirror and the scanning focusing mirror (such as a normal focusing mirror or a telecentric scanning lens) into a mutually movable combination, that is, the xy-axis scanning vibrating mirror is fixed in the z-axis direction The scanning focus lens is fixed on a mechanism that can move up and down along the z-axis to realize the three-dimensional processing function.

In addition, the existing patent CN2664011Y discloses a laser scanning system focusing in front of the galvanometer, including a laser, a focusing module, an X-axis scanning head and a Y-axis scanning head. It uses a convex lens group focusing module composed of three combined lenses. One is a movable lens, which is driven by a motor to make a reciprocating linear motion, and the latter two are stationary lenses. The focus system plays the role of focusing on the one hand, and on the other hand, the role of optical leverage. The position of the lens is changed by the electric translation stage to automatically adjust the focal length of the optical system to ensure a good focus spot on the entire scanning surface. The laser beam passes through the focusing module, passes through the X-axis scanning head and the Y-axis scanning head, and reaches the focus working plane.

The galvanometer rear focusing method adopts the traditional F-theta lens focusing method. Due to the limitation of the lens size, the scanning range should not be too large, and the beam focusing characteristics at the edge of the scanning surface have become very poor.

The optical design and focusing model of the laser scanning system of the galvanometer front focusing method are relatively complicated. Too many lenses will increase the errors caused by processing and assembly, which will affect the focusing effect. In addition, this type of 3D scanning system basically has a real focus point in the optical path in addition to the scanning surface. The focus point of the high-energy laser beam will cause excessive temperature and increase the risk of equipment damage.

Therefore, in view of the above technical problems, it is necessary to provide a focusing lens and a vibrating mirror type laser scanning system.

Contents of the invention

In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a focusing lens and a vibrating mirror laser scanning system for laser three-dimensional scanning.

In order to achieve the above object, the technical solutions provided by the embodiments of the present invention are as follows:

A focusing lens, the focusing lens includes a coaxially arranged plano-concave mirror and a convex lens, the plano-concave mirror includes oppositely arranged planes and concave surfaces, and the described convex lens includes oppositely arranged first convex surfaces and second convex surfaces, The convex lens is fixedly arranged, and the plano-concave mirror is movable on the axis. Light is incident from the plane of the plano-concave mirror, passes through the concave surface of the plano-concave mirror and the first convex surface of the convex lens in sequence, and then emerges from the second convex surface of the convex lens.

As a further improvement of the present invention, the material of the plano-concave mirror and the convex lens is zinc selenide.

As a further improvement of the present invention, the curvature radii of the first convex surface and the second convex surface of the convex lens are equal and greater than the curvature radius of the concave surface of the plano-concave mirror.

As a further improvement of the present invention, the distance between the concave surface of the plano-concave mirror and the first convex surface of the convex lens is 10-100 mm.

As a further improvement of the present invention, the distance between the plane and the concave surface of the plano-concave mirror is 1-10 mm, and the distance between the first convex surface and the second convex surface of the convex lens is 1-10 mm.

As a further improvement of the present invention, the distance between the plane and the concave surface of the plano-concave mirror is 5mm, the distance between the first convex surface and the second convex surface of the convex lens is 5mm, and the radius of curvature of the concave surface in the plano-concave mirror is 110.94mm , the radius of curvature of the first convex surface and the second convex surface of the convex lens is 368.78mm, and the distance between the concave surface of the plano-concave mirror and the first convex surface of the convex lens is 50mm.

As a further improvement of the present invention, the focusing length when the light wavelength is 10.64 μm and the initial focal length is 750 mm is:

Among them, ΔS is the focusing length, and Z is the displacement of the plano-concave mirror.

Correspondingly, a galvanometer-type laser scanning system includes: a laser, a focusing lens, a first galvanometer, a second galvanometer, and a scanning surface in sequence along an axis.

As a further improvement of the present invention, a laser beam expander system is provided between the laser and the focusing lens.

As a further improvement of the present invention, the waist radius of the laser beam emitted by the laser is larger than 7.5mm.

The present invention has the following beneficial effects:

The structure of the focusing lens is simple, and the adjustment error is small;

The focusing lens has no real focus so that the focusing lens can be kept relatively low temperature;

In the galvanometer laser scanning system, when the incident laser beam waist radius is greater than 7.5mm, the distance between the laser and the focusing lens does not affect the focusing effect.

Description of drawings

FIG. 1 is a schematic structural diagram of a focusing lens in a first embodiment of the present invention.

FIG. 2 is a schematic structural diagram of a galvanometer-type laser scanning system in a second embodiment of the present invention.

detailed description

In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described The embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

The invention discloses a dual-mirror dynamic focusing lens, which aims at optimizing the existing dynamic focusing module optical system. The structure of the focusing lens is simpler, and the focusing lens has no real focus so that the structure is not easy to generate high temperature.

Specifically, as shown in FIG. 1 , the focusing lens in a specific embodiment of the present invention includes a plano-concave mirror 1 and a convex lens 2 coaxially arranged, the plano-concave mirror includes a plane 11 and a concave surface 12 arranged oppositely, and the convex lens 2 includes The first convex surface 21 and the second convex surface 22 are oppositely arranged. The convex lens 2 is fixedly arranged, and the plano-concave mirror 1 is movable on the axis. Two convex surfaces 22 emerge.

Wherein, the plano-concave mirror 1 and the convex lens 2 in this embodiment are made of the same material, which is zinc selenide. The radius of curvature of the first convex surface 21 and the second convex surface 22 of the convex lens 2 are equal, and larger than the radius of curvature of the concave surface 12 of the plano-concave mirror 1 .

Further, the distance between the concave surface 12 of the plano-concave mirror 1 and the first convex surface 21 of the convex lens 2 is 10-100mm, and the distance between the plane 11 of the plano-concave mirror 1 and the concave surface 12 is 1-10mm, the convex lens 2 The distance between the first convex surface 21 and the second convex surface 22 is 1-10mm.

Specifically, in a specific embodiment of the present invention, the distance between the plane 11 and the concave surface 12 of the plano-concave mirror 1 is 5mm, the distance between the first convex surface 21 and the second convex surface 22 of the convex lens 2 is 5mm, and the plane The radius of curvature of the concave surface 12 in the concave mirror 1 is 110.94mm, the curvature radius of the first convex surface 21 and the second convex surface 22 in the convex lens 2 are both 368.78mm, the concave surface 12 of the plano-concave mirror 1 and the first convex surface 21 of the convex lens 2 The distance is 50mm.

When the focusing lens works, the convex lens 2 is fixed, and the plano-concave mirror 1 can move towards the direction of the convex lens 2 under the driving of the driving mechanism (not shown). Assuming that the amount of movement is Z, the focal length of the entire focusing lens can be changed.

In this embodiment, the focusing length when the light wavelength is 10.64 μm and the initial focal length is 750 mm is:

Among them, ΔS is the focusing length, and Z is the displacement of the plano-concave mirror.

The focus lens in this embodiment can be applied to laser three-dimensional scanning and the like.

Referring to FIG. 2, it is a schematic structural diagram of a galvanometer-type laser scanning system in another embodiment of the present invention, which sequentially includes a laser 6, a focusing lens, a first galvanometer 3, a second galvanometer 4, and a scanning surface 5 along the axis. , wherein the focusing lens is composed of the above-mentioned plano-concave mirror 1 and convex lens 2, the first vibrating mirror 3 is an X vibrating mirror, and the second vibrating mirror 4 is a Y vibrating mirror, and the installation method of the focusing lens is the same as that of the above-mentioned first embodiment , which will not be repeated here.

During the installation of the galvanometer-type laser scanning system, the centers of the laser 6, the plano-concave mirror 1, and the convex lens 2 must be on a straight line, and the centers of the beam entrances of the first galvanometer 3 and the second galvanometer 4 should be in a straight line superior.

In this embodiment, the laser is a carbon dioxide continuous laser, and the waist radius of the laser beam emitted by the laser is greater than 7.5mm.

When the laser beam is processing the workpiece, it is necessary to consider the deviation between the focus point of the laser beam and the scanning surface, that is, the laser is defocused on the working surface. The invention makes the laser beam pass through the focusing lens to complete the defocus correction on the entire working range, and the position of the plano-concave mirror is changed by the electric translation platform to automatically adjust the focal length of the optical system, ensuring that there is a good focus spot on the entire scanning surface .

For the galvanometer laser scanning system, the center point of the scanning surface is selected as the coordinate origin to establish a rectangular coordinate system. Assuming that the reflected laser beam points to the point (x, y) on the scanning surface, the defocus error calculation formula of the system is:

Wherein, d is the distance between the second vibrating mirror 4 and the scanning surface 5 , and e is the distance between the mirror centers of the first vibrating mirror 3 and the second vibrating mirror 4 .

For the galvanometer-type laser scanning system in a specific embodiment of the present invention, the relationship between the distance that the plano-concave mirror 1 moves in the direction of the convex lens 2 and the adjusted focal length is:

Among them, ΔS is the focusing length, and Z is the displacement of the plano-concave mirror.

Through the above two formulas, knowing the scanning point (x, y), the user can calculate the distance Z that the plano-concave mirror 2 should move in the direction of the convex lens 3, so as to ensure that each scanning point on the scanning surface is exactly the focus point, Eliminates out-of-focus errors.

Furthermore, in other implementation manners, in order to obtain smaller diffuse spots on the scanning surface, a laser beam expander system may also be added in front of the focusing lens.

In this embodiment, compared with the existing galvanometer post-focusing system, which is limited by the size of the lens, it is difficult to enlarge the working area, and the beam focusing characteristics at the edge of the scanning surface is poor, the present invention can complete the precision machining of large-size areas.

It can be seen from the above technical solutions that the focusing lens and galvanometer laser scanning system of the present invention have the following advantages:

The structure of the focusing lens is simple, and the adjustment error is small;

The focusing lens has no real focus so that the focusing lens can be kept relatively low temperature;

In the galvanometer laser scanning system, when the incident laser beam waist radius is greater than 7.5mm, the distance between the laser and the focusing lens does not affect the focusing effect.

It will be apparent to those skilled in the art that the invention is not limited to the details of the above-described exemplary embodiments, but that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Accordingly, the embodiments should be regarded in all points of view as exemplary and not restrictive, the scope of the invention being defined by the appended claims rather than the foregoing description, and it is therefore intended that the scope of the invention be defined by the appended claims rather than by the foregoing description. All changes within the meaning and range of equivalents of the elements are embraced in the present invention. Any reference sign in a claim should not be construed as limiting the claim concerned.

In addition, it should be understood that although this specification is described according to implementation modes, not each implementation mode only contains an independent technical solution, and this description in the specification is only for clarity, and those skilled in the art should take the specification as a whole , the technical solutions in the various embodiments can also be properly combined to form other implementations that can be understood by those skilled in the art.

Claims (10)

1. A focusing lens, characterized in that, the focusing lens comprises a coaxial plano-concave mirror and a convex lens, the plano-concave mirror comprises a plane and a concave surface arranged oppositely, and the convex lens comprises a first The convex surface and the second convex surface, the convex lens is fixedly arranged, and the plano-concave mirror is movable on the axis. Convex exit. 2. The focusing lens according to claim 1, wherein the material of the plano-concave mirror and the convex lens is zinc selenide. 3. The focusing lens according to claim 1, wherein the curvature radii of the first convex surface and the second convex surface of the convex lens are equal and larger than the curvature radius of the concave surface of the plano-concave mirror. 4 . The focusing lens according to claim 1 , wherein the distance between the concave surface of the plano-concave mirror and the first convex surface of the convex lens is 10-100 mm. 5. The focusing lens according to claim 1, wherein the distance between the plane and the concave surface of the plano-concave mirror is 1-10 mm, and the distance between the first convex surface and the second convex surface of the convex lens is 1 mm. ~10mm. 6. focusing lens according to claim 1, is characterized in that, the distance between the plane of described plano-concave mirror and the concave surface is 5mm, the distance between the first convex surface and the second convex surface of convex lens is 5mm, the plane The radius of curvature of the concave surface in the concave mirror is 110.94mm, the curvature radii of the first convex surface and the second convex surface in the convex lens are both 368.78mm, and the distance between the concave surface of the plano-concave mirror and the first convex surface of the convex lens is 50mm. 7. The focusing lens according to claim 6, wherein the focusing length when the light wavelength is 10.64 μm and the initial focal length is 750 mm is: $\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; 131.923</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; Z</span>}}{\mathrm{<span\; class="notranslate">\; 28.102</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 28.102</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.032</span>}<span\; class="notranslate">\; ,</span>$ Among them, ΔS is the focusing length, and Z is the displacement of the plano-concave mirror. 8. A galvanometer-type laser scanning system, characterized in that the system sequentially comprises along the axis: a laser, the focusing lens according to any one of claims 1 to 7, a first galvanometer, and a second galvanometer and scan surface. 9. The galvanometer-type laser scanning system according to claim 8, wherein a laser beam expander system is provided between the laser and the focusing lens. 10 . The galvanometer-type laser scanning system according to claim 8 , wherein the beam waist radius of the laser beam emitted by the laser is larger than 7.5 mm. 11 .