阅读说明：本技术 能调节光斑直径的光学装置、方法及激光成像设备 (Optical device and method capable of adjusting diameter of light spot and laser imaging equipment ) 是由 陈乃奇 张向非 于 2021-09-10 设计创作，主要内容包括：本发明公开了一种能调节光斑直径的光学装置、方法及激光成像设备,装置包括：在光路上依次设置的发光光源、准直镜、成像透镜、圆形挡光片以及聚焦平面；发光光源发出的光入射至成像透镜后,外围部分的环形光在聚焦平面上汇聚成衍射图案,中间部分的光束被圆形挡光片遮挡；发光光源的波长为,成像透镜的焦距为f,成像透镜的外直径为a,因圆形挡光片遮挡导致发光光源不能聚焦到聚焦平面上的那部分光束在成像透镜上投射形成的圆形区域的直径为b,b=k×a,发光光源在聚焦平面上得到的位于衍射图案圆心的圆形亮斑的半径r的值为：。本发明能够调小光斑直径,提高成像清晰度,且能降低成像透镜的制造工艺难度。(The invention discloses an optical device capable of adjusting the diameter of a light spot, a method and laser imaging equipment, wherein the optical device comprises: the light source, the collimating lens, the imaging lens, the circular light barrier and the focusing plane are sequentially arranged on the light path; after light emitted by the light-emitting source enters the imaging lens, annular light at the peripheral part is converged into a diffraction pattern on a focusing plane, and light beams at the middle part are shielded by the circular light blocking sheet; the wavelength of the light source is The focal length of the imaging lens is f, the outer diameter of the imaging lens is a, and the diameter of a circular area formed by projection of the part of light beam which cannot be focused on the focusing plane by the light source due to the shielding of the circular light blocking sheet on the imaging lens is bB = k × a, the radius r of the circular bright spot at the center of the diffraction pattern obtained by the light source on the focal plane is: . The invention can reduce the diameter of the light spot, improve the imaging definition and reduce the manufacturing process difficulty of the imaging lens.)

1. Can adjust optical device of facula diameter, its characterized in that: the method comprises the following steps: the light source, the collimating lens, the imaging lens, the circular light barrier and the focusing plane are sequentially arranged on the light path;

light emitted by the light emitting source is collimated by the collimating mirror and then parallelly incident to the imaging lens, after being transmitted by the imaging lens, light beams in the middle part are shielded by the circular light blocking sheet and cannot be focused on the focusing plane, and annular light in the peripheral part forms diffraction patterns on the focusing plane;

the wavelength of the light source is lambda, the focal length of the imaging lens is f, the outer diameter of the imaging lens is a, the diameter of a circular area formed on the imaging lens by the part of light beams which cannot be focused on a focusing plane by the light source due to the shielding of the circular light blocking sheet is b, b = k × a, k is (0,1), the value of b is adjustable, k is a first variable value which is increased along with the increase of b, and the radius of a circular bright spot positioned at the center of the diffraction pattern is bN is a second variable value which decreases as k increases; the part of the imaging lens, the diameter of which is within the b range, is a spherical lens area, and the part of the imaging lens, the diameter of which is between the b range and the a range, is an aspheric lens area.

2. The optical device of claim 1, wherein: the value of b increases, k increases, the value of n decreases, and r decreases.

3. The optical device of claim 2, wherein: the method for increasing the b value comprises the following steps: reducing the distance L from the circular light barrier to the imaging lens and/or increasing the diameter c of the circular light barrier.

4. The optical device of claim 1, wherein: k =0.25, n = 0.58.

5. The optical device of claim 1, wherein: k =0.5 and n = 0.51.

6. The optical device of claim 1, wherein: k =0.75, n = 0.42.

7. A method of adjusting a spot diameter using the optical device of any one of claims 1-6, wherein: the method comprises the following steps:

step 1: a light-emitting light source, a collimating lens, an imaging lens, a circular light blocking sheet and a focusing plane are sequentially arranged on a light path;

step 2: turning on the light-emitting source, collimating light emitted by the light-emitting source through the collimating mirror, and then parallelly emitting the collimated light to the imaging lens, wherein after the light is transmitted by the imaging lens, a light beam at the middle part is shielded by the circular light blocking sheet and cannot be focused on the focusing plane, and annular light at the peripheral part forms a diffraction pattern on the focusing plane;

and step 3: according to the formulaAnd adjusting the radius r of the circular bright spot positioned at the center of the diffraction pattern.

8. The method of claim 7, wherein: the value of r decreases by increasing b.

9. The method of claim 8, wherein: the method for increasing b is to reduce the distance L from the circular light barrier to the imaging lens and/or to increase the diameter c of the circular light barrier.

10. A laser imaging apparatus characterized by: the laser imaging apparatus comprising the optical device according to any one of claims 1 or 2.

Technical Field

The invention belongs to the field of optical equipment, and particularly relates to an optical device and method capable of adjusting the diameter of a light spot and a laser imaging device.

Background

Referring to fig. 1, light emitted from a light source 10 is collimated by a collimating lens 20, and then emitted to a focusing lens 30 in parallel, and after being focused by the focusing lens 30, the light is converged on an imaging surface 40 to form a light spot with a diameter of h. In order to reduce the spot diameter h, it is a common practice in the prior art to insert an annular diaphragm 50 with an adjustable inner diameter d in the optical path between the collimator lens 20 and the focusing lens 30. The size of the spot diameter h is changed by adjusting the size of the inner diameter d of the annular diaphragm sheet 50. However, in fact, the spot diameter h can be adjusted only large, not small, no matter how large the inner diameter d of the annular diaphragm 50 is. Since the diameter of the light spot cannot be adjusted to be small, the development of the industries such as a Printed Circuit Board (PCB) and a lithography machine is greatly restricted. For example: for the PCB, the smaller the diameter of the light spot is, the smaller the occupied area on the PCB is, and the more and more objects printed by laser on the PCB are, the finer the objects are; for the photoetching machine, the smaller the light spot is, the higher the photoetching precision is.

Disclosure of Invention

The invention discloses an optical device capable of adjusting the diameter of a light spot, and aims to solve the problem that the diameter of the light spot cannot be adjusted to be small so that the image resolution cannot be improved.

The scheme of the invention is as follows:

an optical device capable of adjusting a diameter of a light spot, comprising: the light source, the collimating lens, the imaging lens, the circular light barrier and the focusing plane are sequentially arranged on the light path;

light emitted by the light emitting source is collimated by the collimating lens and then parallelly incident to the imaging lens, after being transmitted by the imaging lens, light beams in the middle part are shielded on the circular light blocking sheet and cannot be focused on a focusing plane, and annular light in the peripheral part forms diffraction patterns on the focusing plane;

wherein the wavelength of the light source isThe focal length of the imaging lens is f, and the outer diameter of the imaging lens is fThe light emitted due to the shielding of the circular light barrierThe diameter of a circular area formed on the imaging lens by the part of the light beam of which the source cannot focus on the focusing plane is b, b = k × a, k ∈ (0,1), the value of b is adjustable, k is a first variable value which increases along with the increase of b, and the radius of a circular bright spot positioned at the center of the diffraction pattern isN is a second variable value which decreases as k increases; the portion of the imaging lens within diameter b is a spherical lens region, and the portion of the imaging lens between diameter b and diameter a is an aspherical lens region.

Further: the value of b increases, k increases, the value of n decreases, and r decreases.

Further: the method for increasing the b value comprises the following steps: the distance L from the circular light barrier to the imaging lens is reduced and/or the diameter c of the circular light barrier is increased.

Further: k =0.25, n = 0.58.

Further: k =0.5 and n = 0.51.

Further: k =0.75, n = 0.42.

The invention also discloses a method for adjusting the diameter of the light spot by using the optical device, which comprises the following steps:

step 1: a light-emitting light source, a collimating lens, an imaging lens, a circular light blocking sheet and a focusing plane are sequentially arranged on a light path;

step 2: opening the light source to enable light emitted by the light source to be collimated by the collimating mirror and then to be incident to the imaging lens in parallel, after the light is transmitted by the imaging lens, the light beam in the middle part is shielded by the circular light blocking sheet and cannot be focused on the focusing plane, and the annular light in the peripheral part forms a diffraction pattern on the focusing plane;

and step 3: according to the formulaAnd adjusting the radius r of the circular bright spot positioned at the center of the diffraction pattern.

Further: by increasing b to increaseThe value of (c) is decreased.

Further: the method for increasing b is to decrease the distance L from the circular light-blocking sheet to the imaging lens and/or to increase the diameter c of the circular light-blocking sheet.

The invention also discloses laser imaging equipment which comprises the optical device capable of adjusting the diameter of the light spot.

The optical device has the beneficial technical effects that:

1. the circular light blocking sheet is arranged on the light path of the imaging lens and the focusing plane, so that emergent light transmitted by the imaging lens forms hollow annular light, and the annular light is converged on the focusing plane; b is the diameter of a circular area formed on the imaging lens by the part of light beam which cannot be focused on a focusing plane by the luminous light source due to the shielding of the circular light blocking sheet, so that the k value is increased, and the n value is reduced along with the increase of k according to a formulaAnd since the outer diameter a of the imaging lens cannot be increased without limit, the optical wavelength of the hollow ring light is increasedAnd under the condition that the focal length f of the imaging lens is a fixed value, the radius r of the round bright spot positioned at the center of the diffraction pattern can be reduced by reducing the value of n so as to realize the purposes of reducing the diameter of the light spot and improving the resolution of the image.

2. The technical scheme can reduce the radius of the facula, and the technology is applied to the field of laser plate making, so that the image printing precision of the laser plate making is greatly improved; the PCB printing precision can be improved by applying the PCB printing precision regulator in the PCB industry, so that more and finer circuits can be printed on the same PCB, and the utilization rate of the PCB is improved. For other industries, such as laser surgery, as the spot size becomes smaller, it can be used for more demanding minimally invasive surgery. For example, in the laser welding and cutting industry, the welding seam becomes thinner due to the fact that the light spot becomes smaller, and the laser welding and cutting method is suitable for welding of precise instruments. Of course, these applications are merely exemplary and not limiting.

3. When the imaging lens is manufactured, only the annular part of the outer side of the imaging lens, which is used for transmitting a light source and is not shielded by the circular light blocking sheet, needs to be designed into the aspheric lens, and the part of light beams shielded by the circular light blocking sheet on the circumference of the inner side of the imaging lens is not utilized, so that the imaging lens does not need to be designed into the aspheric lens with high precision, the spherical lens with the precision requirement lower than that of the aspheric lens is designed, the process manufacturing difficulty of the imaging lens is greatly reduced, the cost is reduced, and the optical path difference of the whole optical path is reduced.

The method has the beneficial effects that:

according to the formulaThe value of k can be increased by increasing the value of b, and the radius r of the circular bright spot positioned at the center of the diffraction pattern can be reduced along with the decrease of n, so that the resolution of laser imaging is improved. The method for increasing b is as follows: the distance L from the circular light barrier to the imaging lens is reduced and/or the diameter c of the circular light barrier is increased.

According to the laser imaging device disclosed by the invention, the optical system capable of adjusting the diameter of the light spot is contained, so that the diameter of the focused light spot can be reduced, and the resolution of laser imaging is improved.

Drawings

FIG. 1 is a schematic diagram of an optical path structure of a light-emitting source for imaging in an optical path;

FIG. 2 is a prior art optical path diagram of an annular diaphragm 50 inserted into the optical path to reduce the diameter h of the light spot;

FIG. 3 is a schematic diagram of the optical path structure of the present invention;

FIG. 4 is a schematic diagram of the area between diameter a and diameter b of imaging lens 60 of FIG. 3;

FIG. 5 is a schematic diagram of a diffraction pattern of light formed on the focal plane 40 by the luminescent light source 10 in FIG. 3;

FIG. 6 is a photograph of a circle of bright spots at the center of a diffraction pattern by adjusting the apparatus;

the names and serial numbers corresponding to the components in the figure are respectively: the diffraction grating comprises a luminous light source 10, a collimating mirror 20, a focusing lens 30, a focusing plane 40, an annular diaphragm plate 50, an imaging lens 60, a circular light blocking plate 70 and a circular bright spot 80 positioned at the center of a diffraction pattern.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, light emitted from a light source 10 is collimated by a collimator lens 20 and then emitted in parallel, and is focused on a focusing plane 40 by a focusing lens 30 to form a light spot with a diameter h. For many industries, such as the laser lithography industry, medical equipment, PCB industry, and lithography machine field, it is desirable that the spot diameter is as small as possible, and the smaller the spot diameter h, the higher the imaging resolution and the higher the imaging accuracy. Referring to fig. 2, in order to reduce the spot diameter h, a current practice is to insert an annular diaphragm 50 having an adjustable inner diameter d between the collimator lens 20 and the focusing lens 30. It is desirable to reduce the spot diameter h by adjusting the size of the inner diameter d of the annular diaphragm 50. However, in fact, no matter how large the inner diameter d of the annular diaphragm 50 is, the spot diameter h can only be adjusted to be large, but cannot be adjusted to be small, and the intended purpose of people cannot be achieved.

Referring to fig. 3, the present invention discloses an optical device capable of adjusting a diameter of a light spot, including a light emitting source 10, a collimating mirror 20, an imaging lens 30, a circular light blocking sheet 70, and a focusing plane 40, which are sequentially disposed on a light path; after light emitted by the light emitting source 10 is collimated by the collimating lens 20, the collimated light enters the imaging lens 30 in parallel, after being transmitted by the imaging lens 30, peripheral part annular light which is not shielded by the circular light blocking sheet 70 forms a diffraction pattern on the focusing plane 40, and light beams in the middle part are shielded by the circular light blocking sheet 70 and cannot be focused on the focusing plane 40;

defining the wavelength of the light-emitting source 10 asThe focal length of the imaging lens 30 is f, the outer diameter of the imaging lens 30 is a, the diameter of a circular area formed on the imaging lens 30 by the portion of the light beam that the light source 10 cannot focus on the focusing plane 40 due to being blocked by the circular light blocking sheet 70 is b, b = k × a, k ∈ (0,1), k is a first variable value that increases as b increases, and the value of the radius r of the circular bright spot at the center of the diffraction pattern obtained by the light source 10 on the focusing plane 40 is:n is a second variable value which decreases as k increases; a portion within the diameter b on the imaging lens 30 is a spherical lens region, and a portion between the diameter b and the diameter a of the imaging lens 30 is an aspherical lens region. It should be noted that the spot diameter referred to in this application refers to the inner diameter of the innermost circular spot 80 located at the center of the diffraction pattern as shown in fig. 5, because about 86% of the energy of the light source 10 is distributed on the circular spot 80 located at the center of the diffraction pattern, which is the energy required for exposure.

Referring to fig. 3, light emitted from the light source 10 is collimated by the collimating lens 20, and then enters the imaging lens 60 in parallel, and after being transmitted by the imaging lens 60, the peripheral light beam is not blocked by the circular light blocking sheet 70, so that an annular light is formed and focused on the focusing plane 40 for imaging, and a diffraction pattern is formed. The intermediate portion of the light beam emitted after being transmitted and focused by the imaging lens 60 is blocked by the circular light blocking plate 70, and thus cannot be focused on the focusing plane 40. Therefore, the light emitted from the light source 10 is blocked by the circular light blocking sheet, and a diffraction pattern of the light is formed on the focusing plane 40 as shown in fig. 5. Fig. 5 is a schematic diagram of a diffraction pattern of light, and a physical representation of a circular bright spot at the center of the diffraction pattern is shown as a white circular spot in fig. 6. As can be seen from fig. 6, the diameter of the resulting circular bright spot has been reduced to 0.48 μm using the present device. In fig. 5, among the energy distributions of the diffraction pattern formed by the light source 10 on the focusing plane 40, the energy distributed on the circular bright spot 80 located at the center of the diffraction pattern is the largest, accounting for about 86% of the total energy of the light source 10, and the remaining energy distributions gradually decrease outward.

The reduction in spot diameter described in the present invention essentially means a reduction in the inner diameter 2r of the circular spot 80 at the center of the diffraction pattern as shown in FIG. 5.

The laser plate-making industry, the medical equipment, the PCB industry and the photoetching machine field are all hoped toThe smaller the spot size, the better the radius of the spot with the largest energy is desired, which can improve the resolution of the image, reduce the focal diameter of the spot, and realize high-precision laser imaging.

How r is calculated is described below.

Referring to FIGS. 3 and 5, previously stated, the wavelength of the light source 10 isThe focal length of the imaging lens 60 is f, the outer diameter of the imaging lens is a, and the diameter of the circular area where the light-emitting source 10 cannot enter the middle portion of the imaging lens 60 due to the shielding of the circular light-blocking sheet 70 is b, it can be understood that the value of b does not exceed a. Defining b = k × a, k ∈ (0,1), the value of r is found as:. It should be noted that: k is the ratio of b to a, k is a first variable value that increases as b increases, and n is a second variable value that decreases as k increases.F is also constant when the light-emitting source 10 and the imaging lens 60 are fixed.

Formula (II)The specific derivation process of (2) is as follows:

the circular ring diffraction satisfies the equation:

;

order toWherein t is a constant, and wherein,

;

to obtain 。

Table 1 exemplarily lists that k takes different values, corresponding to the value of n.

Table 1: correspondence of n and k

As can be seen from the above table, the value of n becomes smaller as k increases. To reduce r, according to the formulaThis can be achieved by: when a is a fixed value, the value of n is reduced, and n is a second variable value which is reduced along with the increase of k, so that the value of k needs to be increased to reduce the value of n, namely the ratio of b to a needs to be increased, and the value of b needs to be increased because a is a fixed value. Referring to fig. 4, b is the diameter of the light-tight circular area of the middle portion of the imaging lens 60. Therefore, if the value of a is constant, decreasing the value of n, i.e., increasing k, i.e., increasing the value of b, achieves the object of decreasing the spot diameter 2 r.

In summary, decreasing the spot radius r can be achieved by increasing the value of b.

Referring to fig. 3, only a portion of the light-emitting source incident between the diameter b and the diameter a of the imaging lens 60 is effectively utilized due to the shielding effect of the circular light-blocking sheet 70. Therefore, when the imaging lens 60 is manufactured, only the annular part between the diameter b and the outer diameter a needs to be designed into an aspheric lens, and the part with the diameter within the diameter b needs to be designed into a spherical lens, and the manufacturing process of the aspheric lens is more complicated than that of the spherical lens, so that the manufacturing difficulty of the imaging lens 60 is greatly reduced, and the optical path difference of the whole optical path is also reduced.

The beneficial technical effects are as follows:

1. according to the invention, the circular light blocking sheet is arranged on the light path of the imaging lens and the focusing plane, so that emergent light transmitted by the imaging lens 60 forms circular ring diffraction light, and the circular ring diffraction light is converged on the focusing plane, so that the resolution of the obtained image is greatly improved;

2. according to the technical scheme, the radius of the first-stage bright ring of the light spot can be reduced, so that the technology is applied to the field of laser plate making, and the image printing precision of the laser plate making is greatly improved; the PCB printing precision can be improved by applying the PCB printing precision regulator in the PCB industry, so that more and finer circuits can be printed on the same PCB, and the utilization rate of the PCB is improved. For other industries, such as laser surgery, as the spot size becomes smaller, it can be used for more demanding minimally invasive surgery. For example, in the laser welding and cutting industry, the welding seam becomes thinner due to the fact that the light spot becomes smaller, and the laser welding and cutting method is suitable for welding of precise instruments. Of course, these applications are merely exemplary and not limiting.

3. When the imaging lens is manufactured, only the annular part of the imaging lens, which is used for transmitting the light source and is not shielded by the circular light blocking sheet, on the outer side is designed into the aspheric lens, and the part of light beams shielded by the circular light blocking sheet on the circumference of the inner side is not utilized and is not designed into the high-precision aspheric lens, so that the imaging lens is designed into the spherical lens, the process manufacturing difficulty of the imaging lens is greatly reduced, the cost is reduced, and the optical path difference of the whole light path is reduced.

The invention also discloses a method for adjusting the diameter of the light spot by using the optical device, which comprises the following steps:

step 1: a light-emitting light source, a collimating lens, an imaging lens, a circular light blocking sheet and a focusing plane are sequentially arranged on a light path;

step 2: opening the light source to enable light emitted by the light source to be collimated by the collimating mirror and then to be incident to the imaging lens in parallel, after the light is transmitted by the imaging lens, the light beam in the middle part is shielded by the circular light blocking sheet and cannot be focused on the focusing plane, and the annular light in the peripheral part is converged into a diffraction pattern on the focusing plane;

and step 3: according to the formulaAnd adjusting the radius r of the circular bright spot positioned at the center of the diffraction pattern.

In step 1, the order of placement of the optical elements is shown in FIG. 3. When the optical elements are positioned, a diffraction pattern is obtained on the focal plane according to the method shown in step 2. And then according to the formula shown in the step 3, the purpose of reducing the radius r of the circular bright spot positioned at the center of the diffraction pattern is realized by a method of increasing the diameter b. Specifically, referring to fig. 3, the method of increasing the diameter b is: the distance L of the circular light-blocking sheet 70 to the imaging lens 60 is reduced and/or the diameter c of the circular light-blocking sheet 70 is increased.

The invention also discloses a laser imaging device (not shown) comprising the optical device capable of reducing the diameter of the light spot. The laser imaging device can improve the resolution of laser imaging because the laser imaging device comprises the front optical device.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.