CN113625508B

CN113625508B - High-zoom-ratio illumination optical system

Info

Publication number: CN113625508B
Application number: CN202110951447.7A
Authority: CN
Inventors: 李美萱; 阚晓婷; 王美娇
Original assignee: Changchun College of Electronic Technology
Current assignee: Changchun College of Electronic Technology
Priority date: 2021-08-18
Filing date: 2021-08-18
Publication date: 2022-10-25
Anticipated expiration: 2041-08-18
Also published as: CN113625508A

Abstract

A high-zoom-ratio illumination optical system belongs to the technical field of security laser illumination and solves the problems that the divergence angle zoom ratio of emergent light beams is not high, the energy transmittance of the system is low, the illumination uniformity is not high and the like in the security laser illumination technology. The system comprises a collimating lens group, an imaging lens group, a zooming lens group and an object plane; the incident light beam is collimated after passing through the collimating lens group, is imaged and then is diverged through the imaging lens group, and after the divergence angle is changed through the zoom lens group, the emergent light beam irradiates the object plane; the collimating lens group, the imaging lens group, the zoom lens group and the object plane are sequentially arranged on the same optical axis. The zoom ratio of the system is greatly improved. The system has high energy transmittance, only two coating pots are needed, and the coating cost is saved. The whole light path has no convergent light spot in the lens, and has good machinability and engineering realizability. The system has the advantages of good image quality, high illumination uniformity, short total system length, miniaturization and high integration level, and has a positive promotion effect on the development of the security laser illumination technology in China.

Description

High-zoom-ratio illumination optical system

Technical Field

The invention belongs to the technical field of security laser illumination, and relates to a high-zoom-ratio illumination optical system.

Background

Nowadays, with the rapid development of science and technology, the security industry is continuously developed, the requirements on the lighting technology are continuously improved, and the laser lighting technology has very wide application prospects due to the characteristics of the laser lighting technology.

Within the effective distance of security monitoring, the field of view is as large as possible for close-range monitoring, and when the distance is far, a sufficient angle is ensured to meet the requirement of clear imaging. In practical applications, the focal length of the camera is changed, and the field angle is also changed correspondingly. In view of this, the illumination angle is required to cover all the monitoring viewing angles, that is, while the monitoring viewing angle changes, the illumination viewing angle needs to change correspondingly, so as to meet the requirement of the illumination working condition. To achieve this, it is necessary to determine that the angle of the emitted laser beam is variable and continuous, and to apply the lens zoom technique to laser illumination to achieve an illumination angle that is adjustable over a wide range and variable over a certain angular range. Therefore, the research and development of the laser lighting system with high zoom ratio have important significance for national defense safety and security industry.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a high-zoom-ratio illumination optical system, which solves the problems of low divergence angle zoom ratio, low system energy transmittance, low illumination uniformity and the like of an emergent light beam in a security laser illumination technology.

The technical scheme adopted by the invention for solving the technical problem is as follows:

the high-zoom-ratio illumination optical system comprises a collimating lens group, an imaging lens group, a zoom lens group and an object plane; the incident light beam is collimated after passing through the collimating lens group, is imaged and then is diverged through the imaging lens group, and after the divergence angle is changed through the zoom lens group, the emergent light beam irradiates the object plane; the collimating lens group, the imaging lens group, the zoom lens group and the object plane are sequentially arranged on the same optical axis; wherein:

the collimating lens group comprises a first positive lens; the material of the first positive lens is HZF6;

the imaging lens group includes a second positive lens and a third positive lens; the material of the second positive lens and the third positive lens is HZF62;

the variable power lens group comprises a fourth positive lens and a fifth positive lens; the fourth positive lens and the fifth positive lens are made of HZF6;

and adjusting the position of the imaging lens group between the collimating lens group and the zoom lens group to continuously change the divergence angle of the emergent light beam within the range of 0.25-35 degrees, thereby realizing high zoom laser illumination.

Preferably, when the outgoing beam divergence angle is 0.25 degrees, specific parameters of each positive lens are as follows:

	radius of curvature (mm)	Spacing (mm)	Glass label
				Article surface		4.50
1	32.89	1.73	HZF6
				2	-4.674	4.85
3		0
				4	6.719	2.1	HZF62
5	∞	1.04
				6	3.078	2.62	HZF62
7	3.202	1.3
				8		44.26
9	-62.301	14.05	HZF6
				10	-40.24	7.78
11	∞	13.26	HZF6
				12	-100	20～2000000
Image plane

Preferably, when the outgoing beam divergence angle is 35 degrees, specific parameters of each positive lens are as follows:

	radius of curvature (mm)	Spacing (mm)	Glass label
				Article surface		4.50
1	32.89	1.73	HZF6
				2	-4.674	4.85
3		31.5
				4	6.719	2.1	HZF62
5	∞	1.04
				6	3.078	2.62	HZF62
7	3.202	1.3
				8		12.76
9	-62.301	14.05	HZF6
				10	-40.24	7.78
11	∞	13.26	HZF6
				12	-100	20～2000000
Image plane

Preferably, an illumination light source of the high-zoom-ratio illumination optical system is a fiber laser, the working wavelength is 808 nm, the full height of an object space view field is 400 microns, the object space Numerical Aperture (NA) =0.22, the zoom ratio is 140 times, and the root mean square diameter of a system dot diagram is less than 200 microns.

Preferably, the number of the optical system lenses is 5, and the system energy transmittance is more than 98.5%.

Preferably, the optical system lens BLO value is less than 0.5.

Preferably, the fiber laser emits light beam power of 30W, and the whole light path has no convergent light spot in the lens; the divergence angle of the emergent beam is within the range of 0.25-35 degrees, and no convergent facula exists in the continuous variation process.

Preferably, the total length from the end face of the outgoing beam of the fiber laser to the vertex of the rear surface of the fifth positive lens is 97.49mm.

Preferably, a mechanical assembly on the lens outer frame is used for adjusting the distance between the imaging lens group and the collimating lens group and fixing the final position of the five lenses.

Preferably, the following components: the specific parameters of the five lenses can be adjusted to meet different system parameter requirements in actual operation.

The invention has the beneficial effects that:

1. the zoom ratio is high, the zoom ratio of the invention reaches 140 times, and the zoom ratio is greatly improved compared with the zoom range of 30-80 times in the field of illumination at present.

2. The number of lens is small, 140 times of zoom illumination is realized through 5 lenses, and the energy transmittance of the system is larger than 98.5%.

3. The whole system lens material only adopts HZF6 and HZF62, the number of coating pots only needs two pots, and the coating cost is saved.

4. The power of an emergent beam of the fiber laser is 30W, no convergent light spot exists in the whole light path inside the lens, and no convergent light spot exists in the process that the divergence angle of the emergent beam continuously changes within the range of 0.25-35 degrees, so that the safety of laser illumination is fully considered.

5. The BLO value of the whole system lens is less than 0.5, and the system lens has good processability and engineering realizability.

6. The system has good image quality, the root mean square diameter of the dot-sequence chart is less than 200um, the illumination uniformity is high, the total length from the end face of the light-emitting end of the optical fiber laser to the vertex of the rear surface of the fifth positive lens is 97.49mm, the total length of the system is short, the miniaturization and the integration level are high, and the system has a positive promoting effect on the development of the security laser illumination technology in China.

Drawings

FIG. 1 is a schematic view of a high magnification ratio illumination optical system of the present invention with a 0.25 degree divergence angle configuration;

FIG. 2 is a schematic diagram of a high magnification ratio illumination optical system 35 degree divergence angle configuration of the present invention;

FIG. 3 is a diagram of a 0.25-degree divergence angle root mean square dot array of a high-zoom-ratio illumination optical system of the present invention;

FIG. 4 is a root mean square dot diagram of the divergence angle of 35 degrees of the high magnification ratio illumination optical system of the present invention.

In the figure: 1. a first positive lens, 2, a second positive lens, 3, a third positive lens, 4, a fourth positive lens, 5, a fifth positive lens, 6, an object plane, 7 and an emergent light beam.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

The high zoom ratio illumination optical system in the present embodiment is composed of a collimating lens group, an imaging lens group, a zoom lens group, and an object plane, as shown in fig. 1 and 2, wherein:

the collimating lens group includes a first positive lens 1. The material of the first positive lens 1 is HZF6, and the relative position of the first positive lens and the imaging lens group is fixed through a mechanical assembly on a lens outer frame.

The imaging lens group includes a second positive lens 2 and a third positive lens 3. The second positive lens 2 and the third positive lens 3 are made of HZF62, the two lenses are sequentially arranged, the lenses are arranged on the same optical axis, and the relative positions of the lenses are fixed by a mechanical assembly on a lens outer frame.

The variable power lens group includes a fourth positive lens 4 and a fifth positive lens 5. The fourth positive lens 4 and the fifth positive lens 5 are made of HZF6, the lenses are sequentially arranged, the lenses are arranged on the same optical axis, and the relative positions of the lenses are fixed by a mechanical assembly on a lens outer frame.

When the optical fiber laser device is applied, the object surface 6 of the light emitting surface of the optical fiber laser device is arranged 4.5 mm in front of the vertex of the front surface of the first positive lens 1 of the illumination optical system, a laser beam is changed into a collimated beam through the optical action of the collimating lens group, and the collimated beam is converged to the middle image surface through the optical action of the imaging lens group. The light beam passes through the intermediate image surface and then becomes a divergent light beam, and the divergent light beam 7 irradiates to an illuminated target at a certain divergent angle under the optical action of the zoom lens group. The divergence angle of the emergent light beam is continuously changed within the range of 0.25-35 degrees by adjusting the intervals between the imaging lens group and the collimating lens group and between the imaging lens group and the zoom lens group, namely changing the working distance of an object space of the zoom lens, thereby realizing the high zoom laser illumination.

When the divergence angle of the outgoing light beam 7 is 0.25 degrees, the imaging lens group (including the second positive lens 2 and the third positive lens 3) is regarded as a whole, as shown in table 1, when the divergence angle of the outgoing light beam is 0.25 degrees, the distance between the 3 rd surface is 0, i.e. the distance between the imaging lens group and the collimating lens group, but the outgoing surface of the first lens 1 and the incident surface of the second lens 2 are provided with an initial distance, so that the distance between the 2 nd surface is always 4.85, at this time, the distance between the 2 nd surface and the 4 th surface is 4.85+0, i.e. the initial distance between the 2 nd surface and the movement distance between the 3 rd surface, and the distance between the 8 th surface is 44.26mm, i.e. the distance between the imaging lens group and the variable power lens group, but the outgoing surface of the third lens 3 and the incident surface of the fourth lens 4 are provided with an initial distance, so that the distance between the 7 th surface is always 1.3, at this time, and the distance between the 7 th surface is 1.3 rd surface 44.26, i.e. the initial distance between the 7 th surface and the movement distance between the 8 th surface and the movement distance between the 7 th surface.

TABLE 1 specific parameters of each lens at an exit beam divergence angle of 0.25 DEG

And moving the imaging lens group to the 9 th surface, namely to the incident surface of the fourth lens 4, namely increasing the 3 rd surface distance of the air interval and reducing the 8 th surface distance of the air interval, wherein the 3 rd surface air interval increase is equal to the 8 th surface air interval reduction. When the divergence angle of the outgoing light beam is 35 degrees, as shown in table 2, the maximum travel of the imaging lens group is 31.5mm, namely, the maximum value of the distance between the 3 rd surfaces is 31.5mm, and the divergence angle of the outgoing light beam 7 is continuously changed within the range of 0.25 to 35 degrees in the moving process, so that high-magnification laser illumination is realized. At this time, the distance between the 3 rd surface is 31.5, i.e. the distance between the imaging lens group and the collimating lens group, but the initial distance is set between the exit surface of the first lens 1 and the incident surface of the second lens 2, so the distance between the 2 nd surface is always kept at 4.85, and the distance between the 2 nd surface and the 4 th surface is 4.85+31.5, i.e. the initial distance between the 2 nd surface and the movement distance between the 3 rd surface, and the distance between the 8 th surface is 13.26mm, i.e. the distance between the imaging lens group and the zoom lens group, but the initial distance is set between the exit surface of the third lens 3 and the incident surface of the fourth lens 4, so the distance between the 7 th surface is always kept at 1.3, and the distance between the 7 th surface and the 9 th surface is 1.3+13.26, i.e. the initial distance between the 7 th surface and the movement distance between the 8 th surface.

TABLE 2 concrete parameters of each lens when the divergence angle of the emergent beam is 35 deg

The illumination light source of the high zoom ratio illumination optical system is a fiber laser, the working wavelength is 808 nanometers, the full height of an object space view field is 400 micrometers, the object space Numerical Aperture (NA) =0.22, the zoom ratio is 140 times, the root mean square diameter of a system dot-column diagram is less than 200 micrometers, and the illumination uniformity is high. The coating materials of the whole optical system lens are HZF6 and HZF62, the optical system comprises 5 lenses, and the energy transmittance of the system is more than 98.5%. The BLO value of the whole system lens is less than 0.5 (the BLO value is defined as the ratio of the curvature radius to the clear aperture of the plane), and the system lens has good processability and engineering realizability.

In addition, the power of the outgoing beam 7 of the optical fiber laser is 30W, no convergent light spot exists in the whole optical path in the lens, and no convergent light spot exists in the process that the divergence angle of the outgoing beam 7 continuously changes within the range of 0.25-35 degrees, so that the safety of laser illumination is ensured.

Meanwhile, the total length from the end face of the light outlet end of the optical fiber laser to the vertex of the rear surface of the fifth positive lens 5 is 97.49mm, the total length of the system is short, and the system is miniaturized and high in integration level.

The high magnification ratio illumination optical system manufactured in this example was evaluated by the following means:

1. root mean square diameter evaluation of dot plots

The point map is obtained by dividing a pupil plane into a plurality of small bins by an optical path calculation program, and calculating intersections of light rays passing through the bins with an image plane, the intersections forming a point map. The point diagram of the ideal optical system is one point, the point diagram of the actual optical system is countless points, the imaging quality of the optical system is determined by the distribution of the points, the method has the advantages that the spatial trend of light rays can be known, the shape of a light spot can be roughly estimated, the method is a method commonly used for evaluating an illumination system, the point diagrams with the emergent light beam divergence angle of 0.25 degree and 35 degrees are shown in figures 3 and 4 for the designed high-zoom-ratio illumination optical system, and the imaging quality can ensure that high-uniformity illumination is provided.

Claims

1. The high-zoom-ratio illumination optical system is characterized by comprising a collimating lens group, an imaging lens group, a zoom lens group and an object plane; the incident light beam is collimated after passing through the collimating lens group, is imaged and then is diverged through the imaging lens group, and after the divergence angle is changed through the zoom lens group, the emergent light beam irradiates the object plane; the collimating lens group, the imaging lens group, the zoom lens group and the object plane are sequentially arranged on the same optical axis; wherein:

adjusting the position of the imaging lens group between the collimating lens group and the zoom lens group to enable the divergence angle of the emergent light beam to be continuously changed within the range of 0.25-35 degrees, thereby realizing high zoom laser illumination; the number of the optical system lenses is 5, and the energy transmittance of the system is more than 98.5%.

2. A high magnification ratio illumination optical system as claimed in claim 1, wherein when the exit beam divergence angle is 0.25 degrees, specific parameters of each positive lens are as follows:

。

3. A high magnification ratio illumination optical system as set forth in claim 1, wherein when the exit beam divergence angle is 35 degrees, specific parameters of each positive lens are as follows:

4. the illumination optical system with high zoom ratio as claimed in claim 1, wherein the illumination light source of the illumination optical system with high zoom ratio is a fiber laser, the working wavelength is 808 nm, the full height of the object-side field of view is 400 microns, the object-side Numerical Aperture (NA) =0.22, the zoom ratio is 140 times, and the root-mean-square diameter of the system dot diagram is less than 200 microns.

5. A high magnification illumination optical system as recited in claim 1, wherein a BLO value of a lens of the optical system is less than 0.5.

6. The illumination optical system with high magnification ratio as claimed in claim 1 or 4, wherein the fiber laser emits a beam power of 30W, and the whole optical path has no convergent spot inside the lens; the divergence angle of the emergent beam is within the range of 0.25-35 degrees, and no convergent facula exists in the continuous variation process.

7. The illumination optical system with high magnification ratio as claimed in claim 1, wherein the total length from the fiber laser exit beam end face to the fifth positive lens rear surface vertex is 97.49mm.

8. The high magnification ratio illumination optical system as claimed in claim 1, wherein the distance between the collimating lens group and the magnification varying lens group of the imaging lens group is adjusted by a mechanical assembly on the lens housing and the final position of the five lenses is fixed.

9. A high magnification illumination optical system as set forth in claim 1, wherein: the specific parameters of the five lenses can be adjusted to meet different system parameter requirements in actual operation.