CN219109366U - Focusing-free endoscope imaging lens with wide angle and large depth of field - Google Patents

Abstract

The utility model discloses a wide-angle and large-depth-of-field focusing-free endoscope imaging lens, which is made of plastic materials and sequentially comprises the following components from an object side to an image side along an optical axis direction: a first lens, a second lens and a filter; space rings are adopted between the first lens and the second lens and between the second lens and the optical filter, and the distance between the lenses is controlled; the first lens is made of high-refractive-index materials, and the focal length is positive; the second lens is made of a high Abbe number material, and the focal length is negative; and both lenses are plastic aspheric lenses. The utility model provides the endoscope imaging lens with large depth of field and wide angle, and the large depth of field of the lens ensures that the whole process of the operation is free from focusing, thereby reducing the burden of medical staff; in addition, the cost of the lens module is controlled by adopting a mode of opening the plastic lens.

Description

Focusing-free endoscope imaging lens with wide angle and large depth of field

Technical Field

The utility model belongs to the technical field of electronic endoscope lenses, and particularly relates to a wide-angle large-depth-of-field focusing-free endoscope imaging lens.

Background

With the progress of scientific technology, minimally invasive surgery is rapidly introduced into various fields of surgery due to the characteristics of small wound, light pain, rapid recovery and the like. Endoscopes are also receiving increasing attention as one of the typical devices for minimally invasive surgery. After the imaging lens at the front end of the endoscope images the body, the imaging lens is presented on a display through a transmission line, so that the imaging lens can provide sufficient diagnosis information for doctors to treat diseases.

The traditional endoscope has small depth of field, so the eyepiece end is connected with the adapter, and the imaging of objects at different distances is realized through the adjustment of the adapter. Because the endoscope operation is time, the long-distance focus searching and the short-distance focus observing need to move continuously, the image surface needs to be manually or automatically adjusted when each movement is carried out, a certain waiting time is needed, and the operation time of doctors and patients is prolonged to a certain extent.

In addition, the conventional endoscope has a complicated structure, and is difficult to thoroughly clean and sterilize. The application of the same endoscope between different patients can easily cause cross infection, further damage the health of the infected person and even cause death in severe cases. Therefore, after years of exploration, the disposable endoscope is in a proper state, and the problem of cross infection is effectively avoided. The disposable endoscope also provides new challenges for the endoscope lens, and the cost of the lens is controlled while the requirements of definition, use depth of field and the like are met.

Disclosure of Invention

The utility model aims to provide a wide-angle large-depth-of-field focusing-free endoscope imaging lens, which solves the problems of focusing and cost of a disposable endoscope lens.

The technical scheme adopted by the utility model is as follows:

a wide-angle and large-depth-of-field focusing-free endoscope imaging lens is made of plastic materials, and comprises a first lens, a second lens and an optical filter in sequence from an object plane to an image plane along an optical axis direction, wherein the first lens and the second lens are plastic aspheric lenses.

The first lens is made of a high refractive index material, and the second lens is made of a low dispersion material; the SOMA lens is used for the lens diaphragm, and is arranged in front of the first lens, so that invalid light is limited to enter the lens, and the problem of stray light is avoided; the right-most lens of the lens is a light filter, so that light rays meeting the requirements of wave bands are emitted and imaging is carried out; and a space ring is adopted between the first lens and the second lens and between the second lens and the optical filter, so that the distance between the lenses is controlled.

The beneficial effects of the utility model are as follows:

1. the wide-angle large-depth-of-field endoscope imaging lens has the visual field angle of 80 degrees and the working depth of field of 35-200 mm, can cover the operation observation range, can avoid focusing in the operation process, is simple to use, and can shorten the operation duration;

2. the aspheric design concept is adopted, and corresponding imaging effects can be achieved by using two lenses, so that the assembly is convenient;

3. the lens is made of plastic, so that a mode of die sinking can be used, the precision is high, the consistency of the imaging effect of the lens can be well controlled, and the qualification rate is greatly improved; after the mold is opened, the lens production process is simple, the cost is lower, the method is suitable for the application requirement of the disposable endoscope, the related cost of the endoscope is effectively controlled, and the popularization of the endoscopic surgery in primary hospitals can be promoted.

Drawings

Fig. 1 is a block diagram of an imaging lens according to an embodiment of the present utility model;

FIG. 2 is a graph of spherical aberration curves of an imaging lens according to an embodiment of the present utility model;

FIG. 3 is a full field MTF plot of an imaging lens according to an embodiment of the present utility model;

FIG. 4 is a graph of color aberration curves of an imaging lens according to an embodiment of the present utility model;

FIG. 5 is a full field point column of an imaging lens according to an embodiment of the present utility model;

FIG. 6 is a graph of curvature of field and distortion of an imaging lens according to an embodiment of the present utility model;

FIG. 7 is a graph of MTF for an imaging lens of an embodiment of the present utility model at an object distance of 35 mm;

fig. 8 is an MTF graph of an imaging lens of an embodiment of the present utility model at an object distance of 200mm.

In the figure: 1. a diaphragm; 2. a first lens; 3. a first spacer; 4. a second lens; 5. a second spacer ring; 6. a light filter; 7. lens barrel.

Detailed Description

The utility model will be further described with reference to the accompanying drawings:

the utility model provides the endoscope imaging lens with large depth of field and wide angle, and the large depth of field of the lens ensures that the whole process of the operation is free from focusing, thereby reducing the burden of medical staff; in addition, the cost of the lens module is controlled by adopting a mode of opening the plastic lens.

The structure of the wide-angle and large-depth-of-field endoscope imaging lens of the embodiment of the utility model is shown in fig. 1, and the sequence from the object side to the image side of the lens is as follows: a diaphragm 1, a first lens 2, a first space ring 3, a second lens 4, a second space ring 5 and an optical filter 6; the above elements are assembled in the lens barrel 7 in order.

The focal lengths of the first lens 2 and the second lens 4 are positive and negative respectively, and the two lenses are plastic aspheric lenses, and under the premise of ensuring the function, the aspheric degree of the lenses is increased by increasing the order of the even aspheric surfaces, so that the use quantity of the lenses is reduced, and the use efficiency is improved.

The first lens 2 is made of high-refractive-index materials, so that the correction of spherical aberration and coma aberration in the optical system is facilitated; the second lens 4 is made of a high abbe number material, so that chromatic aberration of the optical system is reduced. Through the cooperation of the two lenses, the system has better definition, aberration is corrected, and an endoscope lens with an angle of view of 80 degrees and a depth of field of 35-200 mm is realized based on the two lenses.

An optical system diaphragm 1 is arranged on the left side of the first lens 2, so that light rays which do not participate in imaging are intercepted, and the problem of stray light is avoided; an infrared filter 6 is arranged on the right side of the second lens 4, so that light rays in a visible light wave band are emitted. A first space ring 3 is arranged between the first lens 2 and the second lens 4, and the distance between the two lenses is controlled; a second spacer ring 5 is arranged between the second lens 4 and the infrared filter 6 to control the distance between the second lens and the infrared filter. The above elements are assembled in the lens barrel 7 in sequence, the total length of the barrel is 3.8mm, the maximum outer diameter is 4.2mm, and the infrared filter is used for packaging and fixing the lens in a dispensing mode.

Tables 1 and 2 show lens design parameters of the wide-angle large depth-of-field lens of the present embodiment.

TABLE 1 lens design parameters

Face numbering	Surface type	Radius of curvature	Thickness of (L)	Semi-caliber	Refractive index	Abbe number
							OBJ	STANDARD	Infinity	60	/	/	/
1	Stop	Infinity	0.08	0.17	/	/
							2	EVEN ASPHERE	8.46	1.6	0.35	1.534	55.795
3	EVEN ASPHERE	-0.622	0.04	0.85	/	/
							4	EVEN ASPHERE	6.44	0.49	0.85	1.635	23.784
5	EVEN ASPHERE	0.87	0.32	1.1	/	/
							6	STANDARD	Infinity	0.3	1.5	1.516	64.212
7	STANDARD	Infinity	/	1.5	/	/

Table 2 aspherical coefficients of lenses

Face numbering	Coefficient of taper	a4	a6	a8	a10	a12
								2	0	-0.12	-10.393	229.791	-2010.929	0
3	-0.368	1.019	-4.818	11.879	-14.022	5.937
							4	0	0.468	-3.681	8.529	-8.824	3.283
5	-0.176	-0.688	0.363	2.75e-3	-0.125	0.031

In the above table, the surface numbers 2, 3 represent the left side surface and the right side surface of the first lens 2, respectively; the surface numbers 4, 5 represent the left and right side surfaces of the second lens 4, respectively; the surface numbers 6 and 7 indicate the left and right sides of the infrared filter 6, respectively.

The design results of the lens are shown in fig. 2 to 7. Fig. 2 shows a spherical aberration result diagram of the whole lens, and it can be seen that the spherical aberration is corrected to be within + -0.015 mm in the whole field of view, and the spherical aberration is better corrected in the effective spectrum range, so that the cleanliness of the imaging picture can be increased.

Fig. 3 shows the optical transfer function (MTF) of the lens at the designed working distance, and it can be seen from the graph that the MTF values of the full field of view are all very close to the diffraction limit, and the MTF values are all greater than 0.2 at 160lp/mm under the full field of view, so as to meet the requirements of the imaging definition of the endoscope.

Fig. 4 shows a transverse chromatic aberration diagram of the lens at a designed working distance, and it can be seen from the diagram that in a selected wave band range (450 nm-610 nm), the transverse chromatic aberration value of a visible wave band is less than 1 μm under a full view field, and the value of a far-smaller Yu Aili spot radius is better for chromatic aberration correction.

Fig. 5 is a dot column diagram of the lens at a designed working distance, which shows dot column diagrams of each wave band on an image plane under a full view field, wherein the size of the dot column diagrams under each view field is smaller than Yu Aili speckles, which indicates that the lens images clearly.

FIG. 6 is a graph showing the field curvature and distortion of a lens at a designed working distance, wherein the maximum field curvature is controlled to be 40 μm, and the maximum field curvature does not affect imaging when the maximum field curvature is within the focal depth range; the optical distortion is controlled within 20 percent, and the distortion is increased along with the increase of the field of view, so that the imaging influence is small.

Fig. 7 and 8 are graphs of MTF curves of the lens at working distances of 35mm and 200mm, respectively, and according to the graph, the MTF values of each field of view are relatively close to the diffraction limit at both working distances, and the MTF values are greater than 0.2 at 140lp/mm, namely, the lens has higher imaging quality in the depth of field range of 35mm to 200mm.

In summary, the optical system of the utility model adopts two aspheric lenses, can realize the imaging effect of 80 degrees of field angle, has an effective depth of field range of 35 mm-200 mm, and can completely cover the operation observation range of the endoscope, so that the endoscope is free from focusing in the use process.

It will be readily appreciated by those skilled in the art that the foregoing is merely a preferred embodiment of the utility model and is not intended to limit the utility model, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the utility model are intended to be included within the scope of the utility model.

Claims (7)

1. The utility model provides a wide angle large depth of field exempts from focusing endoscope imaging lens which characterized in that, this camera lens adopts plastics material, includes from object space to image space in proper order along the optical axis direction: a first lens, a second lens and a filter; space rings are adopted between the first lens and the second lens and between the second lens and the optical filter, and the distance between the lenses is controlled;

the first lens is made of high-refractive-index materials, and the focal length is positive; the second lens is made of a high Abbe number material, and the focal length is negative; and both lenses are plastic aspheric lenses.

2. The wide-angle, large depth-of-field focus-free endoscopic imaging lens of claim 1, further comprising a lens stop, the lens stop being a SOMA plate and disposed in front of the first lens.

3. The wide-angle, large depth-of-field focus-free endoscopic imaging lens of claim 2, further comprising a lens barrel in which the elements are assembled in sequence.

4. A wide-angle, large depth-of-field focus-free endoscopic imaging lens as defined in claim 3, wherein the filter encapsulates and secures the elements in the lens barrel.

5. A wide-angle, large depth-of-field focus-free endoscopic imaging lens as claimed in claim 3, wherein the total length of the lens barrel is 3.8mm and the maximum outer diameter is 4.2mm.

6. The wide-angle, large depth-of-field, focus-free endoscopic imaging lens of any one of claims 1 to 5, wherein the filter is an infrared filter.

7. The wide-angle, large depth-of-field focus-free endoscopic imaging lens of claim 6, wherein the lens field angle is 80 ° and the working depth of field is 35 mm-200 mm.

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