CN209117961U - An infrared confocal lens - Google Patents

Abstract

The embodiment of the utility model discloses infrared confocal camera lens. The infrared confocal lens comprises a refraction lens group and an imaging component positioned on the light-emitting side of the refraction lens group; the refraction lens group comprises a negative focal power first lens, a negative focal power second lens, a positive focal power third lens, a negative focal power fourth lens, a positive focal power fifth lens, a positive focal power sixth lens, a negative focal power seventh lens and a positive focal power eighth lens which are sequentially arranged along the light incidence direction; wherein a focal length f4 of the fourth lens and a focal length f5 of the fifth lens satisfy the following relationship: 0.8< | f4/f5 | 1.5; a focal length f6 of the sixth lens and a focal length f7 of the seventh lens satisfy the following relationship: 0.5< | f6/f7 | 1.2. The utility model discloses technical scheme is applicable to the infrared confocal camera lens design in security protection field, and this camera lens has the confocal advantage of visible light and infrared light, simple structure and resolution ratio height.

Description

An infrared confocal lens

technical field

The embodiments of the utility model relate to optical device technology, in particular to an infrared confocal lens.

Background technique

With the rapid development of science and technology, people have a higher level of understanding of security, and surveillance cameras were born. Compared with the zoom lens, the fixed focus lens is simple in design and manufacture, and the image of the moving object captured is clear and stable, and the picture is delicate, which makes it occupy an important position in the security monitoring industry.

With the improvement of the society's awareness of security, all-weather monitoring is a necessary condition for security lenses, requiring consistent image clarity in both visible and infrared lighting environments. Therefore, visible and infrared confocal lenses have a wide range of needs. Because the traditional fixed-focus lens often has a large number of lenses, the lens is bulky and heavy, and it is very inconvenient to use while wasting manpower and material resources. The lens size is too large or the cost is too high, which will affect the popularity and use of the product.

Utility model content

The embodiments of the present utility model provide an infrared confocal lens, so as to realize the design of the infrared confocal lens suitable for the security field, which has the advantages of visible light and infrared light confocal, simple structure and high resolution.

The embodiment of the present utility model provides an infrared confocal lens, comprising a refractive lens group and an imaging component located on the light-emitting side of the refractive lens group;

The refractive lens group includes a first lens with negative refractive power, a second lens with negative refractive power, a third lens with positive refractive power, a fourth lens with negative refractive power, and a fifth lens with positive refractive power, which are sequentially arranged along the incident direction of light. , the sixth lens with positive refractive power, the seventh lens with negative refractive power and the eighth lens with positive refractive power;

The focal length f4 of the fourth lens and the focal length f5 of the fifth lens satisfy the following relationship:

0.8<︱f4/f5︱<1.5;

The focal length f6 of the sixth lens and the focal length f7 of the seventh lens satisfy the following relationship:

0.5<︱f6/f7︱<1.2.

Optionally, the refractive lens group is coaxial with the imaging component, and the imaging component is located on the focal plane of the refractive lens group.

Optionally, the imaging assembly includes a photosensitive element and a transparent protective plate, and the transparent protective plate is located between the photosensitive element and the refractive lens group.

Optionally, it further includes a diaphragm located between the third lens and the fourth lens.

Optionally, the fourth lens and the fifth lens form a cemented lens.

Optionally, the first lens, the third lens, the fourth lens and the fifth lens are spherical lenses, and the second lens, the sixth lens, the seventh lens and the The eighth lens is an aspheric lens.

Optionally, the surface type of the aspheric lens is defined by the formula:

Determine, where z is the vector height, c is the curvature at the vertex of the surface, r is the distance between the projection of the coordinates of the surface point on the plane perpendicular to the optical axis and the optical axis, k is the conic coefficient, a ₁ , a ₂ , a ₃ , a ₄ , a ₅ , a ₆ , a ₇ , and a ₈ represent coefficients corresponding to even-order terms.

Optionally, the first lens is a meniscus lens, the second lens is a meniscus lens, the third lens is a biconvex lens, the fourth lens is a biconcave lens, and the fifth lens is A biconvex lens, the sixth lens is a biconvex lens, the seventh lens is a meniscus lens, and the eighth lens is a biconvex lens.

Optionally, the refractive lens group satisfies the following parameters:

f1=-6～-8.3 n1=1.55～1.75 R1=50～65 R2=4.5～5.2 f2=-12～-15 n2=1.55～1.75 R3=-4.2～-4.6 R4=-9.3～-11.2 f3=6.5～8.3 n3=1.83～2.23 R5=15.3～16.8 R6=-15.3～-16.8 f4=-6.5～-8.3 n4=1.83～2.23 R7=-38.5～-40.2 R8=8.1～8.42 f5=6.5～8.3 n5=1.55～1.75 R9=8.1～8.5 R10=-8.1～-8.5 f6=10.2～11.8 n6=1.45～1.65 R11=8.2～8.4 R12=-18.5～-20.3 f7=-17～-21 n7=1.55～1.65 R13=-5.5～-6.3 R14=-13.5～14.8 f8=13.6～15.8 n8=1.45～1.55 R15=9.8～11.5 R16=-32.5～-36

Wherein, f1-f8 represent the focal lengths from the first lens to the eighth lens, in mm, n1-n8 represent the refractive indices from the first lens to the seventh lens, R1, R3, R5, R7 , R9, R11, R13, R15 respectively represent the curvature radius of the center of the surface of the first lens to the eighth lens facing the object side in order, R2, R4, R6, R8, R10, R12, R14, R16 according to The order represents the curvature radius of the center of the surface of the first lens to the eighth lens facing the image side respectively, the unit is mm, and "-" indicates that the direction is negative.

Optionally, the aperture F of the refractive lens group is greater than or equal to 1.1.

The infrared confocal lens provided by the embodiment of the present invention includes a refraction lens group and an imaging component located on the light-emitting side of the refraction lens group; a second lens with positive power, a third lens with positive power, a fourth lens with negative power, a fifth lens with positive power, a sixth lens with positive power, a seventh lens with negative power, and an eighth lens with positive power; wherein The focal length f4 of the fourth lens and the focal length f5 of the fifth lens satisfy 0.8<︱f4/f5︱<1.5; the focal length f6 of the sixth lens and the focal length f7 of the seventh lens satisfy 0.5<︱f6/f7︱<1.2. By designing the refractive power of each lens in the refractive lens group to match each other, by setting the focal length f4 of the fourth lens and the focal length f5 of the fifth lens to satisfy 0.8<︱f4/f5︱<1.5; the focal lengths of the sixth lens f6 and the seventh lens The focal length f7 of the lens satisfies 0.5<︱f6/f7︱<1.2, and a confocal optical lens for visible light and infrared light with simple structure and high resolution can be designed.

Description of drawings

1 is a schematic structural diagram of an infrared confocal lens provided by an embodiment of the present invention;

2 is a schematic diagram of a modulation transfer function MTF curve of visible light provided by an embodiment of the present invention;

3 is a schematic diagram of an MTF curve of infrared light provided by an embodiment of the present invention.

Detailed ways

The present utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for the convenience of description, the drawings only show some but not all structures related to the present invention.

FIG. 1 is a schematic structural diagram of an infrared confocal lens provided by an embodiment of the present invention. Referring to FIG. 1, the infrared confocal lens includes a refractive lens group 10 and an imaging component 20 located on the light-emitting side of the refractive lens group 10; The second lens 102 with positive power, the third lens 103 with positive power, the fourth lens 104 with negative power, the fifth lens 105 with positive power, the sixth lens 106 with positive power, the seventh lens 107 with negative power and The eighth lens 108 with positive refractive power; wherein the focal length f4 of the fourth lens 104 and the focal length f5 of the fifth lens 105 satisfy the following relationship: 0.8<︱f4/f5︱<1.5; the focal length f6 of the sixth lens 106 and the seventh lens 107 The focal length f7 satisfies the following relationship: 0.5<︱f6/f7︱<1.2.

Among them, it can be understood that the optical power is equal to the difference between the convergence degree of the image-side beam and the convergence degree of the object-side beam, which represents the ability of the optical system to deflect light. The larger the absolute value of the optical power is, the stronger the bending ability of the light is, and the smaller the absolute value of the optical power is, the weaker the bending ability of the light is. When the optical power is positive, the refraction of the light is convergent; when the optical power is negative, the refraction of the light is divergent. Optical power can be used to characterize a certain refractive surface of a lens (ie, a surface of a lens), a certain lens, or a system formed by multiple lenses (ie a lens group). In this embodiment, each lens can be fixed in a lens barrel (not shown in FIG. 1 ), and by rationally distributing the optical power of the lens, the lens can be confocal in the wavelength range of 436 nm to 850 nm. In one embodiment of the present invention, the aperture of the refractive lens group is F=1.1, which can match the imaging components of 6 million pixels and above, and has the advantages of large light transmission and high resolution.

In the technical solution of this embodiment, the refractive power of each lens in the refractive lens group is designed to match each other, and the focal length f4 of the fourth lens and the focal length f5 of the fifth lens are set to satisfy 0.8<︱f4/f5︱<1.5; the sixth The focal length f6 of the lens and the focal length f7 of the seventh lens satisfy 0.5<︱f6/f7︱<1.2, and a confocal optical lens for visible light and infrared light with simple structure and high resolution can be designed.

On the basis of the above technical solutions, optionally, continuing to refer to FIG. 1 , the refractive lens group 10 and the imaging assembly 20 are disposed coaxially, and the imaging assembly 20 is located on the focal plane of the refractive lens group 10 .

It can be understood that, by arranging the refraction lens group 10 and the imaging assembly 10 coaxially, the complexity of the design of the refraction lens group 10 can be reduced, and the imaging accuracy of the refraction lens group 10 can be improved. side of the focal plane.

Optionally, the imaging assembly 20 includes a photosensitive element 201 and a transparent protective plate 202 , and the transparent protective plate 202 is located between the photosensitive element 201 and the refractive lens group 10 .

Exemplarily, the transparent protective plate 202 may be a glass plate, or a filter having a function of filtering out certain light, for protecting the photosensitive element 201, and the photosensitive element 201 may include a charge coupled device CCD or a complementary metal oxide semiconductor CMOS, In this embodiment, COMS is optionally selected as the photosensitive element, which can effectively reduce the cost of the lens.

Optionally, continuing to refer to FIG. 1 , the infrared confocal lens further includes a diaphragm 30 located between the third lens 103 and the fourth lens 104 . The diaphragm 30 is used to pass the amount of light of the infrared confocal lens.

Optionally, the fourth lens 104 and the fifth lens 105 constitute a cemented lens.

It can be understood that the cemented lens includes two lenses, and the surfaces of the two lenses adjacent to each other have the same shape and are attached together. Cemented lenses have good aberration correction capabilities, especially for chromatic aberration correction. In the embodiment of the present invention, the fourth lens 104 and the fifth lens 105 constitute a cemented lens, which is beneficial to the correction of chromatic aberration in the infrared confocal lens.

Optionally, the first lens 101 , the third lens 103 , the fourth lens 104 and the fifth lens 105 are spherical lenses, and the second lens 102 , the sixth lens 106 , the seventh lens 107 and the eighth lens 108 are aspherical lenses .

Exemplarily, in this embodiment, the first lens 101 , the third lens 103 , the fourth lens 104 and the fifth lens 105 are made of glass materials to form spherical lenses, which have the function of correcting infrared rays. The second lens 102 and the sixth lens 106 , the seventh lens 107 and the eighth lens 108 are made of plastic materials to form aspherical lenses, which can effectively eliminate aberrations.

Optionally, the surface shape of an aspheric lens is given by the formula:

Determine, where z is the vector height, c is the curvature at the vertex of the surface, r is the distance between the projection of the coordinates of the surface point on the plane perpendicular to the optical axis and the optical axis, k is the conic coefficient, a ₁ , a ₂ , a ₃ , a ₄ , a ₅ , a ₆ , a ₇ , and a ₈ represent coefficients corresponding to even-order terms.

In this embodiment, the even-order coefficient of the aspheric lens is:

Table 1 Surface parameters of aspheric lens

a₁ a₂ a₃ a₄ a₅ a₆ a₇ a₈ face number 3 0 -3.34E-03 -1.87E-05 3.85E-06 -2.40E-07 1.17E-09 2.37E-07 0 face number 4 0 -9.08E-02 1.15E-06 5.32E-06 2.79E-06 3.13E-09 2.34E-08 0 face number 11 0 4.48E-03 -2.14E-03 -6.47E-05 2.28E-07 -1.93E-07 -2.37E-09 0 face number 12 0 -2.59E-02 -1.21E-04 4.35E-06 4.28E-07 1.96E-08 2.85E-08 0 face number 13 0 -1.30E-03 -7.83E-06 3.47E-06 -6.24E-08 6.33E-09 1.87E-07 0 face number 14 0 -3.11E-06 3.53E-06 -4.54E-05 2.54E-07 -3.50E-06 -9.12E-06 0 Noodle No. 15 0 -1.52E-05 -9.62E-06 2.36E-06 -5.08E-08 7.53E-08 1.19E-08 0 face number 16 0 -2.11E-04 2.43E-04 -3.54E-07 2.31E-06 -2.50E-07 -2.14E-07 0

Among them, the surface number 3, the surface number 11, the surface number 13 and the surface number 15 correspond to the front surface of the second lens 102, the sixth lens 106, the seventh lens 107 and the eighth lens 108, respectively, which are close to the object surface. The serial number 12, the surface number 14 and the surface number 16 respectively correspond to the rear surfaces of the second lens 102, the sixth lens 106, the seventh lens 107 and the eighth lens 108 close to the image plane.

Optionally, referring to FIG. 1, in a specific example of the embodiment of the present invention, the first lens 101 is a meniscus lens, the second lens 102 is a meniscus lens, the third lens 103 is a biconvex lens, and the third lens 103 is a biconvex lens. The fourth lens 104 is a biconcave lens, the fifth lens 105 is a biconvex lens, the sixth lens 106 is a biconvex lens, the seventh lens 107 is a meniscus lens, and the eighth lens 108 is a biconvex lens.

It can be understood that, the specific lens shape can be selected according to the design of the light angle, and the above is only a specific example, not a limitation of the embodiments of the present invention.

Optionally, the refractive lens group 10 satisfies the following parameters:

Table 2 Refractive lens group parameters

Among them, f1~f8 represent the focal length of the first lens to the eighth lens, the unit is mm, n1~n8 represent the refractive index of the first lens to the seventh lens, R1, R3, R5, R7, R9, R11, R13, R15 In order to represent the curvature radius of the first lens to the eighth lens toward the center of the object side surface, R2, R4, R6, R8, R10, R12, R14, R16 respectively represent the first to the eighth lens in order to the image The radius of curvature of the center of the surface on one side of the square, in mm, "-" means the direction is negative.

Optionally, the aperture F of the refractive lens group 10 is greater than or equal to 1.1. In this embodiment, the aperture of the refractive lens group is F=1.1, which has the advantage of a large amount of light passing.

Table 3 shows the lens parameter design values of a specific embodiment of the present invention:

Table 3 A design value of the lens in the refractive lens group

Among them, the surface number 1 represents the front surface of the first lens 101 close to the object side, and so on, and PL represents that the surface is a plane. Since the fourth lens 104 and the fifth lens 105 are cemented lenses, they share the surface 9, the surface numbers 17 and 18 represents the two surfaces of the transparent protective plate 202; R represents the radius of the spherical surface, positive means that the center of the spherical surface is close to the side of the image plane, and negative means that the center of the spherical surface is close to the side of the object surface; D means the distance on the optical axis from the current surface to the next surface ; nd is the refractive index of the lens; k is the conic coefficient of the aspheric surface.

In addition, a spacer (not shown in FIG. 1 ) is also set between each lens. Specifically, the first lens 101 and the second lens 102 are closely contacted by the SOMA sheet, and the second lens 102 and the third lens are closely contacted by a metal spacer In combination, the third lens 103 and the fourth lens 104 are tightly combined through the spacer, the fifth lens 105 and the sixth lens 106 are closely matched through the spacer, the sixth lens 106 and the seventh lens 107 are closely connected through the SOMA sheet, and the seventh lens 107 is in close contact with the eighth lens 108 through the SOMA sheet.

The infrared confocal lens provided in this embodiment can achieve a resolution of 6 million pixels in both visible light and infrared states, can match a 6 million 1/2.7-inch CMOS chip, and can obtain clear images even in a low-light environment at night. At the same time, the design will not run out of focus when used in the environment of -40℃～80℃.

Specifically, FIG. 2 shows a schematic diagram of a modulation transfer function MTF curve of visible light provided by an embodiment of the present invention, and FIG. 3 is a schematic diagram of an MTF curve of infrared light provided by an embodiment of the present invention. To achieve a resolution of 6 million pixels, when the spatial resolution is 200 line pairs/mm, the MTF of visible light in the central field of view is greater than 0.4, the MTF of the edge field of view is greater than 0.2, and the MTF of infrared light in the central field of view is greater than 0.4, The MTF for 0.7x fringe field is greater than 0.2. Referring to FIG. 2 and FIG. 3 , it can be seen that both visible light and infrared light satisfy the condition that the resolution is greater than 6 million pixels.

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments and substitutions can be made to those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present utility model has been described in detail through the above embodiments, the present utility model is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present utility model. Rather, the scope of the present invention is determined by the scope of the appended claims.

Claims (10)

1. a kind of infrared confocal camera lens, which is characterized in that go out light including a refractor group and positioned at the refractor group The image-forming assembly of side；

The refractor group includes that the first lens of negative power being arranged successively along light incident direction, negative power second are saturating Mirror, positive light coke the third lens, the 4th lens of negative power, the 5th lens of positive focal power, the 6th lens of positive light coke, negative power The 8th lens of 7th lens and positive light coke；

Wherein the focal length f4 of the 4th lens and the focal length f5 of the 5th lens meet following relationship:

︱ < 1.5 0.8 < ︱ f4/f5；

The focal length f6 of 6th lens and the focal length f7 of the 7th lens meet following relationship:

︱ < 1.2 0.5 < ︱ f6/f7.

2. infrared confocal camera lens according to claim 1, which is characterized in that the refractor group and the image-forming assembly Coaxial setting, the image-forming assembly are located on the focal plane of the refractor group.

3. infrared confocal camera lens according to claim 2, which is characterized in that the image-forming assembly include photosensitive element and thoroughly Bright protection board, the transparent protection plate is between the photosensitive element and the refractor group.

4. infrared confocal camera lens according to claim 1, which is characterized in that further include diaphragm, be located at the third lens Between the 4th lens.

5. infrared confocal camera lens according to claim 1, which is characterized in that the 4th lens and the 5th lens structure At balsaming lens.

6. infrared confocal camera lens according to claim 1, which is characterized in that first lens, the third lens, institute Stating the 4th lens and the 5th lens is spherical lens, second lens, the 6th lens, the 7th lens with And the 8th lens are non-spherical lens.

7. infrared confocal camera lens according to claim 6, which is characterized in that the face type of the non-spherical lens is by formula:

It determines, wherein z is rise, and c is the curvature of curved surface apex, and r is surface points coordinate in the projection perpendicular to optical axial plane At a distance from optical axis, k is circular cone coefficient, a₁、a₂、a₃、a₄、a₅、a₆、a₇And a₈Indicate the corresponding coefficient of even order terms.

8. infrared confocal camera lens according to claim 1, which is characterized in that first lens are meniscus shaped lens, institute State the second lens be meniscus shaped lens, the third lens be biconvex lens, the 4th lens be biconcave lens, the described 5th Lens are biconvex lens, and the 6th lens are biconvex lens, and the 7th lens are meniscus shaped lens, and the 8th lens are Biconvex lens.

9. infrared confocal camera lens according to claim 1, which is characterized in that the refractor group meets following parameter:

F1=-6~-8.3 N1=1.55~1.75 R1=50~65 R2=4.5~5.2 F2=-12~-15 N2=1.55~1.75 R3=-4.2~-4.6 R4=-9.3~-11.2 F3=6.5~8.3 N3=1.83~2.23 R5=15.3~16.8 R6=-15.3~-16.8 F4=-6.5~-8.3 N4=1.83~2.23 R7=-38.5~-40.2 R8=8.1~8.42 F5=6.5~8.3 N5=1.55~1.75 R9=8.1~8.5 R10=-8.1~-8.5 F6=10.2~11.8 N6=1.45~1.65 R11=8.2~8.4 R12=-18.5~-20.3 F7=-17~-21 N7=1.55~1.65 R13=-5.5~-6.3 R14=-13.5~14.8 F8=13.6~15.8 N8=1.45~1.55 R15=9.8~11.5 R16=-32.5~-36

Wherein, f1~f8 indicates focal length of first lens to the 8th lens, and unit mm, n1~n8 indicate described the For one lens to the refractive index of the 7th lens, R1, R3, R5, R7, R9, R11, R13, R15 respectively indicate described first in order Radius of curvature of the lens to the 8th lens towards object space side centre of surface, R2, R4, R6, R8, R10, R12, R14, R16 Radius of curvature of first lens to the 8th lens towards image space side centre of surface is respectively indicated in order, and unit is Mm, "-" indicate that direction is negative.

10. infrared confocal camera lens according to claim 1, which is characterized in that the aperture F of the refractor group be greater than or Equal to 1.1.