CN108169882A - A kind of 6mm rear greatly coke ratio, super large thang-kng, double light path optical system - Google Patents

Abstract

The invention discloses a 6mm large rear focal ratio, super-large light-passing, double optical path optical system, comprising a first lens group, a second lens group and a prism beam splitting group; the first lens group includes a first lens and a second lens; One lens is a spherical lens with positive power; the second lens is an aspheric lens with no power; the second lens group includes a third lens, a fourth lens, a fifth lens and a sixth lens; the third lens is a negative The aspheric lens of dioptric power; the fourth lens is a spherical lens of positive dioptric power; the fifth lens is an aspheric lens of negative dioptric power; A diaphragm is arranged between the lenses; the prism light splitting group includes a light splitting prism, a first photosensitive chip and a second photosensitive chip, the first photosensitive chip is arranged perpendicular to the optical axis, and the second photosensitive chip is arranged parallel to the optical axis. The invention has a large back focus ratio, and the back focus ratio is more than 3 times larger than the focal length, so that the volume of the system can be extremely small.

Description

A 6mm large rear focal ratio, super large light, dual optical path optical system

【Technical field】

The invention relates to an optical system, in particular to a 6mm large rear focal ratio, super large light-through, double optical path optical system.

【Background technique】

At present, monitoring fixed-focus lenses are widely used in people's daily life, but the current security monitoring and road condition monitoring devices have the following shortcomings:

1. The existing shooting device adopts the method of matching a single photosensitive chip with a single lens, and the light wave wavelength that needs to be received by a single photosensitive chip is relatively wide, so the overall picture definition is not high, and the shooting effect is not good;

2. The existing shooting device adopts the method of matching a single lens with a single photosensitive chip, which reflects that the wavelengths of each color cannot be reproduced well on a single photosensitive chip, resulting in the phenomenon that the color of the shooting picture is not full enough;

3. The existing shooting device uses a single lens to match a single photosensitive chip. In a low-light environment, some wavelengths of light waves cannot be used, resulting in a decrease in the overall light flux and unclear images;

4. The existing 6mm fixed-focus lens cannot achieve a super-large light-passing F-number of less than 1.2. In a low-light environment, the overall light pass-through decreases and the captured image is not clear;

5. The existing 6mm fixed-focus lens cannot be matched to the current mainstream high-end prism beam splitting system in the industry;

6. The existing 6mm fixed-focus glass-plastic hybrid lens cannot achieve better confocal under high and low temperature environments;

7. The back focus ratio of the existing 6mm fixed-focus lens is small, less than 3, and it needs to be larger when matched to the beam splitting system.

Therefore, the present invention just produces based on above deficiency.

【Content of invention】

The technical problem to be solved by the present invention is to provide a 6mm large back focus ratio, super large light-passing, dual optical path optical system, which has a large back focus ratio, and the back focus ratio is more than 3 times larger than the focal length, so that the system is suitable for the requirements of the back focus Higher prism beam splitting system makes the volume of the system extremely small.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions: a 6mm large rear focal ratio, super-large light-passing, double-light path optical system, is characterized in that a first lens group, a second lens group, and a second lens group are sequentially arranged along the light incident direction Lens group and prism beam splitting group;

The first lens group includes a first lens and a second lens arranged in sequence along the light incident direction; the first lens is a spherical lens with positive refractive power, and the first lens is meniscus; the second lens is an aspheric lens with no optical power, and the second lens is meniscus;

The second lens group includes a third lens, a fourth lens, a fifth lens and a sixth lens arranged in sequence along the light incident direction; the third lens is an aspherical lens with negative refractive power, and the third lens The lens is a meniscus type; the fourth lens is a spherical lens with positive power, and the two faces of the fourth lens are convex; the fifth lens is an aspheric lens with negative power, and the fifth lens The two surfaces are concave; the sixth lens is an aspherical lens with positive refractive power, and the two surfaces of the sixth lens are convex;

A diaphragm is arranged between the third lens and the fourth lens;

The prism beam splitting group includes a beam splitting prism, a first photosensitive chip and a second photosensitive chip, the first photosensitive chip is arranged perpendicular to the optical axis, and the second photosensitive chip is arranged parallel to the optical axis.

A 6mm large rear focal ratio, super large light-passing, dual optical path optical system as described above is characterized in that the air gap between the first lens group and the second lens group is 3mm; The air gap between the second lens group and the prism beam splitting group is 1.5mm.

A 6mm large back focus ratio, super large light-passing, dual optical path optical system as described above is characterized in that the curvature radii of the two surfaces of the first lens are 28mm and 5mm respectively; the two surfaces of the second lens The radii of curvature are -16mm and -9mm, respectively.

A 6mm large rear focal ratio, super-large light-passing, and dual optical path optical system as described above, is characterized in that the curvature radii of the two surfaces of the third lens are respectively -8mm and -29mm; the fourth lens The radii of curvature of the two surfaces of the fifth lens are respectively 13mm and -13mm; the radii of curvature of the two surfaces of the fifth lens are respectively -40mm and 9mm; the radii of curvature of the two surfaces of the sixth lens are respectively 10.2mm and -10.5mm.

The above-mentioned 6mm large back focal ratio, super large light-passing, double optical path optical system is characterized in that the horizontal thickness of the dichroic prism 8 in the direction of the optical axis is 10mm.

Compared with the prior art, the present invention has a 6mm large rear focal ratio, super large light transmission, and dual optical path optical system, which achieves the following effects:

The invention has dual optical paths, which can divide the wavelength into two optical paths of visible light and infrared light, and has a super large aperture, and the F number can reach 1.2, which ensures the perfect use of the lens in a low-light environment. The back focus is large, and the back focus is more than three times the focal length, making the optical system smaller. Under the condition of only using 6 lenses, the total length is less than 55mm, and the cost is extremely low.

Select plastic glass with high refraction and low dispersion and crown glass with high refraction index and high dispersion to achromatism and astigmatism, use plastic aspheric lens to reduce spherical aberration and distortion; plastic aspheric surface is used in combination with positive and negative in the lens group, It ensures that the lens can be used normally in high and low temperature environments.

【Description of drawings】

The specific embodiment of the present invention is described in further detail below in conjunction with accompanying drawing, wherein:

Fig. 1 is a structural representation of the present invention;

Description of drawings: 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Aperture; 8. Dichroic prism; 9. The first photosensitive chip; 10. The second photosensitive chip.

【Detailed ways】

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, a 6mm large back focal ratio, super large light-passing, dual optical path optical system is provided with a first lens group, a second lens group and a prism beam splitting group in sequence along the light incident direction;

The first lens group includes a first lens 1 and a second lens 2 arranged in sequence along the light incident direction;

The first lens 1 is a spherical lens with positive refractive power, and the first lens 1 is meniscus;

The second lens 2 is an aspheric lens with no refractive power, and the second lens 2 is a meniscus type;

The second lens group includes a third lens 3, a fourth lens 4, a fifth lens 5 and a sixth lens 6 arranged in sequence along the light incident direction;

The third lens 3 is an aspheric lens with negative refractive power, and the third lens 3 is meniscus;

The fourth lens 4 is a spherical lens with positive refractive power, and the two surfaces of the fourth lens 4 are convex surfaces;

The fifth lens 5 is an aspheric lens with negative refractive power, and the two surfaces of the fifth lens 5 are concave;

The sixth lens 6 is an aspheric lens with positive refractive power, and the two surfaces of the sixth lens 6 are convex surfaces;

An aperture 7 is arranged between the third lens 3 and the fourth lens 4;

The prism beam splitting group includes a beam splitting prism 8, a first photosensitive chip 9 and a second photosensitive chip 10, the first photosensitive chip 9 is arranged perpendicular to the optical axis, and the second photosensitive chip 10 is arranged parallel to the optical axis to ensure that the beam splitting prism splits The light beam can reach the first photosensitive chip and the second photosensitive chip.

As shown in Figure 1, in the present embodiment, the air interval between the first lens group and the second lens group is 3mm; the air interval between the second lens group and the prism beam splitting group is 1.5mm mm. The air interval between the first lens group and the second lens group is the distance between the second lens and the third lens; the air interval between the second lens group and the prism beam splitting group is the distance between the sixth lens and the beam splitting prism distance.

As shown in Figure 1, in this embodiment, the curvature radii of the two surfaces of the first lens 1 are respectively 28mm and 5mm; the curvature radii of the two surfaces of the second lens 2 are respectively -16mm and -9mm;

The first lens includes a first surface S1 and a second surface S2 in the light passing direction, the radius of curvature of the first surface S1 of the first lens is 28mm, and the radius of curvature of the second surface S2 of the first lens is 5mm;

The second lens includes a first surface S3 and a second surface S4 in the light passing direction, the radius of curvature of the first surface S3 of the second lens is -16mm, and the radius of curvature of the second surface S4 of the second lens is -9mm .

As shown in Figure 1, in this embodiment, the curvature radii of the two surfaces of the third lens 3 are respectively -8mm and -29mm; the curvature radii of the two surfaces of the fourth lens 4 are respectively 13mm and -29mm. -13mm; the curvature radii of the two surfaces of the fifth lens 5 are respectively -40mm and 9mm; the curvature radii of the two surfaces of the sixth lens 6 are respectively 10.2mm and -10.5mm.

The third lens includes a first surface S5 and a second surface S6 in the light passing direction, the radius of curvature of the first surface S5 of the third lens is -8mm, and the radius of curvature of the second surface S6 of the third lens is -29mm ;

The fourth lens includes a first surface S7 and a second surface S8 in the light passing direction, the radius of curvature of the first surface S7 of the fourth lens is 13mm, and the radius of curvature of the second surface S8 of the fourth lens is -13mm;

The fifth lens includes a first surface S9 and a second surface S10 in the light passing direction, the radius of curvature of the first surface S9 of the fifth lens is -40mm, and the radius of curvature of the second surface S10 of the fifth lens is 9mm;

The sixth lens includes a first surface S11 and a second surface S12 in the direction of light passing. The radius of curvature of the first surface S11 of the sixth lens is 10.2 mm, and the radius of curvature of the second surface S12 of the sixth lens is -10.5 mm. mm.

The first lens is a glass lens, the second lens is a plastic lens, the third lens is a plastic lens, the fourth lens is a glass lens, the fifth lens is a plastic lens, and the sixth lens is a plastic lens. Only 6 glass and plastic lenses are used, the cost is extremely low, and it can be used in high and low temperature environments.

As shown in FIG. 1 , in this embodiment, the horizontal thickness of the dichroic prism 8 in the direction of the optical axis is 10 mm.

The 6mm Datong light fixed focus lens has reached the following technical indicators: 1. Focal length: f′=6mm; 2. Relative aperture F=1.2; 3. Angle of view: 2w≥65° (image square field of view 2η′≥Ф6 .52mm); 4. Distortion: <-14%; 5. Resolution: Compatible with 6 million pixel high-resolution CCD or CMOS camera; 6. The total length of the optical path ∑≤55mm, the optical back intercept L'≥18mm, Back focus ratio ≥ 3; 7. Applicable spectral line range: 480nm～850nm.

Optically visible and infrared MTF is very high. When imaging at visible wavelengths, the central field of view at 160 line pairs is greater than 0.6, and the edge field of view at 160 line pairs is greater than 0.35; when imaging at infrared wavelengths of 0.85um, the central field of view at 160 line pairs is greater than 0.65. The fringe field of view is greater than 0.5 at 160 line pairs.

Claims (5)

1. A 6mm large rear focal ratio, super large light-passing, dual optical path optical system, is characterized in that a first lens group, a second lens group and a prism beam splitting group are arranged successively along the light incident direction; The first lens group includes a first lens (1) and a second lens (2) arranged in sequence along the light incident direction; the first lens (1) is a spherical lens with positive refractive power, and the first The lens (1) is a meniscus type; the second lens (2) is an aspheric lens with no optical power, and the second lens (2) is a meniscus type; The second lens group includes a third lens (3), a fourth lens (4), a fifth lens (5) and a sixth lens (6) arranged in sequence along the light incident direction; the third lens ( 3) is an aspheric lens with negative refractive power, and the third lens (3) is a meniscus type; the fourth lens (4) is a spherical lens with positive refractive power, and the two of the fourth lens (4) The surface is a convex surface; the fifth lens (5) is an aspherical lens with negative refractive power, and the two surfaces of the fifth lens (5) are concave; the sixth lens (6) is an aspheric lens with positive refractive power. A spherical lens, and the two faces of the sixth lens (6) are convex; A diaphragm (7) is arranged between the third lens (3) and the fourth lens (4); The prism light-splitting group includes a light-splitting prism (8), a first photosensitive chip (9) and a second photosensitive chip (10), the first photosensitive chip (9) is arranged perpendicular to the optical axis, and the second photosensitive chip The chip (10) is arranged parallel to the optical axis. 2. A kind of 6mm large rear focal ratio according to claim 1, super-large light-passing, double optical path optical system, it is characterized in that, the air space between described first lens group and described second lens group is 3mm; the air gap between the second lens group and the prism beam splitting group is 1.5mm. 3. A kind of 6mm large rear focal ratio according to claim 1, super large light-passing, double optical path optical system, it is characterized in that, the curvature radius of two surfaces of described first lens (1) is respectively 28mm and 5mm ; The radii of curvature of the two surfaces of the second lens (2) are respectively -16mm and -9mm. 4. a kind of 6mm large rear focal ratio according to claim 1, super large pass light, double optical path optical system, it is characterized in that, the radius of curvature of the two surfaces of described third lens (3) is respectively-8mm and -29mm; the radius of curvature of the two surfaces of the fourth lens (4) is respectively 13mm and -13mm; the radius of curvature of the two surfaces of the fifth lens (5) is respectively -40mm and 9mm; The curvature radii of the two surfaces of the six lenses (6) are respectively 10.2mm and -10.5mm. 5. A kind of 6mm large rear focal ratio according to claim 1, super-large light-passing, double optical path optical system, is characterized in that, the horizontal thickness of described dichroic prism (8) on optical axis direction is 10mm.