CN102156350A - Camera device and design method thereof - Google Patents

Abstract

The invention discloses a camera device with a large field depth and a design method thereof. A lens with a constant focal distance is adopted by the camera device; parameters of a lens optical system are designed by using an object plane at a focusing object distance as required by the later actual working environment as a reference object plane while the initial design of the lens is carried out. In the method, the focal distance of the lens is determined according to an image face size of an imaging apparatus matched for the lens and a view field range required to be observed; and then the focusing object distance is determined according to a depth range required to be observed; and finally, the reference object plane is selected according to the selected focusing object distance value, and parameter optimization design is carried out on the optical system of the lens according to the reference object plane. The camera device designed by using the method can increase a depth of field without need of inserting an extra element, and has the advantages of no need of focusing and low cost.

Description

Camera head and method for designing thereof

Technical field

The present invention relates to a kind of camera head, relate in particular to the camera head that need not to focus of the big depth of field.The invention still further relates to the method for designing of this big depth of field camera head.

Background technology

In the current society, various camera heads have been deep into each corner of human lives widely, such as the monitoring camera in bank, hotel and the building, and the camera of monitoring road safety, used video camera in the film shooting, hand-held camera.For a long time, these camera heads all are subjected to the puzzlement of not enough this problem of the depth of field.The depth of field is meant the object distance scope of being measured along the imager axis that can obtain picture rich in detail before camera lens or other imagers.Because the depth of field of traditional pick-up lens is all smaller, can't guarantee that close shot and distant view are simultaneously clear.As shown in Figure 1, this photo is the photo that utilizes traditional zooming camera lens (model is " U.S. electric Bel BL0416F ") to take, because the depth of field of camera lens is less, when focusing to medium and long distance, the scenery at medium and long distance place is clearer, but is not positioned at focus and put but very unclear from the nearer business card of camera lens.

In security protection and monitoring field, because camera is to take automatically, can't know in advance the things of being paid close attention to (such as suspect's face) will appear at apart from camera position how far, therefore focusing (promptly focusing a little) can only be arranged on place, a certain fixed position, and can not realize covering simultaneously all positions in the predetermined monitoring range.In case it is far away that the things of being paid close attention to departs from focusing, the smaller traditional camera of the depth of field just can't be to the things blur-free imaging of being paid close attention to.Like this, when public security organ accesses at that time monitoring video after the incident, find through regular meeting that suspect's face is fuzzy and be difficult to distinguish, thereby caused great difficulty to cracking of cases.In order to address the above problem, Japan has developed a kind of camera lens, it is divided into a plurality of zones by distance is far and near with monitoring range, drive camera lens by stepper motor quick scan round is carried out in each zone, at last that each is regional image joint gets up, though this method can increase the depth of field, but strictly speaking, this way is not the image that obtains whole monitoring range simultaneously, and stepper motor continuous running meeting brings mechanical loss to entire mechanism, has shortened the mission life of camera lens greatly.

In the shooting process of film, also can run into the puzzlement of depth of field problem, in taking some during in-plant scene, usually we can find that distant view is all very fuzzy, for extended depth of field, common way adopts a plurality of lens shootings exactly, when montage close shot and distant view image is spliced at last, perhaps is exactly to adopt a lot, the heavy expensive optical lens of number of lenses to take, but complicated operation like this, cost also improve thereupon.

Chinese patent application Publication Specification CN1949024A discloses a kind of non-diffraction large depth field imaging optical system, it is inserted in a Conical Lenses between picture plane and the common imaging system, light beam is transformed into approximate diffraction light-free through Conical Lenses, approximate diffraction light-free along the projection on the panel of the arbitrary position of optical axis all is being an onesize concentric ring diffraction spot, wherein the diameter of anxious spot is determined by the cone angle of Conical Lenses substantially, the out of focus fuzzy problem that can change in diverse location place focal spot size that does not have common imaging system has reached the purpose that increases the depth of field.But its Conical Lenses that adopts is the lens of the special processing of a kind of needs, and its cone angle need be through relating to complicated calculations and the design such as Bessel's function, and cost is higher.

Chinese patent application Publication Specification CN101046547A discloses a kind of digital telescope system with great field depth, it is by having inserted a slice thickness with x in optical imaging system, the aperture modulation sheet of y changes in coordinates increases the depth of field, and it also has calculating and design is complicated, the cost problem of higher.

Summary of the invention

The present invention is directed to the deficiencies in the prior art, propose a kind of based on brand-new design theory, the big depth of field camera system that need not to focus, and the method for designing of this system.Thereby the needs that exist in the solution prior art insert additional element, design is complicated, mission life is short, cost is higher and heavy these technical matterss of equipment.

Design concept of the present invention is:

1. adopt tight shot but not zoom lens.Zoom lens group is because its focal range is bigger, zoom lens should guarantee that various aberrations, aberration are compensated on each focal length, guarantee that again the depth of field is enough big, and the ideal image parameter of pick-up lens is different under each focal length, can't reach simultaneously, Shi Ji camera system also is subjected to the restriction of factors such as glass sheet number and physical dimension in addition, so can't guarantee can both obtain desirable field depth technically at present under each focal length, especially close shot is had suitable shortcoming deeply.But the present invention has adopted tight shot, and this problem is just simplified greatly, thereby has obtained the depth of field more much bigger than traditional zoom camera lens under fixed focal length.

2. the tight shot tight shot different from the past that adopts of the present invention, it has thoroughly changed the traditional optical design concept of tight shot, overcome technology prejudice for a long time, the object plane of infinite distant place is no longer adopted on primary standard substance plane (focusing object plane) during the initial designs of optical system parameter, but the primary standard substance plane when adopting it object plane at the desired focusing object distance of residing actual working environment place is as the parameter of optical system initial designs in the future.The tradition tight shot all carries out design of Optical System by object plane at infinity, thereby obtains the parameters such as surface configuration, abbe number of camera lens.Conventional lenses, even if its is focused at limited object plane place far away by adjusting mechanism, it must not have perfect picture element yet, because its initial optical design basis at infinity, but actual duty is in far limited even very near distance, parameters such as the planform of camera lens, abbe number with mate badly at the image-forming condition of limit remote, therefore can't obtain the enough big depth of field.But the tight shot that the present invention adopts carries out initial design of Optical System according to the focusing object distance place of primary standard substance plane when the real work, so the reference substance plane of the initial designs of camera lens and the desired focusing object plane of its actual working environment coincide, therefore can make the camera lens depth of field farthest near the desirable depth of field value under this focusing object distance.

In order to solve described technical matters, basic scheme of the present invention is:

This camera head uses the constant camera lens of focal length, described camera lens is when carrying out initial designs, carry out the parameter designing of lens optical system by the object plane that adopts the desired focusing object distance of its residing actual working environment in future place as the primary standard substance plane, thereby make camera lens farthest near the desirable depth of field value under this focusing object distance.Camera lens comprises one or more pieces lens, and the optical system parameter of described camera lens comprises radius-of-curvature, refractive index and the abbe number on the position of lens, thickness, surface.

It uses the constant camera lens of focal length, and carries out the initial designs of the parameter of lens optical system as the primary standard substance plane by the object plane of selecting the focusing object distance place of camera lens when the real work.

Described method for designing specifically may further comprise the steps: according to camera lens be made into as the field range of the image planes size of device and required observation determine the focal distance f of camera lens '; Determine focusing object distance P according to the depth range of required observation; According to selected focusing object distance value selected reference object plane, camera lens is carried out optimized design and lens construction design according to this primary standard substance plane.

As a preferred version of the present invention, described camera lens comprises seven optical mirror slips, and light direction is vertical with going into, and is pressed into the light direction series arrangement and is connected to: first lens, and it is the biconvex sheet; Second lens, it is concavo-convex; The 3rd lens, it is the concave-concave sheet; The 4th lens, it is the convex-concave sheet; The 5th lens, it is the biconvex sheet; The 6th lens, it is the concave-concave sheet; The 7th lens, it is the biconvex sheet.Wherein, the 3rd lens and the 4th lens glue lump together; The front surface radius-of-curvature of first lens is 102.57mm, and the rear surface radius-of-curvature is 15.24mm; The front surface radius-of-curvature of second lens is-20.05mm that the rear surface radius-of-curvature is-55.21mm; The front surface radius-of-curvature of the 3rd lens is-30.2mm that the rear surface radius-of-curvature is 9.29mm; The front surface radius-of-curvature of the 4th lens is 9.29mm, and the rear surface radius-of-curvature is 63.68mm; The front surface radius-of-curvature of the 5th lens is 8.166mm, and the rear surface radius-of-curvature is-2128mm; The front surface radius-of-curvature of the 6th lens is-15.488mm that the rear surface radius-of-curvature is 7.345mm; The front surface radius-of-curvature of the 7th lens is 16.711mm, and the rear surface radius-of-curvature is-16.711mm.The thickness of first to the 7th lens is followed successively by 3.5mm, 3mm, 2mm, 3.5mm, 2.8mm, 1.2mm, 2.5mm; The refractive index of first to the 7th lens is followed successively by 1.6221,1.6221,1.7883,1.7847,1.6921,1.6477,1.6921; The abbe number of first to the 7th lens is followed successively by 56.71,56.71,47.39,25.76,54.54,33.87,54.54.

As a preferred version of the present invention, described camera head further comprises image device.

As a preferred version of the present invention, described image device is CCD or CMOS photo-sensitive cell.

As a preferred version of the present invention, described image device can be CCD or cmos camera, and this moment, camera lens adopted the version of plug and play, only needs camera lens is connected on CCD or the cmos camera, and the camera alignment observing object need not be adjusted repeatedly.

The present invention has improved the field depth under the certain observation scene, need not to insert that extra element, cost are lower, simplicity of design, long working life, equipment be light, camera lens of the present invention need not zoom simultaneously, be not easy to occur loosening such as latch mechanism, problems such as focusing is inaccurate, aspect video monitoring, increased effective range of observation, realized good monitoring effect.In film television, during close shot takes, also can adopt this light camera lens of the present invention to obtain good picture effect.

Description of drawings

Fig. 1 is the photo that adopts the little depth of field of traditional zoom camera (U.S. electric Bel BL0416F) shooting

Fig. 2 is the photo that adopts the big depth of field of camera system shooting of the present invention

Fig. 3 is the optical system imaging schematic diagram that tradition focuses pick-up lens

Fig. 4 is the optical system imaging schematic diagram that focuses pick-up lens of the present invention

Fig. 5 is the camera head that a kind of big depth of field method for designing according to the present invention is made

Embodiment

The method for designing of camera head of the present invention comprises following three steps:

1. determine the focal length of camera lens according to the field range of the image planes size of ccd video camera that camera lens is joined and required observation.Focal length value f ' is determined by following formula:

$f^{\&prime;}=\frac{\sqrt{{\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="HSA00000024248200031.png"\; state="\{\{state\}\}">H</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="W"\; filenames="HSA00000024248200031.png"\; state="\{\{state\}\}">W</figure-callout>}}^2}}{4\&CenterDot;\tan \mathrm{\&omega;}}......\left(1\right)$

In the formula: H-CCD video camera image planes height dimension

W-CCD video camera image planes width dimensions

ω-required observation angle of half field-of view

2. determine focusing object distance P according to the depth range of required observation.

As shown in Figure 4, focusing point is focusing object distance P to the distance of camera lens entrance pupil, with the far point of blur circle conjugation be depth of field long distance P to the distance of lens entrance pupil ₁, with the near point of blur circle conjugation be P to the distance of lens entrance pupil ₂, focusing object distance, depth of field long distance and this three of depth of field low coverage satisfy depth of field formula (2) and (3):

Depth of field long distance

Depth of field low coverage $P_{}$ ${}_2=\frac{{\mathrm{Pf}}^{\&prime;2}}{f^{\&prime;2}+\mathrm{\&delta;PF}}......\left(3\right)$

The depth of field

In the formula: the focal length of f '-camera lens

The blur circle diameter that allows on δ-camera lens image planes

The f-number of F-camera lens

Know f-number F big more (being that aperture is more little) by (4) formula, the depth of field is big more.But reducing aperture and but be to reduce luminous flux is cost, and the image that obtains like this is relatively dimer, therefore can select for use suitable little aperture to increase the depth of field when actual design.

Can release following formula by (2) formula and (3) formula:

$P=\frac{P_1{f}^{\&prime;2}}{f^{\&prime;2}+{\mathrm{\&delta;P}}_{1}F}......\left(5\right)$

With $P=\frac{P_2{f}^{\&prime;2}}{f^{\&prime;2}-{\mathrm{\&delta;P}}_{2}F}......\left(6\right)$

All can calculate focusing object distance P from formula (5) and (6), sometimes the client may at first propose a field depth, two P values calculating according to two end values (far-reaching distance inspired by what one sees and depth of field low coverage) of this scope may be different, we can determine it is preferential depth of field long distance P according to the needs of client or camera actual working environment ₁Or depth of field low coverage P ₂Perhaps both take into account, and are taking all factors into consideration depth of field Δ L=P ₁-P ₂Size after, determine focusing object distance P at last.

3. according to selected focusing object distance value selected reference object plane, according to this primary standard substance plane lens optical system is carried out optimum Design of Parameters, thereby obtain the parameters such as radius-of-curvature, refractive index, abbe number on thickness, position, the surface of each lens, determine the camera lens physical construction that the parameter of optical system with camera lens adapts at last.Because the focusing object plane when the reference substance plane of the initial designs of parameter of optical system and its real work coincide, and do not need to consider other focal length situations, thereby the desirable depth of field that the final depth of field that obtains can farthest be calculated near the above-mentioned theory formula.

＜the first embodiment 〉

Fig. 5 illustrates the camera head according to first embodiment of the invention.This big depth of field camera head is by big depth of field pick- up lens 1 and 1/2 ", horizontal resolution is that the ccd video camera 2 (not containing lens) of 480 lines combines.Camera lens 1 comprises seven lens, and wherein the 3rd and the 4th lens are balsaming lens, the focal distance f of camera lens 1 '=5mm, field angle 2 ω=100 ° (80 ° of levels, vertical 57 °), all the other parameters of camera lens 1 are as shown in table 1:

Focusing point is 250mm to the distance L on camera lens sphere summit, can calculate to such an extent that the blur circle diameter δ of the permission on the CCD is 0.02mm according to the size of CCD and resolution, f-number F=5.9, entrance pupil position l _Z=16.0mm.Need L is converted into the focusing object distance of focusing point to the camera lens entrance pupil:

P＝L+l _Z＝250+16＝266mm

Table 1

Depth of field low coverage $P_{}$ ${}_2=\frac{{\mathrm{Pf}}^{\&prime;2}}{f^{\&prime;2}+\mathrm{\&delta;PF}}=\frac{266\&times;5^2}{5^2+0.02\&times;266\&times;5.9}=117.9\mathrm{mm}$

This value is the distance of depth of field near point to the camera lens entrance pupil, and the distance L that is converted to the camera lens surface is:

L＝P ₂-l _Z＝117.9-16＝101.9mm

Focusing object distance P=266mm, and f ' ²/ δ F=211.9mm knows depth of field long distance P by formula (2) ₁=∞.Therefore as long as target is enough big to the subtended angle of camera lens, can see infinity in theory.

Because the focusing object plane when the reference substance plane of the initial designs of the parameter of lens optical system of the present invention and its real work coincide, and do not need to consider other focal length situations, the desirable depth of field that its final depth of field that obtains can farthest be calculated near the above-mentioned theory formula.And traditional pick-up lens differs far away from the desirable depth of field.Fig. 1 is that (model is U.S. electric Bel BL0416F to the traditional zoom camera of employing, its f-number is 1.6, the photo of the little depth of field of ") shooting that image planes are of a size of 1/3; because the depth of field of camera lens is less; when focusing to medium and long distance; scenery such as the good fortune word at medium and long distance place and ladder are clearer, but the business card from camera lens nearer (about 100mm place) that is not positioned on the focusing point is but very unclear.And Fig. 2 is the photo that adopts the big depth of field that camera system of the present invention takes, and can see, no matter is scenery such as the good fortune word at medium and long distance place and ladder, and is still from the business card at the about 100mm of camera lens place, all very clear.The result who camera lens of the present invention is carried out actual measurement is: when focusing object plane position L was 250mm, close shot can reach 100mm deeply, and distant view can reach 20m deeply.This shows that the observing effect of camera head of the present invention is considerably beyond the observing effect of main flow zoom lens.

The invention is not restricted to the foregoing description, the foregoing description can carry out various distortion.For example, the radius-of-curvature of each lens, face interval and refractive index value etc. are not limited to the value shown in the foregoing description, can also get other values.And feature of the present invention especially is its method for designing, and all pick-up lenss according to method for designing manufacturing of the present invention all fall within protection scope of the present invention.

Claims (19)

1. the method for designing of a pick-up lens, it uses the constant camera lens of focal length, and carries out the initial designs of the parameter of lens optical system as the primary standard substance plane by the object plane of selecting to be positioned at the desired focusing object distance of camera lens actual working environment place.

2. method for designing according to claim 1 is characterized in that: described method for designing specifically may further comprise the steps:

According to camera lens be made into as the field range of the image planes size of device and required observation determine the focal distance f of camera lens ';

Determine focusing object distance P according to the field depth of required observation;

Focusing object distance value selected reference object plane according to selected carries out optimum Design of Parameters according to this primary standard substance plane to lens optical system, determines the camera lens physical construction that adapts with parameter of optical system then.

3. method for designing according to claim 2 is characterized in that: described focal length determines by following formula,

$f^{\&prime;}=\frac{\sqrt{H^2+W^2}}{4\&CenterDot;\tan \mathrm{\&omega;}}$

Wherein, H is the image planes height dimension of described image device, and W is image device image planes width dimensions, and ω is required observation angle of half field-of view.

4. method for designing according to claim 2 is characterized in that: described focusing object distance P decides according to depth of field low coverage or depth of field long distance, and its numerical value is respectively by following formula decision:

$P=\frac{P_2{f}^{\&prime;2}}{f^{\&prime;2}-\mathrm{\&delta;}{P}_{2}F}$ Or $P=\frac{P_1{f}^{\&prime;2}}{f^{\&prime;2}-\mathrm{\&delta;}{P}_{1}F}$

Wherein, P ₂Be depth of field low coverage, P ₁Be depth of field long distance, f ' is the focal length of camera lens, and δ is the blur circle diameter that allows on the camera lens image planes, and F is the f-number of camera lens.

5. method for designing according to claim 1 and 2 is characterized in that: described camera lens comprises one or more pieces lens.

6. method for designing according to claim 1 and 2 is characterized in that: the parameter of described lens optical system comprises radius-of-curvature, refractive index and the abbe number on the position of lens, thickness, surface.

7. method for designing according to claim 2 is characterized in that: described image device is CCD or CMOS photo-sensitive cell.

8. method for designing according to claim 2 is characterized in that: described image device is CCD or cmos camera.

9. pick-up lens, it is made according to each described method for designing among the claim 1-6.

10. pick-up lens, it is characterized in that: described camera lens comprises seven optical mirror slips, and light direction is vertical with going into, and is pressed into the light direction series arrangement and is connected to: first lens, it is the biconvex sheet; Second lens, it is concavo-convex; The 3rd lens, it is the concave-concave sheet; The 4th lens, it is the convex-concave sheet; The 5th lens, it is the biconvex sheet; The 6th lens, it is the concave-concave sheet; The 7th lens, it is the biconvex sheet; Wherein, the 3rd lens and the 4th lens glue lump together.

11. method for designing according to claim 10 is characterized in that: the front surface radius-of-curvature of first lens is 102.57mm, and the rear surface radius-of-curvature is 15.24mm; The front surface radius-of-curvature of second lens is-20.05mm that the rear surface radius-of-curvature is-55.21mm; The front surface radius-of-curvature of the 3rd lens is-30.2mm that the rear surface radius-of-curvature is 9.29mm; The front surface radius-of-curvature of the 4th lens is 9.29mm, and the rear surface radius-of-curvature is 63.68mm; The front surface radius-of-curvature of the 5th lens is 8.166mm, and the rear surface radius-of-curvature is-2128mm; The front surface radius-of-curvature of the 6th lens is-15.488mm that the rear surface radius-of-curvature is 7.345mm; The front surface radius-of-curvature of the 7th lens is 16.711mm, and the rear surface radius-of-curvature is-16.711mm.

12. according to claim 10 or 11 described methods for designing, it is characterized in that: the thickness of first to the 7th lens is followed successively by 3.5mm, 3mm, 2mm, 3.5mm, 2.8mm, 1.2mm, 2.5mm; The refractive index of first to the 7th lens is followed successively by 1.6221,1.6221,1.7883,1.7847,1.6921,1.6477,1.6921; The abbe number of first to the 7th lens is followed successively by 56.71,56.71,47.39,25.76,54.54,33.87,54.54.

13. according to claim 10 or 11 described pick-up lenss, it is characterized in that: be spaced apart 7mm between first, second lens, be spaced apart 13mm between second, third lens, three, be spaced apart 0 between the 4th lens, four, be spaced apart 28.5mm between the 5th lens, five, be spaced apart 1.5mm between the 6th lens, be spaced apart 1.5mm between the 6th, the 7th lens.

14. pick-up lens according to claim 12, it is characterized in that: be spaced apart 7mm between first, second lens, be spaced apart 13mm between second, third lens, three, be spaced apart 0 between the 4th lens, four, be spaced apart 28.5mm between the 5th lens, five, be spaced apart 1.5mm between the 6th lens, be spaced apart 1.5mm between the 6th, the 7th lens.

15. pick-up lens according to claim 14 is characterized in that: when focusing object plane position L was 250mm, the actual measured results of described camera lens was, close shot reaches 100mm deeply, and distant view reaches 20m deeply.

16. a camera head, it comprises as each described pick-up lens among the claim 9-15.

17. camera head according to claim 16 is characterized in that: described camera head further comprises image device.

18. camera head according to claim 17 is characterized in that: described image device is CCD or CMOS photo-sensitive cell.

19. camera head according to claim 17 is characterized in that: described image device is CCD or cmos camera, and described camera lens adopts the structure of plug and play, can directly described camera lens be connected on CCD or the cmos camera.

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