CN1261789C - A wide-angle lens and camera based on the lens - Google Patents

Abstract

The invention discloses a wide-angle lens, which at least includes: a convex mirror, a convex lens, a half mirror and a thin lens; there is a circular hole in the center of the convex mirror, and the ratio of the radius of the circular hole to the spherical radius of the convex mirror is not greater than sin45°; the convex lens Embedded in the circular hole of the convex mirror; the semi-reflective half-mirror and the thin lens are sequentially located directly in front of the convex mirror, and the optical centers of the convex mirror, convex lens, semi-reflective half-mirror and thin lens are on the same optical axis. The invention discloses a camera based on the lens, which at least includes: a wide-angle lens and a light receiving and processing unit, and the light receiving part of the light receiving and processing unit is arranged on the real image plane directly behind the wide-angle lens. The wide-angle lens and the camera of the present invention can completely shoot the scenery within the viewing angle range of nearly 180° without being blocked, and the pictures taken have good adhesion.

Description

A wide-angle lens and camera based on the lens

technical field

The invention relates to a lens and a camera, in particular to a wide-angle lens and a camera based on the lens.

Background technique

At present, wide-angle photography or camera lenses and cameras based on wide-angle lenses that can be used for shooting large-scale scenes generally fall into the following categories:

A wide-angle lens using a single lens, as shown in FIG. 1 , is the most common type of wide-angle lens. This lens achieves a large shooting angle by increasing the middle thickness of the lens 101 . Usually, in order to increase the range of receiving light, the mirror surface is changed into an aspherical surface. However, it can be seen from Figure 1 that due to the limitations of the optical imaging principle, the light from a point close to the 180° field of view cannot be approximated to a point for imaging. Therefore, the camera angle of this lens is narrow and cannot be realized For the full-view camera effect, generally speaking, the camera angle of a camera using this type of wide-angle lens can only reach about 150° at most.

The structure of a camera using an ultra-wide-angle lens is shown in FIG. 2 . Consists of a convex mirror 201, a convex lens 202 and a unit for optical signal reception and signal processing, i.e. 203 conversion charge coupled device (CCD, Charge Coupled Device) unit, its shortcoming is because the signal processing unit 203 is located between the scene and the convex mirror, Therefore, there is always an area in the middle of the picture that cannot be photographed. The size of this area is the conical range surrounded by GC and HD as shown in Figure 2. And the data leads of the signal processing unit 203 are drawn from one end of the captured image, which also affects the use to a great extent.

Another type of ultra-wide-angle camera is realized through a composite lens. The composite lens contains multiple lenses, generally at least 4, and each lens shoots a range, and then realizes ultra-wide-angle shooting by splicing pictures taken by multiple lenses. Effect. The biggest problem with this method is that the images taken by multiple lenses are difficult to connect seamlessly.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a wide-angle lens and a camera based on the lens. It can completely shoot the scenery within the range of nearly 180° viewing angle without being blocked, and the captured pictures have good adhesion.

According to one aspect of the above-mentioned purpose, the present invention proposes a wide-angle lens, at least comprising: a convex mirror, a convex lens, a half mirror and a thin lens;

There is a circular hole in the center of the convex mirror, and the ratio of the radius of the circular hole to the spherical radius of the convex mirror is not greater than sin45°;

The convex lens is embedded in the round hole of the convex mirror;

The semi-reflective half-mirror and the thin lens are sequentially located directly in front of the convex mirror, and the optical centers of the convex mirror, the convex lens, the semi-reflective half-mirror and the thin lens are on the same optical axis;

The positions of the convex lens, the thin lens, and the half-mirror, and the focal lengths of the convex lens and the thin lens make the inner boundary of the object point set imaged by the first imaging approach and the outer boundary of the object point set imaged by the second imaging approach The real image formed by the boundary behind the convex mirror coincides exactly;

Wherein, the first imaging approach is the approach in which the incident light emitted from the object point enters the convex lens after being reflected twice by the convex mirror and the half-mirror, and forms a real image behind the convex mirror after being refracted by the convex lens; the second The first imaging method is that the incident light emitted from the object point enters the thin lens, after being refracted by the thin lens, it enters the convex lens through the semi-reflective mirror, and then forms a real image behind the convex mirror after being refracted by the convex lens.

The mirror surface of the said half mirror of the lens is a plane, and the thin lens is a concave lens.

The mirror surface of the half mirror in the lens is a spherical surface, the thin lens is a concave lens, and the convex surface of the half mirror faces the thin lens.

The mirror surface of the half mirror in the lens is a spherical surface, the thin lens is a concave lens, and the convex surface of the half mirror faces away from the thin lens.

The mirror surface of the half-mirror in the lens is a spherical surface, the thin lens is a convex lens, and the convex surface of the half-mirror faces the thin lens.

The diameter of the semi-reflective half mirror of the lens is not smaller than the circular hole diameter of the convex mirror.

The caliber of the half-mirror described in the lens is not larger than the diameter of the circle formed by the vertical plane of the optical axis including the optical center of the half-mirror and the side surface of the boundary circular frustum.

Wherein, the upper bottom of the boundary frustum is a circular hole of a convex mirror, and the lower bottom is a circle formed by the collection of all object points that form a real image through the second imaging approach on a plane perpendicular to the optical axis.

The aperture of the thin lens described in the lens is not larger than the diameter of the circle formed by the vertical plane of the optical axis including the optical center of the thin lens and the side surface of the boundary circular frustum.

Wherein, the upper bottom of the boundary frustum is a circular hole of a convex mirror, and the lower bottom is a circle formed by the collection of all object points that form a real image through the second imaging approach on a plane perpendicular to the optical axis.

The convex mirror of the lens is connected with the circular boundary of the half mirror through a colorless transparent material.

In the lens, the circular boundary between the half mirror and the thin lens is connected by a transparent or opaque material.

According to another aspect of the object of the present invention, the present invention provides a kind of video camera based on wide-angle lens, at least comprises: wide-angle lens, and comprises light-receiving processing unit, and the light-receiving part of light-receiving processing unit is positioned on the real image plane directly behind described wide-angle lens .

The position of the light receiving and processing unit of the camera is fixed, and the position of the real image plane is determined by the position of the best imaging object plane determined when designing the lens.

The light receiving and processing unit of the camera includes a charge-coupled device (CCD) for photoelectric conversion and a signal processing circuit for signal format conversion and signal correction. The CCD is located on the real image plane directly behind the wide-angle lens. The output of the CCD is connected to Input to the signal processing circuit.

The signal processing circuit of the camera includes: a format conversion circuit, an analog-to-digital circuit, and a digital correction circuit. The CCD converts the optical signal into an electrical signal in the CCD format and inputs it to the format conversion circuit. After format conversion, it is input to the analog-to-digital circuit. It is converted into a digital signal and input to the digital correction circuit, and the digital signal is corrected and then output.

The light receiving and processing unit of the camera includes a CMOS photoelectric conversion device for photoelectric conversion and a signal processing circuit for signal format conversion and signal correction. The CMOS photoelectric conversion device is arranged on the real image plane directly behind the wide-angle lens. The output of the conversion device is connected to a signal processing circuit.

The signal processing circuit of the camera includes: a format conversion circuit, an analog-to-digital circuit, and a digital correction circuit. The CMOS converts the optical signal into an electrical signal in a CMOS format and inputs it to the format conversion circuit. After format conversion, it is input to the analog-to-digital circuit. It is converted into a digital signal and input to the digital correction circuit, and the digital signal is corrected and then output.

It can be seen from the above scheme that the wide-angle lens provided by the present invention is composed of a group of optical mirrors composed of reflective mirrors and transmissive mirrors, which can theoretically image objects within the viewing angle range of 180°. parameters, so that the image formed by the lens has a good adhesion effect. The camera based on this lens can fully capture the scene within the viewing angle range of nearly 180°, and the light receiving processing unit can also correct the image formed by the lens to obtain a satisfactory picture effect.

Description of drawings

Fig. 1 is the structure and imaging schematic diagram of the wide-angle lens that adopts single lens in the prior art;

Fig. 2 is a structural schematic diagram of a super wide-angle camera and a lens in the prior art;

Fig. 3 is the structural representation of camera and wide-angle lens of the first embodiment of the present invention;

Fig. 4 is a schematic diagram of determining the relationship between the aperture of a convex mirror and its spherical radius in the first embodiment of the present invention;

Fig. 5 is a schematic diagram of determining the aperture range of a convex mirror in the first embodiment of the present invention;

Fig. 6 is a schematic diagram of determining the position of point A and its virtual image point A ₁ ' in the first embodiment of the present invention;

Fig. 7 is a schematic diagram of determining the boundary position of two imaging approaches in the first embodiment of the present invention;

Fig. 8 is a schematic diagram of determining the positions and parameters of other optical elements in the first embodiment of the present invention;

FIG. 9 is a schematic structural diagram of a signal processing unit according to the first embodiment of the present invention;

10 is a schematic structural diagram of the digital correction circuit in the signal processing unit of the first embodiment of the present invention;

Fig. 11 is a schematic structural diagram of a pixel-by-pixel storage correction parameter acquisition device according to the first embodiment of the present invention;

12 is a schematic structural view of a camera and a wide-angle lens according to a second embodiment of the present invention;

13 is a schematic structural view of a camera and a wide-angle lens according to a third embodiment of the present invention;

FIG. 14 is a schematic structural diagram of a camera and a wide-angle lens according to a fourth embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The wide-angle lens of the present invention is composed of a convex mirror, a convex lens, a half-mirror and a thin lens, and can theoretically image objects within a viewing angle range of 180°. The actual shooting angle exceeds 170°, and has a super large-angle shooting range. The light receiving and processing unit of the video camera based on the lens of the present invention is located at the rear of the lens, which will not block the entrance of light, and has a signal correction function to correct the image formed by the wide-angle lens to compensate for the brightness of the image formed by the lens. average defects.

The structure of the wide-angle lens and the camera based on the lens in the first preferred embodiment of the present invention is shown in FIG. 3 . Fig. 3 is the structure of the whole camera in this embodiment, including two parts of the light receiving and processing unit and the wide-angle lens. The lenses that make up the wide-angle lens are sequentially from left to right: a convex mirror 301 , a convex lens 302 , a half mirror 303 and a concave lens 304 . Wherein, leave a hole in the center of convex mirror 301, convex lens 302 is embedded in this hole; The frame body 306 is connected, and the frame body 306 can be transparent or opaque, tapered or cylindrical depending on different situations. Scenery outside the conical range enclosed by the straight line GC and HD will be reflected by the convex mirror 301 and the half mirror 303, and then imaged by the convex lens 302 and received by the photoelectric conversion device, which is called the first type in this paper. Imaging approach; while the scenery within the conical range enclosed by the straight lines GC and HD is refracted by the concave lens 304 and then passes through the half-mirror 303 and is imaged by the convex lens 302 and received by the photoelectric conversion device, which is called the second an imaging pathway.

The light receiving processing unit can adopt signal processing unit 203 or CMOS photoelectric conversion device etc., select to adopt the signal processing unit 203 that CCD and signal processing circuit are formed in the present embodiment, CCD is arranged on the image plane of certain real image of convex lens 302, will The image formed by the object is converted into a pixel-by-pixel electrical signal, which is converted into a standard video signal format by a signal processing circuit. The positional relationship between the lenses of the wide-angle lens and the determination of lens parameters in this embodiment, as well as the positional relationship between the signal processing unit 203 and the wide-angle lens in the camera, will be described in detail below in conjunction with the drawings.

Before determining the lens parameters of the wide-angle lens, a better spherical radius R of the convex mirror 301 can be determined according to the actual needs of the lens application environment, hereinafter referred to as the radius of the convex mirror 301 .

Then, the allowable range of the circular hole radius of the convex mirror 301 is determined according to the known radius R of the convex mirror 301 .

For a certain radius R of the convex mirror in the present invention, the radius of the round hole of the convex mirror 301 will have an upper limit. Referring to shown in Fig. 4, suppose convex mirror 301 circle hole radius is r, G is the upper end point of circle hole, and the distance of G point to optical axis is circle hole radius r, and G ' is that G is set in the half mirror 303 into a virtual image point, and O is the center of the spherical surface of the convex mirror 301. Want to make the incident light WG from the vertical optical axis of the point W of the 180° view field to the upper end point G of the circular hole enter the convex lens 302 after being reflected twice by the convex mirror 301 and the half mirror 303, instead of exceeding the upper end of the circular hole of the convex mirror Edge G, then the position of point G cannot be too high. It can be seen from FIG. 4 that the critical condition is that the extended line of the reflected light from the 180° angle of view reaching the point G is reflected by the convex mirror 301, and the extended line of the reflected light does not exceed the image point G' of G.

Find the relationship between r and R in this critical case. As shown in Figure 4, the reflected ray GG' in the extreme case is parallel to the optical axis, so the reflected ray GG is perpendicular to the incident ray WG from the 180° viewing angle, ∠WGG'=90°. According to the reflection law, the incident angle is equal to the reflection angle, and the normal line OK should bisect ∠WGG′, so in this case the critical angle of reflection angle ∠KGG′=45°.

Also ∠KGG′=∠KOE, set ∠KOE=α _r , according to the above analysis, if the light WG at point W is to enter the convex lens 302, then α _r ≤45°. Then according to the trigonometric function relation r/R=sinα _r , so get:

r/R≤sin45° (1)

It can be seen that the round hole of the convex mirror 301 cannot be opened too large, otherwise it will affect the light reception in the viewing area of 180°, but the round hole aperture of the convex mirror 301 should not be too small, otherwise it will affect the amount of light entering. Therefore, the better diameter of the circular hole can be designed according to the specific conditions during design.

After the circular hole of the convex mirror 301 is determined, a convex lens 302 is embedded in the circular hole, as shown in FIG. 4 . The optical center of the convex lens 302 is located at the center of the circular hole of the convex mirror 301 .

In order to make the imaging angle of the wide-angle lens of this embodiment reach 180°, it is necessary to limit the allowable minimum value of the caliber of the convex mirror 301:

5, H is the lower endpoint of the convex lens 302, that is, the lower endpoint of the circular hole, H' is the virtual image point of H about the half mirror 303, and Q is the upper endpoint of the convex mirror 301. Want to make the light WQ that the vertical optical axis of point W of 180 ° view field shoot toward point Q not exceed the lower edge of convex lens 302 after being reflected twice by convex mirror 301 and half-mirror 303, then at least need to make the ray WQ from 180 ° view field The incoming light reaches the image point H' of H after being reflected by the convex mirror 301. Assuming that the reflection angle ∠KQH'= _γH in this critical situation, it can be seen from Fig. 5 that only when the incident point of the light rays coming from the vertical optical axis in the 180° view field is behind the point Q, can they reach the convex lens 302, so The boundary of the convex mirror 301 must be selected after point Q to ensure the reception and imaging of light rays in the 180° viewing angle.

The critical angle γ _H is calculated below in conjunction with FIG. 5 . Let the distance from Q to the optical axis, that is, the half of the diameter of the convex mirror 301, be h, the distance between the optical center of the convex lens 302 and the half-mirror 303 be d, ∠QOE=α, and in this critical situation, α=α ₀ , h is h ₀ , sinα ₀ =h ₀ /R, α ₀ =arcsinh ₀ /R can be obtained from the trigonometric relationship. The relationship between the interior and exterior angles of a triangle can be known

γ _H =∠QOE+∠QVO=α ₀ +∠QVO.

Make a vertical line from point Q to the optical axis OE, set the vertical foot as Q ', the optical center of the convex lens 302 is M, and the optical center of the virtual image 501 formed by it through the half mirror 303 is M ', QH ' and optical axis OE intersect at V, and from sinα _r =r/R, we get arcsin(r/R)=α _r , then we can get

ctg∠QVO=Q′V/QQ′=Q′M′/(QQ′+H′M′)={Rcos[arcsin(r/R)]+2d-Rcos[arcsin(h ₀ /R)]} /(h ₀ +r)={Rcos[arcsin(α _r )]+2d-Rcosα _r }/(Rsinα ₀ +r) so we get

γ _H ＝α ₀ +arcctg{Rcos[arcsin(α _r )]+2d-Rcosα _r }/(Rsinα ₀ +r)

It is also known from Figure 6 that α+∠WQK=90°, and in the critical case, the incident angle ∠WQK=∠KQH′=γ _H =90°-α ₀ , thus:

90°-α ₀ ＝α ₀ +arcctg{Rcos[arcsin(α _r )]+2d-Rcosα ₀ }/(Rsinα ₀ +r) (2) The value of α ₀ can be obtained by formula (2), and this is the minimum critical angle of α, which is related to the radius R of the convex mirror 301, the radius r of the circular hole, and the distance d from the convex lens 302 to the half mirror 303. After α ₀ is determined, the minimum diameter h ₀ of the convex mirror 301 can be determined by sin α ₀ =h ₀ /R.

In this way, a group of better aperture h and hole radius r of the convex mirror 301 can be determined according to the constraints of the above formulas (1) and (2) and in combination with actual needs.

Next, a group of special object points and their image points are determined to further determine the remaining parameters of the wide-angle lens lens of the present invention, as well as the position of the signal processing unit 203 in the camera.

Referring to Fig. 6, at first, select an object point A in the field of view of 180°, and the distance from point A to the optical axis of the convex mirror 301 is the object point with the best imaging effect of the camera lens of the present invention in the field of view of 180° This is because the camera lens of the present invention has a fixed focal length, so it is necessary to first determine the object distance of its best imaging effect in the design according to factors such as the installation position and usage of the camera lens.

Referring to FIG. 6 , the light emitted from point A in the viewing area of 180° is reflected by the convex mirror 301 and forms a virtual image A ₁ ′ behind the convex mirror 301 . Slowly move point A along the optical axis, there must be two light rays sent from point A that are reflected by convex mirror 301 and half-mirror 303 and then respectively tangent to the upper and lower edges of convex lens 302, as shown in Figure 6, according to The reversibility of the optical path can also be regarded as the extension of the two reflected rays being tangent to the upper and lower edges of the virtual image 501 formed by the convex lens 302 on the half mirror 303 . Since point A is far away from the convex mirror 301, the light from point A can be approximately regarded as parallel light in order to simplify the calculation. The determination of point A can be realized by the point-by-point drawing method of moving point A along the optical axis point by point, and it can also be obtained by computer simulation. After the point A is determined, the position of the virtual image point A ₁ ′ formed by it on the convex mirror 301 can be determined. Similarly, there will be a point B at the position symmetrical to point A under the optical axis, and the virtual image B ₁ ′ formed by point B is also symmetrical to point A ₁ ′. In fact, there are many such points, and they together form A, Point B is a ring perpendicular to the optical axis. And through A ₁ ′, B ₁ ′ forms an image plane A ₁ ′B ₁ ′ perpendicular to the optical axis.

Next, determine the boundary line of the object point imaged by the first imaging approach and the second imaging approach, that is, the positions of the straight lines GC and HD in FIG. 3 .

Referring to Fig. 7, on the plane shown in the figure, according to the principle of geometric optics, the upper end point G of the circular hole of the convex mirror should be the starting point of the dividing line GC, and the incident light CG directed to the convex mirror 301 along the straight line GC passes through the convex mirror 301 The reflected light should point to the virtual image G' formed by G on the half mirror 303, so GG' should be the reflected light of the incident light CG.

In this way, the incident ray CG of GG' can be inversely deduced by the law of reflection. If an object point C is selected on the GC straight line, so that the virtual image point C′ formed by point C on the convex mirror 301 is located on the image plane A ₁ ′B ₁ ′, then the image point C ₁ ′ should be the reverse extension line of GG′ Intersection point with A ₁ ′B ₁ ′ image plane. According to the geometrical optical characteristics of the convex mirror 301, one of the rays emitted from point C will be the incident ray CO that is incident on the convex mirror 301, and the extension line of this ray passes through the virtual image point C ₁ ' and the sphere of the convex mirror 301 Heart O. Thus, the position of the object point C can be obtained, which is the intersection of the straight lines OC ₁ ′ and GC where the two incident rays are located. Similarly, there will be an object point D and its image point D ₁ ′ at a position symmetrical to the optical axis of points C and C ₁ ′. In this way, two boundary lines GC and HD can be determined.

Determination of the caliber range of the half mirror 303:

From the above analysis, it can be seen that the light emitted from the object in front of the lens above the optical axis is reflected by the convex mirror 301 and the reflected light cannot exceed the reflected light GG' at the highest, and the reflected light below the optical axis cannot exceed HH', so the semi-reflective The aperture of half mirror 303 can not be less than the distance 2r of GG ' and HH '; Otherwise, it can be seen from the above analysis that part of the incident light entering the convex lens 302 after being reflected by the convex mirror 301 will be blocked, which may cause some areas to be invisible and the images of some object points to become dark.

Determination of concave lens 304 position and parameters:

Referring to Fig. 8, C ₁ ″ and D ₁ ″ are virtual images formed by C ₁ ′ and D ₁ ′ with respect to the half mirror 303, and C ₂ ′ and D ₂ ′ are virtual images formed by C and D through the concave lens 304 point. In order to make the same object point image at the same point after passing through the convex lens 302 through different paths, C ₂ ′, D ₂ ′ must coincide with C ₁ ″, D ₁ ″ according to the principle of geometrical optics. In this way, the positions of a group of object points C, D and image points C ₂ ′, D ₂ ′ imaged by the concave lens 304 are determined. Let the optical center of the concave lens 304 be O ₁ , according to the principle of concave lens imaging, the intersection of the incident ray CC ₂ ′ connecting the object point and the image point and the optical axis is the optical center position of the concave lens 304, so that the optical center O ₁ position of the concave lens can be determined . Furthermore, the focal length of the concave lens 304 can be determined, assuming that the distance between the optical center O ₁ of the concave lens 304 and the image plane C ₂ ′D ₂ ′ is d ₁ , the distance between O ₁ and the object plane CD is d ₂ , and the focal length of the concave lens 304 is f _A , then according to the concave lens 304 imaging formula: 1/f _A ＝1/d ₁ -1/d ₂ , get

f _A ＝d ₂ d ₁ /(d ₂ -d ₁ ) (3)

Find the focal length of the concave lens 304. So far, it can be seen that the collection of object points imaged on the image plane A ₁ ′B ₁ ′, that is, the object plane is actually a circular plane parallel to the image plane A′B′ where CD is located plus the AB ring as the edge A rotationally symmetric arc.

The determination of the position of the CCD and the focal length of the convex lens 302 in the signal processing unit 203:

Still referring to Fig. 8, assume that the plane A ₁ ′B ₁ ′ intersects the optical axis at O _V , the distance between O _V and the optical center O is OO _V =L, and the distance d ₃ between the plane C ₂ ′D ₂ ′ and the convex lens 302 It is: d ₃ =Rcosα _r -L+2d, the distance between the CCD and the convex mirror 301 is d ₄ , if the CCD can receive the image formed by C ₂ ′ through the convex lens 302, the image is actually the object point C through For the image formed after the concave lens 304, the half mirror 303 and the convex lens 302, _d3 should be regarded as the object distance, and _d4 should be regarded as the image distance, so according to the imaging formula of the convex lens 302, 1/f _T =1/d ₃ +1/d ₄ , get the focal length of the convex lens 302

f _T ＝d ₃ d ₄ /(d ₃ +d ₄ ) (5)

It can be seen from formula (5) that the focal length of the convex lens 302 is related to multiple factors such as the positions of the CCD and the half mirror 303, the radius of the convex mirror 301, and the aperture of the convex mirror 301. The aperture of the concave lens 304 should preferably have its edge just reach the conical surface surrounded by GC and HD in order to maximize the amount of incident light.

In this way, according to the constraints described above and combined with the needs in practical applications, the positions, parameters such as aperture and focal length of each component of the wide-angle camera lens of the present invention can be determined, as well as the position of the signal processing unit 203 .

The light-receiving processing unit of the camera in this embodiment adopts the signal processing unit 203 composed of CCD and signal processing circuit, and the image formed by the object is converted into a pixel-by-pixel electrical signal by the CCD, and converted into a standard video signal format by the signal processing circuit . Referring to FIG. 9 , the signal processing unit 203 includes a CCD and a signal processing circuit, and the signal processing circuit specifically includes: a format conversion circuit 901 , an analog-to-digital conversion circuit 902 and a digital correction circuit 903 . The CCD converts the received optical signal into a CCD-specific video signal format, which is converted into a composite video signal (Composite Video), a bright color separation video signal (S-Video) or a red, green and blue three-color separation signal (RGB) by the format conversion circuit 901 and other forms of analog signals, then enter the analog-to-digital circuit 902 to convert into digital YUV video component signals or RGB video signals, and then enter the digital correction circuit 903 for correction, and finally output the corrected digital YUV or RGB video signals to the monitor or storage devices, etc.

The digital correction circuit 903 is mainly to solve the non-uniform phenomenon in the imaging brightness of the wide-angle lens of the present invention. The specific structure of the digital correction circuit 903 is shown in FIG. 10 , which mainly includes: a correction arithmetic unit 1001 and a memory 1002 . A correction parameter table containing correction parameters stored pixel by pixel is stored in the memory 1002, and the memory 1002 may be a flash memory (FlashROM) or an E ² PROM. After receiving the digital YUV or RGB video signal sent by the digital correction circuit 903, the correction operator 1001 corrects the input signal by reading and comparing the correction parameter table in the memory 1002, and then converts the corrected digital YUV or RGB video signal output.

In order to obtain the pixel-by-pixel stored correction parameters in the correction parameter table, an initial calibration of the CCD is required for the lens used. The initial correction scheme has been developed very maturely and generally, the principles and methods are as follows:

The lens is placed in an optical test room with uniform brightness, and an image is taken with this lens to obtain an image I(i, j) with uneven brightness.

Comparing this image with the standard image with uniform brightness I(i,j)=I ₀ , a correction coefficient k(i,j)=I ₀ /I(i,j) is calculated for each pixel in turn.

Afterwards, when using this lens to take pictures, the brightness of each pixel on the lens is multiplied by a correction coefficient to obtain an image whose brightness is consistent with the actual scene.

The structure of the device for storing correction parameters pixel by pixel is shown in FIG. 11 . It includes: CCD, format conversion circuit 901 , analog to digital circuit 902 , correction parameter generating operator 1101 and memory 1002 . Place the CCD in a uniform light environment, and the uniform light signal received by the CCD is converted into a CCD-specific video signal format, which is converted into digital YUV or RGB video after being processed by the same format conversion circuit 901 and analog-to-digital circuit 902 as in Figure 9 After the signal enters the correction parameter generation calculator 1101, the correction parameters are calculated and stored pixel by pixel, and then stored in the memory 1002.

The device of the present invention is when making, and the frame body 305 that connects convex mirror 301 and half-mirror 303 can adopt transparent materials such as glass in order not to block the incident of light, as to connect the frame body 306 of half-mirror 303 and concave lens 304 then can Choose transparent or opaque materials arbitrarily, and preferably make the frame body 306 just intersect with the cone surrounded by CO ₁ and DO ₁ , so as to block excess light from entering the concave lens 304 .

The shooting angle of the wide-angle lens of the present invention can reach more than 170°, theoretically can reach 180°, which is far larger than that of general wide-angle lenses, and the pictures taken have good adhesion. Although the picture is slightly distorted, it can well meet the application requirements in some specific occasions.

In addition, the wide-angle lens of the present invention is not limited to the structure described in the first embodiment, and other embodiments will be briefly introduced below.

The second preferred embodiment of the present invention is shown in FIG. 12 . The mirror surface of the half mirror 1201 adopts a spherical surface, and the spherical surface faces the concave lens 304 .

The third preferred embodiment of the present invention is the structure shown in FIG. 13 , which replaces the concave lens 304 of the second embodiment with a convex lens 1301 .

The third preferred embodiment of the present invention is the structure shown in FIG. 14 . The difference from the second embodiment is that the back of the spherical mirror surface of the half mirror 1401 is directed to the concave lens 304 .

In a word, the semi-reflective half-lens and the concave lens part of the wide-angle lens of the present invention can adopt different combinations and have various structural forms. The position of the signal processing unit 203 of the wide-angle lens camera is set behind the wide-angle lens, so the incident light will not be blocked, and the determination of the position of the CCD is also similar to the method described in the first embodiment.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (16)

1, a kind of wide-angle lens is characterized in that comprising at least: convex mirror, convex lens, half-reflecting half mirror and thin lens;

At the center of convex mirror one circular hole is arranged, the ratio of the radius of circular hole and convex mirror spherical radius is not more than sin45 °;

Convex lens are embedded on the circular hole of convex mirror;

Half-reflecting half mirror and thin lens are positioned at the dead ahead of convex mirror successively, and the photocentre of convex mirror, convex lens, half-reflecting half mirror and thin lens is on same optical axis;

Convex lens, thin lens, half-reflecting half mirror three's position, and the focal length of convex lens and thin lens make the object point set by the imaging of first kind of imaging approach inner boundary and the outer boundary of gathering by the object point of second kind of imaging approach imaging its behind convex mirror, become real image just in time to overlap;

Wherein, described first kind of imaging approach injected convex lens for the incident light that sends from object point after through convex mirror and half-reflecting half mirror two secondary reflections, and planoconvex lens refraction back becomes the approach of real image at the rear of convex mirror; Second kind of imaging approach injected thin lens for the incident light that sends from object point, after the thin lens refraction, sees through half-reflecting half mirror and injects convex lens, and planoconvex lens refraction back becomes the approach of real image at the rear of convex mirror again.

2, camera lens according to claim 1, the minute surface that it is characterized in that described half-reflecting half mirror is the plane, thin lens is concavees lens.

3, camera lens according to claim 1, the minute surface that it is characterized in that described half-reflecting half mirror is a sphere, and thin lens is concavees lens, and the convex surface of half-reflecting half mirror is towards thin lens.

4, camera lens according to claim 1, the minute surface that it is characterized in that described half-reflecting half mirror is a sphere, and thin lens is concavees lens, and the convex surface of half-reflecting half mirror is thin lens dorsad.

5, camera lens according to claim 1, the minute surface that it is characterized in that described half-reflecting half mirror is a sphere, and thin lens is convex lens, and the convex surface of half-reflecting half mirror is towards thin lens.

6, camera lens according to claim 1 is characterized in that the bore of described half-reflecting half mirror is not less than the Circularhole diameter of described convex mirror.

7, camera lens according to claim 1, the bore that it is characterized in that described half-reflecting half mirror is not more than the optical axis vertical plane and the border frustum cone side that comprise this half-reflecting half mirror photocentre and hands over the diameter of a circle that forms;

Wherein, the upper bottom surface of described border round platform is the convex mirror circular hole, its bottom surface be one with the vertical plane of optical axis on become the belongings point set of real image to be become by second kind of imaging approach circle.

8, camera lens according to claim 1, the bore that it is characterized in that described thin lens is not more than the optical axis vertical plane and the border frustum cone side that comprise this thin lens photocentre and hands over the diameter of a circle that forms;

Wherein, the upper bottom surface of described border round platform is the convex mirror circular hole, its bottom surface be one with the vertical plane of optical axis on become the belongings point set of real image to be become by second kind of imaging approach circle.

9, camera lens according to claim 1 is characterized in that being connected by colourless transparent material between the circular boundary of described convex mirror and half-reflecting half mirror.

10, camera lens according to claim 1 is characterized in that described half-reflecting half mirror is connected by transparent or opaque material with circular boundary between the thin lens.

11, a kind of video camera based on wide-angle lens, it is characterized in that comprising at least: as any described wide-angle lens of claim 1～10, and comprising the light-receiving processing unit, the light receiving part of light-receiving processing unit is positioned on the real image plane in described wide-angle lens dead astern.

12, video camera according to claim 11 is characterized in that the position of described light-receiving processing unit is fixed, the determining positions of the optimal imaging object plane that the position of the real image plane at its place is determined during camera lens by design.

13, video camera according to claim 11, it is characterized in that described light-receiving processing unit comprises the charge coupled device ccd that is used for opto-electronic conversion and is used for the also signal processing circuit of correction signal of signal format conversion, CCD is positioned on the real image plane in described wide-angle lens dead astern, and the output of CCD is connected to the input of signal processing circuit.

14, video camera according to claim 13, it is characterized in that described signal processing circuit comprises: format conversion circuit, analog-to-digital circuit and digital correction circuit, CCD inputs to format conversion circuit with the electric signal that light signal converts the CCD form to, carry out inputing to the analog-to-digital circuit after the format conversion, convert digital signal to and input to digital correction circuit, digital signal is proofreaied and correct back output.

15, video camera according to claim 11, it is characterized in that described light-receiving processing unit comprises the CMOS electrooptical device that is used for opto-electronic conversion and is used for the also signal processing circuit of correction signal of signal format conversion, the CMOS electrooptical device is arranged on the real image plane in described wide-angle lens dead astern, and the output of CMOS electrooptical device is connected to signal processing circuit.

16, video camera according to claim 15, it is characterized in that described signal processing circuit comprises: format conversion circuit, analog-to-digital circuit and digital correction circuit, CMOS inputs to format conversion circuit with the electric signal that light signal converts the CMOS form to, carry out inputing to the analog-to-digital circuit after the format conversion, convert digital signal to and input to digital correction circuit, digital signal is proofreaied and correct back output.

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