CN211236540U

CN211236540U - Front-mounted angle-enlarging mirror used underwater

Info

Publication number: CN211236540U
Application number: CN202020207908.0U
Authority: CN
Inventors: 鲁琴; 黎玉成
Original assignee: Dongguan Litu Precision Technology Co ltd
Current assignee: Dongguan Litu Precision Technology Co ltd
Priority date: 2020-02-25
Filing date: 2020-02-25
Publication date: 2020-08-11
Anticipated expiration: 2030-02-25

Abstract

The utility model discloses a leading angle of enlargement mirror that uses under water, including first lens, second lens, third lens and fourth lens, first lens and second lens are negative lens, and third lens and fourth lens are positive lens, and the effective bore scope of first lens, second lens, third lens and fourth lens is 110 in proper order and gives an eye-friendly 115mm, 80-85mm, 70-75mm and 57-62 mm. The first lens has the functions of isolating external water, resisting external water pressure, enlarging a shooting visual angle and correcting chromatic aberration. The first lens also replaces two lenses in the prior art, the height of the front-mounted angle-increasing mirror is reduced, and the weight and the production cost are reduced. When the front-mounted angle-increasing mirror is used underwater, the front-mounted angle-increasing mirror can be directly matched with a camera with a maximum visual angle of 84 degrees, and the visual angle is widened to 130 degrees; the extra repeated operations of adjusting the visual angle of the zoom lens by an underwater photographer to eliminate a black angle and the like in the prior art are reduced.

Description

Front-mounted angle-enlarging mirror used underwater

Technical Field

The utility model relates to an optical imaging technical field is applied to under water among the record shooting environment, concretely relates to be used for with digital camera sharing back, can provide wider visual angle (field of view) under water with promote the leading angle lens that enlarges of optical imaging quality (for example: reduce the colour difference, optical problems such as deformation). And the preposed angle-increasing mirror is supported to be replaced under water.

Background

The portable digital camera is a first choice for many photographers to enter the door because of small and exquisite body, convenient carrying and high cost performance. In recent years, with the rapid development of electronic technology and image processing technology, portable digital cameras have a qualitative leap in both focusing speed and image quality, and have been able to compete with professional micro single cameras or single lens reflex cameras. Therefore, bringing portable digital cameras into underwater photography has become a hobby of many underwater photographers.

Underwater photography using portable digital cameras is usually mounted in special watertight housings to avoid direct contact with water or seawater. The waterproof shell is made of plastic or aluminum alloy and has enough strength to resist water pressure; the front end is provided with a lens cone for protecting the lens. The front end of the lens cone is provided with a flat glass window or a hemispherical transparent cover, and the flat glass window or the hemispherical transparent cover and the sealing ring are sealed. The camera and the lens installed in the waterproof shell shoot underwater images through the flat glass window or the hemispherical transparent cover and outside water or seawater.

Because of the absorption effect of water on light, the underwater light can be obviously weakened along with the increase of the depth; in nature, moreover, there are also a large number of minute impurities in the water, and visibility is relatively low. When natural light is used for shooting underwater, a clear picture can be shot only in a limited depth by zooming in. Typically, photographers also utilize a flash light or flashlight or the like as a primary or secondary light source for underwater photography, again for the reasons described above, where the light illuminates the subject only at close distances. Therefore, many photographers can take scenes such as large benthos and fish school in a short distance by using a lens with an ultra-large visual angle. The most wide-angle zoom end view angle of a common portable digital camera is only 75-84 degrees, which is far from meeting the requirements of underwater photographers.

On the other hand, due to the optical characteristics of water or seawater, the camera will generate additional color difference problems during underwater imaging, i.e. color distortion and color stripes of the image. In addition, due to the refraction effect (refractive index of 1.33-1.34) of water or seawater, the original visual angle of the camera lens is narrowed after entering the water through the air in the waterproof shell. For example, the combined viewing angle of a lens barrel and a camera using a flat glass window is about two thirds of the original viewing angle. Another common method is to select a hemispherical transparent cover lens barrel, and to precisely measure and calculate to make the spherical center close to the position of the lens entrance pupil; the principle that the advancing direction is not changed when light is positively emitted into another transparent medium from one transparent medium is utilized, and the visual angle of the lens is recovered to the maximum extent.

In summary, when the existing portable digital camera is used for underwater shooting, the problem that the visual angle is not wide enough generally exists; moreover, due to the optical characteristics of water or seawater, when a subject image passes through the medium, the problem of large chromatic aberration exists, and the imaging quality is far lower than that of a photo taken on water.

In order to solve the problems of insufficient wide underwater shooting visual angle and chromatic aberration, one solution is to install a front wide-angle lens at the front end of a lens barrel of a waterproof shell, and a lens assembly in the front wide-angle lens can enlarge the visual angle and correct the chromatic aberration. As shown in fig. 1, the first lens (the leftmost lens in fig. 1) of the conventional front-mounted angle-increasing mirror is a hemispherical lens with a uniform thickness, and the material may be glass or plastic. The hemispherical lens has no effect on increasing the photographing angle of view except for isolating external water or seawater and resisting external water pressure. The design mainly depends on the second lens and the third lens to increase the shooting angle. And the third to fifth lenses correct various chromatic aberration problems by using different optical materials.

Although the existing front-mounted angle-enlarging lens has the capabilities of enlarging a shooting visual angle and correcting chromatic aberration, the height and the weight of the product are larger, and the cost is higher; moreover, the existing underwater front-mounted angle-enlarging mirror is mainly suitable for widening the maximum angle of view of the camera lens from 75 degrees to about 130 degrees at the wide angle end.

In recent years, with the development of portable digital cameras, the angle of view at the maximum wide angle end thereof has increased from 75 degrees to 84 degrees in the past, facilitating photographing of wider scenes. Because the existing underwater angle-enlarging mirror is suitable for corresponding to a camera view angle of 75 degrees, when the camera view angle is larger than 75 degrees, the black angle phenomenon appears at four corners. Therefore, when the existing underwater angle-enlarging lens is matched, an underwater photographer needs to manually zoom in each time to adjust the visual angle of the camera zoom lens, so that the visual angle is reduced to eliminate a black angle, and the method is very complicated and inconvenient.

Disclosure of Invention

The utility model aims at providing a leading angle of enlargement mirror that uses under water for the problem of visual angle not wide enough and colour difference when solving the camera and shooing under water is used for solving current leading angle of enlargement mirror height and weight great, the higher problem of cost simultaneously, and is used for solving current camera complex operation scheduling problem that leading angle of enlargement mirror adaptation visual angle reaches 84 degrees under water.

In one embodiment there is provided a front-mounted extended angle mirror for underwater use, comprising:

the camera waterproof shell comprises a shell, wherein the shell is of a cylindrical structure and is provided with a connecting end, and the connecting end of the shell is provided with a physical structure port for being connected with the camera waterproof shell in a rotary and quick-release manner;

the lens assembly comprises a first lens, a second lens, a third lens and a fourth lens which are coaxially mounted in the shell in sequence, the first lens and the second lens are negative lenses, the third lens and the fourth lens are positive lenses, the effective aperture range of the first lens is 110-115mm, the effective aperture range of the second lens is 80-85mm, the effective aperture range of the third lens is 70-75mm, and the effective aperture range of the fourth lens is 57-62 mm; the first lens is far away from the connecting end of the shell, the fourth lens is close to the connecting end of the shell, the first lens and the fourth lens are respectively connected with the shell in a sealing mode, the first lens, the fourth lens and the shell enclose a sealed containing cavity, and the second lens and the third lens are located in the containing cavity.

In one embodiment, the incident surface of the first lens is a convex surface, and the emergent surface of the first lens is a concave surface; the incident surface and the emergent surface of the second lens are both concave surfaces, and the incident surface and the emergent surface of the third lens are both convex surfaces; the incident surface of the fourth lens is a convex surface, and the emergent surface of the fourth lens is a concave surface.

In one embodiment, the first lens has an Abbe number of 62-66, the second lens has an Abbe number of 25-35, the third lens has an Abbe number of 44-48, and the fourth lens has an Abbe number of 24-28.

In one embodiment, the refractive index of the first lens is 1.4-1.6, the refractive index of the second lens is 1.8-2.0, the refractive index of the third lens is 1.5-1.7, and the refractive index of the fourth lens is 1.7-1.9.

In one embodiment, a broadband antireflection coating is attached to a surface of the first lens, the second lens, the third lens, and the fourth lens.

In one embodiment, a radially extending annular seat is provided on the inner wall of the housing, the surface of the first lens facing the second lens includes a concave surface in the middle and an annular flat surface located around the concave surface, and the annular flat surface of the first lens is mounted on the annular seat.

In one embodiment, the housing cavity of the housing is expanded to form a buoyancy chamber that generates buoyancy under water to offset the weight of the front-mounted angle-increasing mirror itself.

In one embodiment, the physical structure port of the housing is provided with a snap-fit device for connecting with a quick release interface.

In one embodiment, the physical structure port of the housing is provided with a water inlet channel for introducing water between the fourth lens and the flat glass of the waterproof camera housing.

According to the front-mounted angle-enlarging lens used underwater in the embodiment, the first lens adopts a negative lens structure, can isolate external water or seawater and resist external water pressure, and is matched with the three lenses to form images, so that the effects of increasing the shooting visual angle and correcting various chromatic aberrations are achieved. The first lens 21 with optical characteristics has the functions of waterproofing, correcting chromatic aberration and expanding visual angle, replaces two lenses in the prior art, and reduces the length of the front angle-enlarging lens in the optical axis direction, thereby reducing the height of the front angle-enlarging lens, reducing the number of lenses and reducing the weight and the production cost; in addition, the four lenses of the front-mounted angle-enlarging mirror adopt effective apertures within a specific range, and the visual angle of the camera at 84 degrees can be widened to 130 degrees under water. Therefore, when the front-mounted angle-increasing mirror is adapted to a camera with a maximum angle of view of 84 degrees, manual zooming is not needed each time, the angle of view of a zoom lens of the camera is narrowed to about 75 degrees, and extra operation in use is greatly reduced.

Drawings

FIG. 1 is a schematic diagram of a lens of a front-mounted magnifying lens in the prior art;

FIG. 2 is an axial sectional view of a front-mounted magnifying lens in an embodiment in use;

FIG. 3 is an exploded perspective view of the front-mounted magnifying lens according to an embodiment;

FIG. 4 is an exploded perspective view of the front-mounted magnifying lens according to an embodiment;

FIG. 5 is an optical diagram of a lens assembly in one embodiment;

FIG. 6 is a color difference plot of an underwater image of Panasonic LX100II with a hemispherical lens barrel and analyzed using ImatestSFRplus;

FIG. 7 is a color difference plot of an underwater image of Panasonic LX100II with a pre-wide angle lens of one embodiment analyzed using Imatest SFRplus;

the camera comprises a front-mounted angle-enlarging lens 100, a front-mounted angle-enlarging lens 200, a quick-release interface 300, a camera 10, a shell 11, a light shield 12, a buckle 13, an accommodating cavity 14, an annular seat 15, a buoyancy cavity 20, a lens assembly 21, a first lens 22, a second lens 23, a third lens 24, a fourth lens 24, a camera waterproof shell 400 and flat glass 401.

Detailed Description

The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.

Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.

The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings). For convenience of description, in the present embodiment, the end facing the object side is a front end, and the end facing the image side is a rear end.

The embodiment discloses a leading angle of enlargement mirror that uses under water, this leading angle of enlargement mirror mainly takes into the use in the water for diving fan, especially shoots the use in the sea. The front-mounted angle-amplifying mirror can be mounted at the front end of a lens barrel of a camera waterproof shell through a quick-release interface, a camera is located in the camera waterproof shell, the front-mounted angle-amplifying mirror has the effects of expanding a visual angle and correcting absolute differences, a land camera is assisted to shoot high-quality images underwater, and meanwhile the front-mounted angle-amplifying mirror has the advantages of small height, light weight and low cost.

The optical design of the front-mounted angle-enlarging mirror used underwater in the embodiment is suitable for a portable digital camera with a maximum wide-angle end viewing angle of 84 degrees. Therefore, when the product is used, even if the angle of view of the camera reaches 84 degrees, manual zooming is not needed each time, the angle of view of the zoom lens of the camera is narrowed to about 75 degrees, and extra operation in use is greatly reduced.

As shown in fig. 2, the front-mounted wide-angle mirror 100 of the present embodiment mainly includes a housing 10 and a lens assembly 20, the housing 10 is made of a waterproof material, such as an aluminum alloy material, the housing 10 is a cylindrical structure, and the housing 10 has a through hole penetrating the whole. The front end of the shell 10 is provided with a light shield 11, and the light shield 11 is composed of four trapezoidal light shields and used for eliminating reflection and stray light and improving the definition of imaging and color restoration. The light shield 11 can be mounted at the front end of the housing 10 in a clamping manner, and the light shield 11 and the housing 10 can also be of an integrated structure. The rear end of the shell 10 is a connecting end, the connecting end of the shell 10 has a physical structure port for being connected with a quick-release interface 200 (a quick-release interface device for installing a conversion lens underwater in patent document CN 206710779U) in a rotating and quick-release manner, the quick-release interface 200 is connected with a lens barrel of a camera waterproof housing 400, a camera 300 (such as a portable digital camera) is installed in the camera waterproof housing 400, a lens of the camera 300 is located in the lens barrel of the camera waterproof housing 400, the shell 10 can be quickly disassembled and assembled with the camera waterproof housing 400 through the quick-release interface 200, and underwater replacement and use are facilitated. The quick release interface 200 and the lens barrel of the waterproof camera housing 400 may be an integrated structure.

As shown in fig. 3 and 4, in order to realize quick assembly and disassembly of the front enhanced angle mirror 100, the physical structure port of the housing 10 is provided with three snaps 12, and the three snaps 12 are evenly distributed on the outer circumference of the physical structure port of the housing 10. The three buckles 12 are adapted to the clamping grooves of the quick-release connector 200, the housing 10 can be quickly disassembled from the quick-release connector 200 through rotation, and the quick-release connector 200 is connected with the lens barrel of the camera waterproof housing 400 through threads. The buckle 12 is arranged, so that the front-mounted angle-increasing mirror 100 can be rapidly assembled and disassembled with the waterproof camera shell 400 underwater, and the use is very convenient.

As shown in fig. 2, in the present embodiment, the lens assembly 20 includes a first lens 21, a second lens 22, a third lens 23 and a fourth lens 24, the first lens 21 to the fourth lens 24 are sequentially installed in the housing 10, and the four lenses are aligned and assembled on the same optical axis. The first lens 21 is located at the front end and the fourth lens 24 is located at the rear end, i.e. the first lens 21 is far away from the connecting end of the housing 10 and the fourth lens 24 is close to the connecting end of the housing 10. The first lens 21 and the fourth lens 24 are respectively connected to the housing 10 in a sealing manner, the first lens 21 and the fourth lens 24 are respectively connected to the housing 10 in a sealing manner through a sealing element, for example, the first lens 21 and the fourth lens 24 are respectively connected to the housing 10 in a sealing manner through a sealing ring, so that the first lens 21, the fourth lens 24 and the housing 10 are enclosed to form a sealed accommodating cavity 13, the second lens 22 and the third lens 23 are located in the accommodating cavity 13, and a corresponding limiting structure is arranged in the accommodating cavity 13 and used for fixing the second lens 22 and the third lens 23, for example, the limiting structure is an annular seat or a cylinder, which is not shown in fig. 2.

The first lens 21 is a negative meniscus lens, the incident surface of the first lens 21 is a convex surface, the exit surface is a concave surface, and the first lens 21 is mainly used for enlarging the viewing angle. The second lens 22 is a negative lens, the incident surface and the exit surface of the second lens 22 are both concave surfaces, and the second lens 22 is used for smoothing the light path, so that the turning is gentle and gentle to avoid generating high-order aberration. The third lens 23 is a positive lens, and an incident surface and an exit surface of the third lens 23 are convex surfaces, and are configured to converge light. The fourth lens 24 is a positive lens, an incident surface of the fourth lens 24 is a convex surface, an exit surface of the fourth lens 24 is a concave surface, the fourth lens 24 is also a meniscus lens, and the fourth lens 24 is used for reducing a focal length, reducing spherical aberration, and increasing a system numerical aperture by matching with the third lens 23.

The first lens 21 is a large negative lens, the front convex spherical radius is 80-85mm, the rear concave spherical radius is 50-55mm, the middle thickness is 5-6mm, and the first lens and the second lens are replaced by the prior lenses. The specially designed geometric shape can isolate external water or seawater, resist external water pressure, and is matched with the three lenses, so that the lens has the functions of increasing the shooting visual angle and correcting various chromatic aberrations. Compared with the past hemispherical design, the first lens 21 protrudes forward less, and the overall height of the product is reduced. The first lens 21 with optical characteristics has the functions of waterproofing, correcting chromatic aberration and expanding the angle of view, replaces the two lenses in the prior art, reduces the height (length in the direction of the optical axis) of the front-mounted angle-expanding lens 100, and reduces the weight and the production cost of the product.

As shown in fig. 5, the first lens 21, the second lens 22, the third lens 23 and the fourth lens 24 constitute a lens assembly 20 having functions of correcting chromatic aberration and enlarging an angle of view. Wherein, the effective aperture (diameter) range of the first lens 21 is 110-115mm, the effective aperture range of the second lens 22 is 80-85mm, the effective aperture range of the third lens 23 is 70-75mm, and the effective aperture range of the fourth lens 24 is 57-62 mm. The first lens 21, the second lens 22, the third lens 23 and the fourth lens 24 are overlapped with the optical axis of the camera 300 to form a wide-angle objective lens, so that a larger optical angle of view can be obtained, a larger picture can be shot, the front-mounted angle-increasing mirror 100 can be adapted to a camera with a maximum angle of view of 84 degrees, and the angle of view of the maximum angle of view of the camera is widened from 84 degrees to 130 degrees.

In order to realize better effects of widening the visual angle and correcting chromatic aberration, the first lens 21 is made of crown glass with an Abbe number of 62-66 and a refractive index of 1.4-1.6; the second lens 22 is made of heavy lanthanum flint glass with the Abbe number of 25-35 and the refractive index of 1.8-2.0, and the second lens 22 has the characteristics of high refractive index and large dispersion; the third lens 23 is made of light flint glass with Abbe number of 44-48 and refractive index of 1.5-1.7; the fourth lens 24 is made of heavy flint glass with an Abbe number of 24-28 and a refractive index of 1.7-1.9.

In this embodiment, for better fixing the first lens 21, an annular seat 14 formed by extending radially is provided on the inner wall of the housing 10, the surface of the first lens 21 facing the second lens 22 includes a concave surface in the middle and an annular flat surface around the concave surface, wherein the concave surface is the exit surface of the first lens 21, the annular flat surface is the fixing and mounting surface of the first lens 21, the annular flat surface of the first lens 21 is mounted on the annular seat 14 of the housing 10 in a fitting manner, and the first lens 21 is connected with the housing 10 in a sealing manner through an O-ring. The annular seat 14 and the first lens 21 block the front end of the housing 10, and the annular seat 14 plays a role in limiting and water isolating.

In this embodiment, the accommodating cavity 13 of the housing 10 is radially expanded to form a buoyancy cavity 15, the accommodating cavity 13 and the buoyancy cavity 15 are integrated cavities, and the buoyancy cavity 15 increases the buoyancy generated by the entire front-mounted augmented angle mirror 100 in water. Preferably, the buoyancy chamber 15 has a volume with a preset size, so that the buoyancy of the front-mounted angle-increasing mirror 100 in water is approximately equal to the self weight, and therefore the front-mounted angle-increasing mirror 100 does not increase the burden of a photographer under water, and the shooting is more stable. Specifically, because the densities of the fresh water and the seawater are different, the front-mounted augmented angle mirror 100 can also be divided into a fresh water applicable style and a seawater applicable style, and the sizes of the buoyancy chambers 15 of the fresh water applicable style and the seawater applicable style are slightly different, so that the buoyancy of the fresh water applicable style and the seawater applicable style in the fresh water and the seawater respectively is equal to the self weight; in actual experience, the buoyancy difference between fresh water and seawater is not obvious, and a universal shell 10 can also be adopted.

In this embodiment, a water inlet channel is disposed on a physical structure port of the housing 10, and the water inlet channel is a notch or a through hole, and the water inlet channel is used to introduce water between the fourth lens 24 and the flat glass 401 in the lens barrel at the front end of the waterproof camera housing 400. For this reason, the optical characteristics of the lens assembly 20 of the present embodiment take water between the fourth lens 24 and the flat glass 401 into account, and the lens assembly 20 simultaneously eliminates chromatic aberration and reduction of the angle of view caused by water between the fourth lens 24 and the flat glass 401. The structure enables the front-mounted angle-increasing lens 100 and the quick-release interface 200 to be directly disassembled and assembled and replaced underwater without considering the sealing problem between the front-mounted angle-increasing lens and the quick-release interface, and greatly facilitates quick replacement of the front-mounted lens during underwater photography.

In this embodiment, a plurality of broadband antireflection coatings are plated on the incident surface and the exit surface of the first lens 21, the second lens 22, the third lens 23 and the fourth lens 24, so as to reduce the problem of light reflection and further improve the imaging quality. In one embodiment, the optical parameters of the four lenses of lens assembly 20 are shown in Table 1 below:

TABLE 1

In the above table, the surface orders 1 to 9 are the incident surface and the exit surface of the first lens 21, the incident surface and the exit surface of the second lens 22, the incident surface and the exit surface of the third lens 23, the incident surface and the exit surface of the fourth lens 24, and the flat glass 401 at the front end of the lens barrel of the waterproof camera case 400, respectively. The thickness, the refractive index and the abbe number of the same column of the order 1 represent the thickness, the refractive index and the abbe number on the optical axis of the first lens 21; the thickness of the same column in order 2 represents the distance on the optical axis between the first lens 21 and the second lens 22; the thickness, refractive index and abbe number of the same column of order 3 represent the thickness, refractive index and abbe number on the optical axis of the second lens 22; the thickness of the same column of the order 4 represents the distance on the optical axis between the second lens 22 and the third lens 23; the thickness, refractive index and abbe number of the same column of the order 5 represent the thickness, refractive index and abbe number on the optical axis of the third lens 23; the thickness of the same column of the order 6 represents the distance on the optical axis between the third lens 23 and the fourth lens 24; the thickness, the refractive index and the abbe number of the same column of the order 7 represent the thickness, the refractive index and the abbe number on the optical axis of the fourth lens 24; the thickness of the same column in the sequence 8 represents the distance on the optical axis between the fourth lens 24 and the flat glass 401 at the front end of the lens barrel of the waterproof camera housing 400; the thickness, refractive index and abbe number of the same column in the order of 9 represent the thickness, refractive index and abbe number on the optical axis of the flat glass 401 of the lens barrel of the waterproof camera housing 400.

In the front-mounted angle-enlarging mirror used underwater according to the embodiment, since the four lenses are mounted in the housing 10, two of the four lenses located at the front end of the optics are positive lenses, and two of the four lenses located at the rear end of the optics are negative lenses, the lens assembly 20 can correct chromatic aberration caused during underwater shooting, and imaging quality is improved; in addition, the four lenses form a wide-angle objective lens, which enlarges the optical angle of view and can assist the camera 300 in shooting a wider range of images underwater. When the front-mounted angle-enlarging lens of the lens component 20 adopting the optical parameters is assembled with a portable digital camera underwater, the viewing angle at the maximum wide angle end is widened from 84 degrees to 130 degrees. Therefore, the front-mounted angle-increasing lens can widen the field angle of the camera and obtain larger shooting pictures.

FIG. 6 is a color difference plot of an underwater image of Panasonic LX100II with a hemispherical lens barrel and analyzed using ImatestSFRplus, with a combined viewing angle of about 84 degrees.

The analysis position is the lower left corner #4, ca (area) ═ 4.95pixels ═ 0.212% of center-ROI dist.

FIG. 7 is a color difference plot of an underwater image of Panasonic LX100II with a front-mounted gonioscopic lens of one embodiment analyzed using Imatest SFRplus, for a combined viewing angle of 130 degrees.

The analysis position is the lower left corner #4, ca (area) ═ 0.388pixels ═ 0.03% of center-ROI dist.

A Chromatic aberration area in pixels index representing a pixel value used by a Chromatic aberration channel from the highest to the lowest area; the larger the value, the more severe the color difference.

CA (area) as a percentage of the distance from the image center to the ROI: another better color difference index represents the color difference of the analyzed position and the pixel percentage of the distance from the image center to the position. Generally, the chromatic aberration of the imaging system increases proportionally from the center to the edge.

Calculating the formula:

CA(％)＝100％*CA(pixels)/(distance in pixels from the image center tothe ROI)

the severity of the chromatic aberration can be determined by reference to published standards of imatest, as follows:

Severity of chromatic aberration

the above related matters, referred to themselveshttp://www.imatest.com/docs/sfr_chromatic/。

It can be seen that when the Panasonic LX100II is matched with a common hemispherical transparent cover, the integral image chromatic aberration is in an over 0.15 range, and the chromatic aberration is relatively serious; in 100% mode, it is very obvious. When the Panasonic LX100II is matched with the lens assembly 20 with the optical parameters, the whole image chromatic aberration is still in the range of 0-0.04 even under the condition that the visual angle is widened to 130 degrees, and can be ignored; in 100% mode, not visible. Therefore, the front-mounted angle-increasing mirror can eliminate chromatic aberration caused by water or seawater, and high-quality images under large viewing angles can be obtained.

It should be noted that the scope of application of the underwater front-mounted wide-angle lens includes, but is not limited to, portable digital cameras, and is also applicable to other types of digital cameras, for example, when a lens with a specific viewing angle is used with a micro-lens or a single lens reflex camera for underwater photography, the lens can also play a role in widening the viewing angle and eliminating chromatic aberration.

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims

1. A pre-amble angle-enhancing mirror for underwater use, comprising:

2. The underwater front-mounted wide-angle mirror of claim 1, wherein the first lens has a convex entrance surface and a concave exit surface; the incident surface and the emergent surface of the second lens are both concave surfaces, and the incident surface and the emergent surface of the third lens are both convex surfaces; the incident surface of the fourth lens is a convex surface, and the emergent surface of the fourth lens is a concave surface.

3. The underwater front-mounted extended-angle mirror as claimed in claim 2, wherein the first lens has an abbe number of 62 to 66, the second lens has an abbe number of 25 to 35, the third lens has an abbe number of 44 to 48, and the fourth lens has an abbe number of 24 to 28.

4. The underwater front-mounted magnifying lens of claim 2, wherein the refractive index of the first lens is 1.4 to 1.6, the refractive index of the second lens is 1.8 to 2.0, the refractive index of the third lens is 1.5 to 1.7, and the refractive index of the fourth lens is 1.7 to 1.9.

5. The pre-amble angle mirror for underwater use of claim 1, wherein a surface of the first lens, the second lens, the third lens and the fourth lens is attached with a broadband antireflection coating.

6. The pre-amble angle of elevation mirror for underwater use of any of claims 1 to 5, wherein the inner wall of the housing is provided with a radially extending annular seat, the face of the first lens facing the second lens comprising a concave surface in the middle and an annular flat surface around the concave surface, the annular flat surface of the first lens being mounted on the annular seat.

7. The pre-amble angle mirror for underwater use according to any of claims 1 to 5, wherein the housing cavity of the housing is expanded to form a buoyancy chamber which generates buoyancy under water to offset the weight of the pre-amble angle mirror itself.

8. A pre-amble angle-enhancing mirror for underwater use according to any of claims 1 to 5, characterized in that the physical structure port of the housing is provided with snap means for connection with a quick release interface.

9. The pre-amble angle-enhancing mirror for underwater use of claim 8, wherein the physical structure port of the housing is provided with a water inlet channel for introducing water between the fourth lens and the flat glass of the waterproof camera housing.