WO2015016382A1

WO2015016382A1 - Imaging apparatus

Info

Publication number: WO2015016382A1
Application number: PCT/JP2014/070657
Authority: WO
Inventors: Kensuke Masuda; Yuji Yamanaka; Go Maruyama
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2013-07-31
Filing date: 2014-07-30
Publication date: 2015-02-05
Anticipated expiration: 2016-01-31
Also published as: JP2015046867A

Abstract

An imaging apparatus including an image sensor (40) that receives a light having passed through an opening part (51) of an aperture member having a quadrangular shape of a hexagonal shape and condensed by an imaging optical system (20) via a micro lens array (30), a light condensing unit, a micro light-condensing member array, and a light receiving element array are arranged so as to reduce a non-correspondence light reception area that does not deal with any micro light-condensing member and not receive the light on the light receiving element array more than a case where correspondence light reception areas that deal with each micro light-condensing member and receive the light having passed through a circular opening part are circumscribed with each other.

Description

DESCRIPTION

IMAGING APPARATUS

TECHNICAL FIELD

The present invention relates to an imaging apparatus that receives, by a light receiving element array in which a lot of light receiving elements are arranged in two dimensions via a micro light-condensing member array in which a plurality of micro light-condensing members are arranged in two dimensions, a light from an imaging area.

BACKGROUND ART

When a light from a certain subject spot comes into an imaging lens, the light is condensed at a point on an image sensor and light amount information at the certain subject spot is obtained in a normal imaging apparatus. The light amount information includes not only luminance information at the subject spot but also light amount information of a specific wavelength, light amount information of a specific polarization component at the subject spot, and the like with intervention of optical filters of various kinds.

Also known is a special imaging apparatus, which is called "light field camera" or "plenoptic camera" and in which a micro lens array in which a lot of small lenses (micro lenses) are arranged in two dimensions is arranged

immediately before the image sensor In which a lot of light receiving elements are arranged in two dimensions.

In the special imaging apparatus, when a light from a certain subject spot comes into the imaging lens, the light is condensed on at least one micro lens on the micro lens array. The light beam that comes from the subject spot and is condensed. on the micro lens changes in outgoing direction from the micro lens depending on a difference in incoming direction towards the micro lens, and is split to and received by the plurality of light receiving elements, which deal with the micro lens, on the image sensor. On this occasion, a light coming into the micro lens from a given incoming direction is received by a specific light receiving element among the plurality of light receiving elements dealing with the micro lens. Therefore, it is possible to specify the difference in incoming direction towards the micro lens depending on the difference of the light receiving elements.

According to the special imaging apparatus having such characteristics, it is possible for example to change a focus position of an image after shooting (Japanese Patent No. 4752031) . To explain this respect, a light to be received by one light receiving element on the image sensor is equal to a light coming from a particular incoming direction with respect to a corresponding micro lens. In other words, the light to be received by one light

receiving element is equal to a light having exited towards a particular outgoing direction from a particular location on the imaging lens. In the light having exited towards the particular outgoing direction from the particular location on the imaging lens, there are mixed lights from a plurality of subject spots which are present with different distances away from the imaging lens. While the lights, to be received by the one light receiving element, from the plurality of subject spots exit from any other locations on the imaging lens, respective outgoing directions from respective locations are different from each other

depending on the plurality of subject spots and the lights are to be received by respective light receiving elements different from each other. Therefore, a combination of the plurality of light receiving elements that receive the light from one subject spot among the plurality of subject spots is different depending on each of the plurality of subject spots. By utilizing this respect and tallying a light reception amount of the plurality of light receiving elements involved in a certain combination, it is possible to obtain light amount information of a subject spot

corresponding to the combination. In other words, it is possible to selectively obtain light amount information of multiple subject spots which are present with different distances away from the imaging lens by changing the

combination for tally. As a result, it becomes possible to generate a plurality of images whose focus positions are different from each other based on pixel data obtained by a single imaging operation.

According to this special imaging apparatus, it is also possible to obtain a plurality of filter images whose optical characteristics are different based on pixel data obtained by a single imaging operation, for example (United States Patent No. 7433042). This respect will be explained by taking, as an example, a configuration of arranging, on an incoming optical path to the imaging lens or on an outgoing optical path from the imaging lens, an optical filter which is divided into a plurality of filter areas that allow a selective transmission of lights each having its own optical characteristics (wavelength characteristics, polarization characteristics, and the like). A light from a certain one subject spot, after passing through all locations on the imaging lens, is to be split to and

received by the plurality of light receiving elements on the image sensor via the micro lens array. Specifically, while coming from the same subject spot, the light to be received by these light receiving elements passes through different locations on the imaging lens. With the

arrangement of the optical filter provided with the

plurality of filter areas on the optical path, the light having been emitted from the same subject spot and having passed through the plurality of filter areas different from each other can be received by different light receiving elements. As a result, it becomes possible to obtain a plurality of filter images each of which has selected optical characteristics for each filter area based on the pixel data obtained in a single imaging operation.

When correspondence light reception areas for each micro lens is configured to overlap on the image sensor, the number of the micro lens dealing with a light receiving element at the overlapping portion becomes not one. Since not being associated with an incoming direction to a

corresponding single micro lens, the light receiving

element becomes wasted enough not to contribute to the function of the special imaging apparatus. Besides, when an interval between correspondence light reception areas for each micro lens is made wide, the number of light receiving elements not dealing with a micro lens (light receiving elements that do not receive the light having passed through the micro lens) increases. Such light receiving elements also become wasted enough not to

contribute to the function of the special imaging apparatus. It is important in the special imaging apparatus to use as many finite light receiving elements on the image sensor as possible without waste and it is desired to reduce the number of wasted light receiving elements and increase the usage efficiency of the image sensor.

In FIG. 10, (a) is a view showing a frame format of a relation of an imaging lens, a micro lens array, and an image sensor in a conventional apparatus; (b) is an explanatory view of correspondence light reception areas (only three areas are illustrated) for each micro lens on the image sensor.

Here, while being actually configured by an imaging optical system including a plurality of optical parts such as a lens, a mirror, and the like, the imaging lens is illustrated equivalently as a single lens.

In the conventional apparatus, a relation of an imaging lens (imaging optical system) 20, a micro lens array 30, and an image sensor 40 is normally determined to satisfy Equation (1') below. In Equation ( 1 ') , a symbol "D" denotes a diameter of an entrance pupil of the imaging lens 20, a symbol "F" denotes a focal point distance of the imaging lens 20, a symbol "d" denotes a diameter of an entrance pupil of a micro lens 31, and a symbol "f" denotes a focal point distance of the micro lens 31. Here, the micro lens array 30 is arranged in the vicinity of the focal point distance of the imaging lens 20.

D/F = d/f (1' ) Generally, an aperture of the conventional apparatus has a circular shape as illustrated in (b) in FIG. 10 and correspondence light reception areas (macro pixels) for each micro lens on the image sensor 40 also have a circular shape. When the relation of the imaging lens (imaging optical system) 20, the micro lens array 30, and the image sensor 40 satisfies Equation (1'), the circular

correspondence light reception areas for each micro lens 31 are arranged by being mutually circumscribed without overlapping with each other as illustrated in (b) in FIG. 10. Since the correspondence light reception areas for each micro lens 31 do not overlap with this configuration, there is no wasted light receiving element because of overlapping. ; Besides, since the circular correspondence light reception areas for each micro lens 31 are arranged in the manner of being circumscribed, there are fewer wasted light receiving elements than the arrangement in which a gap is present among correspondence light reception areas.

However, even in this configuration, there are still a lot of wasted light receiving elements that do not deal with any micro lens 31. In this respect, an explanation will be made specifically by using an image example

illustrated in FIG. 11. The example illustrated in FIG. 11 shows an image having pixel values corresponding to

respective light reception amounts of respective light receiving elements on the image sensor in the conventional apparatus. In this image, while the circular

correspondence light reception areas for each respective micro lens 31 have respective pixel values, the other portion, i.e., a portion surrounded by 2 x 2, four in total, correspondence light reception areas is a pixel in black with no pixel value. In the conventional apparatus, light receiving elements in this portion become wasted since not dealing, with any micro lens.

SUMMARY OF THE INVENTION

It is an object of the present invention to at least partially solve the problems in the conventional technology.

According to an embodiment, there is provided an imaging apparatus that includes an aperture member having an opening part through which light from an imaging area passes, the opening part having a quadrangular shape or a hexagonal shape; a light condensing unit that condenses the light from the imaging area; a micro light-condensing member array in which a plurality of micro light-condensing members are arranged in two dimensions; and a light receiving element array in which a plurality of light receiving elements that receive the light having passed through the opening part of the aperture member and

condensed by the light condensing unit via the micro light- condensing member array are arranged in two dimensions so that at least two light receiving elements receive the light through one micro light-condensing member. The light having passed through each micro light-condensing member is to be received by corresponding one of light receiving elements which are different from each other, depending on an incoming direction of the light incident to the each micro light-condensing member. The light condensing unit, the micro light-condensing member array, and the light receiving element array are arranged so that a non- correspondence light reception area becomes smaller than that in a configuration in which the opening part has a circular shape and correspondence light reception areas are circumscribed with each other, where the correspondence light reception areas are light reception areas

corresponding to the micro light-condensing members on the light receiving element array for receiving the light having passed through the opening part of the aperture member, and the non-correspondence light reception area is a light reception area not corresponding to any of the micro light-condensing members on the light receiving element array.

The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the

accompanying drawings . BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory view of a general principle of an imaging apparatus capable of specifying a difference in incoming direction to a micro lens depending on a difference of light receiving elements.

FIG. 2 shows a frame format of a brief configuration of the imaging apparatus.

FIG. 3 is a front view, seen from an incoming optical axis direction, of an aperture member to which an optical filter is attached in the imaging apparatus.

FIG. 4 is a cross sectional view of the aperture member taken along the incoming optical axis direction.

FIG. 5 is an explanatory view of a structure of the optical filter.

FIG. 6 illustrates (a) a relation of an imaging optical system, a micro lens array, and an image sensor in the imaging apparatus, and (b) light reception areas for each micro lens on the image sensor.

FIG. 7 illustrates (a) an example of an image of raw image data when an opening part of the aperture member has a circular shape like the conventional way, and (b) an example of an image of raw image data when the opening part of the aperture member has a square shape like the

embodiment .

FIG. 8 illustrates a relation between an entrance pupil diameter D and an entrance pupil length D' of the imaging optical system according to the embodiment.

FIG. 9 illustrates a relation between the entrance pupil diameter D and the entrance pupil length D' of the imaging optical system when the opening part of the

aperture member has a regular hexagonal shape.

FIG. 10 illustrates (a) a relation of an . imaging lens, a micro lens array, and an image sensor in the conventional apparatus, and (b) correspondence light reception areas for each micro lens on the image sensor.

FIG. 11 illustrates an example of an image of raw image data in the conventional apparatus.

DESCRIPTION OF EMBODIMENTS

An embodiment of an imaging apparatus according to the present invention will be explained below with reference to the accompanying drawings .

Before explaining a specific configuration of an imaging apparatus according to the embodiment, a general principle of an imaging apparatus capable of specifying a difference in incoming direction to a micro lens depending on a difference of light receiving elements will be

explained with reference to FIG. 1.

Here, an imaging optical system is illustrated as a single lens 20' and an aperture position S of the imaging optical system is illustrated at the center of the single lens 20' to explain the principle in an easy-to-understand way. Besides, three kinds of filters fR (R: red), fG (G: green) , and fB (B: blue) constituting an optical filter is illustrated at the center of the single lens 20' .

In the vicinity of a light condensing position of the single lens 20', arranged is a micro lens array 30 as a micro light-condensing member array in which a plurality of micro lenses (micro light-condensing members) 31 are arranged in two dimensions. Besides, in the vicinity of a focus position of each micro lens 31, arranged is an image sensor 40 as a light receiving element array in which a lot of light receiving elements that receive a light condensed by the single lens 20' via the micro lens array 30 are arranged in two dimensions in such a manner that at least two light receiving elements deal with one micro lens 31. Here, a monochrome sensor is used as the image sensor 40 for easy understanding.

A light from one subject spot 10 which is present at a focal point distance of the single lens 20' within an imaging area radiates and is incident on different

locations on the single lens 20' and passes through the filter areas fR, fG, and fB having different spectral characteristics depending on the locations of the incidence. The light having passed through each of the filter areas fR, fG, and fB is condensed on a corresponding micro lens 31

(one micro lens 31 is assumed here) on the micro lens array 30. On this occasion, an incoming direction (incoming angle) to the micro lens 31 differs depending on the

location where the light passes on the single lens. When the incoming direction to the micro lens 31 differs, an outgoing direction from the micro lens 31 differs and the light is received by different light receiving elements on the image sensor 40. The light having passed through different locations on the single lens, i.e., the light having passed through different filter areas fR, fG, and fB is received by different light receiving elements. Thus, it is possible in a single imaging operation to detect, by the image sensor 40, a light having different wavelength components at a certain one subject spot 10.

As for a subject spot which is present at the focal point distance of the single lens 20' and different from the subject spot 10 illustrated in FIG. 1, too, a light having passed through each of the filter areas fR, fG, and fB is condensed on a different micro lens 31 on the micro lens array and received by different light receiving

elements on the image sensor 40 similarly to what is

explained above. Thus, it is possible in a single imaging operation to detect a light having different wavelength components with respect to each spot of the subject which is present at the focal point distance of the signal lens 20' by the image sensor 40. As a result, it is possible in a single imaging operation to obtain filter images having respective wavelength components for the filter areas fR, fG, and fB by extracting image signals for the respective filter areas fR, fG, and fB from an image signal (signal indicating an amount of light received by each light receiving element) output from the image sensor 40.

While, as for a subject spot present at a distance out of the focal point distance of the single lens 20', a light having passed through the filter areas fR, fG, and fB is split to and received by a plurality of micro lenses 31 on the micro lens array, the fact remains that the light is received by different light receiving elements on the image sensor 40. A relation between the distance of the subject spot and a light receiving element that receives the light having passed through the filter areas fR, fG, and fB from the subject spot is defined unambiguously. Therefore, it is also possible in a single imaging operation to detect, by the image sensor 40, a light having different wavelength components with respect to each spot, present at a distance out of the focal point distance of the single lens 20' , of the subject, similarly to what is explained above.

FIG. 2 shows a frame format of a brief configuration of the imaging apparatus according to the embodiment.

The imaging apparatus according to the embodiment is provided with the imaging optical system 20 as a light condensing unit constituted by optical parts such as a plurality of lenses, the micro lens array 30 as a micro light-condensing member array, and the image sensor 40 as a light receiving element array. The imaging optical system 20 includes: an aperture member 50 provided with an opening part 51 through which a light from the imaging area passes; and an optical filter 60 that is arranged in a manner of blocking the opening part 51 of the aperture member 50 and has , i.e., sixteen filter areas each of which has different spectral characteristics. In the imaging

apparatus according to the embodiment, it is therefore possible in a single imaging operation to obtain filter images on sixteen kinds of different wavelength components.

FIG. 3 is a front view, seen from an incoming optical axis direction, of the aperture member 50 to which the optical filter 60 is attached.

FIG. 4 is a cross sectional view of the aperture member 50 to which the optical filter 60 is attached, taken along the incoming optical axis direction.

FIG. 5 is an explanatory view of a structure of the optical filter 60.

As illustrated in FIG. 5, filter areas fl to fl6 having sixteen kinds of different spectral characteristics are created in the optical filter 60 according to the embodiment by arranging strip-shaped filter members F5 to F8 on the 2 x 2 matrix arrangement of four filter members Fl to F4 each of which has different spectral

characteristics (each of which allows different wavelength component to pass). Specifically, the filter area fl has only the spectral characteristics of the filter member Fl, the filter area f2 has a combination of the spectral characteristics of the filter members Fl and F5, the filter area f3 has a combination of the spectral characteristics of the filter members F2 and F6, the filter area f4 has only the spectral characteristics of the filter member F2 , the filter area f5 has a combination of the spectral characteristics of the filter members Fl and F7, the filter area f6 has a combination of the spectral characteristics of the filter members Fl, F5, and F7, the filter area f7 has a combination of the spectral characteristics of the filter members F2, F6, and F7 , the filter area f8 has a combination of the spectral characteristics of the filter members F2 and F7 , the filter area f9 has a combination of the spectral characteristics of the filter members F3 and F8, the filter area flO has a combination of the spectral characteristics of the filter members F3, F5, and F8, the filter area fll has a combination of the spectral

characteristics of the filter members F4 , F6, and F8, the filter area fl2 has a combination of the spectral

characteristics of the filter members F4 and F8 , the filter area fl3 has only the spectral characteristics of the filter member F3, the filter area fl4 has a combination of the spectral characteristics of the filter members F3 and F5, the filter area fl5 has a combination of the spectral characteristics of the filter members F4 and F6, and the filter area f16 has only the spectral characteristics of the filter member F4.

While the configuration of attaching, to the optical filter 60, the aperture member 50 from the imaging area side as illustrated in FIG. 4 is adopted in the embodiment, a configuration of attaching the aperture member 50 from the side of the image sensor 40 may be adopted.

Next, a characterizing portion of the present

invention will be explained.

In FIG. 6, (a) illustrates a relation of the imaging optical system 20, the micro lens array 30, and the image sensor 40 in the imaging apparatus according to the

embodiment.

In FIG. 6, (b) illustrates light reception areas (only three areas are illustrated) for each micro lens on the image sensor. In FIG. 6, the imaging optical system 20 is

illustrated as a single lens, and the aperture member 50 and the optical filter 60 are illustrated at the center of the single lens.

In the aperture member 50 according to the embodiment, the opening part 51 thereof has a square shape as

illustrated in FIG. 3 and the area of the opening part 51 is fixed with no possibility of change allowed. Here, a correspondence light reception area (hereinafter referred to as "macro pixel") for each micro lens 31 on the image sensor 40 has a similarity shape of the shape of the opening part 51 of the aperture member 50. Since the opening part 51 of the aperture member 50 has the square shape in the embodiment, the shape of the macro pixel on the image sensor 40 is a square as illustrated in (b) in FIG. 6. As long as a macro pixel on the image sensor 40 has the square shape, it becomes possible in theory to eliminate the presence of non-macro pixel that does not receive the light having passed through the micro lens 31 with such an arrangement that adjacent macro pixels are in contact by sides without overlapping with each other as illustrated in (b) in FIG. 6.

When the opening part of the aperture member has a circular shape like the conventional way, there are a lot of non-macro pixel portions as illustrated in (a) in FIG. 7 even by arranging adjacent macro pixels without overlapping in a manner of being circumscribed with each other to minimize the non-macro pixel portion (non-correspondence light reception area, more specifically, a black pixel portion surrounded by 2 x 2, i.e., four circular macro pixels) which does not form a macro pixel. On the other hand, when the opening part 51 of the aperture member 50 is configured to have the square shape like the embodiment, it is possible in theory with the above-described arrangement relation to eliminate the presence of the non-macro pixel portion as illustrated in (b) in FIG. 7, to eliminate or substantially decrease wasted light receiving elements, and to enhance a usage efficiency of the image sensor.

In general, as the number of light receiving elements constituting one macro pixel is larger, it is easier to increase the number of filter images (the number of filter areas) that can be obtained at the same time, and the precision of a filter image is enhanced since the number of light receiving elements for each filter image is increased. Moreover, since resolution of directional information becomes high by focusing on a function as a refocus camera capable of generating a plurality of images each of which has a different point of focus based on pixel data obtained in a single imaging operation, a precision of an image in refocus calculation is heightened.

Here, a relation of the imaging optical system 20, the micro lens array 30, and the image sensor 40 according to the embodiment will be explained with reference FIG. 6.

In the explanation below, an entrance pupil diameter (the entrance pupil diameter indicates the maximum length of the entrance pupil in the specification) of the imaging optical system 20 is denoted by "D", a focal point distance of the imaging optical system 20 is denoted by "F", an entrance pupil diameter of the micro lens 31 is denoted by "d", and a focal point distance of the micro lens 31 is denoted by "f". Besides, an entrance pupil length of the imaging optical system 20 (hereinafter simply referred to as "entrance pupil length") is denoted by "D"', the

entrance pupil length being equivalent to a distance

between facing sides of the square of the opening part 51 of the aperture member 50. To. realize such an arrangement relation of the embodiment that adjacent macro pixels are in contact by sides without overlapping with each other, it is only necessary to satisfy Equation (9) below.

F/D' = f/d (9) FIG. 8 is an explanatory view of a relation between the entrance pupil diameter D and the entrance pupil length D' of the imaging optical system 20.

The entrance pupil length D' in the embodiment

satisfies Equation (10) below in relation to the entrance pupil diameter D (maximum length of the entrance pupil). Here, k = 2 in the expression.

D = k x D' (10) Hence, the relation of the entrance pupil diameter D of the imaging optical system 20, the focal point distance F of the imaging optical system 20, the entrance pupil diameter d of the micro lens 31, and the focal point distance f of the micro lens 31 satisfies Equation (11) below in the embodiment. Here, k = V2 in the equation.

D/F = k x d/f (11) The embodiment is to be configured to satisfy Equation

(11) by adjusting at least one of the entrance pupil diameter D of the imaging optical system 20, the focal point distance F of the imaging optical system 20, the entrance pupil diameter d of the micro lens 31, and the focal point distance f of the micro lens 31. Among them, the entrance pupil diameter D (entrance pupil length D' ) of the imaging optical system 20 can be changed in such an easy method as to change the dimension of the opening part 51 of the aperture member 50. The entrance pupil diameter d of the micro lens 31 can also be changed in such an easy method as to adjust the distance between the imaging optical system 20 and the micro lens array 30. The relation shown by Equation (9) can be realized by changing the distance between the micro lens array 30 and the image sensor 40. Specifically, when the distance between the micro lens array 30 and the image sensor 40 is "g", Equation (12) below is obtained. Here, k = 2 in the equation. To realize such an arrangement relation of the embodiment that adjacent square-shaped macro pixels are in contact by sides without mutual overlap of the square- shaped macro pixels, Equation (12) below may be satisfied.

D' /F = k x d/g (12)

This case is to be configured to satisfy Equation (12) by adjusting at least one of the entrance pupil diameter D of the imaging optical system 20, the focal point distance F of the imaging optical system 20, the entrance pupil diameter d of the micro lens 31, and the distance g between the micro lens array 30 and the image sensor 40. The distance g between the micro lens array 30 and the image sensor 40 can be changed in an easy method. Specifically, the micro lens array 30 and the image sensor 40 are set to have such a distance as to be away from each other by k times as far as the focal point distance f of the micro lens array 30.

While the opening part 51 of the aperture member 50 is configured to have a square shape in the embodiment, the shape may be other polygonal shapes. Especially, when the shape of the opening part 51 of the aperture member 50 is a regular hexagon as illustrated in FIG. 9, it becomes possible in theory to eliminate the presence of non-macro pixel similarly to the case of the square shape.

A relation of the imaging optical system 20, the macro lens array 30, and the image sensor 40 in the case where the shape of the opening part 51 of the aperture member 50 is a regular hexagon will be explained. The entrance pupil length, equivalent to a distance between facing sides of the regular hexagon of the opening part 51 of the aperture member 50, of the imaging optical system 20 is set as D' . To realize such an arrangement relation of the embodiment that adjacent macro pixels are in contact by sides without overlapping with each other here, it is only necessary to satisfy Equation (9). Here, a coefficient k in Equation (10) between the entrance pupil length D' and the entrance pupil diameter D (maximum length of the entrance pupil) is 2/V3. Therefore, when the shape of the opening part 51 of the aperture member 50 is a regular hexagon, it is only necessary to adjust the

entrance pupil diameter D of the imaging optical system 20, the entrance pupil diameter d of the micro lens 31, and the like so that Equation (11) is satisfied (k = 2/>/3) and to adjust the distance g between the micro lens array 30 and the image sensor 40 so that Equation (12) is satisfied (k =

2/V3) .

Here, to eliminate the presence of non-macro pixel when the shape of the opening part 51 of the aperture member 50 is a regular hexagon, it becomes necessary to arrange micro lenses on the micro lens array 30 in a manner of being displaced horizontally by half of each piece in the even number sequence and the odd number sequence as illustrated in FIG. 9. ,

While the configuration that enables eliminating the presence of non-macro pixel portion is explained in the embodiment, the present invention is not limited thereto as long as the configuration enables reducing non-macro pixel portion more than the case where the opening part 51 of the aperture member 50 has a circular shape. For example in the case of square-shaped macro pixels, adjacent square- shaped macro pixels may be arranged in such a manner that sides of the macro pixels are close and in parallel with a small gap therebetween as long as the macro pixels do not overlap with each other. In this case, the value of the coefficient k in Equations (11) and (12) becomes smaller than Similarly, in the case of regular hexagonal macro pixels for example, adjacent regular hexagonal macro pixels are arranged in such a manner that side of the macro pixels are close and in parallel with a small gap therebetween as long as the macro pixels do not overlap with each other. In this case, the value of the coefficient k in Equations (11) and (12) becomes smaller than 2/V3. It is not

necessary that the shape of the opening part 51 of the aperture member 50 is an exact square or an exact regular hexagon.

What has been explained so far is just an example and the present invention has unique advantages for each of the following aspects.

Aspect A

An imaging apparatus includes an aperture member 50 provided with an opening part 51 through which light from an imaging area passes, the opening part 51 having a quadrangular shape or a hexagonal shape; a light condensing unit such as an imaging optical system 20 that condenses the light from the imaging area; a micro light-condensing member array such as a micro lens array 30 in which a plurality of micro light-condensing members such as micro lenses 31 are arranged in two dimensions; and a light receiving element array such as an image sensor 40 in which a plurality of light receiving elements that receive the light having passed through the opening part of the

aperture member and condensed by the light condensing unit via the micro light-condensing member array are arranged in two dimensions so that at least two light receiving

elements receive the light through one micro light- condensing member. The light having passed through each micro light-condensing member is to be received by

corresponding one of light receiving elements which are different from each other, depending on an incoming

direction of the light incident to the each micro light- condensing member. The light condensing unit, the micro light-condensing member array, and the light receiving element array are arranged so that a non-correspondence light reception area becomes smaller than that in a

configuration in which the opening part has a circular shape and correspondence light reception areas (macro pixels) are circumscribed with each other, where the correspondence light reception areas are light reception areas corresponding to the micro light-condensing members on the light receiving element array for receiving the light having passed through the opening part of the

aperture member, and the non-correspondence light reception area is a light reception area not corresponding to any of the micro light-condensing members on the light receiving element array.

Each of the correspondence light reception areas for each micro light-condensing member on the light receiving element array has a similarity shape of the shape of the opening part of the aperture member. Therefore, when the opening part of the aperture member has a quadrangular shape or a hexagonal shape, the correspondence light reception area on the light receiving element array has a quadrangular shape or a hexagonal shape. Due to the correspondence light reception area on the light receiving element array's having a quadrangular shape or a hexagonal shape, it is possible to realize one of a configuration in which the correspondence light reception areas do not overlap with each other and the non-correspondence light reception area is substantially decreased more than the case where the opening part has a circular shape and a configuration in which the correspondence light reception areas do not overlap with each other and the non- correspondence light reception area is eliminated.

Aspect B

In the imaging apparatus according to aspect A, the opening part of the aperture member has a square shape and when an entrance pupil diameter of the light condensing unit is D, a focal point distance of the light condensing unit is F, an entrance pupil diameter of the micro light- condensing member is d, and a focal point distance of the micro light-condensing member is f, Equations below are satisfied:

D/F = k x d/f

k < V2.

According to this aspect, it is possible to realize one of a configuration in which the correspondence light reception areas do not overlap with each other and the non- correspondence light reception area is decreased more than the case where the opening part has a circular shape and a configuration in which the correspondence light reception areas do not overlap with each other and the non- correspondence light reception area is eliminated.

Aspect C

In the imaging apparatus according to aspect A, the opening part of the aperture member has a square shape and when an entrance pupil diameter of the light condensing unit is D, a focal point distance of the light condensing unit is F, an entrance pupil diameter of the micro light- condensing member is d, and a distance between the micro light-condensing member and the light receiving element array is g, Equations below are satisfied:

D/F = k x d/g

k < 2.

Aspect D

In the imaging apparatus according to aspect A, the opening part of the aperture member has a regular hexagon and the plurality of micro light-condensing members are arranged in the micro light-condensing member array in a manner of being displaced horizontally by half of each piece in an even number sequence and an odd number sequence.

According to this aspect, it is possible to realize one of a configuration in which the correspondence light reception areas do not overlap with each other and the non- correspondence light reception area is substantially

decreased more than the case where the opening part has a circular shape and a configuration in which the

correspondence light reception areas do not overlap with each other and the non-correspondence light reception area is eliminated.

Aspect E

In the imaging apparatus according to aspect D, when an entrance pupil diameter of the light condensing unit is D, a focal point distance of the light, condensing unit is F, an entrance pupil diameter of the micro light-condensing member is d, and a focal point distance of the micro light- condensing member is f, Equations below are satisfied:

D/F = k x d/f

k < 2/V3.

Aspect F

In the imaging apparatus according to aspect D, when an entrance pupil diameter of the light condensing unit is

D, a focal point distance of the light condensing unit is F, an entrance pupil diameter of the micro light-condensing member is d, and a distance between the micro light- condensing member and the light receiving element array is g, Equations below are satisfied:

D/F = k x d/g

k < 2/V3.

Aspect G

The imaging apparatus according to any. one of aspects A to F includes an optical filter 60 that is arranged on an optical path from the imaging area to the micro light- condensing member array and has at least two kinds of areas selected from at least one kind of selection filter area that allows a particular optical component in the light from the imaging area to be selectively transmitted and a non-selection filter area that allows the light from the imaging area to be directly transmitted.

According to this aspect, it is possible in a single imaging operation to obtain respective filter images corresponding to respective filter areas fl to fl6 provided in the optical filter.

Aspect H

In the imaging apparatus according to, aspect G, the optical filter is provided in a manner of blocking the opening part of the aperture member.

According to this aspect, it is possible to easily obtain a high-quality filter image.

Aspect I

In the imaging apparatus according to aspect G or H, the at least two kinds of areas provided in the optical filter include at least two spectral filter areas fl to fl6 each of which allows a different wavelength component to be transmitted.

According to this aspect, it is possible in a single imaging operation to obtain respective filter images having respective wavelength components corresponding to

respective spectral filter areas fl to fl6 provided in the optical filter.

According to the embodiment, it is possible . to obtain an excellent advantage of enabling using a light receiving element which is wasted due to no correspondence with any micro lens in the conventional apparatus and enhancing a usage efficiency of an image sensor in an imaging apparatus capable of specifying the difference in incoming direction to a micro light-condensing member depending on the

difference of light receiving elements.

Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.

Claims

1. An imaging apparatus, comprising:

an aperture member having an opening part through which light from an imaging area passes, the opening part having a quadrangular shape or a hexagonal shape;

a light condensing unit that condenses the light from the imaging area;

a micro light-condensing member array in which a plurality of micro light-condensing members are arranged in two dimensions; and

a light receiving element array in which a plurality of light receiving elements that receive the light having passed through the opening part of the aperture member and condensed by the . light condensing unit via the micro light- condensing member array are arranged in two dimensions so that at least two light receiving elements receive the light through one micro light-condensing member,

wherein the light having passed through each micro light-condensing member is to be received by corresponding one of light receiving elements which are different from each other, depending on an incoming direction of the light incident to the each micro light-condensing member, and

the light condensing unit, the micro light-condensing member array, and the light receiving element array are arranged so that a non-correspondence light reception area becomes smaller than that in a configuration in which the opening part has a circular shape and correspondence light reception areas are circumscribed with each other, where the correspondence light reception areas are light

reception areas corresponding to the micro light-condensing members on the light receiving element array for receiving the light having passed through the opening part of the aperture member, and the non-correspondence light reception area is a light reception area not corresponding to any of the micro light-condensing members on the light receiving element array.

2. The imaging apparatus according to claim 1, wherein the opening part of the aperture member has a square shape, and

D/F = k x d/f, and

k < 2

are satisfied, where D is an entrance pupil diameter of the light condensing unit, F is a focal point distance of the light condensing unit, d is an entrance pupil diameter of the micro light-condensing member, and f is a focal point distance of the micro light-condensing member.

3. The imaging apparatus according to claim 1, wherein the opening part of the aperture member has a square shape, and

D/F = k x d/g, and

k < 2

are satisfied, where. D is an entrance pupil diameter of the light condensing unit, F is a focal point distance of the light condensing unit, d is an entrance pupil diameter of the micro light-condensing member, and g is a distance between the micro light-condensing member and the light receiving element array.

4. The imaging apparatus according to claim 1, wherein the opening part of the aperture member has a regular hexagon, and

the plurality of micro light-condensing members are arranged in the micro light-condensing member array so as to be displaced horizontally by half of each piece in an even number sequence and an odd number sequence.

5. The imaging apparatus according to claim 4, wherein D/F = k x d/f, and

k < 2/V3

6. The imaging apparatus according to claim 4, wherein D/F = k x d/g, and

k < 2/V3

are satisfied, where D is an entrance pupil diameter of the light condensing unit, F is a focal point distance of the light condensing unit, d is an entrance pupil diameter of the micro light-condensing member, and g is a distance between the micro light-condensing member and the light receiving element array.

7. The imaging apparatus according to any one of claims 1 to 6, further comprising an optical filter that is arranged on an optical path from the imaging area to the micro light-condensing member array and has at least two kinds of areas selected from at least one kind of selection filter area that allows a particular optical component in the light from the imaging area to be selectively transmitted and a non-selection filter area that allows the light from the imaging area to be directly transmitted.

8. The imaging apparatus according to claim 7, wherein the optical filter is provided in a manner of blocking the opening part of the aperture member.

9. The imaging apparatus according to claim 7 or 8, wherein the at least two kinds of areas provided in the optical filter include at least two spectral filter areas each of which allows a different wavelength component to be transmitted .