KR20140051030A - Imaging optical system for 3d image acquisition apparatus, and 3d image acquisition apparatus including the imaging optical system - Google Patents

Abstract

Disclosed are an imaging optical system which can be manufactured in a reduced size to make the size of a 3D image acquisition device small and the 3D image acquisition device including the same. The disclosed imaging optical system comprises a common object lens; first and second image sensors having sizes different from each other; a beam splitter providing light for the first image sensor by transmitting part of light focused by the object lens and providing light for the second image sensor by reflecting the remaining part of the light; and at least one optical element disposed between the beam splitter and the second image sensor and reducing an image which is incident on the second image sensor. The optical element includes at least one among a Fresnel lens and a diffractive optical element. [Reference numerals] (105) Display; (106) Memory; (107) Control unit

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an imaging optical system for a three-dimensional image acquisition apparatus, and a three-

The disclosed embodiments relate to an imaging optical system for a three-dimensional image acquiring apparatus and a three-dimensional image acquiring apparatus including the same. More particularly, the present invention relates to a three-dimensional image acquiring apparatus, such as a 3D camera, And a three-dimensional image acquisition apparatus including the same.

In recent years, the importance of 3D contents has been highlighted along with the development of 3D display devices capable of displaying deep-seated images and the increasing demand. Accordingly, a three-dimensional image acquiring device such as a 3D camera capable of directly producing 3D contents by a general user is being studied. Such a 3D camera should be able to acquire depth information together with existing two-dimensional color image information in one shot.

Depth information on the distance between the surface of the subject and the 3D camera can be obtained by using a stereoscopic vision method using two cameras or a triangulation method using a structured light and a camera have. However, in this method, it is difficult to obtain accurate depth information because the accuracy of the depth information is drastically deteriorated as the distance of the subject becomes farther away, and it depends on the surface condition of the subject.

Time-of-flight (TOF) has been introduced to solve this problem. TOF technology is a method of measuring the light flight time from the time when the light reflected from the subject is received by the light receiving unit after illuminating the subject with the illumination light. According to the TOF technique, light of a specific wavelength (for example, near-infrared light of 850 nm) is projected to a subject using an illumination optical system including a light emitting diode (LED) or a laser diode (LD), and light of the same wavelength After the light is received by the light receiving unit, a series of processing is performed to extract the depth information by modulating the received light with a modulator having a known gain waveform. A variety of TOF technologies are introduced in this series of optical processes.

A 3D camera employing TOF technology typically has an illumination optical system for emitting illumination light for obtaining depth information and an imaging optical system for acquiring an image of a subject. The imaging optical system senses visible light reflected from a subject to generate a general color image, and detects illumination light reflected from the subject to generate a depth image having only depth information. For this purpose, the imaging optical system may separately include an objective lens for visible light, an image sensor, an objective lens for illumination light, and an image sensor, respectively (i.e., a two-lens two-sensor structure). However, since the viewing angle of the color image and the depth image are different from each other in the 2-lens 2-sensor structure, a separate procedure for accurately matching the two images is required, and the size of the 3D camera and the manufacturing cost may increase.

Accordingly, a 3D camera having one common objective lens and two image sensors has been proposed (i.e., a 1-lens 2-sensor structure). Also in this 1-lens 2-sensor structure, suppression of an increase in the volume and weight of the imaging optical system and the 3D camera and an increase in the manufacturing cost thereof is one of the main issues.

There is provided an imaging optical system that can be manufactured in a reduced size so as to reduce the size of a three-dimensional image acquiring apparatus having one common objective lens and two image sensors of different sizes.

Further, there is provided a three-dimensional image acquiring device including the imaging optical system.

An imaging optical system according to one type of the present invention includes: a common objective lens; First and second image sensors having different sizes; A first wavelength band light is divided into a first wavelength band light and a second wavelength band light by the objective lens, and the first wavelength band light is provided to the first image sensor, 2 beam splitter provided to the image sensor; And at least one optical element disposed between the beam splitter and the second image sensor to reduce an image incident on the second image sensor, wherein the at least one optical element comprises a Fresnel lens and Diffractive optical element.

For example, the at least one optical element may comprise at least two Fresnel lenses sequentially disposed along the optical path between the beam splitter and the second image sensor.

Also for example, the at least one optical element comprises a first optical element and a second optical element, respectively, which are in turn disposed along the optical path between the beam splitter and the second image sensor, A Fresnel lens, and the second optical element may be a diffractive optical element.

For example, the first optical element may be a collimating element for converting the light from the beam splitter into parallel light, and the second optical element may converge the parallel light onto the second image sensor to reduce the image.

The imaging optical system may further include an optical shutter disposed between the at least one optical element and the second image sensor and modulating the light of the first wavelength band and providing the modulated light to the second image sensor.

For example, the second image sensor may be smaller in size than the first image sensor, the light of the first wavelength band may be visible light, and the light of the second wavelength band may be infrared light.

The beam splitter may be configured to transmit light in the first wavelength band and reflect light in the second wavelength band.

According to another aspect of the present invention, there is provided an imaging optical system including: a common objective lens; First and second image sensors having different sizes; And a light source for emitting light of a first wavelength band and light of a second wavelength band by separating light of a first wavelength band and light of a second wavelength band among light focused by the objective lens, And a beam splitter provided to the second image sensor, wherein the beam splitter can be inclined at an angle larger than 45 degrees with respect to the optical axis of the objective lens.

For example, the beam splitter is formed on the light incident surface of the beam splitter and includes a plurality of fine first inclined surfaces formed to be inclined at 45 degrees with respect to the optical axis of the objective lens; And a plurality of microscopic second inclined surfaces formed on the light exit surface of the beam splitter and complementary to the plurality of first inclined surfaces, wherein the first inclined surface and the second inclined surface may be parallel to each other .

The beam splitter may further include a wavelength division filter that transmits light in the first wavelength band and reflects light in the second wavelength band, and the wavelength division filter may be coated on the first slope.

In another example, the beam splitter is formed on the light incident surface of the beam splitter, and transmits light in the first wavelength band and reflects light in the second wavelength band, and the reflection angle of the reflected light is 45 degrees A first diffraction pattern of the reflection type formed so as to be formed; And a second diffraction pattern formed on the light exit surface of the beam splitter and formed in a complementary manner to the reflection type first diffraction pattern.

The imaging optical system may further include at least one optical element disposed between the beam splitter and the second image sensor to reduce an image incident on the second image sensor, May include at least one of a Fresnel lens and a diffractive optical element.

According to still another aspect of the present invention, there is provided an imaging optical system comprising: a common objective lens; First and second image sensors having different sizes; And a light source for emitting light of a first wavelength band and light of a second wavelength band by separating light of a first wavelength band and light of a second wavelength band among light focused by the objective lens, And a beam splitter for providing a beam to the second image sensor, wherein the beam splitter has a concave light entrance surface coated with a wavelength division filter that transmits light in the first wavelength band and reflects light in the second wavelength band, . ≪ / RTI >

The imaging optical system may further include a convex mirror that reflects light of a second wavelength band reflected by the beam splitter, and a plane mirror that reflects light of a second wavelength band reflected by the convex mirror toward the second image sensor And may further include a mirror.

In another example, the imaging optical system may include a plane mirror that reflects light of a second wavelength band reflected by the beam splitter, and a second mirror that reflects light of a second wavelength band reflected by the plane mirror toward the second image sensor And a convex mirror.

According to still another aspect of the present invention, there is provided an imaging optical system comprising: a common objective lens; First and second image sensors having different sizes; And a light source for emitting light of a first wavelength band and light of a second wavelength band by separating light of a first wavelength band and light of a second wavelength band among light focused by the objective lens, And a beam splitter provided to the second image sensor, wherein the beam splitter includes a first dichroic mirror and a second dichroic mirror disposed respectively on the upper and lower sides of the optical axis of the objective lens And the first dichroic mirror and the second dichroic mirror are in contact with each other on the optical axis and bent at a predetermined angle with respect to each other, and the first dichroic mirror reflects light of the first wavelength band And the second dichroic mirror transmits the light of the first wavelength band and the light of the second wavelength band to the optical axis It can be configured to reflect downward.

The imaging optical system may further include: a first mirror disposed to face the first dichroic mirror, the first mirror reflecting the light of the first wavelength band reflected from the first dichroic mirror toward the second image sensor; And a second mirror arranged to face the second dichroic mirror and reflect the light of the first wavelength band reflected from the second dichroic mirror toward the second image sensor.

In one embodiment, a reflection type diffraction pattern having an image reduction function may be formed on the reflection surfaces of the first and second mirrors.

According to still another aspect of the present invention, there is provided an imaging optical system comprising: a common objective lens; First and second image sensors having different sizes; A first wavelength band light is divided into a first wavelength band light and a second wavelength band light by the objective lens, and the first wavelength band light is provided to the first image sensor, 2 beam splitter provided to the image sensor; And an optical fiber taper disposed between the beam splitter and the second image sensor, the optical fiber taper having a light incident surface having a larger area than the light exit surface.

The imaging optical system may further include at least one optical element disposed between the beam splitter and the optical fiber taper and configured to reduce an image incident on the second image sensor, wherein the at least one optical element includes a Fresnel lens And a diffractive optical element.

In one embodiment, the at least one optical element includes a Fresnel lens that converts light from the beam splitter into parallel light, the optical fiber taper converging the parallel light onto the second image sensor to reduce .

In another embodiment, the at least one optical element includes a Fresnel lens for converting light from the beam splitter into parallel light, and a diffractive optical element for converging the parallel light to reduce the image, And the image reduced by the diffractive optical element may be further reduced.

According to another aspect of the present invention, there is provided an apparatus for acquiring a three-dimensional image comprising: an imaging optical system having the above-described structure; A light source for generating light in a second wavelength band and irradiating the object with light; An image signal processor for generating a 3D image using an output image of the first image sensor and an output image of the second image sensor; And a control unit for controlling operations of the light source and the image signal processing unit.

For example, the light source may be configured to irradiate the subject with light of a second wavelength band having a predetermined period and a waveform under the control of the control unit.

For example, the light in the first wavelength band is visible light and the light in the second wavelength band is light in the infrared region, and the first image sensor has red (R), green (G), and blue (B) And the second image sensor may generate a depth image relating to the distance between the 3D image acquisition device and the subject.

In one embodiment, the image signal processing unit calculates the distance between the 3D image acquisition apparatus and the subject by each pixel using the depth image from the second image sensor, and outputs the calculation result to the first image sensor So that a final 3D image can be generated.

According to embodiments of the disclosed imaging optical system, since one common objective lens is used, the optical axes of the color image and the depth image are the same, so that the consistency between the color image and the depth image can be improved. In addition, since two image sensors of different sizes can be used, various combinations of image sensors can be operated. For example, a color image can be a large-area image sensor of a high-resolution pixel, and a low-pixel small area and a high-speed image sensor can be used as a depth image. Since the image sensor for depth image can use a pixel with a smaller size than the image sensor for color image, the cost can be reduced.

Further, according to the embodiments of the disclosed imaging optical system, since the image incident on the image sensor for depth image is reduced by using the thin plate type Fresnel lens or the diffractive optical element, the size of the imaging optical system can be reduced, Do. In addition, the reduction ratio of the image can be improved.

1 is a conceptual diagram illustrating an example of a structure of an imaging optical system and a three-dimensional image acquiring apparatus including the same according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view and a plan view exemplarily showing the structure of the optical element shown in FIG. 1;
3 is a conceptual diagram illustrating an exemplary structure of an imaging optical system and a three-dimensional image acquisition apparatus including the same according to another embodiment of the present invention.
4A is a conceptual view schematically showing the structure of an imaging optical system according to another embodiment.
Fig. 4B shows a modification of the embodiment shown in Fig. 4A.
5 is a conceptual diagram schematically showing the structure of an imaging optical system according to still another embodiment.
6A is a conceptual diagram schematically showing the structure of an imaging optical system according to still another embodiment.
6B is a conceptual diagram schematically showing a structure of an imaging optical system according to another embodiment.
Figs. 7A and 7B are conceptual diagrams of side and front portions schematically showing the structure of an imaging optical system according to another embodiment, respectively.
Fig. 7C shows a modification to the embodiment shown in Fig. 7B.
8 is a conceptual diagram schematically showing the structure of an imaging optical system according to still another embodiment.
9 is a perspective view exemplarily showing a fiber optic taper (FOT) shown in FIG.
10 is a conceptual diagram schematically showing the structure of an imaging optical system according to another embodiment.

Hereinafter, an imaging optical system for a three-dimensional image acquiring apparatus and a three-dimensional image acquiring apparatus including the same will be described in detail with reference to the accompanying drawings. In the following drawings, like reference numerals refer to like elements, and the size of each element in the drawings may be exaggerated for clarity and convenience of explanation.

1 is a conceptual diagram illustrating an example of a structure of an imaging optical system and a three-dimensional image acquiring apparatus including the same according to an embodiment of the present invention. Referring to FIG. 1, a three-dimensional image acquisition apparatus 100 according to an exemplary embodiment includes a light source 101 for generating illumination light having a predetermined wavelength, a light source 101 for focusing visible light and illumination light reflected from an external subject (not shown) A first image sensor 103 for sensing a visible light focused by the objective lens 102 to generate a color image, a second image sensor 103 for detecting illumination light focused by the objective lens 102, A depth image module 110 for generating depth images, a video signal processor 104 for generating a 3D image using a color image and a depth image, and a light source 101, a first image sensor 103, a depth image module And a controller 107 for controlling operations of the image signal processor 110 and the image signal processor 104. The 3D image acquisition apparatus 100 may further include a memory 106 for storing the final 3D image and a display panel 105 for displaying the 3D image.

The light source 101 may be a light emitting diode (LED) or a laser diode (LD) capable of emitting illumination light having a near infrared (NIR) wavelength of about 850 nm which is invisible to human eyes for safety . However, this is merely an example, and other kinds of light sources other than the illumination light of another wavelength band suitable for the design may be used. The light source 101 may emit illumination light having a specially defined waveform such as a sine wave, a ramp wave, a square wave or the like according to a control signal received from the control unit 107. [

The depth image module 110 further includes a beam splitter 111 that transmits visible light focused by the objective lens 102 to the first image sensor 103 and reflects the illumination light, A second image sensor 115 for detecting the reflected illumination light to generate a depth image, at least one optical element 112, 113 disposed between the beam splitter 111 and the second image sensor 115, And an optical shutter 114 disposed between the optical elements 112 and 113 and the second image sensor 115 and modulating the illumination light with a predetermined gain waveform according to the optical time-of-flight method (TOF). The surface of the beam splitter 111 may be coated with, for example, a wavelength division filter that transmits light in a visible light region and reflects light in a near-infrared region. Although beam splitter 111 is shown in Figure 1 as transmitting visible light and reflecting illumination light, this is only exemplary. Depending on the design, it is also possible that the beam splitter 11 transmits the illumination light and reflects the visible light. Hereinafter, for convenience, the beam splitter 111 transmits visible light and reflects the illumination light.

1, the objective lens 102, the first image sensor 103, the beam splitter 111, the optical elements 112 and 113, the optical shutter 114, and the second image sensor 115, Dimensional image capturing apparatus 100 constitute an imaging optical system. 1, the objective lens 102 may be a zoom lens including a plurality of lens groups. The first image sensor 103 and the second image sensor 115 may be a semiconductor image pickup device such as a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The first and second image sensors 103 and 115 have a plurality of pixels, and convert the light amount of incident light into electrical signals for each pixel and output the electrical signals. The first image sensor 103 for generating a general color image may have a higher resolution than the second image sensor 115 for generating a depth image having only depth information. Thus, the second image sensor 115 may have a smaller size than the first image sensor 103. [ In addition, the optical shutter 114 serves to modulate the illumination light with a predetermined gain waveform according to a general TOF technique to obtain depth information on the object. For example, the optical shutter 114 may be a GaAs-based semiconductor modulator capable of driving at a very high speed of several tens to several hundreds of MHz.

When the size of the first image sensor 103 and the size of the second image sensor 115 are different from each other, a difference between the color image generated by the first image sensor 103 and the depth image generated by the second image sensor 115 A discrepancy in the field of view may occur. That is, although the first image sensor 103 having a large size produces a color image having a wide viewing angle, the second image sensor 115 can generate a depth image having a relatively narrow viewing angle. Therefore, in order to match the viewing angles between the first image sensor 103 and the second image sensor 115, a reduction optical system having a function of reducing the image (that is, a magnification smaller than 1) is connected to the beam splitter 111 And further disposed between the second image sensor 115. Since the image reduced by the reduction optical system is incident on the second image sensor 115, the viewing angle of the depth image generated by the second image sensor 115 can be increased accordingly. The at least one optical element 112, 113 shown in Fig. 1 is intended to serve as such a reduction optical system.

When the reduction optical system is made of a combination of a general refractive lens (i.e., a convex lens or a concave lens), the volume and weight of the imaging optical system and the three-dimensional image acquisition device 100 may increase, . Therefore, according to the present embodiment, at least one optical element 112, 113 serving as a reduction optical system can be made of a thin plate-like optical element, such as a Fresnel lens or a diffractive optical element. FIG. 1 illustrates an example in which at least one optical element 112, 113 is a Fresnel lens.

As shown in FIG. 2, the Fresnel lens has a plurality of curved surfaces for refracting light arranged on a plane in the form of a series of concentric circles, and has a larger thickness and weight than a general convex lens or a concave lens. And it is possible to form the focal length very short. Therefore, by using a Fresnel lens as the optical elements 112 and 113 of the reduction optical system, the distance between the beam splitter 111 and the second image sensor 115 can be greatly reduced. As a result, it is possible to reduce the size and weight of the 3D image acquisition apparatus 100, and to reduce the manufacturing cost.

In FIG. 1, two optical elements 112 and 113, which are illustratively made up of Fresnel lenses, are shown disposed between the beam splitter 111 and the second image sensor 115. For example, both the first optical element 112 composed of a Fresnel lens and the second optical element 113 composed of a Fresnel lens can both serve to reduce the image. Alternatively, the first optical element 112 serves as a collimating element for converting the light reflected from the beam splitter 111 into parallel light, and the second optical element 113 serves as a collimating element for converting the parallel light into the parallel light. And converge on the image plane 115 to reduce the image. Also, depending on the design, only one Fresnel lens may be used, or three or more Fresnel lenses may be used to obtain a sophisticated image with aberration compensated.

Hereinafter, the operation of the above-described three-dimensional image acquisition apparatus 100 will be briefly described. First, under control of the control unit 107, the light source 101 irradiates the subject with, for example, infrared light. For example, according to the optical time-of-flight method (TOF), the light source 101 can irradiate the subject with light having a predetermined period and waveform. Then, the infrared illumination light reflected by the subject is focused by the objective lens 102. [ At the same time, general visible light reflected from the subject is also focused by the objective lens 102. [ Of the light focused by the objective lens 102, the visible light passes through the beam splitter 111 and is incident on the first image sensor 103. The first image sensor 103 can generate a color image having red (R), green (G), and blue (B) components for each pixel in the same manner as an image pickup device of a general camera.

On the other hand, among the light focused by the objective lens 102, the infrared illumination light is reflected by the beam splitter 111, and then enters the optical elements 112 and 113. As described above, the optical elements 112 and 113 serve to converge the illumination light onto the second image sensor 115 to reduce the image. The reduction magnification of the image can be determined, for example, according to the ratio of the sizes of the first image sensor 103 and the second image sensor 115. [ The illumination light converged by the optical elements 112 and 113 is modulated by the optical shutter 114 and is then incident on the second image sensor 115. [ The optical shutter 114 may modulate the illumination light with a predetermined gain waveform having the same period as the period of the illumination light according to the optical time-of-flight (TOF) method.

The second image sensor 115 converts the light amount of the modulated illumination light into an electrical signal for each pixel to generate a depth image. Then, the depth image output from the second image sensor 115 may be input to the image signal processing unit 104. The image signal processing unit 104 calculates the distance between the subject and the 3D image capturing apparatus 100 for each pixel using the depth image from the second image sensor 115, Can be combined with the color image from the color image processor 103 to generate the final 3D image. The 3D image thus generated can be stored in the memory 106 or displayed on the display panel 105, for example.

In the embodiment shown in Fig. 1, the two optical elements 112 and 113 are all composed of a Fresnel lens. However, a part of the optical elements for forming the reduction optical system may be composed of a diffractive optical element (DOE) instead of the Fresnel lens. 3 is a conceptual diagram illustrating a structure of an imaging optical system according to another embodiment including a diffractive optical element and a three-dimensional image acquisition device including the same.

3, a three-dimensional image acquisition apparatus 100 'includes a reduction optical system including a first optical element 112 composed of a Fresnel lens and a third optical element 116 composed of a diffractive optical element, 111) and the second image sensor 115. [0033] The diffractive optical element has a plurality of concentric circular patterns arranged on a plane similar to a Fresnel lens, but each concentric circular pattern has a form of a lattice pattern that diffracts light, not a curved shape that refracts light. The diffractive optical element can act to strongly converge light according to the shape of a plurality of grid patterns arranged in a concentric circle. In addition, it can be made very thin and light as the Fresnel lens.

In the embodiment shown in FIG. 3, the first optical element 112 composed of a Fresnel lens serves as a collimating element for converting the light reflected from the beam splitter 111 into parallel light, 3 optical element 116 may serve to converge the parallel light onto the second image sensor 115 to reduce the image. To this end, the first optical element 112 composed of a Fresnel lens can be arranged on the focal plane of the objective lens 102. [ Since the divergent light is not directly converged but is once converted into parallel light and then converged, the deviation between the central portion and the peripheral portion of the image can be reduced. 3 shows an example of a reduction optical system composed of only two optical elements 112 and 116. However, depending on the design, a reduction optical system in which a plurality of Fresnel lenses and three or more diffractive optical elements are combined may be used have. The remaining configuration and functions of the 3D image acquisition apparatus 100 'shown in FIG. 3 are the same as the configurations and functions of the 3D image acquisition apparatus 100 shown in FIG. 1, and a detailed description thereof will be omitted.

4A is a conceptual view schematically showing the structure of an imaging optical system according to another embodiment. In the embodiment shown in Figs. 1 and 3, the beam splitter 111 is coated with a wavelength division filter on a flat surface. Typically, such a beam splitter 111 is disposed at an angle of about 45 degrees with respect to the optical axis of the objective lens 102, so that the transmitted image and the reflected image have the same size. However, in the case of the embodiment shown in FIG. 4A, a beam splitter 117 arranged at an angle greater than 45 degrees with respect to the optical axis, for example, at an angle of about 60 degrees, may be used. By thus arranging the beam splitter 117 at an angle larger than 45 degrees, it is possible to further reduce the width of the reduction optical system. By reducing the width of the reduction optical system, the distance between the objective lens 102 and the first image sensor 103 can be reduced, and as a result, the width of the three-dimensional image acquisition apparatuses 100 and 100 'can be reduced. In addition, when the beam splitter 117 inclined at an angle larger than 45 degrees is used, an effect of reducing the image incident on the second image sensor 115 by the beam splitter 117 can be obtained. Therefore, in the embodiment shown in FIG. 4A, the optical fibers 112 and 116 may be omitted.

So that the image transmitted by the beam splitter 117 inclined at an angle larger than 45 degrees advances toward the first image sensor 103 and the reflected image advances toward the second image sensor 115, As described above, the light incident surface of the beam splitter 117 may be formed with a plurality of fine slopes 117a inclined at about 45 degrees with respect to the optical axis. For example, if the beam splitter 117 is inclined at about 60 degrees with respect to the optical axis, the plurality of fine slopes 117a may be inclined about 15 degrees with respect to the light incident surface of the beam splitter 117. [ Then, the inclined surfaces 117a can maintain an inclination angle of about 45 degrees with respect to the optical axis. Like the beam splitter 111 shown in Figs. 1 and 3, the surface of the slopes 117a can be coated with a wavelength division filter that transmits light in a visible light region and reflects light in a near-infrared region.

In order to prevent the light transmitted through the beam splitter 117 from being distorted due to the plurality of fine slopes 117a, a fine slope 117b may be formed on the light output surface of the beam splitter 117. [ For example, the inclined surface 117b formed on the light output surface of the beam splitter 117 may have a shape complementary to the inclined surface 117a formed on the light incident surface of the beam splitter 117. [ The inclined surface 117b formed on the light output surface of the beam splitter 117 and the inclined surface 117a formed on the light incident surface of the beam splitter 117 can be parallel to each other.

In the above-described structure of the beam splitter 117, a part of the light reflected by one of the slanted faces 117a may be covered by another adjacent slanted face 117a. However, since the beam splitter 117 is disposed in the non-image position, i.e., on the non-focal plane of the objective lens 102, the final image focused on the second image sensor 115 is It may be hardly affected by the array of the plurality of inclined surfaces 117a. In addition, when the plurality of inclined surfaces 117a are formed sufficiently small, the optical interference occurring between the inclined surfaces 117a can be minimized to obtain a smooth reflected image.

The remaining configuration of the imaging optical system excluding the beam splitter 117 in Fig. 4A may be the same as that of the imaging optical system shown in Fig. 1 or Fig. For example, optical elements 112 and 113 composed of Fresnel lenses are disposed between the beam splitter 117 and the second image sensor 115, or optical elements 112 and 113 composed of a Fresnel lens and a diffractive optical element, 116 may be disposed. However, the optical elements 112 and 116 may be omitted in the embodiment shown in FIG. 4A because there is also an effect that the image is shrunk by the beam splitter 117 inclined at an angle larger than 45 degrees. In Fig. 4A, optical elements 112 and 116 composed of a Fresnel lens and a diffractive optical element are shown for convenience, but this is only one example.

4B, a reflection type diffraction pattern 117c having a wavelength division function and an image reduction function is provided instead of the beam splitter 117 in which the array of the slopes 117a coated with the wavelength division filter is disposed, A beam splitter 117 'may be used. This reflection type diffraction pattern 117c can perform the same function as the array of the slopes 117a coated with the wavelength division filter and can also contribute to shrink the image additionally with other optical elements 112 and 116 have. For example, the reflection type diffraction pattern 117c may be formed such that the reflection angle is uniformly 45 degrees with respect to the optical axis of the objective lens 102. [ In order to prevent distortion of the image transmitted through the beam splitter 117 ', a diffraction pattern 117d of a complementary shape to the reflection type diffraction pattern 117c is formed on the light output surface of the beam splitter 117' . The reflection type diffraction patterns 117c and 117d may have various shapes depending on an angle at which the beam splitter 117 'is inclined, a wavelength band of light to be transmitted, a wavelength band of light to be reflected, a size of the beam splitter 117' . ≪ / RTI >

5 is a conceptual diagram schematically showing the structure of an imaging optical system according to still another embodiment. Although the beam splitters 111 and 117 shown in Figs. 1, 3 and 4A are all plate type, the imaging optical system shown in Fig. 5 includes a beam splitter 118 having a concave reflecting surface coated with a wavelength division filter do. That is, as shown in Fig. 5, the light incident surface of the beam splitter 118 is a concave surface. Since the concave reflecting surface serves to converge the light, the beam splitter 118 can additionally contribute to the reduction of the image incident on the second image sensor 115. Further, by using the beam splitter 118 having a concave reflecting surface, it is possible to reduce the width of the reduction optical system.

6A and 6B, in order to compensate for the distortion of the image caused by the concave reflecting surface of the beam splitter 118, the beam splitter 118 and the first optical element 112 are convex A convex mirror 118a having a reflective surface may be additionally disposed. 6A, the image reflected by the beam splitter 118 is reflected first by the convex mirror 118a and then again by the plane mirror 119 toward the second image sensor 115 Can be reflected. 6B, the image reflected by the beam splitter 118 is first reflected by the plane mirror 119, and then reflected by the convex mirror 118a toward the second image sensor 115 . In the case of the embodiment shown in Figs. 6A and 6B, unlike the embodiment shown in Fig. 5, the image reflected by the beam splitter 118 need not proceed directly toward the second image sensor 115. [ Therefore, the beam splitter 118 can be further inclined. Also, since the beam splitter 118 having a concave reflecting surface can shrink the image, the optical elements 112 and 116 may be omitted in the embodiment shown in Figs. 6A and 6B.

Further, in order to further reduce the width of the reduction optical system, it is also possible to use a plurality of bent beam splitters instead of a single flat beam splitter. Figs. 7A and 7B are conceptual diagrams of side and front portions schematically showing the structure of the imaging optical system according to this embodiment. Fig.

7A and 7B, a beam splitter 120 disposed between the objective lens 102 and the first image sensor 103 is disposed above and below the optical axis of the objective lens 102 The first dichroic mirror 120a and the second dichroic mirror 120b may include a first dichroic mirror 120a and a second dichroic mirror 120b. As shown in the side view of FIG. 7A, the first dichroic mirror 120a and the second dichroic mirror 120b are in contact with each other on the optical axis, and are bent at a predetermined angle with respect to each other. For example, the first dichroic mirror 120a disposed above the optical axis transmits visible light, and reflects the illumination light of infrared rays upward of the optical axis. Further, the first dichroic mirror 120b disposed below the optical axis transmits visible light, and reflects the infrared illumination light to the lower side of the optical axis. Therefore, the image of the visible light focused by the objective lens 102 can reach the first image sensor 103 through the beam splitter 120. [

In order to provide the reflected infrared image to the second image sensor 115 by being divided upward and downward by the first dichroic mirror 120a and the second dichroic mirror 120b, And may further include a first mirror 121a opposed to the roky mirror 120a and a second mirror 121b opposed to the second dichroic mirror 120b. 7B, the first mirror 121a reflects an image upwardly reflected by the first dichroic mirror 120a toward the second image sensor 115, and the second mirror 121b reflects the image reflected upward by the first dichroic mirror 120a toward the second image sensor 115, Can reflect the image reflected downward by the second dichroic mirror 120b toward the second image sensor 115. [ Therefore, the infrared image divided into two by the first dichroic mirror 120a and the second dichroic mirror 120b is reflected by the first mirror 121a and the second mirror 121b by the second image sensor 115). ≪ / RTI > Unlike the previous embodiments in which the second image sensor 115 is disposed below the beam splitters 111, 117 and 118, in the case of the embodiment shown in FIGS. 7A and 7B, the second image sensor 115 May be disposed on the side surface of the beam splitter 120.

By using the bent beam splitter 120 in this way, the width of the reduction optical system can be reduced to about 1/2 as compared with the case of using a single flat beam splitter. In addition, instead of the first and second dichroic mirrors 120a and 120b, a beam splitter 117 having a plurality of fine slopes 117a shown in FIG. 4A is used to further reduce the width of the reduction optical system It is possible. 7A and 7B, since the image can be reduced by the first and second dichroic mirrors 120a and 120b and the mirrors 121a and 121b, the optical elements 112 and 116 ) May be omitted.

Instead of the mirrors 121a and 121b described above, mirrors 121c and 121d having reflection diffraction patterns 123a and 123b having an image reduction function, respectively, as shown in FIG. 7C, may be used. The reflection type diffraction patterns 123a and 123b formed on the reflection surfaces of the mirrors 121c and 121d may contribute to further reducing the image together with other optical elements 112 and 116. [

8 is a conceptual diagram schematically showing the structure of an imaging optical system according to still another embodiment. Referring to FIG. 8, the imaging optical system according to the present embodiment may include a fiber optic taper 122 instead of the third optical element 116 composed of a diffractive optical element. That is, the imaging optical system may include a reduction optical system including the first optical element 112 composed of a Fresnel lens and the optical fiber taper 122, between the beam splitter 111 and the second image sensor 115. As shown in FIG. 9, the optical fiber taper 122 typically has a structure in which the compressing ratios of the incident surface portion and the emergent surface portion of the optical fiber bundle are different so that the incident side image and the emergence side image have different sizes. For example, when the light incident surface of the optical fiber taper 122 is wider than the light exit surface, the optical fiber taper 122 can function to reduce the image.

In the embodiment shown in Fig. 8, the optical elements 112 and 116 may be omitted because the optical fiber taper 122 can shrink the image. Alternatively, only the first optical element 112 composed of a Fresnel lens may be used. In this case, the first optical element 112 composed of a Fresnel lens can serve as a collimating element for converting the light reflected from the beam splitter 111 into parallel light. The optical fiber taper 122 may serve to converge the parallel light formed by the first optical element 112 onto the second image sensor 115 to reduce the image.

On the other hand, as in the embodiment shown in Fig. 10, it is also possible to use the optical fiber taper 122 together with the third optical element 116 constituted by the diffractive optical element. For example, the first optical element 112 constituted by the Fresnel lens converts the light reflected from the beam splitter 111 into parallel light, and the third optical element 116 constituted by the diffractive optical element primarily reduces the image The optical fiber taper 122 can be used to further reduce the image.

Up to now, to facilitate understanding of the present invention, an exemplary embodiment of an imaging optical system for a three-dimensional image acquiring apparatus and a three-dimensional image acquiring apparatus including the same is described and shown in the accompanying drawings. It should be understood, however, that such embodiments are merely illustrative of the present invention and not limiting thereof. And it is to be understood that the invention is not limited to the details shown and described. Since various other modifications may occur to those of ordinary skill in the art.

100, 100 '..... 3D image acquisition device 101 ..... light source
102 ..... objective lens 103 ..... image sensor
104 ..... video signal processing unit 105 ..... display panel
106 ..... memory 107 ..... controller
110 ..... Depth imaging module 111, 117, 118, 120 ..... beam splitter
112, 113, 116 ..... optical element 114 ..... optical shutter
115 ..... image sensor 120a, 120b ..... dichroic mirror
121a, 121b ..... mirror 122 ..... optical fiber taper

Claims (28)

One common objective lens;
First and second image sensors having different sizes;
A first wavelength band light is divided into a first wavelength band light and a second wavelength band light by the objective lens, and the first wavelength band light is provided to the first image sensor, 2 beam splitter provided to the image sensor; And
And at least one optical element disposed between the beam splitter and the second image sensor to reduce an image incident on the second image sensor,
Wherein the at least one optical element includes at least one of a Fresnel lens and a diffractive optical element. The method according to claim 1,
Wherein the at least one optical element comprises at least two Fresnel lenses sequentially disposed along the optical path between the beam splitter and the second image sensor. The method according to claim 1,
Wherein the at least one optical element comprises a first optical element and a second optical element, respectively, arranged in turn along the optical path between the beam splitter and the second image sensor, wherein the first optical element comprises a Fresnel lens And the second optical element is a diffractive optical element. The method of claim 3,
Wherein the first optical element is a collimating element for converting the light from the beam splitter into parallel light and the second optical element converges the parallel light onto the second image sensor to reduce the image. The method according to claim 1,
And an optical shutter disposed between the at least one optical element and the second image sensor, for modulating light in a first wavelength band and providing the modulated light to the second image sensor. The method according to claim 1,
Wherein the second image sensor is smaller in size than the first image sensor, the light in the first wavelength band is visible light, and the light in the second wavelength band is light in the infrared region. The method according to claim 1,
Wherein the beam splitter is configured to transmit light in the first wavelength band and reflect light in the second wavelength band. One common objective lens;
First and second image sensors having different sizes; And
A first wavelength band light is divided into a first wavelength band light and a second wavelength band light by the objective lens, and the first wavelength band light is provided to the first image sensor, 2 image sensor, wherein the beam splitter comprises:
Wherein the beam splitter is disposed obliquely at an angle larger than 45 degrees with respect to an optical axis of the objective lens. 9. The method of claim 8,
The beam splitter comprises:
A plurality of microscopic first inclined surfaces formed on the light incident surface of the beam splitter and inclined at 45 degrees with respect to the optical axis of the objective lens; And
And a plurality of fine second inclined surfaces formed on the light exit surface of the beam splitter and formed in a shape complementary to the plurality of first inclined surfaces,
Wherein the first inclined surface and the second inclined surface are parallel to each other. 10. The method of claim 9,
Wherein the beam splitter further comprises a wavelength division filter that transmits light in the first wavelength band and reflects light in the second wavelength band, wherein the wavelength division filter is coated on the first sloped surface. 9. The method of claim 8,
The beam splitter comprises:
A reflection type first diffraction pattern formed on the light incident surface of the beam splitter and configured to transmit light in the first wavelength band and reflect light in the second wavelength band and to have a reflection angle of 45 degrees with respect to the optical axis; And
And a second diffraction pattern formed on the light exit surface of the beam splitter and formed in a complementary manner to the reflection type first diffraction pattern. 9. The method of claim 8,
And at least one optical element disposed between the beam splitter and the second image sensor to reduce an image incident on the second image sensor,
Wherein the at least one optical element includes at least one of a Fresnel lens and a diffractive optical element. One common objective lens;
First and second image sensors having different sizes; And
A first wavelength band light is divided into a first wavelength band light and a second wavelength band light by the objective lens, and the first wavelength band light is provided to the first image sensor, 2 image sensor, wherein the beam splitter comprises:
Wherein the beam splitter includes a concave light incident surface coated with a wavelength division filter that transmits light in the first wavelength band and reflects light in the second wavelength band. 14. The method of claim 13,
A convex mirror that reflects light in a second wavelength band reflected by the beam splitter and a plane mirror that reflects light in a second wavelength band reflected by the convex mirror toward the second image sensor, Optical system. 14. The method of claim 13,
A plane mirror for reflecting the light of the second wavelength band reflected by the beam splitter and a convex mirror for reflecting the light of the second wavelength band reflected by the plane mirror toward the second image sensor, Optical system. 14. The method of claim 13,
And at least one optical element disposed between the beam splitter and the second image sensor to reduce an image incident on the second image sensor,
Wherein the at least one optical element includes at least one of a Fresnel lens and a diffractive optical element. One common objective lens;
First and second image sensors having different sizes; And
A first wavelength band light is divided into a first wavelength band light and a second wavelength band light by the objective lens, and the first wavelength band light is provided to the first image sensor, 2 image sensor, wherein the beam splitter comprises:
Wherein the beam splitter includes a first dichroic mirror and a second dichroic mirror arranged respectively on the upper and lower sides of the optical axis of the objective lens,
The first dichroic mirror and the second dichroic mirror have one ends on the optical axis and are bent at a predetermined angle with respect to each other,
The first dichroic mirror transmits the light of the first wavelength band and reflects the light of the second wavelength band above the optical axis, and the second dichroic mirror transmits the light of the first wavelength band And reflects the light of the second wavelength band below the optical axis. 18. The method of claim 17,
A first mirror disposed to face the first dichroic mirror, the first mirror reflecting light of a first wavelength band reflected from the first dichroic mirror toward a second image sensor; And
And a second mirror disposed so as to face the second dichroic mirror and reflects the light of the first wavelength band reflected from the second dichroic mirror toward the second image sensor. 19. The method of claim 18,
And a reflection type diffraction pattern having an image reduction function is formed on the reflection surfaces of the first and second mirrors. 18. The method of claim 17,
And at least one optical element disposed between the beam splitter and the second image sensor to reduce an image incident on the second image sensor,
Wherein the at least one optical element includes at least one of a Fresnel lens and a diffractive optical element. One common objective lens;
First and second image sensors having different sizes;
A first wavelength band light is divided into a first wavelength band light and a second wavelength band light by the objective lens, and the first wavelength band light is provided to the first image sensor, 2 beam splitter provided to the image sensor; And
And an optical fiber taper disposed between the beam splitter and the second image sensor, the optical fiber taper having a light incident surface having a larger area than a light exit surface. 22. The method of claim 21,
And at least one optical element disposed between the beam splitter and the optical fiber taper to reduce an image incident on the second image sensor,
Wherein the at least one optical element includes at least one of a Fresnel lens and a diffractive optical element. 23. The method of claim 22,
Wherein the at least one optical element includes a Fresnel lens that converts light from the beam splitter into parallel light and the optical fiber taper converges the parallel light onto the second image sensor to reduce the image. 23. The method of claim 22,
Wherein the at least one optical element includes a Fresnel lens for converting light from the beam splitter into parallel light and a diffractive optical element for converging the parallel light to reduce the image, wherein the optical fiber taper is formed by the diffractive optical element And an image-forming optical system configured to further reduce the reduced image. An imaging optical system according to any one of claims 1 to 24;
A light source for generating light in a second wavelength band and irradiating the object with light;
An image signal processor for generating a 3D image using an output image of the first image sensor and an output image of the second image sensor; And
And a control unit for controlling operations of the light source and the image signal processing unit. 26. The method of claim 25,
Wherein the light source is configured to irradiate light of a second wavelength band having a predetermined period and a waveform to a subject under the control of the control unit. 26. The method of claim 25,
Wherein the light of the first wavelength band is visible light and the light of the second wavelength band is light of an infrared ray region and the first image sensor is a color light source having red (R), green (G), and blue (B) And the second image sensor generates a depth image related to the distance between the 3D image acquisition device and the subject. 28. The method of claim 27,
Wherein the image signal processing unit calculates the distance between the three-dimensional image acquiring device and the subject by using the depth image from the second image sensor for each pixel and outputs the calculation result to the color image from the first image sensor And a final 3D image is generated.

Images