Abstract:
In one example embodiment, an apparatus for obtaining status information of a crystalline lens of an eye includes a light projector configured to project a reference light to the crystalline lens; an intensity detector configured to detect an intensity of scattered light that is generated from the reference light by being scattered at the crystalline lens; and a calculator configured to calculate thickness information of the crystalline lens based on the intensity of scattered light.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This is a continuation application of U.S. patent application Ser. No. 13/332,735, filed on Dec. 21, 2011 which claims the benefit under 35 U.S.C. §119(a) of a Korean Patent Application No. 10-2011-0004767, filed on Jan. 18, 2011, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes. 
     
    
     BACKGROUND 
       [0002]    1. FIELD 
         [0003]    The following description relates to an apparatus for obtaining status information about a crystalline lens of a person&#39;s eyeball, and optical/electronic equipment including the apparatus. 
         [0004]    2. Description of the Related Art 
         [0005]    A person has an eyeball structure that may adjust a thickness of a crystalline lens to focus objects with different distances from the crystalline lens. A person&#39;s eyeball focuses on objects by increasing the thickness of the crystalline lens while the person views objects located close to the crystalline lens and by decreasing the thickness of the crystalline lens while viewing objects far from the crystalline lens. Accordingly, the radius of curvature of the crystalline lens (specifically, the cornea surrounding the crystalline lens) also decreases or increases depending on a distance from the crystalline lens to an object. 
         [0006]    Optical devices, such as a telescope, a microscope, a camera, and the like, or direct view displays such as a head-mount display, generally include an external focusing terminal or a mechanical focusing device that may correct focus deviations based on a person&#39;s sights and/or various environments. A person who utilizes such an optical device or direct view display may manually manipulate the external focusing terminal to correct focus deviations or conduct refocusing. 
         [0007]    Various methods for detecting changes in thickness of a crystalline lens to obtain status information of the crystalline lens have been proposed. For example, Japanese Laid-open Patent Application No. 2000-139841, entitled “a Method of Measuring Changes in Thickness of Crystalline Lens, and a Training System for Self-Care of Pseudomyopia Using the Method” relates to a method of irradiating an infrared light on an eyeball, photographing the eyeball with a CCD camera, and analyzing the photographed images using a computer to measure changes in thickness of a crystalline lens. Also, Japanese Laid-open Patent Application No. 2006-195084 entitled “display apparatus” relates to a display apparatus for estimating the thickness of a crystalline lens using light reflected from an eyeball and displaying images adaptively according to the status of the eyeball. According to the conventional techniques, a light emitted from a light source is incident to an eyeball via a translucent mirror and a pair of convex lenses, and a reflection light that is to be measured by a crystalline lens thickness measurer passes through the convex lenses and is deflected by the translucent mirror, so that the path of the reflection light is directed towards the crystalline lens thickness measurer. 
         [0008]    Meanwhile, there are currently many displays that support Full High Definition. Thus, in spite of development of data compression technologies, an amount of video data that has to be processed is increasing as a result of the high resolution. The increase in the amount of video data that has to be processed increases the load of an encoder (or an image acquisition apparatus having an encoder). In this example, an image acquisition apparatus for acquiring stereoscopic images or a display for reproducing the stereoscopic images has greater load because the apparatus has to process left-eye and right-eye images. 
       SUMMARY 
       [0009]    In one exemplary embodiment, there may be provided an apparatus for obtaining status information of a crystalline lens of an eye. The apparatus includes a light projector configured to project a reference light to the crystalline lens, an intensity detector configured to detect an intensity of scattered light that is generated from the reference light by being scattered at the crystalline lens; and, a calculator configured to calculate thickness information of the crystalline lens based on the intensity of scattered light. 
         [0010]    In another exemplary embodiment, there may be provided a three-dimensional (3D) glasses apparatus. The 3D glasses apparatus includes a light projector configured to project a reference light to a crystalline lens of an eye of a user wearing the 3D glasses, an intensity detector configured to detect an intensity of scattered light that is generated from the reference light by being scattered at the crystalline lens, a calculator configured to calculate thickness information of the crystalline lens based on the intensity of scattered light; and a transmitter configured to transmit the thickness information of the crystalline lens to an external device. 
         [0011]    In yet another exemplary embodiment, there may be provided a three-dimensional (3D) image display system. The 3D image display system includes a 3D image reproducing apparatus configured to reproduce 3D images on a 3D display and a 3D glasses used to view the 3D images displayed on the 3D display. The 3D glasses includes a crystalline lens thickness detector configured to detect thickness information of a crystalline lens of an eye of a wearer, and a transmitter configured to transmit the thickness information of the crystalline lens to the 3D image reproducing apparatus. The 3D image reproducing apparatus includes a receiver configured to receive the thickness information of the crystalline lens from the 3D glasses, and a controller configured to adjust the 3D images based on the thickness information of the crystalline lens. The crystalline lens thickness detector includes a light projector configured to project a reference light to the crystalline lens of the eye of the wearer, an intensity detector configured to detect an intensity of scattered light that is generated from the reference light by being scattered at the crystalline lens and a calculator configured to calculate the thickness information of the crystalline lens based on the intensity of scattered light. 
         [0012]    In still another exemplary embodiment, there may be provided a three-dimensional (3D) image acquisition apparatus. The 3D image acquisition apparatus includes a left camera, a right camera spaced away from the left camera, a crystalline lens thickness detector positioned on at least one of the left camera and right camera, and configured to detect thickness information of a crystalline lens of an eye of a user who is photographing with the 3D image acquisition apparatus and an image processor configured to encode at least one of a left image acquired by the left camera and a right image acquired by the right camera based on the thickness information of the crystalline lens. The crystalline lens thickness detector includes a light projector configured to project a reference light to the crystalline lens of the eye of the wearer, an intensity detector configured to detect an intensity of scattered light that is generated from the reference light by being scattered at the crystalline lens and a calculator configured to calculate the thickness information of the crystalline lens based on the intensity of scattered light. 
         [0013]    In still another exemplary embodiment, there may be provided a method for obtaining information of a crystalline lens of an eye. The method includes projecting a reference light to the crystalline lens of the eye, detecting an intensity of scattered light that is generated from the reference light by being scattered at the crystalline lens and calculating the thickness information of the crystalline lens based on the intensity of scattered light. 
         [0014]    Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIGS. 1A and 1B  are diagrams illustrating examples of a focal length of a human being&#39;s eyeball varying according to a distance to an object. 
           [0016]      FIGS. 2A and 2B  are diagrams illustrating examples of lights perpendicularly incident to crystalline lenses having different radiuses of curvature. 
           [0017]      FIG. 3  is a diagram illustrating an example of an apparatus for obtaining status information of a crystalline lens. 
           [0018]      FIG. 4  is a diagram illustrating an example of a 3D image display system. 
           [0019]      FIG. 5  is a diagram illustrating an example of a 3D image acquisition apparatus. 
           [0020]      FIG. 6  is a diagram illustrating an example of a 3D imaging method. 
       
    
    
       [0021]    Throughout the drawings and the detailed description, unless otherwise described, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. The relative size and depiction of these elements may be exaggerated for clarity, illustration, and convenience. 
       DETAILED DESCRIPTION 
       [0022]    The following description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. Accordingly, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be suggested to those of ordinary skill in the art. Also, descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness. 
         [0023]    The following description relates to an apparatus capable of accurately measuring the thickness of a crystalline lens and of obtaining status information of the crystalline lens without deteriorating the staring capacity, and optical/electronic equipment including the same. 
         [0024]    The following description also relates to an optical/electronic device that can perform automatic control according to the focal length of a user&#39;s eyeball. 
         [0025]    The following description also relates to a 3D image acquisition apparatus or a 3D image display capable of reducing the amount of data that has to be processed. 
         [0026]      FIGS. 1A and 1B  illustrate examples of a focal length of a human being&#39;s eyeball varying according to a distance to an object. For example,  FIG. 1A  is the case in which an object  2   a  is located relatively close to the eyeball and  FIG. 1B  is the case in which an object  2   b  is located relatively far from the eyeball. 
         [0027]    Referring to  FIGS. 1A and 1B , a thickness of the crystalline lens ( 4   a ,  4   b ) of a human being&#39;s eyeball adjusts based on the distances to the objects  2   a  and  2   b  so that the focal length is controlled. For example, as illustrated in  FIG. 1A , if the object  2   a  is located relatively close to the eyeball, the crystalline lens  4   a  is thickened so that the focal length of the eyeball is shortened. In this example, the radius of curvature of the crystalline lens  4   a  is relatively small. Meanwhile, as illustrated in  FIG. 1B , if the object  2   b  is located farther from the eyeball, the crystalline lens  4   b  becomes thinner so that the focal length of the eyeball is lengthened. In this example, the radius of curvature of the crystalline lens  4   b  is relatively great. 
         [0028]      FIGS. 2A and 2B  illustrate examples of light that is perpendicularly incident to crystalline lenses having different radiuses of curvature. 
         [0029]    Typically, light scattering is a phenomenon in which light is scattered in all directions when it encounters a certain object having a rough surface. That is, scattered lights mean lights that have directions that change by scattering of light. As described herein, the term “scattered lights” is not limited to lights that are scattered by light scattering, and includes all lights scattered in all directions from a certain light perpendicularly incident to a surface having a predetermined radius of curvature. It should also be understood that a light reflected through the same path as a light incident to a crystalline lens does not belong to the “scattered lights”. 
         [0030]    When a certain light is incident to a crystalline lens, the light may have different scattering ranges according to a radius of curvature of the crystalline lens. For example, a scattering range θ 1  of scattered lights L 2a  when the radius of curvature of the crystalline lens  4   a  (specifically, the cornea surrounding the crystalline lens  4   a ) is small, as illustrated in  FIG. 2A , is relatively larger than a scattering range θ 2  of scattered lights L 2b  when the radius of curvature of the crystalline lens  4   b  is great, as illustrated in  FIG. 2B  (θ 1 &gt;θ 2 ). As a result, when the radius of curvature of the crystalline lens  4   a  is small, the intensity (that is, the intensity of scattered lights per a unit area) of the scattered lights L 2a  becomes weaker, while when the radius of curvature of the crystalline lens  4   b  is great, the intensity of the scattered lights L 2b  becomes stronger. In the current example, changes in intensity of scattered lights according to changes in radius of curvature of a crystalline lens are used to obtain status information of the crystalline lens. The status information may include thickness information about the crystalline lens. 
         [0031]      FIG. 3  illustrates an example of an apparatus for obtaining status information of a crystalline lens. 
         [0032]    Referring to  FIG. 3 , the apparatus for obtaining status information of a crystalline lens includes a light source unit  10 , a light receiving unit  20 , and a calculating unit  30 . The light source unit  10  creates a reference light L 1  and directs the reference light L 1  incident to a crystalline lens  4  of a person. In order to directly measure scattered lights L 2  beyond the visual field of an eyeball and efficiently measure changes in intensity of the scattered lights L 2  according to changes in radius of curvature of the crystalline lens  4 , the light source unit  10  may direct the reference light L 1  straightly incident to the crystalline lens  4 . A part of the reference light L 1  that is straightly incident to the crystalline lens  4  becomes a reflection light that reflects back along the incident path of the reference light L 1 , however, the remaining part of the reference light L 2  becomes scattered lights L 2 . 
         [0033]    The light source unit  10  may be disposed between the eyeball and an object  2 . For example, the light source unit  10  may be disposed at an arbitrary location on an imaginary line connecting the eyeball to the object  2 . In this example, the light source unit  10  may become an obstacle in the visual field. The apparatus for obtaining the status information of a crystalline lens may be applied to applications in which it does not matter that the light source unit  10  becomes an obstacle in the visual field. 
         [0034]    As another example, the light source unit  10  may be spaced a predetermined distance away from an imaginary line connecting the eyeball to the object  2 . In this example, the light source unit  10  may be disposed as far away from the imaginary connection line as possible in order not to become an obstacle in the visual field. However, if the light source unit  10  is spaced too far from the imaginary connection line and accordingly it has too large angle with the reference light L 1 , the intensity of scattered lights received by the light receiving unit  20  may become weak and also measurement sensitivity in measuring changes in thickness of the crystalline lens may deteriorate. 
         [0035]    In order to overcome these potential drawbacks, the light source unit  10  may direct the reference light L 1  straightly incident to the eyeball along the imaginary line connecting the eyeball to the object  2 , so that the light source unit  10  does not become an obstacle in the visual field of the eyeball. For example, the light source unit  10  may include a light source  12  for generating the reference light L 1  and a light path changing unit  14  for changing a path of the reference light L 1  emitted from the light source  12 . In this example, the light source  12  may be disposed beyond the visual field so that it does not become an obstacle in the visual field. For example, the light source  12  may be disposed above or below the imaginary line connecting the eyeball to the object  2 . 
         [0036]    In this example, light generated by the separate light source  12 , instead of a peripheral light, is used as the reference light L 1 . In the case of using a peripheral light as the reference light L 1 , it is needed to accurately measure the intensity, amount, and the like, of the peripheral light in order to obtain status information of the crystalline lens  4 . However, if a light from the separate light source  12  is used as the reference light L 1 , the intensity, amount, and the like, of the reference light L 1  may be arbitrarily adjusted to ensure a sufficient intensity and amount of light for enabling the light receiving unit  20  to measure status information of the crystalline lens  4 . In this case, in order to avoid the reference light L 1  from blurring vision, an invisible light, such as ultraviolet, infrared, and the like, may be used as the reference light L 1 . 
         [0037]    In the example of  FIG. 3 , the light path changing unit  14  is disposed on the imaginary line connecting the eyeball to the object  2 . The light path changing unit  14  changes the path of the reference light L 1  emitted from the light source  12  toward the eyeball. For example, the path of the reference light L 1  may be changed approximately 90 degrees by means of the light path changing unit  14 . It will be also apparent to one skilled in the art that the path of the reference light L 1  can be changed by another angle than 90 degrees. The reference light L 1  that has a path that is changed by means of the light path changing unit  14  may be straightly incident to the crystalline lens  4 . 
         [0038]    For example, the light path changing unit  14  may be a prism. As illustrated in  FIG. 3 , the prism  14  may change the path of the reference light L 1  by 90 degrees to make the reference light L 1  straightly incident to the crystalline lens  4 . In this example, the prism  14  may have an optical characteristic that it is shown transparent in the direction of a line of sight, in order not to become an obstacle in the visual field. As another example, the prism  14  may have a very small size that cannot be recognized with the naked eye or at least that becomes no obstacle in the visual field. For example, the prism  14  may be a dot prism pattern formed on a transparent lens, and the like. 
         [0039]    The apparatus for obtaining status information of a crystalline lens may include at least one light receiving unit  20 . The light receiving unit  20  may receive scattered lights L 2  of a reference light L 1  that is incident to the crystalline lens  4 , convert information about the scattered lights L 2  to an electrical signal, and output the electrical signal. For example, the light receiving unit  20  may include a photosensitive device, such as a CMOS image sensor or a CCD, in order to receive the scattered lights L 2 . The type of the photosensitive device is not limited thereto. The photosensitive device may sense lights corresponding to the wavelength of the reference light L 1 . 
         [0040]    The light receiving unit  20  may have an entrance with a predetermined width. As illustrated in  FIG. 2A , in the case where the distance between an eyeball and an object is relatively short so that the radius of curvature of the crystalline lens is small, a scattering range of scattered lights L 2  is wide. Accordingly, the intensity of the scattered lights L 2  that are received by the light receiving unit  20  is relatively weak. On the contrary, as illustrated in  FIG. 2B , if the distance between an eyeball and an object is relatively distant so that the radius of curvature of the crystalline lens is great, a scattering range of scattered lights L 2  is narrow. Accordingly, the intensity of the scattered lights L 2  that are received by the light receiving unit  20  is relatively strong. In order to efficiently receive the scattered lights L 2  passing through the entrance of the light receiving unit  20 , a predetermined optical lens may be positioned between the entrance of the light receiving unit  20  and the photosensitive device. 
         [0041]    The light receiving unit  20  directly receives scattered lights L 2  that are scattered against the crystalline lens  4 , for example, against the surface of the cornea surrounding the crystalline lens  4 . In this example, there is no subsidiary optical means such as a reflector for changing the path of light between the crystalline lens  4  and the light receiving unit  20 . Therefore, loss of the scattered lights L 2  due to reflection, and the like, can be prevented, which improves the measurement accuracy of the light receiving unit  20 . As another example, in consideration of polarization degrees (for example, ¼ of the wavelength of the reference light L 1 ) of the scattered lights L 2  with respect to the reference light L 1 , a polarizer (not shown) for efficiently passing polarized ones of the scattered lights L 2  through may be positioned at the entrance of the light receiving unit  20 . 
         [0042]    The light receiving unit  20  may be disposed beyond the visual field of the eyeball in order to not be an obstacle in the visual field. For example, the light receiving unit  20  may be disposed at an angle of about 15 through 60 degrees with respect to the incident path of the reference light L 1 , or at an arbitrary location in which the light receiving unit  20  is not an obstacle in the visual field according to an application. If the light receiving unit  20  is disposed beyond the visual field and close to the crystalline lens  4  as much as possible, the measurement efficiency of the scattered light L 2  can be improved. 
         [0043]    The calculating unit  30  may obtain thickness information of the crystalline lens  4  using information about the scattered lights L 2  received by the light receiving unit  20 . The calculating unit  30  may be electrically connected to the light receiving unit  20  and may obtain thickness information of the crystalline lens  4  using information (for example, intensity) about the scattered lights L 2  output from the light receiving unit  20 . This distinction between the calculating unit  30  and the light receiving unit  20  is only functional distinction. For example, the calculating unit  30  and the light receiving unit  20  may be implemented as two physically separated units or may be integrated into a single unit. 
         [0044]    For example, the calculating unit  30  may be means for calculating a change in thickness of the crystalline lens  4  or a relative thickness of the crystalline lens  4 , instead of being a means for calculating an absolute thickness of the crystalline lens  4 . For example, the calculating unit  30  may compare the intensity of the scattered lights L 2  measured by the light receiving unit  20  to a predetermined reference value or a previously measured value, in order to calculate a change in thickness of the crystalline lens  4 . As another example, the calculating unit  30  may determine only whether the measured intensity of the scattered lights L 2  is above or below a predetermined reference value. 
         [0045]    Because the thicknesses, radiuses of curvature, surface roughness, and the like, of crystalline lenses have deviations, a reference value that is used in calculating a change in thickness of a crystalline lens may be set differently for each user. For example, the light receiving unit  20  may measure the intensity of scattered lights L 2  from a reference light L 1  generated by the light source unit  10  and incident to the crystalline lens of a specific user who views an object placed at a predetermined distance from the crystalline lens. The predetermined distance may be based on an application type of the apparatus for obtaining status information of a crystalline lens, and the measured intensity of the scattered lights L 2  may be used as a reference value. As another example, the calculating unit  30  may estimate a change in thickness of the crystalline lens  4  using a difference between a value previously measured by the light receiving unit  20  and a value currently measured by the light receiving unit  20 . 
         [0046]    In this example, the apparatus for obtaining status information of a crystalline lens may obtain status information of a crystalline lens by directly receiving scattered lights from a reference light straightly incident to the crystalline lens. Also, the apparatus for obtaining status information of a crystalline lens may use a prism to change a path of a reference light generated by a light source disposed at a location in which the prism is not an obstacle in the visual field, thereby making the reference light straightly incident to the crystalline lens. Accordingly, it is unnecessary to provide a separate translucent mirror for passing a reference light through to change the path of a reflection light. Also, the light receiving unit  20  has excellent measurement efficiency because it directly receives scattered lights and measures the intensity of the scattered lights. 
         [0047]      FIG. 4  illustrates an example of a 3D image display system. The 3D image display system is an example of an application apparatus for obtaining status information of a crystalline lens, as described herein with reference to  FIG. 3 . Referring to  FIG. 4 , the 3D image display system includes 3D glasses  110  which a user may wear to view 3D images that are displayed on a 3D display, and a 3D image reproducing apparatus  120  for reproducing the 3D images on the 3D display. 
         [0048]    The type of the 3D glasses  110  is not limited. For example, the 3D glasses  110  may be active shutter glasses or polarization glasses. As another example, the 3D glasses  110  may be new type glasses that will be developed in the future. 
         [0049]    The 3D glasses  110  include a frame  112  and lenses  114 . The frame  112  includes a pair of frame bodies  112   a  (also,  112   a  for each) surrounding the lenses  114  (also,  114  for each), and frame legs  112   b  (also,  112   b  for each) that respectively extend from the frame bodies  112   a  and are to be placed on a user&#39;s ears. The frame  112  of the 3D glasses  110  may further include additional means (for example, a pair of nose supporting plates attached to a connection point of the frame bodies  112   a , which are not shown in the drawing) for assisting a user wearing the 3D glasses  110 . 
         [0050]    As another example, the 3D glasses  110  may be rimless glasses without frame bodies. In this example, the light source  12  of the apparatus for obtaining status information of a crystalline lens may be disposed, instead of at the frame body  112   a , at the frame leg  112   b , for example, at a connection point between the frame leg  112   b  and the lens  114 . Other components except for the light source  12  may be disposed at the same locations as in the 3D glasses  110 , which is described later. Hereinafter, the 3D glasses  110  having the frame bodies  112   a  are described. 
         [0051]    The 3D glasses  110  include the apparatus for obtaining status information of a crystalline lens, as described above with reference to  FIG. 3 . For example, the 3D glasses  110  include the light source unit  10 , the light receiving unit  20 , and the calculating unit  30 . The 3D glasses  110  may have one apparatus for obtaining status information of a crystalline lens, or multiple apparatuses of obtaining status information of a crystalline lens at the left and right sides. 
         [0052]    The light source unit  10  includes a light source  12  for generating a reference light, and a light path changing unit  14  for changing the path of the reference light emitted from the light source  12  toward crystalline lens. The light source  12  may be disposed at a predetermined location on the frame body  112   a . For example, the light source  12  may be disposed between the lenses  114  or at a connection point between the lens  114  and the frame leg  12   b  in order not to become an obstacle in the visual field. As another example, the light source  12  may be disposed at a frame leg part connected to the frame body  112   a . Also, the light path changing unit  14  may be formed at the center portion of the lens  14 , as a dot for creating a micro-sized prism that cannot be recognized with a naked eye or that becomes a very little obstacle in the visual field. The light path changing unit  14  formed in the center portion of the lens  114  may reflect a reference light emitted from the light source  12  at a predetermined angle to make the reference light straightly incident to the crystalline lens of a user who wears the 3D glasses  110 . 
         [0053]    The light receiving unit  20  which receives scattered lights may be disposed at a predetermined location on the frame leg  112   b . For example, the light receiving unit  20  may be disposed at a frame leg portion that is closest to the eyeball of the user who is wearing the 3D glasses. In this example, the light receiving unit  20  may be disposed slightly in front of the eyeball in order to efficiently receive the scattered lights. The calculating unit  30  may be integrated with the light receiving unit  20  or disposed adjacent to the light receiving unit  20 . As described above, the calculating unit  30  may obtain thickness information of a crystalline lens using the intensity of scattered lights or obtain changes in intensity of the scattered lights, which is measured by the light receiving unit  20 . 
         [0054]    The 3D glasses  110  further include a transmission unit  116 . The transmission unit  116  is used to transmit thickness information of a crystalline lens obtained by the calculating unit  30  to an external electronic device. For example, the transmission unit  116  may transmit thickness information of a crystalline lens to a 3D image reproducing apparatus  120  of a 3D image display system. For example, the transmission unit  116  may be a transmitter, such as BLUETOOTH® or Zigbee, based on a Near Field Communication (NFC) standard. 
         [0055]    The thickness information that is transmitted by the transmission unit  116  may relate to the radius of curvature of the crystalline lens. For example, the thickness information may indicate that the radius of curvature of the crystalline lens is above or below a predetermined reference value. As another example, the thickness information may include a degree at which the radius of curvature (or the thickness) of the crystalline lens increases or decreases, or information about an amount of deviation from a reference value. 
         [0056]    As described above, the 3D image display system includes the 3D image reproducing apparatus  120  for reproducing 3D images on a 3D display. The 3D image reproducing apparatus  120  may reproduce 3D images on the 3D display by decrypting encrypted 3D video content. Operation of decrypting encrypted 3D video content may be performed by an image processor  126  of the 3D image reproducing apparatus  120 . For example, the 3D image reproducing apparatus  120  may be installed in a television, a computer monitor, a display of a mobile terminal, or in an external electronic apparatus electrically connected to the electronic appliance so that 3D images can be reproduced on the electronic appliance. 
         [0057]    For example, the 3D image reproducing apparatus  120  may receive thickness information of a crystalline lens from the 3D glasses  110  and change the format of 3D images that are to be reproduced on a display adaptively based on the thickness information. For example, if the thickness of the crystalline lens exceeds a predetermined reference value, the 3D image reproducing apparatus  120  may reproduce 3D images based on binocular disparity. As another example, if the thickness of the crystalline lens is less than the predetermined reference value, the 3D image reproducing apparatus  120  may reproduce 2D images based on brightness or depth perception, or reproduce new 3D images that can be represented with a small amount of data compared to existing 3D images. 
         [0058]    The images may be reproduced based on the assumption that when an object is relatively far away from a crystalline lens, binocular disparity is small and also a human being&#39;s vision is not easy to recognize a cubic effect. In the case in which an object is far away from a crystalline lens, a viewer may little recognize deterioration of cubic effect although 2D images are reproduced. Meanwhile, if the distance between an object and a crystalline lens is longer than a predetermined distance (for example, 3 m), the 3D image reproducing apparatus  120  reproduces 2D images or new 3D images that can be represented with a relatively small amount of data, on the 3D display, resulting in reduction of an amount of data processing and improvement of processing speed. 
         [0059]    For this operation, the 3D image reproducing apparatus  120  includes a receiving unit  122  and a control unit  124 . The receiving unit  122  may be used to receive thickness information transmitted from the transmission unit  116  of the 3D glasses  110 . A communication method of the receiving unit  122  corresponds to a communication method of the transmission unit  116 , and the configuration of the receiving unit  122  is not limited. The control unit  124  may control the format of 3D images that are reproduced on the display, based on the thickness information. For example, the controller  124  may control the image processing unit  126  of the 3D image reproducing apparatus  120  to decrypt encrypted 3D video content and restore 3D or 2D images based on binocular disparity, thereby adaptively changing the format of images that are restored by the 3D image reproducing apparatus  120  and transferred to the display. 
         [0060]      FIG. 5  illustrates an example of a 3D image acquisition apparatus. 
         [0061]    The 3D image acquisition apparatus is another example of an application apparatus that uses status information of a crystalline lens, as described above with reference to  FIG. 3 . 
         [0062]    Referring to  FIG. 5 , the 3D image acquisition apparatus includes a pair of cameras (that is, a left camera  202  and a right camera  204 ), an apparatus  206  for obtaining status information of a crystalline lens, and an image processor  210 . 
         [0063]    The configuration of the cameras  202  and  204 , which are image acquisition devices for photographing 3D images, is not limited thereto. In this example, the left camera  202  is spaced a predetermined distance from the right camera  204 . The distance between the left and right cameras  202  and  204  may be fixed or may not be fixed. The distance between the left and right cameras  202  and  204  may correspond to the distance between a human being&#39;s eyes. The left camera  202  photographs a left image of a 3D image and the right camera  204  photographs a right image of the 3D image. One or both of the left and right cameras  202  and  204  may include the apparatus  206  for obtaining status information of a crystalline lens. The apparatus  206  for obtaining status information of a crystalline lens may have the configuration illustrated in  FIG. 3 . Accordingly, the apparatus  206  for obtaining status information of a crystalline lens includes the light source unit  10 , the light receiving unit  20 , and the calculating unit  30 . 
         [0064]    Referring again to  FIG. 3 , the light source unit  10  includes the light source  12  for generating a reference light, and the light path changing unit  14  for changing the path of the reference light emitted from the light source  12  toward crystalline lens. For example, the light source  12  may be installed at or around an eyepiece frame into which an eyepiece of the left and/or right camera  202  and/or  204  is inserted. The light path changing unit  14  is formed at the center of the eyepiece, as a dot for creating a micro-sized prism that cannot be recognized with a naked eye or that is a little obstacle in the visual field. The light path changing unit  14  formed at the center of the eyepiece reflects a reference light emitted from the light source  12  at a predetermined angle, to make the reference light straight incident to the crystalline lens of a user who photographs 3D images through a 3D image acquisition apparatus. In addition, the light receiving unit  20  for receiving scattered lights may be disposed at or around the eyepiece frame. Also, the calculating unit  30  may be integrated with the light receiving unit  20  or disposed adjacent to the light receiving unit  20 . 
         [0065]    The image processor  210  may encode one or both of left and right images acquired by the left and right cameras  202  and  204  based on thickness information that is received from the apparatus  206  for acquiring status information of a crystalline lens. For example, if the thickness of the crystalline lens exceeds a predetermined reference value, the image processor  210  may encode both the left and right images, and if the thickness of the crystalline lens is below the predetermined reference value, the image processor  210  may encode one of the left and right images. 
         [0066]    The operation of the image processor  210  may be controlled by the control unit  208 . Like the 3D image display system illustrated in  FIG. 4 , the current example is also based on the assumption that when an object is relatively far away from a crystalline lens, binocular disparity is small and also a human being′ vision is not easy to recognize a cubic effect. Accordingly, if the distance from a crystalline lens to an object is longer than a predetermined distance (for example, 3 meters), the image processor  210  encodes only one of the left and right images, thereby reducing the amount of data processing and increasing processing speed. For example, image data processed by the image processor  210  may be stored in a memory  212 . 
         [0067]      FIG. 6  illustrates an example of a 3D imaging method. For example, the method may be used to obtain information of a crystalline lens of an eyeball of a person. 
         [0068]    Referring to  FIG. 6 , in  601 , light is directed towards the crystalline lens of the eyeball. For example, the directing may be performed by a source that is not in the field of view of the person. As merely one example, the source may be included in a pair of three-dimensional (3D) glasses. 
         [0069]    In  602 , light scattered against the crystalline lens of the eyeball is received. For example, light may be directed in  601  to be perpendicularly incident on the crystalline lens of the eyeball. As a result, the light may reflect in a scattered pattern and may be received by an imaging element in  602 . 
         [0070]    In  603 , thickness information of the crystalline lens is calculated based on the received scattered lights. 
         [0071]    The Examples described herein with respect to  FIGS. 1-5  are also applicable to the method of  FIG. 6 , however, additional description thereof is omitted here for conciseness. 
         [0072]    A number of examples have been described above. Nevertheless, it will be understood that various modifications may be made. For example, suitable results may be achieved if the described techniques are performed in a different order and/or if components in a described system, architecture, device, or circuit are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Accordingly, other implementations are within the scope of the following claims.