Abstract:
An ophthalmology apparatus has an illuminating system which illuminates an eye to be examined, an imaging system which takes images of the eye to be examined illuminated by the illuminating system, and a controller capable of controlling the imaging system so as to obtain the plurality of images sequentially while changing focusing states.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ophthalmology apparatus, such as a retinal camera or the like, used in ophthalmic hospitals, in health screening, and so on. 
     2. Related Background Art 
     There are conventionally known, digital, retinal cameras for taking electronic images in low light amounts by use of a CCD camera or the like to record images of the eyeground and the like. FIG. 4 is a structural diagram to show the structure of a conventional retinal camera, in which light emitted from an observation light source  1  travels via lenses  2 ,  3 , a ring stop  4 , a lens  5 , a bored mirror  6 , an objective  7 , etc. to illuminate the eyeground Er of an eye to be examined E. Reflected light from the eyeground travels through the objective  7  and a taking lens  8  and then is bent by a path changeover mirror  9  and a dichroic mirror  10  to travel via a field lens  11 , a field stop  12 , and an imaging lens  13  to be focused on an observation TV camera  14 . A small mirror  15  is put into the optical path, whereby a split chart  17 , illuminated by a split projection light source  16 , is projected via an optical system  18  onto the eyeground Er. 
     Based on a projection image of this split chart  17 , an operator moves the taking lens  8  along the optical path so as to align left and right bright lines with each other, thereby bringing the eye to be examined E into focus. After completion of focusing, the operator manipulates a fixation target moving switch, not illustrated, in order to photograph a predetermined portion of the eye to be examined E, and then moves an opening portion of liquid-crystal shutter  19  to guide the desired portion of the eye to be examined E into the field by a fixation target  20 . Unless there is any defocus at this time, the operator depresses a photograph switch  21  to light a photograph light source  22  in the illumination optical system, thereby illuminating the eyeground Er. The reflected light from the eyeground Er is guided through the objective  7 , the aperture of the bored mirror  6 , the taking lens  8 , a field lens  23 , a field stop  24 , and an imaging lens  25  to form an image on an image pickup device  26 . The output of the image pickup device  26  is supplied through a controller  27  to an image recording device  28  to record a still image and to a television monitor  29  to display a dynamic picture. 
     In the above-stated example, however, since the target projected for focusing of the eye to be examined E is only one meridian of the eye to be examined E, there will exist in-focus and out-of-focus portions in a single image if the eye to be examined E suffers an ametropia such as astigmatism or the like. The human eye also has spherical aberrations which cause the existence of in-focus and out-of-focus portions. Therefore, the operator needs to adjust the focus position again before photography and these operations require some time and labor. Problems which are troublesome. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to solve the above-stated problem, thereby providing an ophthalmology apparatus capable of taking a plurality of images at different focus positions by a single photographing operation. 
     For accomplishing the above object, the present invention provides an ophthalmology apparatus comprising: 
     an illuminating system which illuminates an eye to be examined; 
     an imaging system which takes image of the eye to be examined illuminated by the illuminating system; and 
     a controller capable of controlling the imaging system so as to obtain the plurality of images sequentially while changing focusing states. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a retinal camera according to an embodiment of the present invention; 
     FIG. 2 is an explanatory diagram of a screen of the TV monitor; 
     FIGS. 3A,  3 B, and  3 C are explanatory diagrams of images of the image recording device; and 
     FIG. 4 is a side view of the conventional example. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described hereinafter in detail, based on the embodiment illustrated in FIG. 1 to FIG.  3 C. 
     FIG. 1 is a structural diagram of a digital, retinal camera according to the embodiment, in which a relay lens  32 , a photograph light source  33 , a relay lens  34 , a ring stop  35 , a relay lens  36 , a small mirror  37  retractable from the optical path, a relay lens  38 , and a bored mirror  39  having an aperture in the central part are arranged in the order named on the optical path from an observation light source  30  to an objective  31  opposed to the eye to be examined E. Arranged on the optical path along the direction of incidence to the small mirror  37  are a lens  40 , a two-hole stop  41  approximately conjugate with the pupil position of the eye to be examined E with respect to the objective  31  and the relay lens  38 , a split chart  42  approximately conjugate with the eyeground Er of the eye to be examined E with respect to the objective  31 , the relay lens  38 , and the lens  40 , a split prism  43 , a relay lens  44 , a stop  45 , and a split projection light source  46 . These split projection optics are movable along the optical path of the illumination optical system, as indicated by arrows, together with the small mirror  37 . 
     A taking lens  47 , which is movable on the optical path in directions of arrows in association with movement of the small mirror  37  by a driving mechanism, is placed on the optical path behind the bored mirror  39 . Further, a path changeover mirror  48 , a field lens  49 , a field stop  50 , an imaging lens  51 , and an image pickup device  52  such as the CCD or the like, are arranged in the stated order after the taking lens  47 . Arranged on the optical path along the direction of reflection of the path changeover mirror  48  are a dichroic mirror  53 , a liquid-crystal shutter  54  which has an opening portion and which presents the fixation target for the eye to be examined E, and an illumination light source  55  for illuminating this liquid-crystal shutter  54 . A field lens  56 , a field stop  57 , an imaging lens  58 , and a TV camera  59  for observation of the eye to be examined are arranged on the optical path along the direction of reflection of the dichroic mirror  53 . 
     The image pickup device  52  and the TV camera  59  are connected to a controller  60 . Further connected to the controller  60  are an image recording device  61 , a TV monitor  62 , an image pickup switch  63 , a correction amount input device  64  such as a keyboard or the like, and the driving mechanism of the taking lens  47 . 
     Light emitted from the observation light source  30  travels through the relay lenses  32 ,  34 , the ring stop  35 , and the relay lenses  36 ,  38  to be reflected by the bored mirror  39  to illuminate the eyeground Er of the eye to be examined E through the objective  31 . Reflected light from the eyeground Er travels through the objective  31 , the bored mirror  39 , and the taking lens  47  to be bent by the path changeover mirror  48  and the dichroic mirror  53  and then the light travels through the field lens  56 , the field stop  57 , and the imaging lens  58  to form an image on the observation TV camera  59 . 
     At this time the small mirror  37  is brought into the optical path and the split projection light source  46  is switched on. Light from this light source  46  travels through the stop  45 , the relay lens  44 , and the split prism  43  to illuminate the split chart  42 . Then the light travels via the two-hole stop  41 , relay lens  40 , small mirror  37 , relay lens  38 , bored mirror  39 , and objective  31  to be projected onto the eyeground Er of the eye to be examined E. This causes a small mirror image  37 ′, together with an eyeground image Er′, to be displayed on the screen of the TV monitor  62 , as illustrated in FIG. 2, and split bright lines  42 ′ from the split chart  42  are displayed in the upper part of the small mirror image. 
     Based on this picture, the operator moves the taking lens  47  along the optical path in synchronism with the small mirror  37  by manipulating an unrepresented dial or the like so as to align the split bright lines  42 ′ with each other, thereby bringing the eye to be examined E into focus. After completion of focusing, the operator enters a correction amount before and after the focus position through the correction amount input switch  64 . In order to photograph a desired portion of the eye to be examined E, the operator then manipulates an unrepresented fixation target moving switch to move the opening portion of the liquid-crystal shutter  54  illuminated by the light source  55 , thereby guiding the desired portion of the eye to be examined E into the field. On that occasion, the operator checks whether there exists defocus. If there is some defocus, the operator will again perform the focusing operation. 
     After confirming the absence of defocus, the operator depresses the photograph switch  63  to switch the photograph light source  33  on. Light from the photograph light source  33  travels through the optical path similar to the observation optical path, to illuminate the eyeground Er of the eye to be examined E. Reflected light from the eyeground Er travels through the objective  31 , the aperture of the bored mirror  39 , the taking lens  47 , the field lens  49 , the field stop  50 , and the imaging lens  51  to form an image on the image pickup device  52 . A digital image signal of the eyeground image Er′ obtained thereby is recorded as a still image in the image recording device  61 . 
     FIGS. 3A to  3 C show images recorded in the image recording device  61 . With the reference being the image of FIG. 3A of the aligned split bright lines  42 ′, the controller  60  performs such control as to obtain a plurality of images of the same eye to be examined E at the positions of FIGS. 3B and 3C sequentially while moving the taking lens  47  by the driving mechanism, for example, in accordance with the correction amounts of ±0.5 diopter entered through the correction amount input switch  64 . During this period of sequential photography, the small mirror  37  and path changeover mirror  48  are each off the optical path. 
     The present embodiment is arranged to carry out the photography of three consecutive photographs with entry of the correction amount before and after the focus position, but the apparatus may also be modified to be able to perform an arbitrary number of photographing operations at any focus position. The present embodiment is arranged to give the entry of correction amount after the focusing operation, but the entry of correction amount may be made anytime before photography. Further, the correction amount may also be preliminarily stored in a memory, without entering it as occasion demands. 
     Further, the apparatus may also be arranged to receive input of spherical and astigmatic diopters obtained by a measuring device such as a refractor or the like and take consecutive photographs at the strongest principal meridian, at the weakest principal meridian, and at an intermediate or another focus position of the eye to be examined E. In this case, the measurement data from the other ophthalmology instrument is entered into the apparatus through the keyboard or the like by the operator, or an interface is prepared for the entry by communication. 
     Since the ophthalmology apparatus described above is constructed to take a plurality of images at different focus positions by a single photographing operation, it does not have to perform another photographing operation even if the eye to be examined suffers an ametropia, such as astigmatism or the like, or otherwise has a spherical aberation; therefore, it permits the photography with good efficiency.