Abstract:
Confocal microscope equipment which provides real time 3-dimensional display by scanning at high speeds in the direction of the optical axis, wherein sliced images of a sample are obtained by scanning the sample surface with a light beam using a confocal scanner having an objective lens actuator which scans the objective lens in the optical axis direction faster than a one image integrating time when photographing the slice images with an image pickup device or when observing the sliced images direction with the naked eye.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to confocal microscopic equipment that displays an object under test in three-dimensional form using a confocal microscope. More precisely, the present invention relates to an improvement for optical production of real-time three-dimensional displays of an object by realizing high resolution and large depth of focus in real-time at high speed. 
     2. Description of the Prior Art 
     FIG. 7 shows an example of the conventional type of confocal microscopic equipment. The equipment captures an image of sample  11  using confocal scanner  20  mounted on optical microscope  10  and takes photographs of this image with camera  30 . To confocal scanner  20 , the laser beam generated from laser light source  50  is supplied. 
     The output signal of camera  30  is converted to a digital signal through converter  40  and stored in a memory means (not shown in the figure) in computer  60 . 
     In optical microscope  10 , stage  12  on which sample  11  is mounted is built to be movable in the optical axis direction (Z-axis direction) by controller  13  (illustrated separately from optical microscope  10  in FIG. 7 to avoid complication). Controller  13  is constructed to move stage  12  in the Z-axis direction by turning the rotary knob (not shown in the figure) of stage  12  using a pulse motor (not shown in the figure). 
     Sliced images of sample  11  can be obtained by scanning the beam in directions perpendicular to the optical axis (X- and Y-axis directions) using confocal scanner  20 . In this case, if multiple sliced images are sampled progressively by moving stage  12  in the Z-axis direction with controller  13  and then are reconstructed using computer  60 , a three-dimensional image of sample  11  can be obtained. 
     However, there are the following problems in confocal microscopic equipment constructed as described above: 
     (1) Problems caused by the fact that controller  13  is driven by a pulse motor. 
     (a) The entire body of stage  12  is moved up and down. However, since the weight of stage  12  is heavy and thus its inertia is also large, stage  12  cannot be moved at high speed and so its movement takes a long time. 
     (b) It is not accurate. Since the rotary knob of stage  12  is turned by a pulse motor, out-of-step (the pulse motor appears to move but actually does not move) or hysteresis occurs during motion at the rack-pinion portion linking the rotary knob to stage  12 . Hence, it is not known whether stage  12  has actually moved and so the movement is not accurate. 
     (c) Usually, a pulse motor has a large external size and is difficult to install. 
     (2) Problems caused by reconstructing a three-dimensional image with computer  60 . 
     (a) It takes a long time; it typically takes from several minutes to tens of minutes to obtain an image sheet. 
     (b) Software for reconstructing three-dimensional images is expensive and is also difficult to operate. 
     SUMMARY OF THE INVENTION 
     The objective of the present invention is to solve the problems described above in providing confocal microscopic equipment in which scanning in the optical axis direction is performed at high speed and the real-time three-dimensional image can be easily displayed. 
     In order to solve those problems, the invention is characterized by confocal microscopic equipment that can capture sliced images of a sample by scanning the sample surface with a light beam using a confocal scanner as shown below. The confocal microscopic equipment comprises an objective lens actuator that scans the objective lens in the optical axis direction faster than the one-image integrating time when photographing the above sliced images with an image pickup device or when observing the above sliced images directly with the naked eye. 
     In the invention, the objective lens is scanned in the optical axis direction with the objective lens actuator provided in the confocal microscopic equipment. In this case, the objective lens is scanned faster than the one-image integrating time when the one-image is observed by an image pickup device or the naked eye. This allows images of large depth of focus to be seen in real-time and so real-time three-dimensional display of samples can be achieved. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows the configuration of an essential part of an embodiment for the confocal microscopic equipment in accordance with the present invention. 
     FIGS.  2 ( a ) and  2 ( b ) show illustrative drawings of sliced images. 
     FIG. 3 shows a drawing as an example of movement of the objective lens. 
     FIGS.  4 ( a )- 4 ( d ) show illustrative drawings in the case where the stage is moved in a direction transverse to the optical axis. 
     FIGS.  5 ( a ) and  5 ( b ) show the drawings indicating statuses of control for the intensity of the laser beam or the sensitivity of the camera. 
     FIGS.  6 ( a ) and  6 ( b ) show conceptual drawings of sliced images corresponding to the statuses of control indicated in FIG.  5 . 
     FIG. 7 shows a drawing of the configuration of an example of conventional confocal microscopic equipment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described below in detail using the drawings. FIG. 1 shows the configuration of an essential part of an embodiment for the confocal microscopic equipment in accordance with the present invention. In FIG. 1, the part of confocal scanner  20  has the well-known configuration and comprises microlens disk  22 , pinhole disk  23 , beam splitter  25  and lens  26 . 
     Normally, a plurality of microlenses (not shown in the figure) are arranged in microlens disk  22  and formed to focus light beam (herein laser beam is used)  21  on each pinhole (a plurality of pinholes are arranged) in pinhole disk  23 . Pinhole disk  23  is linked to microlens disk  22  in parallel and is designed to be able to rotate around the same shaft integral with microlens disk  22  at the same speed. Light beams emitted from pinhole disk  23  being rotated in a plane perpendicular to the optical axis (X- and Y-axis plane) are incident to microscope  10  and scanned over the surface of sample  11 . 
     Beam splitter  25  is located between microlens disk  22  and pinhole disk  23  and reflects the return light from microscope  10 . This return light is incident to the image-receiving surface of an image pickup device (for example, camera  30 ) through lens  26 . 
     Objective lens actuator  15  is provided in microscope  10  to be able to move objective lens  14  in the optical axis direction (Z-axis direction). Objective lens actuator (hereinafter simply called actuator)  15  can be constructed, for example, with a piezoelectric element and its driving means that can freely move objective lens  14  in the Z-axis direction by driving the piezoelectric element with external driving signals. 
     The operations of a system configured as mentioned above will be described below. Laser beam  21  is focused on pinholes  24  on pinhole disk  23  by microlenses in microlens disk  22 . Laser beams transmitted through pinholes  24  focus on focusing point  17  on focal plane  16  on sample  11  located in a position conjugate with pinhole disk  23  by means of objective lens  14 . 
     Focal plane  16  on sample  11  is optically scanned by the rotation of microlens disk  22  and pinhole disk  23 . The return light beam from the sample surface is again transmitted through objective lens  14  and pinhole disk  23 , then return with beam splitter  25 , and finally forms an image on the image reception plane of camera  30  through lens  26 . 
     In this case, objective lens  14  is driven with actuator  15  and the sliced images in positions Z 1 , Z 2 , Z 3 , . . . Z n  in the direction of depth of objective lens  14  are photographed with camera  30  over one period of the drive. 
     FIG. 2 shows illustrative drawings of the above sliced images. In FIG. 2, drawing (a) presents each sliced image in the Z-axis direction and drawing (b) indicates the relationship between the sample and each slicing plane. In addition, Z sum  in in drawing (a) of FIG. 2 represents the resultant image obtained by superimposing sliced images of Z 1 , Z 2 , Z 3 , . . . Z n . 
     In this case, each sliced image is obtained by scanning objective lens  14  faster than one-image integrating time when one image is viewed with a camera or the naked eye. 
     If camera  30  is herein operated by the National Television System Committee (NTSC) scheme (30 pictures/second) and objective lens  14  is moved at 30 Hz f or a stroke of Z 1 , Z 2 , Z 3 , . . . Z n , the resultant image of Z 1 , Z 2 , Z 3 , . . . Z n  can be photographed in real-time with camera  30 . This resultant image can also be observed in real-time by viewing it with the naked eye in place of camera  30 . 
     Further, although large depth of focus can be obtained also in conventional non-confocal microscopes, they can produce only wholly unclear, faded images. Confocal microscopes have an advantage that clear images (sliced images) that are wholly in focus are obtained. 
     Furthermore, since only sliced images can be viewed with a confocal microscope, in the initial positioning step, first the entire object is viewed using a non-confocal image and then the microscope is optically switched to the confocal system. However, positioning according to the present invention has another advantage in that it is managed only by the switching of electrical signals that control the start and stop of actuator  15 . 
     In addition, since objective lens  14  is moved so as to go and return (deflection amplitude a of the objective lens) in one period (time t) as shown in FIG. 3, two resultant images can be obtained in one period. Thus, there is virtually no problem if objective lens  14  is designed to move at 15 Hz. In general, the scanning time may be taken as an integer multiple of the image integrating time. 
     It may also be suitable that the beam is always focused at the position of focus of objective lens  14  even if the objective lens is moved up and down by insertion of a tube lens between pinhole disk  23  and objective lens  14 . 
     Further, by moving stage  12  (refer to FIG. 7) in synchronization with the above action in the direction perpendicular to the optical axis (transverse direction), an integrated image of sample  11  viewed obliquely can be obtained. Drawings (a), (b) and (c) of FIG. 4 show sliced images and drawing (d) of FIG. 4 indicates the external view of the sample. Drawing (a) of FIG. 4 shows the sliced images viewed from directly above (in the direction of D 1  in drawing (d) of FIG. 4) sample  11  with stage  12  fixed to the initial position. Drawing (b) of FIG. 4 shows the sliced images viewed by moving stage  12  to the right (viewed in the direction of D 2  in drawing (d) of FIG.  4 ). Drawing (c) of FIG. 4 shows the sliced images viewed by moving stage  12  to the left (viewed in the direction of D 3  in drawing (d) of FIG.  4 ). 
     As described above, images when sample  11  is viewed obliquely can be obtained in real-time by scanning stage  12  transversely. 
     If the above Z-direction scanning is herein implemented at 30 Hz and the variation from drawing (a) to drawing (c) in FIG. 4 is carried out at, for example, about 1 Hz, sample  11  appears to be slowly deflected to the right and left. Thus, a stereoscopic impression is obtained through dynamic stereoscopic vision. In this case, the object to be moved in the transverse direction described above is not limited to sample  11  but transverse movement of any of the objective lens, tube lens, confocal scanner or camera provides similar results. In short, the above result can be obtained by changing the relative positions between the sample and image pickup device in the transverse direction. 
     In addition, the intensity of the laser beam or sensitivity of camera  30  may also be increased or decreased corresponding to movement in the Z-axis direction by providing a control mechanism that can control the intensity of the laser beam or sensitivity of camera  30 . 
     With such a control mechanism, the intensity of the laser beam or the sensitivity of camera  30  may be increased as the piezoelectric element driving voltage increases, that is, as the depth of the confocal plane position (called sample depth) is increased as shown in drawing (a) of FIG.  5 . Otherwise, the intensity of the laser beam or the sensitivity of camera  30  may be reduced as the sample depth is decreased as shown in drawing (b) of FIG.  5 . 
     Drawing (a) of FIG. 6 conceptually indicates the sliced images obtained by the control as shown in drawing (a) of FIG. 5; drawing (b) of FIG. 6 conceptually indicates the sliced images obtained by the control as shown in drawing (b) of FIG. 5, respectively. In FIG. 6, the thickness of the solid line represents changing intensity of the laser beam or the sensitivity of camera  30 . 
     Since humans receive a stereoscopic impression when the foreground is made bright and the depths dark, the implementation as described above enables an image display with a stereoscopic impression to be easily obtained. 
     In addition, the above description of the present invention is only illustrative for a specific preferred embodiment for the purpose of explanation and example. Accordingly, it is apparent that the present invention is not restricted by the above embodiment and can include many changes and modifications without departing from the spirit of the essential characteristics thereof. 
     As explained above, the present invention has the following effects: 
     According to the invention, images of large depth of focus can easily be obtained in real-time by scanning the objective lens at a speed equal to or higher than the one-image integrating time in the optical axis direction. 
     According to the invention, images without frame shift can be easily obtained by taking the scanning time of the objective lens as an integer multiple of the one-image integrating time. 
     According to the invention, a dynamic stereoscopic view can be achieved and images with a stereoscopic impression can be obtained by the following means: 
     scanning the objective lens at a speed equal to or higher than the one-image integrating time in the optical axis direction as well as scanning the relative position of the sample to the image pickup device in the direction perpendicular to the optical axis in synchronization with the above scanning of the objective lens in the optical axis direction. 
     According to the invention images with a stereoscopic impression having a front-to-rear relation can be obtained by the following: 
     increasing or decreasing the above intensity of the light beam or the sensitivity of the image pickup device corresponding to the position of the confocal plane as well as scanning the objective lens in the optical axis direction faster than the one-image integrating time. Accordingly, the invention has the effects described below. The confocal images of a sample reacting differently in the direction of depth can be measured in real-time. In addition, the trend of an observation target can always be grasped even if the target moves in the direction of depth provided it is in the range of capturing confocal images.