Abstract:
The invention aims to make it unnecessary to reposition an objective lens when repeatedly carrying out examinations. It is possible to carry out in vivo examination of tissue such as cells and muscle tissue or various internal organs, such as the heart, liver, and so forth, of mammals, especially small experimental animals, over a comparatively long period of time. A microscope system having an objective optical system unit and a structure or member for fixing the objective optical system unit to a living body is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a divisional application of U.S. application Ser. No. 10/964,866 filed Oct. 14, 2004, which claims priority to Japanese Patent Application Nos. 2003-357577, 2003-363501 and 2004-72236. The contents of U.S. application Ser. No. 10/964,866 and each of Japanese Patent Application Nos. 2003-357577, 2003-363501 and 2004-72236 are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to objective lens units disposed at the subject side in optical apparatuses, to objective lens insertion tools for inserting objective lens units of optical apparatuses, to microscopes provided with such objective lens units or objective lens insertion tools, to microscope systems including such microscopes, and to objective optical system fixing devices.  
         [0004]     2. Description of Related Art  
         [0005]     Conventionally, a confocal laser-scanning microscope is a known apparatus for obtaining surface and tomographic images of samples of living cells and tissue in order to observe cellular function or the like, by illuminating a sample of a living body with excitation light from the surface thereof and by selectively detecting fluorescence emitted from a location at a predetermined depth in the sample (see, for example, Japanese Unexamined Patent Application Publication No. HEI 3-87804 (page 2, etc. therein) and Japanese Unexamined Patent Application Publication No. HEI 5-72481 (FIG. 1, etc. therein)). In a confocal laser-scanning microscope, a laser light source and an optical detector are disposed so as to have an optically conjugated positional relationship with respect to an objective lens. Furthermore, a scanning optical system is provided between the laser light source and the objective lens, and images of the sample are obtained while two-dimensionally or three-dimensionally scanning the laser beam over the sample.  
         [0006]     In addition to standard microscope observation, by scanning the laser light, which is focused to a minute spot region on the sample, using scanning means such as a galvano mirror, this confocal laser-scanning fluorescence microscope detects fluorescence emitted from the sample to obtain images.  
         [0007]     Since this confocal laser-scanning microscope can therefore eliminate light other than that from the minute spot being examined due to its excellent resolving power, it has the advantage of being able to obtain detailed examination images with a high signal-to-noise (S/N) ratio.  
         [0008]     Moreover, in conventional confocal laser-scanning microscopes, there are devices for optically connecting the scanning optical system and the objective lens, which is adjacent to the site being examined, using a fiber bundle (see, for example, Japanese Unexamined Patent Application Publication No. HEI 11-133306, paragraphs 0012 to 0015 and FIG. 1 therein).  
         [0009]     However, when examining the same sample a plurality of times with these types of confocal laser-scanning microscope, the sample and the objective lens must be aligned for each examination. In cases where the sample is tissue or the like of a small animal, such alignment is particularly difficult.  
         [0010]     Alignment must also be carried out when the magnification of the objective lens is changed.  
         [0011]     Also, when examining a cell or the like a plurality of times, it is essential that foreign objects do not get into the subject under examination.  
         [0012]     Furthermore, microscopes including conventional confocal laser-scanning microscopes are not designed for in vivo examination of various organs of small experimental animals, such as rats and mice. Therefore, in cases where vibration occurs due to the pulsation of blood vessels or the like, there are conceivably disadvantages such as images of the subject site under examination becoming blurred or the focal point becoming out of focus as a result of movement in the relative positions of the examination site of the subject and the objective optical system disposed adjacent to the examination site of the subject.  
         [0013]     In particular, to carry out time-lapse examination, in order to allow the small experimental animal or the like to behave like normal during examination, the alignment state of the objective optical system must be temporarily released. In such a case, it is extremely difficult to re-align the objective optical system at the site of the subject under examination. Moreover, when the objective optical system repeatedly comes into and out of contact with the site of the subject being examined, the site of the subject being examined may be damaged, and it may not be possible to continue to reliably carry out examination of the site of the subject under examination.  
       BRIEF SUMMARY OF THE INVENTION  
       [0014]     In light of such problems, it is an object of the present invention to make it unnecessary to align an objective lens, which normally must be carried out for each examination. It is also an object of the present invention to provide a microscope to which such an objective lens unit is attached and a microscope system including this microscope.  
         [0015]     It is a further object of the present invention to prevent the intrusion of foreign objects into the subject under examination, and to provide a microscope to which such an objective lens unit is attached and a microscope system including such a microscope.  
         [0016]     It is yet a further object of the present invention to provide an objective optical system fixing device with which it is possible to carry out in vivo examination, for a relatively long period of time, of tissue such as cells, muscles, etc. or individual organs such as the heart, liver, etc. of mammals, especially small experimental animals.  
         [0017]     In order to accomplish the objects described above, the present invention provides the following solving means.  
         [0018]     The present invention provides a microscope system including an objective optical system unit, and a structure or member for fixing the objective optical system unit to a living body.  
         [0019]     According to this aspect of the invention, the objective optical system unit can be positioned and fixed with respect to the subject under examination. Therefore, when repeatedly carrying out examination of animal tissue or the like, it is not necessary to perform positioning of the objective lens for each examination.  
         [0020]     In the aspect of the invention described above, an objective optical system unit inserting and fixing member may be provided between the objective optical system unit and the living body.  
         [0021]     Accordingly, even if examinations are carried out over a relatively long period of time, it is not necessary to perform positioning of the objective lens for each examination.  
         [0022]     The objective optical system unit described above can be an objective lens unit configured so as to hold at least one lens in a frame part, the objective lens unit including, on the frame part, a contact surface making close contact with the subject under examination, and a fixing device for fixing the frame part to the subject under examination.  
         [0023]     This objective lens unit can be directly placed in close contact with the subject under examination, and can be fixed at that location by a certain fixing device. Therefore, even if examination is carried out a plurality of times, since the examination position does not shift, a particular site of the subject under examination can be irradiated with light.  
         [0024]     Furthermore, the present invention provides a microscope including the objective lens unit described above, a light source for radiating light onto the subject under examination, and a photo-detector for detecting light obtained from light radiating from the light source onto the subject under examination.  
         [0025]     This microscope radiates light via the objective lens unit fixed to the subject under examination, and obtains images of a particular site of the subject under examination. The light obtained by illuminating the subject under examination using a laser oscillator or a lamp in the light source may be reflected light or fluorescence, in the case where the subject under examination is dyed with a fluorescent dye. Also, the microscope may be a confocal laser-scanning microscope, but it need not be a confocal laser-scanning microscope. With this microscope, since the objective lens unit is fixed to the subject under examination and thus the examination position does not change even when carrying out examination repeatedly, accurate examination of the subject can be carried out.  
         [0026]     Furthermore, the present invention provides a microscope system including a multi-axis motion mechanism; a microscope, which is attached to the multi-axis motion mechanism; a stage on which the subject under examination is mounted; and a stereo microscope which is disposed above the stage, wherein the microscope is freely movable with respect to the stage.  
         [0027]     This microscope system is provided with at least two microscopes, and the objective lens unit can be positioned and fixed while checking the subject under examination with the microscope. Therefore, the site to be examined can be positioned more reliably. Also, since the objective lens unit is fixed to the subject under examination, accurate examination can be carried out.  
         [0028]     Furthermore, the present invention provides an objective lens insertion tool including a main body in which an insertion part for inserting into a subject under examination extends from a base in contact with the skin of the subject under examination, the main body being provided with an insertion hole into which an objective lens used for examining the interior of the subject under examination can be inserted and positioned; and a fixing member which can be fitted onto the insertion part and which clamps the skin between the base and the fixing member.  
         [0029]     This objective lens insertion tool can be positioned and fixed with respect to the subject under examination by clamping the skin with the base and the fixing member. When the objective lens unit is inserted into the insertion hole in this state, the objective lens unit is positioned and fixed with respect to the subject under examination by means of the objective lens insertion tool. Therefore, if the objective lens insertion tool is fixed to the subject under examination, positioning of the subject under examination and the objective lens is not needed for each examination. Also, positioning of the objective lens is not necessary when examination of the same site using an objective lens with a different magnification is desired.  
         [0030]     Furthermore, the present invention provides a microscope including the above-described objective lens insertion tool; an objective lens unit for inserting into the objective lens insertion tool; and a photo-detector for detecting, through the objective lens, light obtained by illuminating a subject under examination with light from a light source.  
         [0031]     When carrying out examination with this microscope, the objective lens insertion tool is fixed to the site to be examined, and thereafter, the objective lens unit is inserted into the insertion hole of the objective lens insertion tool. With the objective lens insertion tool, the position of the objective lens is fixed with respect to the subject under examination. Therefore, examination can be carried out repeatedly without positioning the subject under examination and the objective lens each time. Also, positioning of the objective lens is not necessary when examination of the same site using an objective lens with a different magnification is desired.  
         [0032]     Furthermore, the present invention provides a microscope system including a multi-axis motion mechanism; the above-described microscope, which is attached to the multi-axis motion mechanism; a stage on which the subject under examination is mounted; and a stereo microscope which is disposed above the stage, wherein the microscope is freely movable with respect to the stage.  
         [0033]     This microscope is provided with at least two microscopes, and the objective lens insertion tool and the objective lens can be inserted and fixed, once positioned, while checking the subject under examination with the microscope.  
         [0034]     Furthermore, the present invention provides an objective optical system fixing device including a support member for supporting, while being inserted into an incision formed in tissue, an objective optical system unit that contains an objective optical system inside an outer tube; and a fixing mechanism for positioning and fixing the support member with respect to the tissue.  
         [0035]     According to this aspect of the invention, by disposing the support member in an incision formed in the tissue of an animal having the subject examination site, and by supporting the objective optical system unit in the support member once the support member is positioned and fixed with respect to the tissue by operating a fixing mechanism, the objective optical system is disposed so as to be inserted inside the incision in the tissue and is fixed so as not to move relative to the examination site of the subject. Accordingly, even if the animal moves, it is possible to carry out blur-free examination of the examination site of the subject with the objective optical system unit.  
         [0036]     Furthermore, the present invention provides an objective optical system fixing device including an animal securing stage to which an animal is to be secured once the animal is positioned, and a fixing mechanism for fixing an objective optical system unit including an objective optical system to the animal securing stage once the objective optical system unit is positioned.  
         [0037]     According to this aspect of the invention, since the animal is secured to the animal securing stage and, the objective optical system unit is fixed with the fixing mechanism to the animal securing stage, once positioned, the objective optical system of the objective optical system unit is positioned with respect to the animal. As a result, blur-free examination of the examination site of the subject can be carried out with the objective optical system unit. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0038]      FIG. 1  shows the configuration of a microscope system according to an embodiment of the present invention.  
         [0039]      FIG. 2  is a schematic structural diagram of a microscope to which an objective lens unit is attached.  
         [0040]      FIG. 3  is a cross-sectional view showing the configuration of the objective lens unit.  
         [0041]      FIG. 4  is a cross-sectional view taken along line A-A in  FIG. 3 .  
         [0042]      FIG. 5  is a diagram for describing a state in which the subject under examination is sucked by an objective lens unit.  
         [0043]      FIG. 6  is a cross-sectional view showing the configuration of an objective lens unit.  
         [0044]      FIG. 7  is a view for describing a state in which the subject under examination is sucked by an objective lens unit.  
         [0045]      FIG. 8  is a cross-sectional view showing the configuration of an objective lens unit.  
         [0046]      FIG. 9  is a plan view of an objective lens unit.  
         [0047]      FIG. 10  is a perspective view of an objective lens unit.  
         [0048]      FIG. 11  is a diagram showing the configuration of a microscope system according to an embodiment of the present invention.  
         [0049]      FIG. 12  is a schematic structural diagram of a microscope including an objective lens unit and an objective lens insertion tool.  
         [0050]      FIG. 13  is a cross-sectional view showing a state in which an objective lens unit is fixed to a subject under examination.  
         [0051]      FIG. 14  is a schematic structural diagram of a microscope including an objective lens unit and an objective lens insertion tool.  
         [0052]      FIG. 15  is a cross-sectional view of an objective lens.  
         [0053]      FIG. 16  is a cross-sectional view showing a state in which an objective lens is fixed to a subject under examination.  
         [0054]      FIG. 17  is a cross-sectional view showing a state in which an objective lens unit is fixed to a subject under examination.  
         [0055]      FIG. 18  is a cross-sectional view of an objective lens insertion tool.  
         [0056]      FIG. 19  is a plan view of an objective lens insertion tool.  
         [0057]      FIG. 20  is a cross-sectional view showing a state in which an objective lens unit is fixed to a subject under examination.  
         [0058]      FIG. 21  is a cross-sectional view showing a state in which an objective lens unit is fixed to a subject under examination.  
         [0059]      FIG. 22  is a cross-sectional view showing a state in which an objective lens unit is fixed to a subject under examination.  
         [0060]      FIG. 23  is a cross-sectional view showing a state in which an objective lens unit is fixed to a subject under examination.  
         [0061]      FIG. 24  is a cross-sectional view showing a state in which an objective lens unit is fixed to a subject under examination.  
         [0062]      FIG. 25  is a diagram showing an example of an objective lens insertion tool.  
         [0063]      FIG. 26  is a schematic structural diagram of a microscope including an objective lens unit and an objective lens insertion tool.  
         [0064]      FIG. 27  is a schematic structural diagram of a microscope including an objective lens unit and an objective lens insertion tool.  
         [0065]      FIG. 28  is vertical sectional view showing an objective optical system fixing device according to an eleventh embodiment of the present invention.  
         [0066]      FIG. 29  is a perspective view showing the fixing device of  FIG. 28 .  
         [0067]      FIG. 30  is a perspective view showing an objective optical system fixing device according to a twelfth embodiment of the present invention.  
         [0068]      FIG. 31  is a side view showing a subject under examination, wherein the fixing device of  FIG. 30  is attached to a small experimental animal.  
         [0069]      FIG. 32  is a plan view showing the subject under examination.  
         [0070]      FIG. 33  is a partially cut-away front view showing a modification of the fixing device in  FIG. 30 .  
         [0071]      FIG. 34  is a partially cut-away side view showing an objective optical system fixing device according to a thirteenth embodiment of the present invention.  
         [0072]      FIG. 35  is a vertical sectional view showing a support member of the fixing device in  FIG. 34 .  
         [0073]      FIG. 36  is a vertical sectional view showing a modification of the support member in  FIG. 35 .  
         [0074]      FIG. 37  is a vertical sectional view showing another modification of the support member in  FIG. 35 .  
         [0075]      FIG. 38  is a vertical sectional view showing another modification of the support member in  FIG. 35 .  
         [0076]      FIG. 39  is a vertical sectional view showing yet another modification of the support member in  FIG. 35 .  
         [0077]      FIG. 40  is a partially cut-away side view showing an objective optical system fixing device according to a fourteenth embodiment of the present invention.  
         [0078]      FIG. 41  is a perspective view showing the fixing device in  FIG. 40 .  
         [0079]      FIG. 42  is a partially cut-away side view showing a modification of the fixing device in  FIG. 40 .  
         [0080]      FIG. 43  is a partially cut-away side view showing another modification of the fixing device in  FIG. 40 .  
         [0081]      FIG. 44  is a partially cut-away side view showing yet another modification of the fixing device in  FIG. 40 .  
         [0082]      FIG. 45  is a perspective view showing the fixing device in  FIG. 44 .  
         [0083]      FIG. 46  is a perspective view showing an objective optical system fixing device according to a fifteenth embodiment of the present invention.  
         [0084]      FIG. 47  is a partially cut-away side view showing a microscope body directly fixed to an animal securing stage in  FIG. 46 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0085]     Preferred embodiments of the present invention will be described in more detail with reference to the drawings.  
         [0086]      FIG. 1  shows the schematic configuration of a microscope system according to a first embodiment of the present invention.  
         [0087]     As shown in  FIG. 1 , a microscope system  1  includes a stage  3  on a platform  2 , and above the stage  3 , a binocular stereo microscope  4  for observing an upright image of a subject W over a relatively wide field of view is provided. Between the stage  3  and the binocular stereo microscope  4 , a microscope  5  (hereinafter referred to as a micro microscope) for observing the subject W at a relatively high magnification is provided in a freely movable manner.  
         [0088]     The binocular stereo microscope  4  has an objective lens  11  and eyepieces  12  attached thereto, and inside, an ocular lens, an image-forming lens, etc. (not shown in the drawing) are disposed. Two eyepieces  12  are provided, one for each of the left and right eyes, and the optical axes of the individual eyepieces  12  are adjusted so as to be coincident at the surface of the subject W under examination. Furthermore, a CCD (Charge Coupled Device) camera  13 , which is connected to a monitor  6 , is attached to this binocular stereo microscope  4 . The CCD camera  13  and the monitor  6 , however, are not essential to the configuration of the binocular stereo microscope.  
         [0089]     This binocular stereo microscope  4  is supported by a multi-axis arm  8 . The multi-axis arm  8  moves the binocular stereo microscope  4  horizontally with respect to the subject W under examination, and moves closer to or away from the subject W. Also, a space for inserting a head portion  21  of the micro microscope  5  is arranged between the objective lens  11  and the subject W under examination.  
         [0090]     In the micro microscope  5 , the head unit  21  containing the optical system is supported by a multi-axis stage  22 , which is a multi-axis motion mechanism. The objective lens unit  22  is attached to the lower surface of the head portion  21 . Also, a light source  26  and an optical detector  27  are connected to the head portion  21  via optical fibers  24  and  25 , and a controller  28  for controlling the individual units and the monitor  7  for displaying images examination images are also provided.  
         [0091]     In the light source  26 , a laser oscillator  29   a , for example, an argon-ion laser or a helium-neon laser, is used. As shown in  FIG. 2 , a focusing lens  29   b  and one end of the optical fiber  24  are disposed, in this order, in the light path of the laser beam emitted from the light source  26 , and the laser beam focused by the focusing lens  29   b  is launched into the optical fiber  24 .  
         [0092]     One end of the optical fiber  24  is connected to the light source  26  and the other end is connected to the head unit  21 . This optical fiber  24  is connected to the optical fiber  25 , which is connected to the optical detector  27 , at an intermediate part extending from one end to the other end thereof via an optical fiber coupler  30 . One end of this optical fiber  25  is connected to the optical detector  27 .  
         [0093]     A photomultiplier, a PD (photodiode), or a CCD camera, for example, is used in the optical detector  27 . The light entering this optical detector  27  is reflected light or fluorescence light from the light illuminating the subject W from the light source  26 , after being split off from the optical fiber coupler  30 .  
         [0094]     In a case  31  of the head unit  21 , a retaining part  33  for retaining a connector  32  attached to the other end of the optical fiber  24  is provided. Also, a collimator lens  34  and an optical scanner  35  are disposed, in this order, in the light path of the laser beam emerging from the optical fiber  24 . The optical scanner  35  is a two-dimensional laser beam scanner formed of a combination of, for example, a galvano mirror that scans the laser beam in the X-direction (the lateral direction of the subject W under examination) and a galvano mirror that scans in the Y-direction (the longitudinal direction of the subject W under examination). Also, at the lower face of the case  31 , at a position beneath the optical scanner  35 , a window  36  through which the laser beam passes is provided. The edges of the window  36  extend downward to provide a mounting part  37  for fixing the objective lens unit  23 . An attachment groove, threaded groove, or the like is formed inside this mounting part  37  so as to allow attachment of the objective lens unit  23  while it is fixed to the subject under examination.  
         [0095]     As shown in  FIG. 3 , the objective lens unit  23  has a frame part  41  which is attached to the head unit  21 . Objective lenses  42  composed of a plurality of lenses is held inside the frame part  41 . A plurality of the objective lens units  23  composed of different objective lenses  42  are used, depending on the image magnification ratio of the subject under examination.  
         [0096]     As shown in  FIG. 3  and  FIG. 4 , the frame part  41  has an inner frame  44 , with a substantially circular cross-section, for holding the objective lenses  42 . At the upper part of the inner frame  44 , a detachable mounting part  45  is attached to the mounting part  37  of the head unit  21 , and a contact surface  46  making close contact with the subject under examination W is provided at the lower part of the frame part  41 .  
         [0097]     Also, a substantially ring-shaped extension  47 , which is made to protrude towards the outer side in the radial direction of the inner frame  44  from one part thereof, is provided at the lower part of the inner frame  44 . A plurality of air vents  48  penetrating the extension  47  in the vertical direction are formed in this extension  47  at regular intervals. The outer edge of the extension  47  is continuous with an outer frame  49 , which is provided concentrically with respect to the inner frame  44 . The outer frame  49  is provided so as to enclose the circumference of the inner frame  44 , and, at the lower part thereof, a contact surface  50  making close contact with the subject under examination W is provided. The contact surface  50  is formed in the same plane as the contact surface  46  of the inner frame  44 . The length (height) of the outer frame  49  is shorter than that of the inner frame  44 , and the top of the outer frame  49  is positioned below the top of the inner frame  44 .  
         [0098]     Here, a circular slot  51  is formed between the inner frame  44  and the outer frame  49 . As shown in  FIG. 3 , this circular slot  51  has an opening  51   a  at the side of the contact surfaces  46  and  50 , and an opening  51   b  at the upper end of the outer frame  49 . A piston  52  is inserted into the circular slot  51  from the opening  51   b . As a result, the circular slot  51  constitutes a cylinder for holding the piston  52  in such a manner that it is slidable towards the subject under examination W.  
         [0099]     The piston  52  has a main body  53  whose inner diameter is approximately equal to the outer diameter of the inner frame  44  and whose outer diameter is approximately equal to the inner diameter of the outer frame  49 . An airtight member  54 , such as a rubber member, in close contact with both the inner frame  44  and the outer frame  49 , is fixed to the lower end of the main body  53 .  
         [0100]     The piston  52  is capable of reciprocating motion along the inner frame  44  and the outer frame  49  from an inserted position where the airtight member  54  is in contact with the extension  47  to a retracted position where the airtight member  54  is pulled out to a point close to the upper end of the outer frame  49 , while maintaining the airtightness of the circular slot  51 . In addition, at the top of the piston  52 , an overhanging part  55 , which protrudes outwards in the radial direction of the inner frame  44 , is provided around the circumference of the piston  52 . Grasping this overhanging part  55  with the fingers or a tool allows the piston  52  to be easily reciprocated.  
         [0101]     Here, the frames  44  and  49  and the airtight member  54  are made of airtight parts, and the frames  44  and  49 , the extension  47 , and the piston  52  thus form a suction apparatus (fixing device).  
         [0102]     As shown in  FIG. 1 , the controller  28  of the micro microscope  5  is connected to the head unit  21  (including the multi-axis stage  22 ), the light source  26 , the optical detector  27 , and the monitor  7  for the micro microscope  5  by cables. For example, for the light source  26 , ON/OFF control and output control of the laser beam are performed; for the head unit  21 , feedback control of the optical scanner  35  (see  FIG. 2 ) is performed; and detection signals are obtained from the optical detector  27 , subjected to data processing, and displayed on the monitor  7 . In addition, when carrying out three-dimensional examination with the micro microscope  5 , the collimator lens  34  is moved towards and away from the optical scanner  35 .  
         [0103]     Furthermore, the multi-axis stage  22  is formed of a combination of motorized stages that translate the head unit  21  in the back-and-forth, left-and-right, and up-and-down directions.  
         [0104]     Next, a description is given below of one example of the procedure for examining a subject W using this microscope system  1 .  
         [0105]     First, as shown in  FIG. 1 , the subject W to be examined is placed on the stage  3  beneath the field of view of the binocular stereo microscope  4 . At this time, the multi-axis stage  22  is operated by the controller  28  to retract the head unit  21  of the micro microscope  5  to a position where it does not obstruct examination with the binocular stereo microscope  4 . If the head unit  21  is not attached to the multi-axis stage  22 , in this step, the head unit  21  is mounted to the multi-axis stage  22 . Also, as shown in  FIG. 3 , the airtight member  52  is pushed in to a position where it makes contact with the extension  47 .  
         [0106]     Then, while checking the part to be examined (the examination site) with the binocular stereo microscope  4 , the skin of the subject W under examination is cut open. At this time, the examination site may be dyed with a fluorescent dye, if necessary.  
         [0107]     When the preparations up to this point have been completed, the multi-axis stage  22  is operated again with the controller  28  to move the head unit  21  of the micro microscope  5  over the examination site. Positioning of the head unit  21 , that is to say, the tip of the objective lens unit  23 , is carried out while checking the binocular stereo microscope  4  or the monitor  6 .  FIG. 1  shows an example in which an image of the subject under examination, whose skin has been cut open, as well as the head unit  21  and the objective lens unit  23 , is shown on the monitor  6 .  
         [0108]     Then, the head unit  21  is lowered so that the contact surfaces  46  and  50  (see  FIG. 3 ) of the objective lens unit  23 , which is fixed to the head unit  21 , make contact with the subject W under examination.  
         [0109]     As shown in  FIG. 3 , when the contact surfaces  46  and  50  of the objective lens unit  23  and the subject W under examination make contact, the openings  51   a , delimited by the contact surface  46  and the contact surface  50 , become plugged by the area surrounding the examination site, and the circular slot  51  is sealed off by the subject W under examination, the frames  44  and  49 , the extension  47 , and the piston  52  (airtight member  54 ).  
         [0110]     In this state, the sides of the piston  52  or the overhanging part  55  are gripped with the fingers, forceps, or the like, and, as shown by the arrows in  FIG. 5 , the piston  52  is raised towards the head unit  21  along the frames  44  and  49 . Then, the extension  47  and the airtight member  54  separate, and the volume of the circular slot  51  increases by that amount. As a result, the pressure in the interior of the circular slot  51  is reduced, forming a negative pressure. Since the frames  44  and  49  and the main body  53  of the piston  52 , to which the airtight member  54  is fixed, are not deformed by this level of negative pressure, the subject W under examination, which is relatively flexible, is deformed by stretching and is thus sucked into the piston  52 . As a result, the subject under examination W is fixed to the objective lens unit  23 , and displacement between the objective lens unit  23  and the subject W under examination is prevented until the piston  52  is pushed back in again.  
         [0111]     When the objective lens unit  23  is positioned and fixed to the subject W under examination, the controller  28  is operated to emit a laser beam. As shown in  FIG. 2 , the laser beam passes through the focusing lens  29   b , is launched into the optical fiber  24 , and is guided to the interior of the head unit  21 . In the head unit  21 , the laser beam is scanned by the optical scanner  35 , is focused by the collimator lens  34  and the objective lenses  42 , and illuminates a predetermined position of the subject W under examination. Then, the light reflected from the subject W under examination or fluorescence emitted from the fluorescent dye returns to the optical fiber  24  via the same optical system. As mentioned above, since the optical fiber  24  has the optical fiber coupler  30  disposed in the middle thereof, the reflected light or fluorescence light is split off into the optical fiber  25  and is detected by the optical detector  27 . Then, the optical detector  27  outputs an electrical signal to the controller  28  in accordance with the light intensity.  
         [0112]     Only information on the region the laser beam illuminates is contained in the signal that the optical detector outputs. Therefore, the controller  28  obtains information on the predetermined area scanned by the laser beam, carries out image processing, and outputs it on the monitor  7 . The image displayed on the monitor  7  can be output onto a paper medium or recorded on a magnetic recording medium, as required.  
         [0113]     Since, the laser beam can easily penetrate the subject W under examination with a shallow depth of focus, if the position of the focal point is displaced up or down by the collimator lens  34  (see  FIG. 2 ) and so on, an image of the interior of the subject W under examination can be obtained, thus allowing three-dimensional examination of the examination site.  
         [0114]     Then, when examining changes in the subject W under examination over time, it can be left in that state or the objective lens unit  23  can be removed from the head unit  21 . In the latter case, when re-examining the subject W, the objective lens unit  23  is re-attached to the head unit  21  and examination is carried out.  
         [0115]     Moreover, when examination is completely finished and the objective lens unit  23  is to be removed from the subject W under examination, the piston  52  of the objective lens unit  23  shown in  FIG. 5  is pushed in towards the subject W under examination, and the airtight member  54  and the extension  47  come into close contact. As a result, the space inside the circular slot  51  returns to the same volume as at suction time. Therefore, the pressure in the circular slot  51  returns to a high pressure, and suction of the subject W under examination is stopped. In this state, if the head unit  21  is raised using the multi-axis stage  22 , the objective lens unit  23  is removed from the subject W under examination. Then, to examine another site of the same subject W or to examine another subject W, the procedure described above is repeated.  
         [0116]     According to this embodiment, a fixing device (suction device) for fixing the objective lens unit  23  to the subject W under examination is formed by sucking the subject W under examination with the objective lens unit  23 . Therefore, it is possible to position and fix the objective lenses  42  and the subject W under examination. Accordingly, when examining changes in the examination site over time, it is not necessary to align the subject W under examination and the objective lens unit  23  for each examination.  
         [0117]     Also, since the tip (contact surfaces  46  and  50 ) of the objective lens unit  23  is fixed to the subject W under examination, positioning of the objective lens in the depth direction (height, Z-direction) is carried out.  
         [0118]     Furthermore, since the objective lens unit  23  is fixed so as to surround the examination site, it is difficult for foreign objects to enter the subject W under examination, and in vivo examination of subjects W such as animals can be carried out.  
         [0119]     In addition, since the micro microscope  5 , to which this type of objective lens unit  23  is attached, can be fixed to a predetermined position of the objective lenses  42 , accurate two-dimensional examination or three-dimensional examination of the subject can be carried out, and it is also possible to carry out examination over an extended period of time.  
         [0120]     Since the microscope system  1  including this kind of micro microscope  5  can fix the objective lens unit  23  to the subject W under examination while checking the examination position with the binocular stereo microscope  4 , accurate two-dimensional examination or three-dimensional examination of the subject W can be carried out, and it is also possible to carry out examination over an extended period of time.  
         [0121]     In this embodiment, the extension  47  acts to join the inner frame  44  and the outer frame  49 , and also functions as a stopper when pushing in the piston  52 ; however, an objective lens unit  23  having no extension  47  can also be used. More concretely, the outer frame  49  may be decentered with respect to the inner frame  44 , and the inner frame  44  and part of the outer frame  49  may be in close contact. Also, instead of the circular slot  51  shown in  FIG. 3  and  FIG. 4 , a cylinder may be formed from a through-hole formed by cutting out a circular, polygonal, or ring-shaped piece in cross-sectional view. That is to say, any shape is acceptable as long as the frame part  41  is configured so as to have a hole for holding the objective lenses  42  and a through-hole in which the piston  52  can be inserted. In this case, the piston  52  has a shape matching the through-hole. In light of the fact that deviation between the objective lens unit  23  and the subject W under examination can be prevented, it is preferable that a plurality of through-holes be provided or the opening at the contact surface side have a predetermined area or larger. In the case where a plurality of through-holes are provided, a plurality of pistons  52  are also inserted; however, a structure having a plurality of openings at the contact surface for a single piston  52  is also acceptable.  
         [0122]     Next, a second embodiment of the present invention will be described with reference to the drawings. Elements with the same configuration as in the first embodiment are given the same reference numerals, and any description duplicating that in the first embodiment is omitted.  
         [0123]     The microscope system  1  according to this embodiment is characterized in that an objective lens unit  63  shown in  FIG. 6  is attached to the micro microscope  5 . Here,  FIG. 6  shows the objective lens unit  63  fixed to the subject W under examination.  
         [0124]     As shown in  FIG. 6 , a frame part  64  of the objective lens unit  63  has the inner frame  44  in which objective lenses  42  composed of a plurality of lenses is contained, and a mounting part  45  for attaching to the head unit  21  is formed at the top of the inner frame  44 . In the vicinity of a contact surface  46  of the inner frame  44 , there is a substantially circular extension  47 , and the outer edge of the extension  47  is continuous with an outer frame  49 . The outer frame  49 , surrounds the inner frame  44 , and, in cross-section, the inner frame  44  and the outer frame  49  are disposed substantially concentrically. The outer frame  49  is thinner than the inner frame  44 , but a contact surface  50  of the outer frame  49  is formed in substantially the same plane as the contact surface  46  of the inner frame  44 . At the top of the outer frame  49 , a stepped portion  65  that is reduced in thickness from the outer side is formed around the circumference thereof.  
         [0125]     At a predetermined distance above the outer frame  49  (at the head unit  21  side), a short frame  66  whose length in the vertical direction is small is fixed to the inner frame  44  by a coupling ring  67 . The short frame  66  has an inner diameter and an outer diameter substantially equal to the outer frame  49 , and a stepped portion  68  that is reduced in thickness from the outer side is formed around the circumference thereof at the lower end. The inner edge of the coupling ring  67  is substantially the same as the outer diameter of the inner frame  44 , and the outer edge is substantially the same as the inner diameter of the short frame  66 .  
         [0126]     The upper and lower ends of a circular resilient member  69  are respectively fixed to a stepped portion  65  of the outer frame  49  and the stepped portion  68  of the short frame  66 . The frames  44 ,  49 , and  66 , the coupling ring  67 , and the resilient member  69  are made of airtight parts, and are in close contact with each other so as to ensure airtightness also at the locations where they are joined. As a result, in the frame part  64 , there is an opening  71  in the plane defined by the contact surfaces  46  and  50 , and a concave section  70  defined by the frames  44 ,  49  and  66 , the coupling ring  67 , and the resilient member  69  is formed.  
         [0127]     The resilient member  69 , is preferably deformable in the direction towards the inner frame  44  by an external pressure. As shown in  FIG. 7 , when the resilient member  69  is pressed towards the inner frame  44 , the volume of the concave section  70  formed by the frames  44 ,  49 , and  66 , the coupling ring  67 , and the resilient member  69  is reduced.  
         [0128]     A description will now be given of the examination procedure using this microscope system  1 . The procedure for positioning the objective lens unit  63  while carrying out examination with the binocular stereo microscope  4  is the same as in the first embodiment.  
         [0129]     After positioning the objective lens unit  63 , the resilient member  69  of the objective lens unit  63  is pressed so as to be deformed in the direction that reduces the diameter with the fingers or forceps, and the volume of the concave section  70  is reduced (refer to  FIG. 7 ). Then, in this state, the multi-axis stage  22  is operated to lower the head unit  21 .  
         [0130]     When the end (the contact surfaces  46  and  50 ) of the objective lens unit  63  is in close contact with the subject W under examination, lowering of the head unit  21  is stopped, and the fingers or the like are removed from the resilient member  69 . As a result, the outer surface of the resilient member  69  returns to substantially the same position as the outer walls of the outer frame  49  and the short frame  66 , and the volume of the concave section  70  increases. Then, since the concave section  70  at the inside is sealed by the objective lens unit  63  and the subject W under examination, a low pressure occurs. Therefore, the vicinity of the site of the subject W to be examined is sucked into the objective lens unit  63 , and the objective lens unit  63  thus becomes fixed to the subject W under examination.  
         [0131]     Then, when two-dimensional examination or three-dimensional examination of the subject W is completed, the resilient member  69  is pressed again in the diameter-reducing direction with the fingers or the like. The volume of the concave section  70  then becomes the same as the volume when the objective lens unit  63  was in close contact with the subject W under examination, and the internal pressure thereof increases. As a result, since the pressure sucking the subject W under examination becomes lower, if the head unit  21  is raised in this state, the objective lens unit  63  can be raised away from the subject W under examination.  
         [0132]     According to this embodiment, a fixing device (sucking apparatus) is formed by providing a concave section  70  having an opening  71  in the surface contacting the subject W under examination and forming part of the wall of the concave section  70  of the resilient member  69 . Therefore, by deforming the resilient member  69 , the objective lens unit  63  can be fixed to the subject W under examination. Accordingly, accurate examination of changes in the subject W over time can be carried out. Also, the micro microscope  5  or microscope system  1  having such an objective lens unit  63  is capable of high-accuracy examination and examination over an extended period of time, similarly to the first embodiment described above.  
         [0133]     The resilient member  69  is a ring-shaped member, but it may have a shape formed by cutting out part of a ring. For example, it is also possible to directly connect the outer frame  49  and the coupling ring  67 , to provide an opening in part of the outer frame  49 , and to fix the resilient part  69  so as to cover this opening.  
         [0134]     Also, the concave section  70  may have any shape, as long as it forms a space having an opening  71  in the contact surface. For example, it is acceptable to form a hole or slot in the frame part  64 , and to block the mouth of the opening  71  with the resilient member  69 .  
         [0135]     Furthermore, a member that presses the resilient member  69  may be attached to the frame part  64 . One concrete example of such a member is a structure having one end connected to the resilient member  69  and the other end pulled upwards, with the central part between the ends being supported on the frame part  64  with a pin or the like.  
         [0136]     Next, a third embodiment of the present invention will be described with reference to the drawings. Elements with the same structure as in the first and second embodiments are given the same reference numerals, and any description duplicating the first and second embodiments is omitted.  
         [0137]     A microscope system according to this embodiment is characterized in the an objective lens unit  73  shown in  FIG. 8  is attached to the micro microscope  5 .  
         [0138]     As shown in  FIG. 8 , the objective lens unit  73  has a frame part  74  containing objective lenses  42  formed of a plurality of lenses. At the upper part of the frame part  74 , there is a mounting part  75  for connecting to the mounting part  37  of the head unit  21 . Also, a glass plate  76  is attached at the bottom of the frame part  74 . The lower surface of this glass plate  76  is positioned higher than a contact surface  77 , but it may be positioned so as to be in substantially the same plane as the contact surface  77 . As shown in  FIG. 8  and  FIG. 9 , a plurality of equally spaced projections  78  are provided in the contact surface  77 . Projections  78  are substantially cone-shaped, and the apexes thereof are disposed downwards, that is, towards the subject W under examination.  
         [0139]     In  FIG. 9 , the projections  78  are provided at six positions. The number of projections  78  is not limited to this; however, from the viewpoint of preventing displacement between the objective lens unit  73  and the subject W under examination, the number of projections  78  is preferably two or more. When the projections are provided at two positions, as shown in  FIG. 10 , projections  79  may be disposed at two diametrically aligned positions of the cylindrical frame part  74 . The shape of the projections  78  is not limited to a cone, and, for example, a long, thin rod-shape is also acceptable. A pointed needle is also acceptable. It is also possible to select the length of the projections from the short ones shown in  FIG. 8  to the long ones shown in  FIG. 10 .  
         [0140]     A description will now be given of the examination procedure using this microscope system  1 . The procedure for positioning the objective lens unit  73  while carrying out examination using the binocular stereo microscope  4  is the same as in the first embodiment.  
         [0141]     When positioning the objective lens unit  73 , the head unit  21  is lowered until the contact surface  77  of the objective lens unit makes close contact with the subject W under examination. At this time, the projections  78  extending from the contact surface  77  directly pierce the tissue or an organ of the subject W under examination, and the objective lens unit  73  is fixed to the subject W under examination.  
         [0142]     Then, when two-dimensional or three-dimensional examination of the subject W is completed and the head unit  21  is raised, the projections  78  are extracted from the subject W under examination, and the objective lens unit  73  is pulled away from the subject W under examination.  
         [0143]     According to this embodiment, by pushing the projections  78  or  79  into the subject W under examination, it is possible to fix the objective lens unit  73  to the subject W under examination. Therefore, examination of changes in the subject W over time can be accurately carried out. Also, the micro microscope  5  and the microscope system  1  having such an objective lens unit  73  is capable of high-accuracy examination and examination over an extended period of time, as in the first embodiment described above.  
         [0144]     The present invention is not limited to the first to third embodiments described above, but can be applied more widely.  
         [0145]     For example, the micro microscope  5  to which the objective lens units  23 ,  63 , and  73  of the individual embodiments are attached has been described in terms of a confocal laser scanning microscope; however, it is also applicable to microscopes of the type in which the subject W under examination is illuminated with a light guide and images of the subject W under examination are obtained by a CCD. The same effects and results as described above can also be obtained with a micro microscopes of this kind.  
         [0146]     The projections  78  or  79  shown in  FIG. 8  or  FIG. 9  may also be provided on the contact surface  46  of the inner frame  44  in the objective lens unit  23  shown in  FIG. 3  and the objective lens unit  63  shown in  FIG. 6 . It is thus possible to more strongly fix the objective lens unit  23  or  63  to the subject W under examination.  
         [0147]     As another example of a suction apparatus, a configuration in which the opening  51   b  of the inner space  51  shown in  FIG. 3  can be blocked off with a tube and a pump for sucking out the air from the inner space  51  is attached to the end of the tube may be used. According to this suction apparatus, fixing or removal can be carried out with ease.  
         [0148]     The outer frame is not limited to a circular shape; various shapes are possible, such as quadrangular shapes in cross-section, and so on. It is also permissible for the binocular stereo microscope  4  to be omitted from the microscope system  1 .  
         [0149]     Next, other embodiments of the present invention will be described with reference to the drawings. Elements with the same structure as the first embodiment are given the same reference numerals, and any description duplicating the first embodiment is omitted.  
         [0150]     The structure of a microscope system according to a fourth embodiment is schematically shown in  FIG. 11 .  
         [0151]     A microscope system  101  of the present embodiment has the same configuration of the microscope system of the first embodiment except that an objective lens unit  123  that differs from the objective lens unit  23  used in the first embodiment is attached to the lower surface of the head unit  21 . An objective lens insertion tool  151 , into which the end of the objective lens unit  123  is inserted and fixed, is attached to the subject W under examination.  
         [0152]     As shown in  FIG. 12  and  FIG. 13 , the objective lens unit  123  has a structure in which a plurality of objective lenses  142  are held inside a frame part  141 . The frame part  141  has a step so as to reduce the diameter thereof, and at the end of a large-diameter frame base part  143 , which is attached to a mounting part of the head unit  21 , a frame base part  144  that is smaller in diameter than the frame base part  143  and that is mainly inserted inside the subject W under examination is provided. This step is formed from the outer walls of the frame base part  143  and the frame base part  144  and from the plane intersecting approximately perpendicularly to the axis C 1  (see  FIG. 13 ) of the objective lens unit  123 . This objective lens unit  123  is attached to the head unit  21  with a mounting part  146  at the end of the frame part  141 , and is used while inserted in the objective lens insertion tool  151 , which is fixed to the subject W under examination.  
         [0153]     The objective lens insertion tool  151  has an insertion tool body  153  which positions and fixes the objective lens unit  123  in an insertion hole  152 . The insertion tool body  153  has a structure in which an insertion part  155 , which is inserted into the subject W under examination, projects from a circular base  154 , and the insertion hole  152  penetrates from an upper surface  154   a  at the head unit  21  side to a tip surface  155   a  at the site desired to be examined (examination site W 1  shown in  FIG. 13 ). In this insertion hole  152 , there is a step with a smaller diameter than the diameter of the opening thereof, and a large-diameter section  157  at the upper surface  154   a  side and a small-diameter section  158  at the tip surface  155   a  side are formed. Moreover, this step is formed from the inner walls of the large-diameter section  157  and the small-diameter section  158  and from the surface  156  connecting them; this surface  156  is provided so as to intersect the axis (axis C 1  in  FIG. 13 ) of the insertion hole  152  substantially perpendicularly.  
         [0154]     As shown in  FIG. 12 , a threaded hole  159  that communicates with the insertion hole  152  is formed in a side surface  154   b  of the base  154 , and a screw  160  is screwed therein.  
         [0155]     The insertion part  155  has a smaller diameter than the base  154 , and an engaging part  161  is provided at the tip of the insertion part  155 . The engaging part  161  protrudes in a direction intersecting with the axis C 1  of the insertion hole  152  substantially perpendicularly. Also, a taper increasing in diameter from the tip surface  155   a  towards the base  154  is provided on the outer surface of the engaging part  161 . A fixing ring  162  is pushed onto the insertion part  155  from the tip surface  155   a  side.  
         [0156]     As shown in  FIG. 13 , the fixing ring  162  is a fixing member for fixing the insertion tool body  153  to the skin W 2 , that is to say, to the subject W under examination, and has a ring shape. The fixing ring  162  may have a shape formed by cutting out part of a ring or it may be U-shaped.  
         [0157]     When the objective lens unit  123  is inserted into the insertion hole  152  of the insertion tool body  153 , while the surface  145  is in contact with the surface  156 , the frame base part  143  of the objective lens unit  123  is contained in the large-diameter section  157  and the frame tip part  144  is contained in the small-diameter section  158 . Then, the surface  156  of the insertion hole  152  and the surface  145  of the frame part  141  make contact, thus positioning the objective lens unit  123  in the height direction. The lengths of the frame base part  143  and the frame tip part  144  are larger than the corresponding lengths of the large-diameter section  157  and the small-diameter section  158 . Therefore, the frame base part  143  protrudes upwards from the large-diameter section  158 , and the frame tip part  144  protrudes towards the examination site W 1  side from the small-diameter section  158 .  
         [0158]     A plurality of objective lens units  123  composed of different objective lenses  142  are used, depending on the image magnification ratio of the subject W under examination.  
         [0159]     Next, a description is given below of one example of the procedure for examining a subject W using this microscope system  101 .  
         [0160]     First, as shown in  FIG. 11 , the subject W to be examined is placed on the stage  3  beneath the field of view of the binocular stereo microscope  4 . At this time, the multi-axis stage  22  is operated by the controller  28  to retract the head unit  21  of the micro microscope  5  to a position where it does not obstruct examination with the binocular stereo microscope  4 . If the head unit  21  is not attached to the multi-axis stage  22 , in this step, the head unit  21  is mounted to the multi-axis stage  22 .  
         [0161]     Then, while checking the position of the examination site W 1  shown in  FIG. 13  with the binocular stereo microscope  4 , the skin W 2  of the subject W under examination is cut open. At this time, the examination site W 1  may be dyed with a fluorescent dye, if necessary.  
         [0162]     When the skin W 2  of the subject W under examination is cut open, the fixing ring  162  is inserted into the subject W under examination, and then the insertion part  155  of the insertion tool body  153  is inserted inside the skin W 2 . Subsequently, after confirming that the insertion hole  152  is above the examination site W 1 , the fixing ring  162  is pushed onto the insertion part  155  from the tip surface  155   a  side. When the fixing ring  162  passes the engaging part  161 , the skin W 2  is clamped between the upper surface of the fixing ring  162  and the lower surface of the base  154  of the insertion tool body  153 , and the objective lens insertion tool  151  is fixed to the skin W 2 .  
         [0163]     When the preparations up to this step have been completed, the multi-axis stage  22  is operated again with the controller  28 , and the head unit  21  of the micro microscope  5  is moved over the examination site. Positioning of the head unit  21 , that is to say, the tip of the objective lens unit  123 , is carried out while checking the binocular stereo microscope  4  or the monitor  6 .  FIG. 11  shows an example in which an image of the subject W under examination, whose skin W 2  has been cut open, as well as the head unit  21  and the objective lens unit  123 , is shown on the monitor  6 .  
         [0164]     Then, the head unit  21  is lowered until the surface  145  of the frame part  141  in the objective lens unit  123 , which is fixed to the head unit  21 , contacts the surface  156  of the insertion hole  152  in the objective lens insertion tool  151 .  
         [0165]     When the surface  145  and the surface  156  make contact, the screw  160  of the objective lens insertion tool  151  is tightened, and the tip of the screw  160  presses against the frame base part  143  of the objective lens unit  123 , thus fixing the objective lens unit  123  in the objective lens insertion tool  151 . Accordingly, the objective lens unit  123  (as well as the objective lens  14 ; and similarly hereinafter) is fixed to the skin W 2 , that is, to the subject W under examination, via the objective lens insertion tool  151 .  
         [0166]     When the objective lens unit  123  is positioned and fixed to the subject W under examination, by carrying out operations similar to those in the first embodiment, images of the subject W under examination can be output and/or recorded.  
         [0167]     Also, similarly to the first embodiment, if the position of the focal point of the laser beam is shifted up and down with the collimator lens  34  and so on (see  FIG. 12 ), internal images of the subject W under examination can be obtained, and three-dimensional examination of the examination site is thus possible.  
         [0168]     In the case where examination of changes in the subject W over time is carried out, the screw  160  is loosened and the head unit  21  is pulled up to remove the objective lens unit  123  from the subject W under examination. On the other hand, the objective lens insertion tool  151  remains fixed to the subject W under examination. Then, when re-examining the same examination site W 1  again, the objective lens unit  123  is inserted in and fixed to the still-fixed objective lens insertion tool  151 , and examination is carried out.  
         [0169]     In this embodiment, by using the objective lens insertion tool  151 , which is fixed in advance to the subject W under examination, the objective lens unit  123  can be fixed to the subject W under examination. Furthermore, according to this objective lens insertion tool  151 , since positioning of the objective lens unit  123  can be carried out in the depth direction and in the left and right directions with the step part (surface  156 ) and the screw  160 , positioning of the objective lens unit  123  with respect to the subject W under examination is possible. Furthermore, when the screw  160  is loosened, the objective lens unit  123  can be easily removed from the objective lens insertion tool  151 , and therefore, the objective lens unit  123  can be removed from the subject W under examination when examination is not being carried out.  
         [0170]     In addition, since the micro microscope  5 , to which this type of objective lens unit  123  is attached, can be fixed to a predetermined position of the objective lenses  142 , accurate two-dimensional examination or three-dimensional examination of the subject can be carried out, and it is also possible to carry out examination over an extended period of time.  
         [0171]     Since the microscope system  101  including this kind of micro microscope  5  can fix the objective lens unit  123  to the subject W under examination while checking the examination position with the binocular stereo microscope  4 , accurate two-dimensional examination or three-dimensional examination of the subject W can be carried out, and it is also possible to carry out examination over an extended period of time.  
         [0172]     In this embodiment, the base  154  and the insertion part  155  of the objective lens insertion tool  151  have a circular shape disposed concentrically with the frame part  141  of the objective lens unit  123 ; however, these may have quadrangular shapes or other shapes. Also, two or more sets of threaded holes  159  and screws  160  may be provided.  
         [0173]     Next, a fifth embodiment of the present invention will be described with reference to the drawings. Elements having the same structure as those of the preceding embodiments are given the same reference numerals, and any description duplicating the preceding embodiments is omitted.  
         [0174]     The microscope system of this embodiment is characterized in that the frame part of the objective lens is L-shaped.  
         [0175]     As shown in  FIG. 14 , an objective lens unit  173  has a frame part  174  holding a plurality of objective lenses  142 . A frame part  174  is formed of an L-shaped frame base part  175  and a frame tip part  144  extending from the frame base part  175 . The frame base part  175  is formed of a vertical part  176  continuous with the frame tip part  144  and extending upwards, and a horizontal part  177  extending horizontally from near the upper end of the vertical part  176 . A mounting part  146 , which is used when attaching to the head unit  21 , is provided at the end of the horizontal part  177 . In this type of objective lens unit  173 , the objective lenses  142  are distributed in the frame tip part  144 , the vertical part  176 , and the horizontal part  177 . In addition, a folding mirror  178  for folding the optical axis by  900  is contained at the position where the axis of the vertical part  176  and the axis of the horizontal part  177  intersect.  
         [0176]     The head unit  21  to which this objective lens unit  173  is attached is provided with a window  36  and a mounting part  37  in the side face of the case  31 , and is provided with a condenser lens  34  for focusing the laser beam introduced through the optical fiber  24  and two galvano mirrors  35   a  and  35   b . The two galvano mirrors  35   a  and  35   b  constitute an optical scanner  35 , and are disposed so as to emit the two-dimensionally scanned laser beam from the window  36  towards the objective lens unit  173 .  
         [0177]     When carrying out examination using this objective lens unit  173 , after fixing the objective lens insertion tool  151  to the skin W 2  of the subject W under examination, the objective lens unit  173  is inserted in and fixed to the objective lens insertion tool  151  while checking the binocular stereo microscope  4 .  
         [0178]     Then, during examination, the laser beam passing through the objective lenses  142  in the horizontal part  177  is deflected downward by the folding mirror  178 , passes through the objective lenses  142  in the vertical part  176  and the frame tip part  144 , and is focused to a predetermined position on the subject W under examination.  
         [0179]     According to this embodiment, since the frame part  174  of the objective lens unit  173  is bent substantially at a right angle between the tip and the mounting part  146  attached to the head unit  21 , the head unit  21  can be disposed towards the subject W under examination. Therefore, since the head unit  21  does not intrude into the field of view of the binocular stereo microscope  4 , it is easier to check the insertion position of the objective lens unit  173 . Also, as described above, by using the objective lens insertion tool  151 , the objective lens unit  173  and the objective lenses  142  can be positioned and fixed with respect to the subject W under examination.  
         [0180]     The L-shaped objective lens unit in the frame part  174  may have other shapes; for example, an objective lens unit  183  shown in  FIG. 15  is conceivable.  
         [0181]     The frame part  174  of this objective lens unit  183  is formed of the above-described frame base part  175  and a frame tip part  184 . The frame tip part  184  is the section that is mainly inserted into the subject W under examination. A folding mirror  185  is provided at the tip near the objective lenses  142  at the side of the frame tip part  184  closest to the subject W under examination (the lower side), which deflects the laser beam by 90°. Also, a window  186  that transmits the laser beam deflected by the folding mirror  185  is provided in the side face of the frame tip part  184 .  
         [0182]     Since the light can be focused onto a region in a direction perpendicular to the axis C 1  of the frame tip part  184  and the vertical part  176  with this objective lens unit  183 , examination of such a region is possible. When the folding mirror  185  is held at an inclined angle of 45 degrees with respect to the axis C 1 , examination of a region in the horizontal direction becomes possible. Also, when the angle formed by the folding mirror  185  and the axis C 1  is from 0 degrees to 45 degrees, examination of a region positioned below the horizontal direction becomes possible. Likewise, when the angle formed by the folding mirror  185  and the axis C 1  is from 45 degrees to 90 degrees, examination of a region positioned above the horizontal axis becomes possible.  
         [0183]     Next, a sixth embodiment of the present invention will be described with reference to the drawings. Elements having the same structure as those in the preceding embodiments are given the same reference numerals, and any description duplicating that of the preceding embodiments is omitted.  
         [0184]     The microscope system of this embodiment is characterized in that a cover for closing the through-hole in the objective lens insertion tool is provided.  
         [0185]     As shown in  FIG. 16 , an objective lens insertion tool  191  has a configuration in which it is fixed to the skin W 2  by a base  154  of an insertion tool body  153  and a fixing ring  162 , the objective lens unit  123  is inserted into the insertion hole  152 , and the objective lens unit  123  is positioned and fixed by a step (surface  156 ) and a screw  160 .  
         [0186]     In addition, a sheet-like member (resilient member)  192 , which is long, thin, and deformable, extends from a side face  154   b  in the vicinity of a top face  154   a  of the base  154 . A cover  193  for closing the mouth of the insertion hole  152  is attached to the end of this sheet-like member  192 . This cover  193  is tapered in such a manner that the cross-sectional area thereof decreases from the base, where the sheet-like member  192  is attached, towards the tip thereof. Also, at the side opposite to the sheet-like member  192 , a flange  194  extends from the base of the cover  193 , so that the cover  193  can be easily grasped with the fingers or forceps.  
         [0187]     In this microscope system  1 , the objective lens insertion tool  191  is attached to the skin W 2  while carrying out examination with the binocular stereo microscope  4 , as described above. When carrying out examination, the objective lens unit  123  is inserted into the insertion hole  152  of the objective lens insertion tool  191 , and two-dimensional examination or three-dimensional examination is carried out with the micro microscope  5 . Then, when examination is not being carried out, the objective lens unit  123  is removed from the insertion hole  152 , and, as shown in  FIG. 17 , the cover  193  is pushed into the insertion hole  152  from the top surface  154   a  side, thus sealing the insertion hole  152 . Moreover, when carrying out re-examination, the cover  193  is pulled out of the insertion hole  152  by gripping the flange  194  or the like, and the objective lens unit  123  is inserted again into the insertion hole  152 .  
         [0188]     According to this type of objective lens insertion tool  191 , by clamping the skin W 2  with the insertion tool body  153  and the fixing ring  162 , it is possible to position and fix the objective lens unit  123  with respect to the subject W under examination. Also, when the objective lens unit  123  is not inserted, since the insertion hole  152  is sealed with the cover  193 , foreign objects are prevented from entering the subject W under examination. Moreover, the micro microscope  5  and microscope system  101  having such an objective lens insertion tool  191  are capable of accurate examination and examination over an extended period of time, as in the fourth embodiment described above.  
         [0189]      FIG. 18  and  FIG. 19  show an objective lens insertion tool  196  in which the cover for preventing entry of foreign objects has a different configuration.  
         [0190]     In this objective lens insertion tool  196 , a cover  197  is provided inside the insertion hole  152  of the insertion tool body  153 . This cover  197  is formed of a plurality of resilient pieces, which are provided inside the insertion hole  152 . These resilient pieces  198  are formed from a cross-shaped cutout  199  cut into a resilient member sealing off the mouth of a large-diameter section  157  of the insertion hole  152 , and their base, that is, the side at the internal wall of the insertion hole, is provided integrally with the internal wall. The cutout  199  may be slit shaped or have a radiating shape.  
         [0191]     When the objective lens unit  123  is not inserted, since the peripheral edges at the cutout  199  sides of the resilient pieces are connected to each other, thus sealing off the insertion hole  152 , foreign objects are prevented from entering the subject W under examination through the insertion hole  152 .  
         [0192]     As shown in  FIG. 20 , when the objective lens unit  123  is inserted into the insertion hole  152 , the resilient pieces  198  are pushed by the frame part  141  of the objective lens unit  123  so as to become bent downwards, the peripheral edges of the resilient pieces  198  separate, and an opening through which the objective lens unit  123  can be inserted is formed. Then, once the objective lens unit  123  is inserted, since the deformed resilient pieces  192  are in contact with the frame part  141  of the objective lens unit  123 , the objective lens unit  123  can be more reliably positioned and fixed.  
         [0193]     Next, a seventh embodiment of the present invention will be described with reference to the drawings. Elements having the same structure as those in the preceding embodiments are given the same reference numerals, and any description duplicating that of the preceding embodiments is omitted.  
         [0194]     The microscope system of this embodiment is characterized in that a mechanism for finely moving the objective lens unit  123  is provided, as shown in  FIG. 21  and  FIG. 22 .  
         [0195]     As shown in  FIG. 21 , an objective lens insertion tool  201  has a configuration in which the skin W 2  of the subject W under examination is clamped with a fixing ring  162  and a fixed part  202 , and the objective lens unit  123  is inserted into a finely movable part  203 , which can be finely moved with respect to the fixed part  202 .  
         [0196]     The fixed part  202  has a base part  204  and an insertion part  205 , having the same function as those in the preceding embodiments, and a through-hole  206  for inserting the finely movable part  203  through the center thereof is formed. The through-hole  206  has openings in each of an upper surface  204   a  and a tip surface  205   a , and a large-diameter section  207  at the upper face  204   a  side and a small-diameter section  208  at the tip face  205   a  side are formed by a step. The step is formed by the inner wall of the large-diameter section  207  and the inner wall of the small-diameter section  208  and by a flat surface  209  intersecting the axis of the through-hole  206  substantially perpendicularly. A bottom surface  203   a  of the finely movable part  203  is in contact with this surface  209 .  
         [0197]     The tip of a finely movable knob  210 , which is screwed into the base  204  from the side surface  204   b , is in contact with the side wall of the finely movable part  203 . One end of a pushing member (coil spring)  211  is fixed at a position of the internal wall of the through-hole  206  opposing the tip of the finely movable knob  210 , and the other end of the pushing member  211  is fixed to the side wall of the finely movable part  203 .  
         [0198]     An insertion hole  152  into which the objective lens unit  123  is inserted is formed inside the finely movable part  203 , and a flat surface  145  of the objective lens unit  123  is in contact with a flat surface  156  in the insertion hole  152 . Also, a plurality of concave sections  212  are disposed in this insertion hole  152 , and a ball  214  that is urged towards the axis of the insertion hole  152  by a resilient member  213  such as a coil spring is contained in each concave section  212 .  
         [0199]     Concave-shaped engaging slots  215  are formed in the frame part  141  of the objective lens unit  123  corresponding to the positions of the balls  214 .  
         [0200]     When using this objective lens insertion tool  201 , initially, the skin W 2  is clamped by the fixing ring  162  and the base  204  so as to fix it to the subject W under examination. When the objective lens unit  123  is inserted into the insertion hole  152  of the finely movable part  203  in this state, the balls  214  are engaged with the engaging slots  215  in the frame part  141  of the objective lens unit  123 , thus fixing the objective lens unit  123  at a predetermined position on the finely movable part  203 .  
         [0201]     When finely adjusting the position of the objective lens unit  123  in the lateral direction or the longitudinal direction, the finely movable knob  210  is rotated. When the finely movable knob  21  is pushed in, the finely movable part  203  moves in the direction that presses against the pressing member  211 , and the objective lens unit  123 , which is fixed to the finely movable part  203 , also moves in the same direction. On the other hand, when the finely movable knob  210  is reversed, the pressing member  211  is restored to its original state, the finely movable part  203  moves in the direction in which the pressing member expands, and the objective lens unit  123 , which is fixed to the finely movable part  203 , also moves in the same direction.  
         [0202]     After finely adjusting the position of the objective lens unit  123  in this way, two-dimensional or three-dimensional examination is carried out using the micro microscope  5 , as described above.  
         [0203]     According to this objective lens insertion tool  201 , the objective lens unit  123  can be fixed to the subject W under examination via the finely movable part  203  and the fixed part  202 . Also, by moving the finely movable part  203  in parallel with respect to the fixed part  202  using the finely movable mechanism formed of the finely movable knob  210  and the pressing member  211 , the position of the objective lens unit  123  can be finely adjusted. Only one set consisting of the finely movable knob  210  and the pressing member  211  is shown in  FIG. 21 ; however, if two sets of finely movable knobs  210  and pressing members  211  are provided at positions intersecting at right angles, it is possible to finely adjust the objective lens unit  123  longitudinally and laterally (in the X and Y directions).  
         [0204]     The micro microscope  5  and microscope system  1  including this type of objective lens insertion tool  201  are capable of carrying out accurate examination and examination over an extended period of time, as in the fourth embodiment described above.  
         [0205]     Furthermore, it is also possible to finely move the objective lens unit  123  upwards and downwards with an objective lens insertion tool  221  shown in  FIG. 22 .  
         [0206]     This objective lens insertion tool  221  has a structure in which the finely movable part  203  is inserted into the through-hole  206  of the fixed unit  202 . One end of a pressing member  211  is fixed to a flat surface  209  in the through-hole  206 , and the other end of the pressing member is fixed to a bottom surface  203  of the finely movable part  203 . Also, part of the base  203  of the fixed part  202  extends towards the axis of the through-hole  206 , and a support part  222  for rotatably supporting the finely movable knob  210  is formed. Since the finely movable knob  210  pushes the finely movable part  203  in the vertical direction, the tip thereof is in contact with the upper surface of the finely movable part  203 .  
         [0207]     In this objective lens insertion tool  221 , when the finely movable knob  210  is pushed in while turning it, the pushing member  211  is compressed and the finely movable part  203  is lowered. On the other hand, when the finely movable knob  210  is reversed by turning it, the pushing member  211  pushes up against the finely movable part  203 , thus raising the finely movable part  203 . Then, after finely adjusting the position of the objective lens unit  123 , two-dimensional or three-dimensional examination is carried out with the micro microscope  5 , as described above.  
         [0208]     When this type of objective lens insertion tool  221  is used, since it is possible to finely adjust the objective lens unit  123  upwards and downwards, for example, when focusing the laser beam onto the surface of an examination site or when carrying out three-dimensional examination, the operation thereof is easy. It is possible to focus the objective lens unit  123  using only the finely movable mechanism formed of the finely movable knob  210  and the pressing member  211 , or to perform focusing together with the optical system of the head unit  21 . When using only the finely movable mechanism of the objective lens insertion tool  221 , the structure of the head unit  21  can be simplified.  
         [0209]     Moreover, if the mechanism which can be finely moved in the horizontal direction as shown in  FIG. 21  and the mechanism which can be finely moved in the vertical direction as shown in  FIG. 22  are combined, it is possible to finely adjust the objective lens unit  123  in the lateral and longitudinal directions as well as in the up and down directions.  
         [0210]     It is also possible to inject a liquid such as water or the like between the objective lens unit  123  and the subject W under examination, and to perform focus adjustment of the light according to the amount of liquid. For example, in the case of the objective lens insertion tool  151  shown in  FIG. 14 , the insertion part  154  is lengthened so as to protrude further towards the examination site W 1  side than the tip of the objective lens unit  123 . Also, a gap through which the liquid can flow is formed between the insertion hole  152  and the objective lens unit  123 . Then, a tube connected to a pump (a syringe may also be used) for supplying the liquid is inserted into this gap.  
         [0211]     During examination, the insertion part  154  is brought into close contact with the vicinity of the examination site W 1 , and then the objective lens insertion tool is fixed to the skin W 2 . Since the examination site W 1  is sealed by the space formed between the insertion hole  152  and the objective lens unit  123 , if liquid is injected into this space, the focus position at the objective lens unit  123  side changes due to the difference in the degree of sealing between air and liquid. As a result, the focus position is changed by adding or reducing the amount of liquid while checking the image displayed on the monitor  7 .  
         [0212]     According to the objective lens insertion tool of this type, the objective lens can be positioned and fixed with respect to the examination site, and in addition, the focal position can be adjusted. To prevent leakage of the liquid from the end of the insertion part, a watertight gasket or the like may be attached to the end of the insertion part.  
         [0213]     Next, an eighth embodiment of the present invention will be described with reference to the drawings. Elements having the same structure as those of the preceding embodiments are given the same reference numerals, and any description duplicating that of the preceding embodiments is omitted.  
         [0214]     The microscope system of this embodiment is characterized in that there are two or more holes into which the objective lenses can be inserted.  
         [0215]     As shown in  FIG. 23 , an objective lens insertion tool  231  is formed of a fixing ring  162  and an insertion tool body  153 , and a first insertion hole  232  and a second insertion hole  233  are formed in parallel in the insertion tool body  153 .  
         [0216]     The first insertion hole  232  and the second insertion hole  233  are provided along the height direction of the insertion tool body  153 , at a position towards the outer side from the central axis C 2 , extend through a base  154  and an insertion part  155  of the insertion tool body  153 , and have axes that are parallel to each other. Also, the first insertion hole  232  and the second insertion hole  233  each have a large-diameter section  157  and a small-diameter section  158 .  
         [0217]     A threaded hole  159  is bored through the base  154  from the side thereof to the first insertion hole  232 , and a screw  160  for fixing the objective lens unit  123  inside the first insertion hole  232  is screwed therein. In the same way, a threaded hole  159  is bored through the base  154  from the side thereof to the second insertion hole  233 , and a screw  160  for fixing the objective lens unit  123  inside the second insertion hole  233  is screwed therein.  
         [0218]     The number of insertion holes is not limited to two; three or more holes are also acceptable. In this case, the number of threaded holes  159  and screws  160  provided corresponds to the number of insertion holes. In addition, a plurality of threaded holes  159  and screws  160  may be provided for one insertion hole  232  or  233 .  
         [0219]     When carrying out examination of the subject W, initially, the objective lens insertion tool  231  is positioned and fixed with respect to the subject W under examination. At this time, positioning of the two insertion holes  232  and  233  in the up and down directions at the site to be examined is checked using the binocular stereo microscope  4 . Then, the objective lens units  123  are inserted into the corresponding insertion holes  232  and  233 , and are fixed with their respective screws  160 . When examination is completed or when the objective lens units  123  are to be replaced, the screws  160  are loosened and the objective lens units  123  inserted in the insertion holes  232  and  233  are removed from the objective lens insertion tool  231 . The objective lens units  123  inserted in the respective insertion holes  232  and  233  may have different magnifications or the same magnifications.  
         [0220]     According to this objective lens insertion tool  231 , when the sites to be examined are close to each other, the objective lens units  123  can be positioned and fixed using a single objective lens insertion tool  231 . Therefore, accurate examination is possible even in the case where the subject W under examination is a small animal or the like, to which attachment of a plurality of objective lens insertion tools would be difficult.  
         [0221]     When the cover  193  shown in  FIG. 16  is provided in each of the insertion holes  232  and  232 , even when the objective lens units  123  are removed from the insertion holes  232  and  233 , foreign objects can be prevented from entering the subject W under examination from the insertion holes  232  and  233 . The cover  193  may be provided for only one of the insertion holes  232  and  233 .  
         [0222]     Next, a ninth embodiment of the present invention will be described with reference to the drawings. Elements having the same structure as those in the preceding embodiments are given the same reference numerals, and any description duplicating that of the preceding embodiments is omitted.  
         [0223]     The microscope system of this embodiment is characterized in that, instead of an insertion hole for inserting an objective lens or the like, a hole used for a purpose other than insertion of an objective lens is provided.  
         [0224]     As shown in  FIG. 24 , an insertion hole  152  of an objective lens insertion tool  241  has a large-diameter section  157  and a small-diameter section  158 , and is formed such that an objective lens unit  123  is fixed by means of a flat surface  156  and a screw  160 . A treatment hole  242  extends through a base  154  and a tip part  155  along an axis parallel to a central axis C 2 , and its internal diameter is substantially uniform. At the peripheral edge of an opening  243  at the top of the treatment hole  242 , the base  154  projects upwards along the central axis C 2 , forming a ring-shaped protrusion  244 . This ring-shaped protrusion  244  is used for fixing or guiding a treatment instrument. Also, at the side wall close to the upper surface  154   a  of the base  154 , a curved sheet-like member is integrally provided, and a cover  193  fitted into the ring-shaped protrusion for sealing the opening  243  is integrally attached to the end of this sheet-like member  192 . The outer surface of the ring-shaped protrusion  244  may be provided with indented grooves and projecting grooves around the circumference thereof, to improve the fixing of the treatment instrument.  
         [0225]     With this microscope system  101 , the objective lens insertion tool  241  is positioned and fixed to the subject W under examination. Then, the objective lens unit  123  is inserted into the insertion hole  152  and fixed, and the cover  193  fitted into the ring-shaped projection  244  is removed. If the examination site W 1  is concealed by another organ or the like, a basket is inserted from the treatment hole  242 , and the basket is opened inside the subject W under examination to press against the interior of the subject W under examination, thus exposing the examination site W 1  to allow examination with the objective lens unit  123 .  
         [0226]     As shown in  FIG. 25 , when a sheath  245  is connected to the ring-shaped protrusion  244  and air is supplied to the interior of the subject W under examination, it is possible to widen the area surrounding the examination site W 1 . Also, if a drug is supplied from the sheath  245 , inflammation of the examination site W 1  or its vicinity can be prevented.  
         [0227]     By using this type of treatment hole  242 , examination of the examination site W 1  can be reliably carried out. Furthermore, it is possible to administer the required treatment to the examination site W 1  or its vicinity. The treatment instrument attached to or inserted in the treatment hole  242  is not limited to those described above; a catheter, forceps or the like can also be used.  
         [0228]     Next, a tenth embodiment of the present invention will be described with reference to the drawings. Elements having the same structure as those in the preceding embodiments are given the same reference numerals, and any description duplicating that of the preceding embodiments in omitted.  
         [0229]     As shown in  FIG. 26 , a micro microscope  5  of a microscope system  101  has a light source  26  for illuminating an examination site W 1 , and a folding mirror  251 , an image-forming optical system  252 , and a CCD  253  are disposed in a head unit  221  to which an objective lens unit  123  is attached. The CCD  253  is connected to a controller  28 , and images of the examination site W 1  captured by the CCD  253  are output on a monitor  7  (see  FIG. 11 ). A light guide  250  formed of an optical fiber bundle is connected to the light source  26 .  
         [0230]     An objective lens insertion tool  254  is formed of an insertion tool body  153  and a fixing ring  162 . An insertion hole  152  is formed in the center of the insertion tool body  153  along an axis in the vertical direction, and the objective lens unit  123  is inserted therein. Also, in the insertion tool body  153 , a light guide hole  255  for inserting the end of the light guide  250  relative to the central axis of the insertion tool body  153  (that is, the optical axis of the objective lens unit  123 ) is provided in a part on the opposite side from the part where a threaded hole  159  is formed. The openings of the light guide hole  255  are provided at an upper face  154   a  of the base  154  and at a position close to the opening of the insertion hole  152  in an end face  155   a  of the insertion part  155 . The light guide hole  255  may be inclined so that the examination site W 1  side (the lower side) goes towards the central axis of the insertion tool body  153 .  
         [0231]     When this type of objective lens insertion tool  254  is used, the objective lens unit  123  can be positioned and fixed with respect to the subject W under examination. Also, since the end of the light guide is disposed close to the examination site W 1 , the examination site W 1  can be brightly illuminated and detailed examination images can be obtained.  
         [0232]     Instead of providing the opening of the light guide hole  255  at the upper surface  154   a  of the base  154 , the opening of the light guide hole  255  may be provided in the side face of the base  154 . Also, the light guide hole  255  may be gently curved or in the form of a straight line.  
         [0233]     Furthermore, as shown in  FIG. 27 , the light guide hole  255  may be provided in a frame part  262  of an objective lens unit  261 . The frame part  262  has a hole  263  for holding a plurality of objective lenses  142  and a light guide hole  255   a  through which a light guide  267  passes, and these holes  255   a  and  263  are provided in parallel along the axis extending in the height direction of the frame part  262 .  
         [0234]     On the other hand, a hole  265  with the same diameter as the outer diameter of the light guide  250  is provided in the side face of the head unit  21  of the micro microscope  5 . Also, a hole  266  with the same diameter as the outer diameter of the light guide  250  is provided at a position close to a window  36  inside a mounting part  37  of the head unit  21 . The light guide  250 , which is connected to the light source  26  of the micro microscope  5 , is lead into the head unit  21  from the hole  265  and is inserted into the hole  266 . The hole  266  is sealed so that light from the light guide  250  does not leak inside the head unit  21 .  
         [0235]     With this microscope system  101 , when the objective lens unit  261  is attached to the head unit  21 , the hole  266  and the light guide hole  255   a  are secured together so as to be continuous. Then, the objective lens unit  261  is inserted in the insertion hole  152  of the objective lens insertion tool  151 , which is positioned and fixed with respect to the subject W under examination, and is fixed with the flat surface  156  and the screw  160 . During examination, light from the light guide  26  passes through the light guide  250  and is guided to the light guide hole  255   a  from the hole  266 . Then, it is radiated towards the examination site W 1  from the opening at the end of the light guide  267  in the light guide hole  255   a.    
         [0236]     The light guide  250  may be inserted into the light guide hole  255   a  to directly illuminate the examination site W 1  with the light guide  250 . In this case, the light guide  250  is removed from the hole  266  in advance and is inserted into the light guide hole  255   a , and then the objective lens unit  261  is fixed to the head unit  21 .  
         [0237]     According to this embodiment, since light from the vicinity of the objective lenses  142  in the objective lens unit  261  is radiated, shadows do not easily occur, and the examination site W 1  can thus be illuminated more reliably.  
         [0238]     The present invention is not limited to the embodiments described above, but can be applied more widely.  
         [0239]     For example, the micro microscope  5  according to the embodiments has been described in terms of a confocal laser scanning microscope; however, it may also be a microscope of the type that illuminates the examination site with a light guide and obtains images of the subject W under examination using a CCD, which achieves the same effects and results as described above.  
         [0240]     Also, the embodiments may be combined. For example, a cover  193  (see  FIG. 16 ) or a cover  197  (see  FIG. 18 ) may be provided in the objective lens insertion tools  201  and  221  having a finely movable part  203 , as shown in  FIG. 21  and  FIG. 22 , or in the objective lens insertion tool  254  having a light-guide hole  255 , as shown in  FIG. 26 .  
         [0241]     Next, a fixing apparatus of an objective optical system according to an eleventh embodiment of the present invention will be described below with reference to  FIG. 28  and  FIG. 29 .  
         [0242]     A fixing apparatus  301  of the objective optical system according to this embodiment is an apparatus for fixing an objective optical system unit  302  in an aligned state to a site A of a subject under examination, such as an internal organ of an animal, and, as shown in  FIG. 28  and  FIG. 29 , is provided with a support member  303  for supporting the objective optical system unit  302  and a fixing mechanism  304  for holding the support member  303  in an aligned and fixed state with respect to an arm or a leg X of the animal.  
         [0243]     In the example shown in  FIG. 28  and  FIG. 29 , the support member  303  is a tube-shaped member having a through-hole  305  in which the arm or leg X of the animal is inserted, and an insertion hole  306  for inserting the objective optical system unit  302  and threaded holes  307 , disposed at both sides in the longitudinal direction thereof, are provided at substantially the central position in the length direction thereof, through a side wall. Also, fastened bolts  308  whose ends can protrude inside the through-hole  305  are disposed in the threaded holes  307 . Thus the fixing mechanism  304  for fixing the support member  303  in an aligned state with respect to the tissue X is constituted by the through-hole  305 , the threaded holes  307 , and the bolts  308 .  
         [0244]     The objective optical system unit  302  is arranged so as to contain an objective optical system  310  formed of a plurality of lenses  309  inside a substantially circular outer tube  311 . The outer tube  311  is provided with a step portion  312  at an intermediate position in the longitudinal direction thereof, and is also provided with a small-diameter section  313  whose outer diameter at the side towards the tip from the step portion  312  is reduced stepwise, and a large-diameter section  314  at the rear end whose outer diameter is larger than the small-diameter section  313 .  
         [0245]     The insertion hole  306  is provided with fitting faces  315   a  and  315   b  against which the small-diameter section  313  and the large-diameter section  314  of the outer tube  311  in the objective optical system unit  302  fit. In addition, it is also provided with an abutting face  316  against which the step portion  312  provided in the outer tube  311  abuts.  
         [0246]     Reference number  317  in the drawings is the main body of the microscope. An optical fiber  317   a  for conveying light from a light source (not shown), a collimator lens  317   b  for making the light emitted from the optical fiber  317   a  substantially parallel, and an optical scanner  317   c , like a galvano mirror, for scanning the parallel light beam emitted from the collimator lens  317   b  over the examination site A are provided in the microscope main body  317 .  
         [0247]     The effects of the fixing apparatus  301  according to the present embodiment, when configured in this way, are described below.  
         [0248]      FIG. 28  depicts the case where an examination of the bone marrow, serving as the site A of the subject under examination, is carried out. To fix the objective optical system unit  302  using the fixing apparatus  301  according to this embodiment, the tissue of the animal, for example, the skin tissue and the muscle tissue of the arm or leg X, is cut open, thus forming a hole extending to the bone marrow A in the bone B. In this state, the arm or leg X is inserted into the through-hole  305  of the support member  303 , and the insertion hole  306  is aligned with the incised region.  
         [0249]     Then, the objective optical system unit  302  is inserted through the insertion hole  306  into an incision Y in the tissue X, and the tip of the objective optical system unit  302  is disposed so as to be in contact with the bone marrow A. Subsequently, in this state, the support member  303  is fixed with respect to the arm or leg X of the animal by tightening the bolts  308  screwed into the threaded holes  307  of the support member  303 .  
         [0250]     In other words, since the support member  303  is fixed to the arm or leg X of the animal and the objective optical system unit  302  is disposed in the support member  303  in an aligned state, it is possible to fix, in an aligned state, the tip of the objective optical system unit  302  with respect to the bone marrow A, which is the site of the subject under examination, disposed inside the arm or the leg X of the animal.  
         [0251]     According to the fixing apparatus  301  of this embodiment, since an abutting face  316 , against which the step portion  312  of the objective optical system unit  302  abuts, is provided in the support member  303 , it is possible to position the objective optical unit  302 , in the optical axis direction thereof, with respect to the support member  303 . Also, since the fitting faces  315   a  and  315   b , against which the small-diameter section  313  and the large-diameter section  314  of the objective optical system unit  302  fit, are provided in the support member  303 , the objective optical system unit  302  can be disposed in an aligned state, in the radial direction thereof, with respect to the support member  303 .  
         [0252]     Thus, since it is possible to position the objective optical system unit  302  with respect to the support member, in the optical axis direction and in the direction perpendicular thereto, even if the objective optical system unit  302  is removed from and inserted into the insertion hole  306 , the tip can be positioned with a high degree of repeatability at the same position of the bone marrow A.  
         [0253]     Next, a fixing apparatus  320  of an objective optical system according to a twelfth embodiment of the present invention will be described with reference to FIGS.  30  to  32 . In the description of this embodiment, identical reference numerals are used where the description and structure overlap with the above-described eleventh embodiment, and the description thereof is thus omitted.  
         [0254]     The fixing apparatus  320  according to this embodiment is provided with a support member  321  having an insertion hole  306  similar to the insertion hole  306  of the fixing apparatus  301  according to the above-described embodiment, and a fixing mechanism  322  provided on the support member  321 .  
         [0255]     An abutting face  316  against which fitting faces  315   a  and  315   b  (not shown in the drawings) abut is provided in the insertion hole  306 .  
         [0256]     Also, the fixing mechanism  322  is constituted, as shown in  FIG. 30  for example, by clamping members  324  which are urged shut by springs  323 .  
         [0257]     As shown in  FIG. 31  and  FIG. 32 , the fixing device  320  according to this embodiment is implanted inside a small experimental animal X, and is fixed inside by the fixing mechanism  322 . By clamping the clamping members  324  of the fixing mechanism  322  to a bone  325  of the small experimental animal X, the support member  321  becomes fixed to the bone  325 .  
         [0258]     The bone  325 , such as a rib, is deformed little due to its comparative rigidity and also has a relative positional relationship with respect to the tissue, such as an organ, thus providing a certain degree of stability. Accordingly, by fixing the support member  321  to this bone  325 , it is possible to maintain the objective optical system unit  302 , which is positioned and fixed with respect to the support member  321 , in a stable aligned state with respect to the examination site A of the subject.  
         [0259]     The fixing device  320  according to this embodiment is not limited to devices for fixing to the bone  325  shown in FIGS.  30  to  32 . For example, in the case where the examination site A of the subject is brain tissue disposed inside a cranium  326 , as shown in  FIG. 33 , by clamping the cranium  326  in the radial direction with bolts  328  provided at the ends of arc-shaped members  327 , which are clamped to the head X of the small experimental animal, the support member  321 , which is fixed to the arc-shaped members  327 , may be positioned and fixed with respect to the tissue X.  
         [0260]     Next, an objective optical system fixing device according to a thirteenth embodiment of the present invention is described with reference to  FIG. 34  and  FIG. 35 .  
         [0261]     In the description of this embodiment, identical reference numerals are used where the description and structure overlap with the above-described eleventh embodiment, and the description thereof is thus omitted.  
         [0262]     A fixing device  330  according to this embodiment is provided, at the end of a support member  331 , with a fixing mechanism  332  for fixing the support member  331  with respect to tissue A′. As shown in  FIG. 35 , this fixing mechanism  332  is constituted by a circular-ring-shaped pointed portion (hereinafter occasionally referred to as a tip part  332 ) where the tip of the substantially cylindrical support member  331  is sharply formed. The fitting faces  315   a  and  315   b , as well as the abutting face  316 , for positioning the objective optical system unit  302  in the radial direction and in the axial direction are the same as in the fixing devices  301  and  320  according to the embodiments described above.  
         [0263]     To position and fix the end of the objective optical system unit  302  with respect to the subject examination site A, such as an organ, disposed inside a small experimental animal X or the like by means of the fixing device  330  according to this embodiment, the support member  331  is inserted inside an incision C formed through the skin tissue or muscle tissue of the small experimental animal X. Since the pointed portion  332  is provided at the end of the support member  331 , by sticking the pointed portion  332  into the internal organ A′, the support member  331  becomes fixed in the radial direction thereof with respect to the organ A′.  
         [0264]     Since the insertion hole  306  of the support member  331  is formed inside the circular-ring-shaped pointed portion  332  and the tip of the objective optical system unit  302  is exposed at an opening  306   a  thereof, it is possible to examine the subject examination site A that is disposed inside the pointed portion  332  via the objective optical system unit  302 .  
         [0265]     In the fixing device  330  according to this embodiment, the circular-ring-shaped pointed portion  332  is employed as a fixing mechanism; however, as shown in  FIG. 36 , a plurality of micro needles  332  may be provided at the tip surface of the support member  331 . In this case, little damage is caused to the tissue such as the organ A′ into which the micro needles  332  are stuck, and it is possible to maintain the support member  331  in a stable aligned state with respect to the tissue A′ disposed around the examination site A of the subject.  
         [0266]     Moreover, as shown in  FIG. 37 , a reverse part  333  formed of a plurality of projections protruding in the radial direction may be provided around the pointed portion  332 . With such an arrangement, once the pointed portion  332  of the support member is thrust into the organ A′, the reverse part  333  provided around the pointed portion  332  becomes lodged in the organ A′, thus preventing the support member  331  from being removed from the organ A′. As a result, since the support member  331  is fixed to the organ A′ not only in the radial direction thereof but also in the axial direction, the objective optical system unit  302  can be fixed to the subject examination site A in a stable aligned state in both the radial direction and the axial direction.  
         [0267]     Furthermore, as shown in  FIG. 38 , it is also possible to provide a window member  334 , formed of an optically transparent material, for blocking an opening  306   a  disposed inside the pointed portion  332  of the support member  331  in  FIG. 35 . When the support member  331  having such a structure is inserted into an incision C formed in the tissue X and is stuck into the organ A′ or the like in the vicinity of the examination site A of the subject, the support member  331  is disposed so as to cover the inner surface of the incision C formed in the tissue X and so that the window member  334  comes into close contact with the subject examination site A and covers the subject examination site A. As a result, even if the objective optical system unit  302  is removed from the insertion hole  306  of the support member  331 , the interior of the tissue X is covered so as not to be exposed to the air, and the tissue X can thus be maintained in a healthy condition.  
         [0268]     In addition, in the embodiments described above, the pointed portion  332  for sticking into the tissue such as the organ A′ is provided at the tip of the support member  331 , which fixes the support member  331  to the tissue in an aligned state; however, instead of this, as shown in  FIG. 39 , a biocompatible adhesive  335  may be applied to the tip surface of the support member  331 . Accordingly, instead of sticking the support member  331  into the tissue A′ such as an organ, it is possible to fix it in an aligned state to the tissue A′ in the vicinity of the examination site A of the subject. This is preferable because it can be aligned and fixed without causing a significant amount of damage to the tissue A′. As examples of the adhesive  335 , a silane coupling agent, a thermo-responsive polymer, and other biocompatible adhesives are possible.  
         [0269]     Next, an objective optical system fixing device according to a fourteenth embodiment of the present invention is described with reference to  FIG. 40  and  FIG. 41 . In the description of this embodiment, the same reference numerals are used where the description and structure overlap those of the thirteenth embodiment described above, and the description thereof is omitted.  
         [0270]     A fixing device  340  according to this embodiment is provided with a support member  341  which is inserted into an incision C formed in the torso of a small experimental animal X or the like, and a fastening apparatus  342  for fastening the support member  341  to the torso (the surface of the body) of the small experimental animal X.  
         [0271]     The support member  341  may be provided with a pointed portion  332  or an adhesive  335  at the tip thereof, like the support member  331  in the thirteenth embodiment, or, as shown in  FIG. 40 , it may also be provided with a flat tip surface  341   a.    
         [0272]     As shown in  FIG. 40  and  FIG. 31 , the fastening apparatus  342  is formed of two metallic arc-shaped flat gripping parts  343  which are urged in the closing direction by a spring or the like (not shown), and a coupling member  344  for coupling the gripping parts  343  and the support member  341 .  
         [0273]     By inserting the torso of the small experimental animal between the arc-shaped flat gripping parts  343  constituting the fastening apparatus, which are pushed apart by the resilient force of the spring, and gripping the torso by means of the resilient force of the spring, the gripping parts  342  can be fastened to the torso of the small experimental animal X.  
         [0274]     According to the thus-configured fixing device  340  of this embodiment, by fastening the fastening apparatus  342  to the torso of the small experimental animal X, the support member  341  and the objective optical system unit  302  inserted in the support member  341  can be fixed in an aligned state with respect to the examination site A of the subject. In particular, this is effective in cases where the support member  341  cannot be fixed to a bone or to the organ A′ itself. Also, even if the support member  341  is fixed to a bone or the organ A′ itself, by employing the fastening apparatus  342  of this embodiment, the objective optical system unit  302  can be maintained in a more stable aligned state with respect to the examination site A of the subject.  
         [0275]     This embodiment has been described in terms of an example base member having a structure in which the torso of the small experimental animal X is gripped by the metallic arc-shaped flat gripping parts  343 ; however, instead of this, the base member may be constituted by, as shown in  FIG. 42 , a belt  345  for strapping around the torso or, as shown in  FIG. 43 , a jacket  346  worn by the small experimental animal X. According to these base members  345  and  346 , no serious damage is caused to any small experimental animal X, and the objective optical system unit  302  can be fixed with respect to the examination site A of the subject. Also, it is possible allow the small experimental animal to behave as normal, and examination of the examination site A of the subject can be carried out over a long period of time.  
         [0276]     Since the base member formed of the arc-shaped flat gripping members  343  or the belt  345  can be adjusted to fit the size of the small experimental animal X, it is versatile and can be used for various purposes.  
         [0277]     In this embodiment, coupling and fixing of the base member  343  and the support member  341  is achieved by the coupling member  343 ; however, instead of this, as shown in  FIG. 42  and  FIG. 43 , coupling and fixing of the base members  345  and  346  and the microscope  317  may be achieved by a coupling member  344 . Also, as shown in  FIG. 44  and  FIG. 45 , coupling and fixing of the base member  311  and an outer tube  311  of the objective optical system unit  302  inserted in the support member may be achieved by the coupling member  344 . With this structure, since the objective optical system unit  302  is supported at two places, that is, at the support member  341  and at the coupling member  344 , more stable examination of the examination site A of the subject can be carried out.  
         [0278]     Next, an objective optical system fixing device according to a fifteenth embodiment of the present invention is described with reference to  FIG. 46  and  FIG. 47 . In this embodiment too, the same reference numerals are used where the description and structure overlap those of the eleventh embodiment described above, and the description thereof is omitted.  
         [0279]     As shown in  FIG. 46 , a fixing device  350  of this embodiment is provided with an animal securing stage  351  for securing a small experimental animal X, an arm  352  fixed to the animal securing stage  351 , and sliders  353  that can move on the arm  352  in the horizontal direction and the vertical direction. A microscope body  317  having an objective optical system  302  is fixed to each slider  353 .  
         [0280]     Also, as shown in  FIG. 47 , a through-hole  355  is provided in a mounting part  354  on which the small experimental animal X is placed, and another objective optical system unit  302  is fixed in an aligned state with respect to the animal securing stage  351  so as to project through the upper face of the mounting part  354  via the through-hole  355 .  
         [0281]     In the example shown in  FIG. 46  and  FIG. 47 , the tips of the objective optical system units  302 , which are positioned in the horizontal direction and the vertical direction by operating the sliders  353 , are disposed so as to be inserted in holes formed in the head and back of the small experimental animal X, which is secured with the mounting part  354  of the animal fixing stage  351  facing the abdominal region. Also, the tip of the objective optical system unit  302  protruding from beneath the mounting part  354  is disposed so at to be inserted in a hole formed in the abdominal region.  
         [0282]     According to the fixing device  350  of this embodiment, the objective optical system units  302 , which are positioned and fixed with respect to the animal securing stage  351  on which the small experimental animal X is secured either directly or by means of the arm  350  and the sliders  350 , are used to carry out examination of subject examination sites disposed inside the body of the small experimental animal X. Therefore, as a result, relative motion between the objective optical system units  302  and the examination sites of the subject can be reduced as much as possible, and detailed, blur-free examination images can be obtained.  
         [0283]     In the embodiments above, the objective optical system units  302  have been described in terms of an example in which at least one objective lens  309  is contained inside the outer tube  311 ; however, instead of this, the objective optical system units  302  may have a configuration in which a probe-type microscope head is aligned and fixed with respect to the support members  303 ,  321 ,  331 , and  341 .