Abstract:
Noise in a fluorescence image acquired during fluoroscopy is eliminated to present a clear fluorescence image, and the relative positional relationship between the fluoroscopy unit and the specimen can be recognized even while fluoroscopy is in progress. A dark box apparatus for fluoroscopy includes: a dark-box main body enclosing a specimen and a fluoroscopy unit for illuminating the specimen with excitation light with a first spectral band and for detecting fluorescence with a second spectral band generated by the specimen; an illumination light source disposed in the dark-box main body to emit light with a third spectral band different from the first spectral band and the second spectral band; and an observation window disposed in the dark-box main body, the observation window being capable of transmitting light with a fourth spectral band which includes at least part of the third spectral band and does not include the first spectral band and the second spectral band.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a continuation of U.S. patent application Ser. No. 11/213,906 filed on Aug. 30, 2005, which claims priority to Japanese Application No. 2004-257240 filed on Sep. 3, 2004, which is expressly incorporated herein to its entirety by reference thereto. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to dark box apparatuses for fluoroscopy, fluoroscopy systems, and fluoroscopy methods.  
         [0004]     This application is based on Japanese Patent Applications No. 2004-257240, the contents of which are incorporated herein by reference.  
         [0005]     2. Description of Related Art  
         [0006]     As a technique for non-invasively examining the interior of a specimen, some known confocal microscopes or multiphoton-excitation microscopes employ a fluoroscopy method for illuminating a specimen with excitation light, such as a laser beam, to examine fluorescence generated by the specimen.  
         [0007]     However, since fluorescence generated by a specimen is very weak, it is difficult to acquire a clear fluorescence image due to external noise if fluoroscopy is performed in the presence of extraneous light. For this reason, if fluoroscopy is to be performed in a darkroom, a specimen is first positioned with respect to the microscope apparatus under external light, and then the specimen is illuminated with excitation light with all extraneous light blocked to detect fluorescence emitted from the specimen.  
         [0008]     Though in a totally different technical field, a so-called dark-place observation device for examining the influence of particular wavelengths of light upon plants in a place dark enough to prevent the plants from being affected by light is also known (e.g., see Japanese Unexamined Patent Application Publication No. 2002-369624).  
         [0009]     For examination with these known dark-place observation devices, plants are first positioned in a dark box completely protected from extraneous light to prevent the plants from experiencing biological effects, such as gene expression, due to extraneous light, and then an infrared light source emitting infrared light with wavelengths that do not affect the plants and an infrared CCD camera are placed in the dark box to observe an image from the infrared CCD camera on a monitor outside the dark box.  
         [0010]     If fluoroscopy is to be performed in a darkroom such that a specimen is first positioned with respect to the microscope apparatus under extraneous light and then the specimen is illuminated with excitation light with all extraneous light blocked to detect fluorescence emitted from the specimen, unsuccessful positioning of the specimen, such as a shift of the specimen from the desired examination position, may occur. In this case, the positional relationship between the microscope apparatus and the specimen needs to be re-adjusted. Thus, the positional relationship between the microscope and the specimen may need to be adjusted by feeling with the hands in a darkroom where extraneous light is blocked. This may cause the objective lens of the microscope apparatus to interfere with the specimen, possibly damaging the objective lens or the specimen. In addition, repeating the procedure of introducing extraneous light for positioning and then blocking the extraneous light again for examination is time-consuming and annoying.  
       BRIEF SUMMARY OF THE INVENTION  
       [0011]     The present invention has been conceived in light of these circumstances, and it is an object of the present invention to provide a dark box apparatus for fluoroscopy, a fluoroscopy system, and a fluoroscopy method for eliminating noise in a fluorescence image acquired during fluoroscopy to present a clear fluorescence image and for checking the relative positional relationship between the fluoroscopy unit and the specimen even while fluoroscopy is in progress.  
         [0012]     In order to achieve the above-described objects, the present invention provides the following solutions.  
         [0013]     According to a first aspect of the present invention, a dark box apparatus for fluoroscopy includes: a dark-box main body enclosing a specimen and a fluoroscopy unit for illuminating the specimen with excitation light with a first spectral band and for detecting fluorescence with a second spectral band generated by the specimen; an illumination light source disposed in the dark-box main body to emit light with a third spectral band different from the first spectral band and the second spectral band; and an observation window disposed on the dark-box main body, the observation window being capable of transmitting light with a fourth spectral band which includes at least part of the third spectral band and does not include the first spectral band and the second spectral band.  
         [0014]     According to this aspect, when fluoroscopy is to be performed by placing the specimen and the fluoroscopy unit in the dark-box main body and radiating excitation light with the first spectral band to detect fluorescence with the second spectral band emitted from the specimen, the illumination light source is operated in the dark-box main body to emit visible light with the third spectral band. Since the observation window provided in the dark-box main body can transmit light with the fourth spectral band including at least part of the third spectral band, part of light with the third spectral band reflected at the specimen and the fluoroscopy unit passes through the observation window and is observed by an external observer.  
         [0015]     In other words, the observer can easily recognize the state of the specimen, the positional relationship between the specimen and the fluoroscopy unit, etc. in the dark-box main body with the aid of light with the third spectral band coming through the observation window. On the other hand, since the third spectral band differs from the first spectral band, even if light with the third spectral band is emitted in the dark-box main body, the fluorescent material of the specimen is not excited with the emitted visible light with the third spectral band. Furthermore, since the third spectral band differs from the second spectral band, light with the third spectral band emitted in the dark-box main body is not detected by the fluoroscopy unit, and hence noise in the acquired fluorescence image does not increase.  
         [0016]     Since the observation window transmits light with the fourth spectral band, light with the fourth spectral band may enter the dark-box main body from outside the dark-box main body. However, since the fourth spectral band does not include the first spectral band and the second spectral band, the fluorescent material is not excited by light entering the dark-box main body or noise in the fluorescence image does not increase, just like in the above-described case. On the other hand, the observation window transmits at least part of other light with the third spectral band from outside the dark-box main body. This transmitted light can be used as illumination light along with the light from the illumination light source.  
         [0017]     In the above-described aspect, it is preferable that the illumination light source be disposed at a location such that the illumination light source is not directly visible from outside through the observation window.  
         [0018]     In this manner, the observer observing from outside the dark-box main body through the observation window does not look directly at the illumination light source. This prevents light of the illumination light source from dazzling the observer. More specifically, the illumination light source may be provided out of the field of view of the observation window or alternatively, a baffle plate etc. may be provided to prevent light from the illumination light source from directly reaching the observation window.  
         [0019]     According to a second aspect of the present invention, a dark box apparatus for fluoroscopy includes: a dark-box main body for blocking entry of extraneous light by enclosing a specimen and a fluoroscopy unit for illuminating the specimen with excitation light with a first spectral band and for detecting fluorescence with a second spectral band generated by the specimen; an illumination light source disposed in the dark-box main body to emit light with a third spectral band different from the first spectral band and the second spectral band; a photography unit disposed in the dark-box main body to photograph the specimen illuminated by the illumination light source and the fluoroscopy unit; and an image display unit disposed outside the dark-box main body to display an image acquired by the photography unit.  
         [0020]     According to this aspect, when the specimen and the fluoroscopy unit are placed in the dark-box main body and excitation light with the first spectral band is radiated to perform fluoroscopy for detecting fluorescence with the second spectral band emitted from the specimen, the illumination light source is operated in the dark-box main body to radiate light with the third spectral band. Light with the third spectral band is radiated onto the specimen and the fluoroscopy unit and is photographed by the photography unit provided in the dark-box main body. An acquired image is displayed on the image display unit outside the dark-box main body. The observer can easily recognize the state of the specimen, the positional relationship between the specimen and the fluoroscopy unit, etc. by observing on the image display unit the specimen and the fluoroscopy unit illuminated with light with the third spectral band.  
         [0021]     On the other hand, since the third spectral band differs from the first spectral band, even if light with the third spectral band is emitted in the dark-box main body, the fluorescent material of the specimen is not excited with the emitted light with the third spectral band. Furthermore, since the third spectral band differs from the second spectral band, light with the third spectral band emitted in the dark-box main body is not detected by the fluoroscopy unit, and hence noise in the acquired fluorescence image does not increase.  
         [0022]     In the above-described aspect, it is preferable that the illumination light source be disposed at a location such that light emitted from the illumination light source is not directly incident upon the photography unit.  
         [0023]     In this manner, an image acquired by the photography unit can be free of noise, such as flare, due to light from the illumination light source. Therefore, light from the illumination light source does not interfere with the observation. More specifically, the illumination light source may be provided out of the field of view of the photography unit or alternatively, a baffle plate etc. may be provided to prevent light from the illumination light source from being directly incident upon the photography unit.  
         [0024]     In the above-described aspect, a camera including the photography unit and the image display unit may be provided on a wall surface of the dark-box main body such that the photography unit faces inward and the image display unit faces outward.  
         [0025]     In this manner, an image which would appear if the interior of the dark box were observed through the observation window can be displayed on the image display unit.  
         [0026]     In the above-described aspect, a bellows member may be provided between the wall surface of the dark-box main body and the camera such that the bellows member supports the camera so that the camera is movable relative to the wall surface.  
         [0027]     In this manner, the image display range on the image display unit can easily be adjusted by moving the camera with respect to the wall surface through deformation of the bellows member.  
         [0028]     In the above-described aspect, the illumination light source may include a wavelength-switching mechanism for switching a spectral band of emitted light.  
         [0029]     When examination is to be performed using the fluoroscopy unit with the wavelength of the excitation light switched, the wavelength-switching mechanism is operated to switch the spectral band of light to be emitted by the illumination light source, thereby allowing the wavelength of the excitation light to be selected more flexibly.  
         [0030]     According to a third aspect of the present invention, a fluoroscopy system includes: a fluoroscopy unit for illuminating a specimen with excitation light with a first spectral band and for detecting fluorescence with a second spectral band generated by the specimen; and one of the above-described dark box apparatuses for fluoroscopy, wherein the dark-box main body includes: a door for opening and closing the dark-box main body; an open/closed sensor for detecting an open/closed state of the door; and an excitation-light control section for stopping emission of excitation light from the fluoroscopy unit when the open/closed sensor detects that the door is opened.  
         [0031]     According to this aspect, the specimen and the fluoroscopy unit are placed in the dark-box main body, the door is closed, excitation light with the first spectral band is radiated onto the specimen in the fluoroscopy unit, and fluorescence with the second spectral band emitted from the specimen is detected to perform fluoroscopy. If the door is opened for some reason during fluoroscopy, the open/closed sensor detects an open state of the door and emission of excitation light in the fluoroscopy unit is stopped by the operation of the excitation light control section. As a result, the excitation light is prevented from leaking from the dark box.  
         [0032]     Furthermore, when the open/closed sensor detects a closed state of the door, excitation light is emitted by the operation of the excitation light control section. As a result, fluoroscopy is performed while light serving as noise from outside the dark box is blocked. This provides a clear fluorescence image with less noise.  
         [0033]     According to a fourth aspect of the present invention, a fluoroscopy system includes: a fluoroscopy unit for illuminating a specimen with excitation light with a first spectral band and for detecting fluorescence with a second spectral band generated by the specimen; and one of the above-described dark box apparatuses for fluoroscopy, wherein the dark-box main body includes: a door for opening and closing the dark-box main body; an open/closed sensor for detecting an open/closed state of the door; and an operation control section for decreasing an operation speed of the fluoroscopy unit when the open/closed sensor detests that the door is closed.  
         [0034]     According to this aspect, the door of the dark-box main body is opened, the specimen is positioned with respect to the fluoroscopy unit, preparations are made for rough alignment of the focal position of the fluoroscopy unit, and then the door is closed to arrange the specimen and the fluoroscopy unit in the dark-box main body. In this state, fluoroscopy is performed by radiating excitation light with the first spectral band onto the specimen in the fluoroscopy unit while the positional relationship between the specimen and the fluoroscopy unit is finely adjusted under light with the third spectral band from the illumination light source to detect fluorescence with the second spectral band emitted from the specimen. In this case, according to the present invention, the operation of the operation control section causes the fluoroscopy unit to operate at a lower operation speed while the open/closed sensor detects a closed state of the door compared to when the open/closed sensor detects an open state of the door. As a result, it is possible to reduce the risk of the fluoroscopy unit mistakenly interfering with the specimen in the dark-box main body because only limited information is obtained through the observation window or the image display unit. Therefore, damage to the fluoroscopy unit and the specimen can be avoided.  
         [0035]     According to a fifth aspect of the present invention, a fluoroscopy method for emitting excitation light with a first spectral band from a fluoroscopy unit onto a specimen and for examining fluorescence with a second spectral band emitted from the specimen, the method includes steps of: enclosing the specimen and the fluoroscopy unit with a dark box; emitting light with a third spectral band different from the first spectral band and the second spectral band in the dark box; and manipulating the specimen or the fluoroscopy unit from outside the dark box while observing light with the third spectral band outside the dark box through an observation window, disposed in the dark box, capable of transmitting light with a fourth spectral band which includes at least part of the third spectral band and does not include the first spectral band and the second spectral band or through a photography unit disposed in the dark box.  
         [0036]     According to this aspect, the fluoroscopy unit and the specimen are irradiated with light with the third spectral band to carry out examination through the observation window or the photography unit. Therefore, the positional relationship between the fluoroscopy unit and the specimen can easily be recognized in the dark box for reliable operation without disturbing fluoroscopy with the fluoroscopy unit. Therefore, blind operation is eliminated, and hence an annoying repeated procedure of turning ON and OFF the illuminating light in the darkroom can be avoided.  
         [0037]     According to the present invention, since the fluoroscopy unit and the specimen are irradiated with light with the third spectral band different from the first and second spectral bands for examination through the observation window or the photography unit, the positional relationship between the fluoroscopy unit and the specimen can easily be recognized in the dark box for reliable operation without disturbing fluoroscopy with the fluoroscopy unit. Therefore, blind operation is eliminated, and hence an annoying repeated procedure of turning ON and OFF the illuminating light in the darkroom can be avoided. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0038]      FIG. 1  is a longitudinal sectional view of a dark box apparatus for fluoroscopy according to a first embodiment of the present invention.  
         [0039]      FIG. 2  is a diagram depicting a spectral band of fluorescence in response to light from an illumination light source of the dark box apparatus for fluoroscopy shown in  FIG. 1  and the transmittance characteristic of an observation window.  
         [0040]      FIG. 3  is a longitudinal sectional view of a dark box apparatus for fluoroscopy according to a second embodiment of the present invention.  
         [0041]      FIG. 4  is a longitudinal sectional view of a modification of the dark box apparatus for fluoroscopy shown in  FIG. 3 .  
         [0042]      FIG. 5  is a longitudinal sectional view of a fluoroscopy system according to a third embodiment of the present invention.  
         [0043]      FIG. 6  is a longitudinal sectional view of a modification of the fluoroscopy system shown in  FIG. 5 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0044]     A dark box apparatus for fluoroscopy  1  according to a first embodiment of the present invention will now be described with reference to  FIGS. 1 and 2 .  
         [0045]     Referring to  FIG. 1 , the dark box apparatus for fluoroscopy  1  according to this embodiment includes a dark-box main body  2 ; an illumination light source  3  arranged in the dark-box main body  2 ; and an observation window  4  arranged in a wall surface  2   a  of the dark-box main body  2 .  
         [0046]     The above-described dark-box main body  2  is a box member composed of a material blocking light of all wavelengths, and is large enough to completely contain an examination head  6  of a fluoroscopy unit  5 , to be described below; a raising-and-lowering mechanism  7  for raising and lowering the examination head  6 ; a specimen A; and a stage  8  holding the specimen A for moving the specimen A two-dimensionally in the horizontal direction or tilting the specimen A.  
         [0047]     As shown in  FIG. 1 , the fluoroscopy unit  5  includes an optical unit  9 ; the examination head  6 ; and an optical fiber  10  for connecting the optical unit  9  and the examination head  6 .  
         [0048]     The optical unit  9  includes an excitation light source  11  emitting excitation light L 1  with a first spectral band B 1  (e.g., a wavelength of 545 nm), such as a laser beam; a collimating lens  12  for converting the emitted excitation light L 1  into collimated light; a coupling lens  13  for focusing the excitation light L 1  converted into collimated light onto an end surface  10   a  of the optical fiber  10 ; a dichroic mirror  14  for separating fluorescence L 2  with a second spectral band B 2  (e.g., a wavelength of 550 nm) from return light returning through the optical fiber  10 ; a focusing lens  15  for focusing the separated fluorescence L 2 ; and a photodetector  16  for detecting the focused fluorescence L 2 . The photodetector  16  is realized by, for example, a photomultiplier tube (PMT).  
         [0049]     The examination head  6  includes a casing  17  which includes a collimating lens  18  for converting the excitation light L 1  from the excitation light source  11  into collimated light; an optical-scanning section  19  performing two-dimensional scanning of the collimated light transmitted from the collimating lens  18 ; a pupil-projection lens  20  for forming an intermediate image by focusing the scanned excitation light L 1 ; and an imaging lens  21  for converting the excitation light L 1  of the intermediate image into collimated light. The casing  17  further includes an objective lens  22  for focusing the excitation light L 1  from the imaging lens  21  to re-form an image at a predetermined focal position.  
         [0050]     The optical-scanning section  19  is realized by, for example, so-called proximity galvano mirrors, which are two galvano mirrors  19   a  and  19   b  arranged so as to oppose each other and which are rockable about mutually orthogonal axes.  
         [0051]     The raising-and-lowering mechanism  7  supporting the examination head  6  such that the examination head  6  can be raised and lowered includes a raising-and-lowering slider  25  which can be raised and lowered by a driving device (not shown) in a support stand  24  extending vertically from a base  23 . The driving device can be operated from outside the dark-box main body  2  through remote operation.  
         [0052]     The above-described illumination light source  3  is realized by, for example, an argon laser light source emitting visible light L 3  with a third spectral band B 3  in the vicinity of, for example, 458 nm.  
         [0053]     As shown in  FIG. 1 , the observation window  4  is provided on a tilted surface in the front of the dark-box main body  2 , namely, on the tilted surface constituting part of the wall surface  2   a  of the dark-box main body  2 . Through the observation window  4 , the examination head  6  of the fluoroscopy unit  5 , which is arranged on the other side of the wall surface  2   a  of the dark-box main body  2 , and the specimen A are in the field of view.  
         [0054]     Referring to  FIG. 2 , the observation window  4  blocks the excitation light L 1  with the first spectral band B 1  emitted from the excitation light source  11  of the fluoroscopy unit  5  and the fluorescence L 2  with the second spectral band B 2  emitted from the specimen A, while transmitting the visible light L 3  with the third spectral band B 3  emitted from the illumination light source  3 . In short, the observation window  4  is characterized by transmitting light with wavelengths shorter than 480 nm and blocking light with wavelengths of 480 nm and longer.  
         [0055]     In this embodiment, the dark-box main body  2  further includes a baffle plate  26  arranged between the observation window  4  and the illumination light source  3 . The baffle plate  26  is arranged to block the illumination light source  3  from the observation window  4 , thus preventing the illumination light source  3  from being viewed directly through the observation window  4 .  
         [0056]     A fluoroscopy method using the dark box apparatus for fluoroscopy  1  according to this embodiment, with the above-described structure, will now be described.  
         [0057]     In order to perform fluoroscopy of the specimen A using the dark box apparatus for fluoroscopy  1  according to this embodiment, first the excitation light source  11  of the fluoroscopy unit  5  is turned OFF, the specimen A is immobilized on the stage  8  outside the dark-box main body  2 , and the raising-and-lowering mechanism  7  is operated to roughly position the objective lens  22  of the examination head  6  with respect to the specimen A. In this state, the specimen A, the examination head  6 , the stage  8 , and the raising-and-lowering mechanism  7  are placed in the dark-box main body  2 . The dark-box main body  2  may be constructed so as to enclose the specimen A, the examination head  6 , etc. Alternatively, the dark-box main body  2  may have a door, as described in another embodiment later, so that the examination head  6  and other members are enclosed by closing this door.  
         [0058]     Next, the illumination light source  3  is operated to emit the visible light L 3  with the third spectral band B 3  in the dark-box main body  2 . The visible light L 3  with the third spectral band B 3  is radiated onto the objective lens  22  of the examination head  6  in the dark-box main body  2  and the specimen A opposed to the objective lens  22 . Part of the visible light L 3  with the third spectral band B 3  reflected at the objective lens  22  and the specimen A goes out of the dark-box main body  2  through the observation window  4 .  
         [0059]     Therefore, outside the dark-box main body  2 , the observer can observe the visible light L 3  with the third spectral band B 3  transmitted through the observation window  4  to clearly learn the positional relationship between the objective lens  22  and the specimen A, as well as the state of the specimen A in the dark-box main body  2 .  
         [0060]     Based on this positional relationship between the objective lens  22  and the specimen A observed through the observation window  4 , the observer operates the raising-and-lowering mechanism  7  and the stage  8  through remote operation from outside the dark-box main body  2  to adjust the positional relationship.  
         [0061]     Next, the fluoroscopy unit  5  is operated to emit the excitation light L 1  with the first spectral band B 1  from the excitation light source  11 . The excitation light L 1  is guided into the examination head  6  in the dark-box main body  2  via the optical fiber  10 . The excitation light L 1  guided into the examination head  6  is converted into collimated light by the collimating lens  18 , is two-dimensionally scanned by the optical-scanning section  19 , and is re-focused onto the specimen A through the pupil-projection lens  20 , the imaging lens  21 , and the objective lens  22 .  
         [0062]     When the specimen A is irradiated with the excitation light L 1 , fluorescent material in the specimen A or a fluorescent agent that has been pre-administered to the specimen A is excited to emit the fluorescence L 2  with the second spectral band B 2 . The emitted fluorescence L 2  enters an end surface  10   b  of the optical fiber  10  through the objective lens  22 , the imaging lens  21 , the pupil-projection lens  20 , the optical-scanning section  19 , and the collimating lens  18 .  
         [0063]     Since the end surface  10   b  of the optical fiber  10  is arranged to have a conjugate positional relationship with the focal position of the objective lens  22 , only the fluorescence L 2  generated near the focal position of the objective lens  22 , from among the fluorescence L 2  returning from the specimen A, enters the end surface  10   b  of optical fiber  10  and is returned to the optical unit  9 . The fluorescence L 2  returned to the optical unit  9  is converted into collimated light by the coupling lens  13 , separated from the light path by the dichroic mirror  14 , focused by the focusing lens  15 , and finally detected by the photodetector  16 .  
         [0064]     The excitation light L 1  is two-dimensionally scanned at the focal position of the objective lens  22  through the operation of the optical-scanning section  19 . In this manner, a clear two-dimensional fluorescence image can be acquired by detecting the fluorescence L 2  from each position of the specimen A with the photodetector  16 .  
         [0065]     According to the dark box apparatus for fluoroscopy  1  of this embodiment, the third spectral band B 3  of the visible light L 3  from the illumination light source  3  differs from the first spectral band B 1  of the excitation light L 1  and the second spectral band B 2  of the fluorescence L 2 . Therefore, even if the visible light L 3  is emitted from the illumination light source  3  onto the specimen A during fluoroscopy, the fluorescent material in the specimen A is not excited. Furthermore, even if the visible light L 3  with the third spectral band B 3  reflected at the specimen A enters the detection light path of the fluorescence L 2  through the objective lens  22 , the visible light L 3  cannot be deflected by the dichroic mirror  14 . Thus, the visible light L 3  does not enter the photodetector  16 , and is not therefore detected as noise by the photodetector  16 .  
         [0066]     In short, the visible light L 3  with the third spectral band B 3  from the illumination light source  3  does not interfere with fluoroscopy, and hence can continue to be emitted during fluoroscopy, as well as at a preliminary stage of fluoroscopy. Since the observation window  4  can transmit the visible light L 3  with the third spectral band B 3 , the visible light L 3  with the third spectral band B 3  is likely to enter the dark-box main body  2  through the observation window  4  from outside the dark-box main body  2 . However, since the visible light L 3  with the third spectral band B 3  does not interfere with fluoroscopy as described above, the visible light L 3  does not adversely affect fluoroscopy even if it enters the dark-box main body  2  through the observation window  4 .  
         [0067]     During fluoroscopy, the observer may wish to adjust the positional relationship between the specimen A and the fluoroscopy unit  5  while checking on the monitor (not shown) a fluorescence image acquired with the photodetector  16 . For this purpose, the observer can perform adjustment work while clearly seeing, through the observation window  4 , the specimen A and the examination head  6  which are brightly illuminated with the visible light L 3  with the third spectral band B 3  emitted from the illumination light source  3 .  
         [0068]     Consequently, unlike with the known method, blind adjustment in a darkroom is not required according to this embodiment, and hence an annoying repeated procedure of turning ON and OFF the illuminating light in the darkroom can be avoided.  
         [0069]     In the dark box apparatus for fluoroscopy  1  according to this embodiment, the baffle plate  26  provided in the dark-box main body  2  prevents the visible light L 3  emitted from the illumination light source  3  from directly reaching the observation window  4 . Therefore, the observer is prevented from looking directly at the illumination light source  3 . Because of this, the observer is not too dazzled to see the interior of the dark-box main body  2 , which would occur if the observer looked directly at the illumination light source  3 .  
         [0070]     Furthermore, according to this embodiment, the optical unit  9  including the excitation light source  11  is arranged outside the dark-box main body  2 . For this reason, the temperature in the dark-box main body  2  is prevented from rising due to heat emission of the excitation light source  11 . This is advantageous in preventing the specimen A from becoming dry and maintaining stable examination conditions.  
         [0071]     Although this embodiment has been described by way of the third spectral band B 3 , which is shorter than the first spectral band B 1  of the excitation light L 1  and the second spectral band of the fluorescence L 2 , alternatively, a spectral band B 3 ′ that is longer than the first spectral band B 1  and the second spectral band B 2  may be adopted, as shown in  FIG. 2 . In this case, it is sufficient to set the transmittance characteristic of the observation window  4  to cover a spectral band including the spectral band B 3 ′.  
         [0072]     In addition, the illumination light source  3  may be provided with a filter-switching unit  27  for switching the spectral band B 3  of the visible light L 3  to be emitted.  
         [0073]     When examination is to be performed using the fluoroscopy unit  5  with the wavelength of the excitation light L 1  switched, the filter-switching unit  27  is operated to switch the spectral band B 3  of the visible light L 3  to be emitted by the illumination light source  3 , thereby allowing the wavelength of the excitation light L 1  to be selected more flexibly.  
         [0074]     A dark box apparatus for fluoroscopy  30  according to a second embodiment of the present invention will now be described with reference to  FIG. 3 .  
         [0075]     The same components in this embodiment as those used in the dark box apparatus  1  according to the first embodiment shown in  FIG. 1  are denoted by the same reference numerals, and thus will not be described.  
         [0076]     Referring to  FIG. 3 , the dark box apparatus for fluoroscopy  30  according to this embodiment includes a dark-box main body  31  in place of the dark-box main body  2  of the dark box apparatus for fluoroscopy  1  according to the first embodiment. The dark-box main body  31  is not provided with the observation window  4  in the dark-box main body  2  to completely block extraneous light. Instead, a camera (photography unit)  32  is provided in the dark-box main body  31  and a monitor  33  is provided outside the dark-box main body  31 .  
         [0077]     The camera  32  has a field of view large enough to allow both the objective lens  22  of the fluoroscopy unit  5  and the specimen A to be photographed simultaneously in the dark-box main body  31 . Furthermore, the camera  32  is arranged opposite to the illumination light source  3  on the other side of the baffle plate  26  and is prevented from directly photographing the illumination light source  3 . The camera  32  may be realized by a CMOS camera or a CCD camera. A CMOS camera has low power consumption, and is advantageous in terms of energy efficiency.  
         [0078]     In the dark box apparatus for fluoroscopy  30  according to this embodiment, with the above-described structure, the interior of the dark-box main body  31  can be observed using the camera  32  and the monitor  33 , even during fluoroscopy, with the aid of the illumination light source  3  emitting light L 3  (not limited to visible light in this case) having the third spectral band B 3 , which does not interfere with fluoroscopy. This allows the observer to finely adjust the positional relationship between the fluoroscopy unit  5  and the specimen A during fluoroscopy, in the same manner as in the first embodiment.  
         [0079]     With the dark box apparatus for fluoroscopy  30  according to this embodiment, the dark-box main body  31  may be provided with a plurality of cameras  32 . This allows images from the plurality of cameras  32  to be observed by switching the screen on the single monitor  33 . In this manner, the specimen A can be examined from a plurality of angles. This is advantageous in adjusting the positional relationship between the fluoroscopy unit  5  and the specimen A more accurately and easily.  
         [0080]     Furthermore, in a case where the specimen A is a living organism, various items of information, such as vital information and temperature information, from several sensors (not shown in the figure) attached to the specimen A and the dark-box main body  31  may be simultaneously displayed on the monitor  33 .  
         [0081]     As shown in  FIG. 4 , a dark box apparatus for fluoroscopy  30 ′ where the camera  32  is integrated with the monitor  33  by means of a wall surface  31   a ′ of a dark-box main body  31 ′ or the camera  32  is provided with the monitor  33  in some way may also be employed. In this case, the camera  32  is mounted so as to face the interior of the dark-box main body  311 , whereas the monitor  33  is mounted so as to face the exterior of the dark-box main body  31 ′, namely, opposite to the camera  32 . In this manner, the observer of the monitor  33  can see into the dark-box main body  31 ′ as if he or she were looking into the dark-box main body  2  through the observation window  4  of the dark box apparatus for fluoroscopy  1  according to the first embodiment. Therefore, the observer can perform adjustment of the examination head  6  and the stage  8  through remote operation while intuitively recognizing the movement direction and the amount of movement of the examination head  6  and the stage  8  on the monitor  33 .  
         [0082]     In addition, as shown in  FIG. 4 , the camera  32  provided or integrated with the monitor  33  may be secured on the wall surface  31   a ′ of the dark-box main body  31 ′ with bellows  34 . The position of the camera  32  can be adjusted through deformation of the bellows  34 , and a region to be examined can be adjusted within the deformation range of the bellows  34 .  
         [0083]     A fluoroscopy system  40  according to a third embodiment of the present invention will now be described with reference to  FIG. 5 .  
         [0084]     The same components in this embodiment as those used in the dark box apparatuses  1  and  30  according to the first and second embodiments are denoted by the same reference numerals, and thus will not be described.  
         [0085]     Referring to  FIG. 5 , a fluoroscopy system  40  according to this embodiment includes the above-described fluoroscopy unit  5  and a dark box apparatus for fluoroscopy  41 . As shown in  FIG. 5 , the dark box apparatus for fluoroscopy  41  is provided on a dark-box main body  42  such that a door  43  can be opened and closed with a hinge  44 . The dark-box main body  42  is provided with an open/closed sensor  46  that can detect a detection member  45  on the door  43  when the door  43  is closed.  
         [0086]     Furthermore, an excitation-light control unit  47  is connected to the open/closed sensor  46 . When the door  43  is opened, the open state of the door  43  is detected by the excitation-light control unit  47  and the open/closed sensor  46 . Since the detection member  45  goes out of the detection range of the open/closed sensor  46  at this time, the excitation light source  11  is turned OFF and stops the excitation light L 1  from being emitted.  
         [0087]     In the fluoroscopy system  40  according to this embodiment, with the above-described structure, when the door  43  is closed, the detection member  45  is detected by the open/closed sensor  46  and a signal indicating a closed state is sent to the excitation-light control unit  47 . As a result, the excitation-light control unit  47  allows the excitation light source  11  to emit the excitation light L 1 . In the same manner as with the dark box apparatus for fluoroscopy  1  according to the first embodiment, the positional relationship between the fluoroscopy unit  5  and the specimen A is adjusted through the observation window  4  with the aid of the illumination light source  3  while fluoroscopy of the specimen A is in progress.  
         [0088]     In this state, for the fluoroscopy system  40  according to this embodiment, when the door  43  of the dark-box main body  42  is opened for some reason, the open/closed sensor  46  is actuated to detect that the door  43  is in an open state. As a result, the excitation-light control unit  47  stops the excitation light source  11  from emitting the excitation light L 1 . In this manner, the excitation light L 1  is prevented from leaking out of the dark-box main body  42 . Consequently, fluoroscopy with the door  43  opened, which would cause extraneous light with various spectral bands to enter the dark-box main body  42 , is prevented. Therefore, photographing a fluorescence image with a high degree of noise is avoided.  
         [0089]     In this embodiment, the excitation light source  11  is prevented from emitting the excitation light L 1  depending on the open/closed state of the door  43 . Alternatively, a shutter (not shown in the figure) may be provided in front of the excitation light source  11  and the excitation light L 1  may be turned ON/OFF according to open/close state of the shutter. Furthermore, when the door  43  is opened, the excitation light L 1  may be blocked and the illumination light source  3  may be turned OFF. As a result of the illumination light source  3  being turned OFF while the dark-box main body  42  is observed through the observation window  4 , the observer is informed of an open state of door  43  earlier.  
         [0090]     Furthermore, a timer that is operatively associated with the operation of the open/closed sensor  46  may be provided to record information about the period of time for which the door  43  is open or to display such information on the monitor.  
         [0091]     In this embodiment, the excitation light source  11  is disabled when the door  43  is open. Instead of or in addition to this, an operation control unit  48  connected to the open/closed sensor  46  may be provided, as shown in  FIG. 6 . The operation control unit  48  is connected to, for example, the raising-and-lowering mechanism  7  of the examination head  6  or to the driving device of the stage  8 , so that when the open/closed sensor  46  detects the closed state of the door  43 , the operation speed in a closed state, such as the speed of the raising-and-lowering mechanism  7  in the dark-box main body  42 , is preferably set to lower than the speed in an open state.  
         [0092]     Although the interior of the dark-box main body  42  can be observed through the observation window  4 , the amount of information acquired from the observation window  4  is restricted, and therefore, by setting the operation speed such as the speed of the raising-and-lowering mechanism  7  to a lower value while the door  43  is closed, the risk of damage to the specimen A and to the objective lens  22  due to interference between the specimen A and the objective lens  22  can be reduced.