Patent Publication Number: US-2007097493-A1

Title: Image recording device for microscopy applications

Description:
The present invention relates to an image acquisition unit for microscopic applications. In particular, the present invention relates to an image acquisition unit for microscopic applications, including at least one microscope objective which is mounted an a housing.  
      German Laid-Open Application DE 196 09 288 A1 discloses a compact microscope, especially for routine medical applications. The microscope takes form of a closed housing into which the preparation to be examined is drawn in through an insertion opening. All optical components are mounted within the housing. Alternatively, the microscope is insertable into the standard bay of a computer. All movable components of the microscope are motor-driven and software-controlled by the computer. The preparation can be moved inside tile microscope in two mutually perpendicular directions for selecting the sample details of interest. When the preparation is drawn in, a line sensor generates an overview image of the preparation.  
      US Patent Application No. 2003/0011883 A1 discloses a microscope system. The microscope system includes a stage which is movable in x and y coordinate directions. Also provided is a lens turret which has formed therein a plurality of openings for receiving an objective lens. Moreover, a TV camera having a CCD chip is mounted on the stand of the microscope. The microscope system is additionally provided with a monitor and a control device. The control device controls the electrically driven stage. The position of the stage can be detected by linear encoders. Using a mouse, the user can input a desired position to which the stage will then be moved correspondingly.  
      The known methods used in classical microscopy include the incident light method, transmitted light method, fluorescent light method, phase contrast method, interference contrast method, etc. In the prior art, there are microscopes of different size and design, which are used for different applications. A large number of microscopes are used in different fields of industry. Here, the microscopes are used in quality and process control. Microscopes cannot be used in all processes because of their size and particular design. Furthermore, the microscopes are often sensitive to dusts, gases, liquids, etc., so that these microscopes often have to be used outside the processes to be monitored. Thus, the objects to be examined have to be removed from the process and taken to a different location for examination. Therefore, examination of toxic substances is generally very complex to accomplish. The processes carried out in extremely clean rooms are very difficult to examine, because microscopes have many exterior surfaces and edges, which act as a dirt trap and therefore constitute a source of contamination for the extremely clean rooms. It is also very problematic to monitor a process at a multiple points. When using individual microscopes, it is difficult to perform process-accompanying automatic documentation. Moreover, performing process control in response to the analysis results of an object examination by the microscopes is only possible with increased effort.  
      German Patent Applications DE 102 46 277 A1 and DE 102 46 275 A1 disclose a microscope the stand of which consists of a minimum number of shell parts. In addition, the stand of the microscope is provided with only a focus adjusting knob. Moreover, the microscope is narrow relative to the height of the stand, and the number of control elements is reduced to a minimum. Nevertheless, the microscope has a plurality of exterior surfaces, so that there, is still a risk of dirt accumulations. In addition, its use is limited in various processes because of the microscope stage.  
      It is an object of the present invention to provide an image acquisition unit for microscopic applications, which is versatile and suitable for different examination conditions. Another object is for the image acquisition Un it to be inexpensive and easy to service and maintain.  
      This objective is achieved by an image acquisition unit for microscopic applications, having the features of Claim  1 .  
      It is advantageous if the housing is formed by a plurality of individual separate modules, said modules including at least an electronic module, a camera module, an illumination module, a focusing module, and a filter module.  
      The housing formed by a plurality of modules provides a housing that is rectangular in shape and dust-tight. The housing formed by a plurality of modules is provided with at least one threaded blind hole for attachment of a holder. The housing is provided with at least one connection for power supply and/or data transmission. An electrical connection is provided for power supply to the image acquisition unit. The electrical connection ensures power supply for the entire image acquisition unit. Moreover, an electrical connection is provided for the control of the image acquisition unit and of the image transmission from the image acquisition unit.  
      The electronic module includes control and analysis electronics. The control and analysis electronics are provided for the camera module, the illumination module and the focusing module.  
      The camera module includes a digital camera and adaptation optics for adaptation to the filter module. The digital camera is formed by at least one two-dimensional CCD array.  
      The illumination module includes a light source and adaptation optics for adaptation to the filter module. The light source is a high-power LED, the high-power LEDs being cooled via the housing formed by the plurality of individual modules.  
      The focusing module includes a focusing mimic and adaptation optics for adaptation to the filter module. The focusing mimic or focusing unit is designed as a mechanical, piezomechanical, electrical or pneumatic unlit, or as an ultrasonic motor the focusing mimic allowing the microscope objective to be moved forward and backward.  
      The filter module includes a beam splitter cube or a conventional beam splitter. Said beam splitter cube or beam splitter is replaceable. When using the image acquisition unit in fluorescence applications, the beam splitter cube or beam splitter separates the excitation light from the emission light.  
      At least one exterior surface of the plurality of individual separate modules is formed from a highly thermally conductive material, the blind holes in the at least one exterior surface being likewise provided with a highly thermally conductive holder.  
      Further advantageous embodiments of the present invention will be apparent from the dependent claims.  
    
    
      The subject matter of the present invention is schematically illustrated in the drawings and will be described below with reference to the Figures, in which:  
       FIG. 1  is a schematic perspective view of the image acquisition unit formed by the plurality of modules;  
       FIG. 2  is a schematic perspective view of the image acquisition unit, the plurality of modules being in the assembled condition, forming a single housing;  
       FIG. 3  is a schematic view showing the image acquisition unit in operative position with an object to be examined;  
       FIG. 4  is a perspective schematic view of the image acquisition unit, illustrating the internal construction of the individual modules; and  
       FIG. 5  is a schematic view of the internal construction of the image acquisition unit. 
    
    
       FIG. 1  is a schematic perspective view of image acquisition unit  1 , which is formed by the plurality of modules  2 ,  4 ,  6 ,  8  and  10 . Housing  9  (see  FIG. 2 ) of image acquisition unit  1  is formed by a plurality of individual separate modules. A first module is an electronic module  2 . A second module is a camera module  4 . A third module is an illumination module  6 . A fourth module is a focusing module  8 . A fifth module is a filter module  10 . Image acquisition unit  1  further includes at least one objective lens  7 . Objective lens  7  is attached to focusing module  8 . Illumination module  6  and/or filter module  10  are each provided with a threaded blind hole  12 . Blind hole  12  is used for attachment of a holder  13  (see  FIG. 3 ). Electronic module  2  is provided with an electrical connection  5  for power supply to image acquisition unit  1 . Image acquisition unit  1  can be supplied with power by a storage battery, by solar cells and/or inductive energy input. Moreover, electronic module  2  is provided with an electrical connection  11  for the control of image acquisition unit  1  and of the image transmission from image acquisition unit  1 . Another electrical connection is provided for the control of the image acquisition unit in the form of an antenna  15  for radio transmission. Objective lens  7  or focusing module  8  may additionally be provided with an adjustment wheel  16  which allows objective lens  7  to be moved forward and backward.  
       FIG. 2  is a schematic perspective view of image acquisition unit  1 , the plurality of modules  2 ,  4 ,  6 ,  8  and  10  being in the assembled condition, forming a single housing  9 . The mechanical design of the individual modules  2 ,  4 ,  6 ,  8  and  10  makes it possible to achieve dust-tightness.  
       FIG. 3  is a schematic view showing image acquisition unit  1  in operative position with an object  20  to be examined. In the exemplary embodiment shown, image acquisition unit  1  examines objects  20  which are moved on a conveyor belt  21  past at least one objective lens  7  of image acquisition unit  1 . In the process, focusing module  8  (see  FIG. 1 ) focuses objective lens  7  of image acquisition unit  1  sharply onto the objects  20  to be examined, the focusing being accomplished either mechanically or electronically by autofocusing.  
      Image acquisition unit  1  is attached, via a holding plate  22 , to an external holder (not shown) by screw  23  and one of blind holes  12  (see  FIG. 1 ). Power supply to image acquisition unit  1  is via electrical connection  5 . The control of image acquisition unit  1  and the image transmission from image acquisition unit  1  is via electrical connection  11 . Electrical connection  5  and electrical connection  11  are each connected to a suitable electric line  24 . Apart from the fixed physical connection via electric lines  24 , it is also possible to provide a radio link via receiving/transmitting antenna  15 .  
       FIG. 4  is a perspective schematic view of image acquisition unit  1 , illustrating the internal construction of the individual modules  2 ,  4 ,  6 ,  8  and  10 . Electronic module  2  includes at least one control board  30 , which is used for controlling camera module  4  (image data and control, such as triggering, frame rate, white balance, shading correction, etc.). Control board  30  includes various microcontrollers, preferably FPGAs, which are responsible for the various control tasks. The control tasks relate, for example, to camera module  4 , illumination module  6 , focusing module  8 , and the self-test, etc.  
      As disclosed earlier, control board  30  is disposed in electronic module  2  and connected to the other modules  4 ,  6 ,  8  and  10  via cable  31  and plug connector  32 . Modules  2 ,  4 ,  6 ,  8  and  10  are reversibly interconnected by plug connectors  32 .  
      Camera module  4  contains camera chip  33  which includes, for example, at least one CCD chip. Moreover, camera module  4  is provided with an optical system  34  which, on the one hand, is adapted to filter module  10  and which, on the other hand, suitably directs light flux  40  from object  20  to camera chip  33 . There are different types of camera chips  33  that may be used, such as those for high sensitivity or high image acquisition speed. It is then necessary to adapt the electronics in electronic module  2 . If the electronics is suitably designed, the adaptation can be done via a firmware update, so that camera module  4  can be replaced individually while all other modules  2 ,  6 ,  8  and  10  of image acquisition unit  1  may continue in use.  
      Illumination module  6  accommodates at least one light source  35 , which may be in the form of LEDs. When using LEDs, very high intensity LEDs are used which have a high light output and are located on a cooling plate  36  at the outer wall  90  of illumination module  6 . This allows heat to be efficiently dissipated to the outside. Illumination module  6  further accommodates an optical adaptation unit  37 , which ensures that the light flux of illumination module  6  is suitably adapted to the illumination requirements of image acquisition unit  1 . LED-type light source  35  can easily be pulsed and is therefore well-suited for stroboscopic effects. The time point of image acquisition can be precisely set using suitable trigger signals (shutter effect). Moreover, it is possible to dim the illumination of the LED. High-power LEDs are available for different wavelengths Thus, in cases where image acquisition unit  1  is used in fluorescence analysis, the required excitation wavelength can be provided by a suitably adapted LED or a suitably adapted illumination module.  
      Filter module  10  contains a beam splitter cube  45  which, in the fluorescence case, is adapted to the desired excitation and emission wavelengths. In the normal case of incident light, beam splitter cube  45  consists only of a beam splitter that directs illuminating light  41  onto object  20  and which directs light  40  emerging or reflected from object  20  to camera module  4 . When using image acquisition unit  1  in fluorescence applications, beam splitter cube  45  has associated therewith an excitation filter  42  and an emission filter  44 .  
      Focusing module  8  adapts the light flux to objective lens  7  via a suitable optical system  46 . In this connection, focusing module  8  can move objective lens  7  in a direction parallel to its optical axis  47 , and thus sharply focus the image of object  20 .  
      Focusing module  8  may further include a mechanical adjusting unit  48 , which may be adjusted by turning a screw. An electronically controlled focus is also possible. The focus position may be adjusted, for example, by a piezoelectric element (not shown). In the process, control is performed via electronic module  2  or via ultrasonic motors. Focus analysis can be performed externally using image analysis, or internally in image acquisition unit  1  using suitable and fast electronic methods which, together with a software which is permanently integrated in the camera using EEPROM or similar devices and can be adapted to different applications via a firmware update.  
       FIG. 5  is a schematic view of the internal construction of image acquisition unit  1 , illustrating the optical signal flow in a manner similar to a circuit diagram. Light is directed from light source  35  through optical adaptation unit  37  to beam splitter cube  45 . The optical properties of the beam splitter cube  45  may also be provided by a dichroic beam splitter. In the fluorescence case, beam splitter cube  45  may further have associated therewith the excitation filter  43  (in the case of incident light, there is no excitation filter) and emission filter  44 .  
      Light beam  41  is deflected by beam splitter or beam splitter cube  45  toward objective lens  7 , whereby it passes through adaptation optics  46 . Focusing is done by adjusting unit  48 . In the case of non-mechanical focus adjustment, adjusting unit  48  of focusing module  8  is controlled via connection  54  of control board  30 . Light  40  emerging or reflected from object  7  passes through beam splitter or beam splitter cube  45  toward camera chip  33  of the digital camera. In fluorescence applications, light  40  passes through emission filter  44 . Light  40  is projected through an optical system  34  onto camera chip  33 . Camera chip  33  of camera module  4  is connected to control board  30  via an electric line  55 . Electric line  55  carries the image signals from camera chip  33  to control board  30 . Power supply to image acquisition unit  1  is via electrical connection  5 . The control of image acquisition unit  1  and the image transmission from the image acquisition unit is via electrical connection  11 , An electric line  58  connects the connection  54  of control board  30  to adjusting unit  48 . Connection  56  of control board  30  is connected to light source  35  by an electric line  59 .