Abstract:
This invention relates to a remote control system which through gear motors coupled to the scanning electron microscope (SEM) manual control knobs readily permits remote adjustments as necessary.

Description:
The U.S. Government has rights in this invention as provided for under the terms of a contract with the U.S. Department of Energy. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a remote control system for use with a scanning electron microscope(SEM) to adjust aperture and gun alignment. 
     BACKGROUND OF THE INVENTION 
     In the past, scanning electron microscopes have used manual knob controls for adjusting the gun alignment as well as the aperture. Typically, electron microscopes disclosed in U.S. Pat. Nos. 5,864,138; 5,510,615 and 5,455,420 show manual knobs for adjustment mechanisms on electron microscopes. The European Patent No. 0510618A1 of Oct. 28, 1992, provides a remote control system for moving samples and also means for preventing leakage of x-rays and other radiation, but does not provide a remote system which can be attached directly to a manual control for operating remotely. 
     U.S. Pat. No. 4,807,966 shows a system for remote controlling of a sighting mechanism in an optical system. The motor control mechanism is built into the system. In general, remote control mechanisms are used in optical systems of various types such as illustrated in U.S. Pat. No. 5,836,694. The problem of adapting typical electron microscopes with manual systems so that they can be remotely controlled is not shown in the art. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is an object of this invention to provide an electron microscope remote control system for the gun alignment and aperture which requires no internal modification of the typical Scanning Electron Microscope(SEM). 
     Another object of this invention is to provide remote control equipment for a SEM which is added to the exterior of the SEM so as to avoid any leakage of any radiation which might be caused by structural modifications of the SEM. 
     A further object of this invention is to provide a remote control for an electron microscope aperture and gun alignment which provides a high degree of safety and which can accomplish coarse or fine adjustment at a remote station. 
     Still a further object of this invention is to provide a remote control mechanism for the gun alignment and aperture which provides minimum backlash and allows for misalignment during adjustment. 
     Yet another object of this invention is to provide individual readouts for each adjustment motor and selection for each motor individually as well as means for controlling the speed of each motor adjustment means. 
     Still a further object of this invention is to provide a display and control panel for the remote system for the gun alignment and aperture which allows the operator to quickly make adjustment changes. 
     Another object of this invention is to provide a remote control system for the gun alignment and aperture that may be easily applied to a standard manual system of an electron microscope as well as easily removed therefrom as desired. 
     In summary, this invention relates to a remote control system for the gun alignment and aperture, which through gear motors coupled to the SEM manual control knobs, readily permits remote adjustments as necessary. This can be used on any commercially available SEM that adjusts the aperture and gun alignment in this manner. 
     These and other objects of the present invention will be apparent from the following description including the following drawings which are identified as follows: 
    
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS 
     FIG. 1 is a schematic perspective view with portions shown in phantom lines which are subsequently shown in details in FIGS. 2,  3 ,  4 ,  5  and  6 ; 
     FIG. 2 is a fragmentary side elevational view with portions broken away of the gun alignment adjustment mechanism; 
     FIG. 3 is a top plan view with portions broken away and with portions shown with hidden lines of the mechanism shown in FIG. 2; 
     FIG. 4 is a top plan view of the aperture remote control in-and-out and side-to-side adjustment mechanism with portions shown in hidden lines; 
     FIG. 5 is a side elevational view of the aperture remote control mechanism shown in FIG. 4; 
     FIG. 6 is the right end elevational view of the aperture remote control mechanism shown in FIG. 4 with portions shown in phantom lines; 
     FIG. 7 is an enlarged front elevational view of the display and control panel of the display control panel box shown to the right in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows schematically a portion of a SEM M. The remote system R includes a remote display and control panel box B with a display and control panel C. Electrical leads  2 ,  4 ,  6 ,  8  and  10  run from the remote display and control panel box B to a first motor drive unit A adapted to be mounted on the SEM M and a second motor drive unit G also adapted to be mounted on the SEM M for purposes hereinafter disclosed. 
     In FIG. 1, leads  2 ,  4 ,  6 ,  8  and  10  respectively run to drive motors  12 ,  14 ,  16 ,  18  and  20  as will be hereinafter described. 
     FIGS.  2  and  3   
     Referring now to FIGS. 2 and 3, the gun adjustment second motor drive unit G is shown mounted at the top of the SEM M. A collar  22  surrounds the electron gun  24  to which a power line  26  leads. Mounting pins  28 ,  30  and  32  secure an upper ring plate  34  to the lower ring plate  58 . Drive motors  16 ,  18  and  20  are mounted on the upper ring plate  34 . Motor drive shafts  36 ,  38  and  40  (not shown) each includes a bellows coupling such as  42  and  44  shown in FIG.  2 . The bellows couplings are to correct for misalignment and backlash when a motor is driven. The motor drive shafts  36 ,  38  and  40  also include splined cams  46 ,  48  and  50  which operate against limit switches  52 ,  54  and  56 . The limit switches  52 ,  54  and  56  may be bypassed by electrical controls (not shown). A lower ring plate  58  is mounted and secured to collar  22  by means of set screws S. Splined drive nuts N replace existing hand knobs and engage existing studs mounted on SEM M. Motor drive shafts  36 ,  38  and  40  couple to the splined drive nuts N by means of splined cams  46 ,  48  and  50 . When rotated, the splined drive nuts N push against collar  22 . Existing springs such as  60  and  62  press against the collar  22  and SEM M. Adjustment of the electron gun  24  will be about the axis X shown in FIG. 3 as controlled by the drive motors  16 ,  18  and  20  which operate on a  3  point basis to shift the gun  24  in the desired direction as needed depending upon which of the motors  16 ,  18  and  20  is driven. 
     FIGS.  4 ,  5  and  6   
     In FIGS. 4,  5  and  6 , a motor drive unit A is provided for adjusting the aperture alignment of the SEM M. An aperture alignment mechanism  64  extends from the aperture (not shown) in the SEM M outwardly to a manual control knob  66  for controlling the in-and-out movement of the aperture. A side-to-side knob  68 , as best shown in FIG. 4, controls side-to-side movement of the aperture (not shown). The knobs  66  and  68  are mounted on shafts  70  and  72  which are connected with the aperture alignment mechanism  64 . 
     A clamp  74  secures a bracket. 76  to the aperture alignment mechanism  64 . Secured to the bracket  76  is a linear slide  78  the movable portion of which is attached to connecting arm  80 . Connecting arm  80  is attached to linear slide  81  and is connected to a lateral extension arm  82 . The extension arm  82  supports a drive motor  12  which has a drive shaft  86  secured to the shaft  87  extending from the knob  66  for in-and-out operation of the aperture (not shown). A bellows coupling  88  is mounted between the drive shaft  86  and shaft  87  to prevent backlash and allow for misalignment. A limit switch  90  mounted on the bracket  76  limits the travel of the drive motor  12 . A limit switch  92  limits the travel of the motor  14  mounted on the linear slide  93  which is mounted on the bracket  100  which is attached to bracket  76 . 
     The motor  14  has a drive shaft  102  which includes a bellows coupling  104 . Bellows coupling  104  is attached to shaft  105  of right-angle gear box  106 . When the motor  14  is activated, the drive shaft  102  drives the gears (not shown) in the right-angle gear box  106  to drive the shaft  107  which is attached to knob  68  to cause side-to-side motion to the aperture alignment mechanism  64  which in turn causes the aperture (not shown) to move side-to-side. 
     FIG.  7   
     In FIG. 7, the display and control panel C includes a power on/off switch  109 , a motor selector switch  110 , a jog left push button  112 , a jog right push button  114 , a motor speed knob  116 , an Off/Spd/Jog switch  118 , a jog left speed knob  120 , and a jog right speed knob  122 . Aperture movement displays  126  and  128  are located on the right side of control panel C. Gun adjustment displays  130 ,  132  and  134  are located on the left side of the control panel C. As will be noted, printed above motor selector switch  110 , there are position numbers  1 ,  2 ,  3 ,  4  and  5 . These position numbers  1 ,  2 ,  3 ,  4  and  5  relate to gun alignment motors  16 ,  18  and  20  and aperture adjustment motors  12  and  14 . Positioning motor selector switch  110  on position number  1 , for example, allows motor  16  to be activated. Similarly positioning motor selector switch  110  on position number  4 , for example, allows motor  12  to be activated. Thus, selected positioning of motor selector switch  110 , activates the desired motor of motors  12 ,  14 ,  16 ,  18  and  20 . 
     It is to be noted that, aperture movement displays  126  and  128  and gun adjustment displays  130 ,  132  and  134  have printed above them numbers  1 ,  2 ,  3 ,  4  and  5  which correspond to the numbers  1 ,  2 ,  3 ,  4  and  5  pointed above motor selector switch  110 . Thus a visual readout of a motor position can be readily determined by the indicia showing up on the display as determined by the position of the motor selector switch  110 . 
     In Operation 
     In operation, any one of the motors  12 ,  14 ,  16 ,  18  and  20  can be operated once the power switch  109  is turned on. To adjust a particular motor, e.g., motor  18 , selector switch  110  is placed in position  2 . For coarse adjustment the Off/Spd/Jog switch  118  is placed in the Spd position. The speed knob  116  is then rotated either clockwise or counter-clockwise from the midpoint. The motor  18  begins moving and the speed is increased as speed knob  116  is rotated farther. The relative distance traveled is shown on display  132 . If fine adjustment is desired, the Off/Spd/Job switch  118  is placed in the Jog position. The JL  120  and JR  122  speed knobs are set at the desired speed. Then the L  112  or R  114  pushbuttons are depressed to achieve either clockwise or counter-clockwise rotation. Again, the relative distance traveled is shown on display  132 . 
     It will now be obvious that the control of the aperture and the gun can be done remotely through the motor drives which operate through the remote display and control panel box B. 
     While this invention has been described as having preferred design, it is understood that it is capable of further modification, uses and/or adaptations following in general the principle of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains, and as may be applied to the essential features set forth, and fall within the scope of the invention or the limits of the appended claims.