Abstract:
Exchanging data between an Atomic Force Microscopy (AFM) measuring device and an external controlling device using a wireless link. The wireless link replaces cables leading to the AFM measuring device and thereby mitigates mechanical noise vibrations. The controlling device can be an AFM controller, a PC workstation, a keyboard or a pointing device. A power supply and cables to provide power to the measuring device can be replaced with a battery power source to further mitigate mechanical noise. The AFM measuring device can reside in a vibration isolation chamber along with the power source and AFM controller to further isolate noise.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Atomic Force Microscopy (AFM) is a high-resolution imaging technique that can resolve features as small as an atomic lattice in real space. It allows researchers to observe and manipulate molecular and atomic level features. 
         [0002]    AFM measurement requires a vibration free environment as every vibration is amplified, thereby leading to a distorted result set. Several techniques exist in order to avoid any type of resonance of the complete AFM setup. An example of such a technique is from Agilent Technologies, Inc. of Santa Clara, Calif. Agilent Technologies sells a vibration isolation chamber as an optional accessory with an AFM measuring device (known as a microscope). The chamber combines acoustic isolation and delivers less than 1 Hz noise resonance. The vibration isolation chamber is compact and permits atomic-resolution imaging in noisy environments. 
         [0003]      FIG. 1  is a diagrammatic representation of an AFM laboratory setup  100 . The laboratory setup  100  comprises a vibration isolation chamber  101 . An AFM measuring device  105  resides within the isolation chamber  101 . 
         [0004]    The AFM measuring device  105  is controlled by an external controlling device  160 . The external controlling device  160  refers to communication equipment that controls the AFM measuring device  105 . The external controlling device typically resides outside the chamber  101 . The external controlling device  160  can comprise a Personal Computer (PC) workstation  141  or a computer input device  149  or both. The computer input device  149  can be a pointing device or a keyboard. The external controlling device can also comprise an AFM controller  109  with an attached pointing device or a keyboard (not shown). The external controlling device  160  can also combine the functions of the PC workstation  141  and the AFM controller  109 . 
         [0005]    In  FIG. 1 , the AFM controller  109  interfaces with the measuring device  105  at a high interrupt handling rate. The workstation  141  enables an operator to interact with the AFM controller  109  through a user-friendly graphical user interface (not shown). The workstation  141  is connected to the AFM controller by an electronic cable  139 . 
         [0006]    Also depicted in  FIG. 1  is a power supply  143  connected to the measuring device  105 . The power supply can be integrated into the external controlling device  160 , in this instance the AFM controller  109 , but is drawn in  FIG. 1  as two separate units. The power supply  143  and the external controlling device  160  both reside outside the isolation chamber  101  and are connected to the measuring device  105  through cables  119 . The cables  119  pass through a side-window  135  of the chamber  101 . 
         [0007]    The cables  119  comprise serial and data cables  133  for bi-directional data signal transfer, and a power cable  131 . The parallel cable can be, for example a DB44 data cable or a DB9 high voltage cable. The data signals transferred between the controller  109  and the device  105  comprise signals to control the AFM laser, to position the cantilever tip, and signals that represent measurement results. The cables  119  are bulky and relatively stiff due their large cross sectional area. 
         [0008]    When performing high-resolution measurements (e.g. at the Angstrom level (0.1 nm resolution)), the minutest of vibrations can induce errors in the measured results. 
         [0009]    The cables  119  are subject to mechanical vibration induced by the environment outside the isolation chamber  101 . Noise induced by footsteps, by cooling fans of electronic equipment (the power supply  143  or the workstation  141 ) in the proximity of the chamber  101 , or by an air-conditioning unit to cool the laboratory are examples of mechanical noise induced onto the cables  119 . Cognizant of the effects of mechanical noise, the operator will position the AFM controller  109  in the near vicinity of isolation chamber  101  to keep the cables  119  to a minimum length to mitigate mechanical noise through the cables  119 . 
         [0010]    Presently two solutions exist to reduce the mechanical noise entering the isolation chamber  101  through the cables  119 . These include: i) removing the insulation jacket of the cables  119  to allow more flexibility; and ii) replacing the data cable  133  with a flexible flat ribbon cable to reduce the stiffness of the data cable  133 . 
         [0011]    However, the two solutions only partially solve the mechanical noise problem and have disadvantages associated with them. Cutting the insulation jacket of the cables  119  and leaving them exposed does not present a professional solution. Removing the insulation jacked of the data cable  133  can have unwanted electro-magnetic interference (EMI) consequences and induce error in the data signals. Flexible flat ribbon cables do not have a robust EMI shield and would not offer a viable solution. 
         [0012]    An alternative option of replacing the data cable  133  with an infrared (IR) link has been investigated. Unfortunately, this solution was not successful. The infrared link between the AFM measuring device  105  and the external controlling device  160  does not enable the two devices to communicate effectively. As an IR link requires a direct and clear path between the remote sensor head and the measuring device  109 , this option could not be implemented efficaciously. 
         [0013]    Another concern common to layout of the laboratory setup  100  is an arduous alignment process. In the laboratory setup  100 , the external controlling device  160  and the visual verification of the AFM measuring device  109  cantilever tip do not facilitate an efficient working environment. As mentioned above, the operator of the AFM measuring device  105  will position the AFM controller  109  in the immediate vicinity of the isolation chamber  101  to keep the cables  119  to a minimum length to mitigate mechanical noise through the cables  119 . Often, the PC workstation  141  is placed in a different location. 
         [0014]    This inconveniences the operator by having to going back and forth between workstation  141  and the chamber  101  in order to adjust the AFM measuring device  105  head and move the cantilever tip to the region of interest. The present setup adds a disproportionate setup time to an AFM measurement. 
         [0015]    Contemporary laboratories are designed to allow operators to work in a distributed environment. This helps reduce cost by not having the workstation  141  dedicated to the AFM measurement system  111 . Having a distributed environment would allow the AFM controller  109  to be accessed by multiple workstations, thereby allowing the AFM measuring device  101  to be centrally located but remotely accessible to multiple scientists. 
         [0016]    Accordingly, a need exists to further reduce the noise induced onto the AFM measuring device  105 , to improve the ease in which the AFM measuring device  105  can be controlled, and to reduce the cost associated with accessing the AFM device  105  remotely. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a diagrammatic representation of an AFM laboratory setup of the prior art; 
           [0018]      FIGS. 2A-B  describe an AFM measuring device and an external controlling device communicating through a wireless link; 
           [0019]      FIG. 3  describes the AFM measuring device and an external controlling device communicating through a wireless link, and utilizing a battery power source; and 
           [0020]      FIG. 4  is a flow chart showing steps for setting up the AFM test apparatuses of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    The solutions described herewith reduce the mechanical vibration noise (“mechanical noise”) by replacing the stiff parallel cable  133  with a wireless link between the external controlling device  160  and the AFM measuring device  105 . In addition to this, the power supply  143  and power cables  131  can be replaced with a battery power source. The individual solutions can also be implemented independently. 
         [0022]    By implementing a wireless link, a concomitant benefit of improving the ease of use is addressed. 
         [0023]      FIGS. 2A and 2B  are diagrams illustrating an AFM laboratory setup  200  employing the solutions described above. 
         [0024]      FIG. 2A  describes the isolation chamber  101  housing the AFM measuring device  105  and a wireless transceiver  227 . The wireless transceiver  227  can be integrated into the AFM measuring device  105  or remain as a separate unit. 
         [0025]    The wireless transceiver  227  is connected to an antenna  231  fitted on the interior or exterior of the chamber  101 . When fitted inside the chamber, the mechanical isolation can be maximized. When the antenna is located outside the chamber, the cables can pass through the side-window  135  ( FIG. 1 ). 
         [0026]      FIG. 2A  depicts an external controlling device  260  which communicates with the AFM measuring device  105 . The external controlling device  260  comprises the PC workstation  141 , a computer input device  249 , and an AFM controller  209 . 
         [0027]    The PC workstation  141  communicates with the AFM controller  209  through the electronic cable  139 . The AFM controller  209  is wireless enabled. The AFM controller  209  is similar to the AFM controller  109  in  FIG. 1  and has a wireless transceiver  229  either integrated into its design or as a stand-alone unit. The AFM measuring device  105  is linked to the AFM controller  209  through a first wireless transmission link  221 . 
         [0028]    The wireless link  221  enables effective communication between the AFM measuring device  105  and the external controlling device  260  as wireless protocol allows for fast interrupt handling requirements of the AFM measuring device  105 . Furthermore, the compact, power sensitive, and low noise characteristics of the wireless transmitter  227 , enable the transmitter  227  to be incorporated into the AFM chamber  101  or incorporated into the AFM measuring device  105 . 
         [0029]      FIG. 2A  describes a power management setup similar to that of  FIG. 1 . The power supply  143  is external to the AFM chamber and is connected to the AFM measuring device  105  through a cable  131 . 
         [0030]    The AFM setup  200  can be used when measuring both non-magnetic and magnetic sensitive material measurement. Wireless transmission link protocols for the wireless link  221  can be short range high speed communications, for example Wireless Local Area Network, Ultra Wideband or Bluetooth. These wireless protocol can offer optimal mechanical isolation. 
         [0031]      FIG. 2B  describes an AFM laboratory setup  201  similar to that of  FIG. 2A . The external controlling device  260  comprises two PC workstations  241  and the AFM controller  209 . A second wireless link  251  to pass signals within the components that comprise the external controlling device  260 , in this instance between the AFM controller  209  and two workstations  241 . The AFM controller  209  is fitted with a second wireless transmitter  233  to access the second wireless link  251 . 
         [0032]    The two workstations  241  can share control and access of the AFM measuring device  105  through the wireless AFM controller  209 . The second wireless link  251  can be the same or different protocol as the wireless link  221  (between the AFM controller  209  and the AFM measuring device  105 ). When the protocol used in the wireless link  251  and  221  are the same, the PC Workstation  241  can directly control the AFM measuring device  105 . This is particularly useful for a coarse grain experiment setup. 
         [0033]      FIG. 2B  also describes a battery power source  243  within the chamber  101 . The battery power source  243  replaces the power supply  143  and power cable  131  of  FIG. 2A . The battery power source  251  supplies the requisite DC power to the measuring device  105 . 
         [0034]    The replacement of the data cables  133  by the wireless link  221  and the power supply and cable  131  with the battery power source  243  mitigates mechanical noise. 
         [0035]      FIG. 3  describes yet another solution to mitigate mechanical noise. In the laboratory setup  300  of  FIG. 3 , the AFM measuring device  105 , the AFM controller  209  and the power supply  243  fit within the AFM chamber  101 . The AFM controller  209  is part of the AFM measuring device  105 . 
         [0036]    The external controlling device  260  comprises the two PC workstations  241  and the computer input device  249 . The wireless link  221  connects the AFM controller  209  and the external controlling device  260 , in this instance, the workstations  241  and the computer input device  249 . The battery power source  243  supplies the requisite DC power to the measuring device  105  and the AFM controller  209 . 
         [0037]    With the solutions offered in  FIGS. 2A-B  and  3 , the concern of improving the ease of use is also addressed. 
         [0038]    With the wireless links  221  and  251 , the operator can maneuver the PC workstation  241  to within a safe distance of the opening of the chamber  101  to visually position the cantilever tip of the measuring device  105 . 
         [0039]    In a distributed PC network of  FIG. 2B  and  FIG. 3 , a portable PC workstation (from one of the PC workstations  241 ) can be used to position the cantilever tip of the AFM measuring device  105 . 
         [0040]      FIGS. 2A and 3  also describe a secondary wireless setup between the computer input device  249  and the PC workstation  241 . Examples of a computer input device are a keyboard, a pointing device, or a joystick. The computer input device  249  can be used as the external controlling device  260  to aid the operator to position the cantilever tip of the measuring device  105 . The operator can take computer input device  249  to within a safe distance of the opening of the chamber  101  to visually position the cantilever tip of the measuring device  105 . The secondary wireless setup can be a Bluetooth connection, an Ultra Wideband connection, or another short range wireless air interface. For example, the external controlling device  260  can be a regular cellular phone where the keyboard is assigned as remote control functionality. The external controlling device  260  can also be a wireless joystick. 
         [0041]      FIG. 4  is a flow chart showing steps for setting up the AFM test apparatuses of the present invention. Block  410  describes positioning the surface to be imaged under the cantilever tip of the AFM measuring device  105  using an AFM setup of  FIG. 2A ,  2 B or  3 . 
         [0042]    Block  420  describes establishing the first wireless link  221  between the AFM measuring device  105  and the external controlling device  260  by powering on the respective devices. The measuring device can be powered by a battery power source. 
         [0043]    Block  430  describes establishing a second wireless link  251  and a secondary wireless link if necessarily to provide a communication link to equipment to control the AFM measuring device  105 . 
         [0044]    Block  440  describes using a computer pointing device  249  or the PC workstation  241  to position the cantilever tip onto the area to be scanned. 
         [0045]    Block  450  describes finalizing the setup, closing the isolation chamber door and commence the AFM scanning. 
         [0046]    While the embodiments described above constitute exemplary embodiments of the invention, it should be recognized that the invention can be varied in numerous ways without departing from the scope thereof. It should be understood that the invention is only defined by the following claims.