Patent Application
20090241648
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.
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.
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.
In
Also depicted in
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
By implementing a wireless link, a concomitant benefit of improving the ease of use is addressed.
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 (
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
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.
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.
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.
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.
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.
With the solutions offered in
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.
In a distributed PC network of
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.
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.
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.
Block 450 describes finalizing the setup, closing the isolation chamber door and commence the AFM scanning.
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.
