# US 7,607,343 B2 · System for nano position sensing in scanning probe microscopes using an estimator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,607,343 B2 - Document ID: US7607343B2 - Status: Granted - Kind: B2 - Application number: 11/428,176 - Filed: 2006-06-30 - Published: 2008-01-03 - Granted: 2009-10-27 - Earliest claimed: 2006-06-30 - Assignees: Agilent Technologies, Inc. - Inventors: Daniel Y Abramovitch - Web page: https://patentgrep.com/patent/US7607343B2 ## CPC - G01Q 20/02: by optical means - G01Q 10/04: Fine scanning or positioning - G01Q 10/065: {Feedback mechanisms, i.e. wherein the signal for driving the probe is modified by a signal coming from the probe itself} - G01Q: SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM] ## Abstract In accordance with the invention, an estimator is used in the controller portion of a scanning probe microscope to provide precise position estimates of the probe tip which is controlled in the vertical direction by a microelectromechanical system (MEMS) actuator. The precise position estimates typically enhance the ability of the scanning probe microscope to follow the surface and typically provide improved measurements of the surface topography. ## Claims ### Claim 1 A scanning probe microscope system comprising: a microelectromechanical system actuator operable to move a flexible cantilever mechanically coupled to a probe tip; an optical detector optically coupled to said flexible cantilever; a controller, said controller electrically coupled to said microelectromechanical system actuator and electrically coupled to said optical detector; and an estimator having an estimator feedback gain, said estimator electrically coupled to said optical detector and electrically coupled to said controller where said estimator is operable to receive an error signal from said optical detector and operable to use said error signal and said estimator feedback gain to generate a state estimate, said state estimate output to said controller, said controller operable to provide a control signal to said microelectromechanical system actuator to maintain a deflection of said flexible cantilever at an approximately constant value, wherein said control signal depends on said state estimate. ### Claim 2 (depends on 1) The system of claim 1 wherein said estimator predicts a future value of said state estimate. ### Claim 3 The system of 1 wherein said estimator is current. ### Claim 4 (depends on 1) The system of claim 1 wherein said estimator is a discrete time estimator. ### Claim 5 (depends on 1) The system of claim 1 wherein said estimator is a higher bandwidth estimator. ### Claim 6 (depends on 1) The system of claim 1 wherein said estimator feedback gain is selected by the method of pole placement. ### Claim 7 (depends on 1) The system of claim 1 wherein said estimator feedback gain is selected by the method of H∞ design. ### Claim 8 (depends on 1) The system of claim 1 wherein said estimator feedback gain is selected by the method of mixed H2/H∞ design. ### Claim 9 (depends on 1) The system of claim 1 wherein the estimator feedback gain is selected by use of a Kalman filter. ### Claim 10 (depends on 9) The system of claim 9 wherein said Kalman filter is a steady state Kalman filter. ### Claim 11 (depends on 1) The system of claim 1 wherein said estimator is operable to generate a surface estimate. ### Claim 12 (depends on 11) The system of claim 11 wherein there is no direct feed through from said control input to said surface estimate. ### Claim 13 A scanning probe microscope system comprising: a microelectromechanical system actuator operable to move a flexible cantilever mechanically coupled to a probe tip, said microelectromechanical system actuator comprising a position sensor operable to provide absolute position information signal for said microelectromechanical system actuator; an optical detector optically coupled to said flexible cantilever, said optical detector operable to provide an error signal; a contoller operable to generate a control input signal, said controller electrically coupled to said microelectromechanical system actuator and electrically coupled to said optical detector; and an estimator having an estimator feedback gain, said estimator electrically coupled to said optical detector and electrically coupled to said controller where said estimator is operable to receive said error signal, said absolute position information signal and said control input signal, said estimator operable to use said error signal, said estimator feedback gain, said absolute position information signal and said control input signal to generate a state estimate receivable by said controller, said controller operable to provide said control input signal to said microelectromechanical system actuator to maintain a deflection of said flexible cantilever at an approximately constant value; wherein said control input signal depends on said state estimate. ### Claim 14 (depends on 13) The system of claim 13 wherein said estimator predicts a futher value of said state estimate. ### Claim 15 (depends on 13) The system of claim 13 wherein said estimator is current. ### Claim 16 (depends on 13) The system of claim 13 wherein said estimator is a discrete time estimator. ### Claim 17 (depends on 13) The system of claim 13 wherein said estimator is a higher bandwidth estimator. ### Claim 18 (depends on 13) The system of claim 13 wherein said estimator feedback gain is selected by the method of pole placement. ### Claim 19 (depends on 13) The system of claim 13 wherein said estimator feedback gain is selected by the method of H∞ design. ### Claim 20 (depends on 13) The system of claim 13 wherein said estimator feedback gain is selected by the method of mixed H2/H∞ design. ### Claim 21 (depends on 13) The system of claim 13 wherein said estimator feedback gain is selected by use of a Kalman filter. ### Claim 22 (depends on 21) The system of claim 21 wherein said Kalman filter is a steady state Kalman filter. ### Claim 23 (depends on 13) The system of claim 13 wherein said estimator is operable to generate a surface estimate. ### Claim 24 (depends on 23) The system of claim 23 wherein there is no direct feed through from said control input to said surface estimate.