Synchronous sampling scanning force microscope

A synchronous sampling scanning force microscope for examining surface contours of a specimen, the microscope comprising:

• a cantilever arm having a free end, said cantilever arm having a fundamental resonance frequency;
• probe means secured to said free end of said cantilever arm, said probe means including a probe tip adapted to follow the surface contours of the specimen with a substantially constant amount of force;
• deflection measuring means for measuring motion of said cantilever arm and for generating an output signal indicative of an amount of deflection of said cantilever arm means;
• oscillator drive means for causing the cantilever arm and probe tip to oscillate toward and away from said specimen surface contours at a desired frequency in cycles of near and far excursions of said probe tip relative to said specimen surface;
• sampling means for sampling selected portions of cycles of said deflection signal corresponding to said cycles of near and far excursions of said probe tip and for generating output signals indicative of elevations of said surface contours of said specimen;
• and
• phase control means for receiving said deflection signal and for controlling the sampling of said selected portions of cycles of said deflection signal.

A method for synchronous sampling detection of an oscillating cantilever of a scanning force microscope for examining surface contours of a specimen, said microscope having a cantilever arm having a free end, said cantilever arm having a fundamental resonance frequency, probe means secured to said free end of said cantilever arm and including a probe tip adapted to follow the surface contours of the specimen with a substantially constant amount of force, deflection measuring means for measuring deflection of said cantilever arm and for generating a deflection signal indicative of an amount of deflection of said cantilever arm, the method comprising:

• causing said free end of said cantilever arm to oscillate to cause the probe tip to oscillate toward and away from said specimen surface contours at a desired frequency in cycles of near and far excursions of said probe tip relative to said specimen surface;
• sampling selected portions of cycles of said output signal corresponding to said cycles of near and far excursions of said probe tip and for generating output signal data indicative of relative elevation of said surface contours of said specimen;
• and
• controlling the sampling of said selected portions of cycles so that said sampling occurs during predetermined phases of each cycle of said deflection signal.

In a scanning force microscope for examining surface contours of a specimen, said microscope having a deflection arm having a free end, said deflection arm having a fundamental resonance frequency, probe means secured to said free end of said deflection arm and including a probe tip adapted to follow the surface contours of the specimen, oscillator drive means for causing an oscillation of said deflection arm and the probe tip toward and away from said specimen surface contours at a desired frequency in cycles of near and far excursions of said probe tip relative to said specimen surface;

• and deflection measuring means for measuring motion of the deflection arm and generating a deflection signal indicative of deflection of said deflection arm, the improvement which comprises:
• sampling means for sampling selected portions of cycles of said output signal corresponding to said cycles of near and far excursions of said probe tip and for generating output signals representing deflection of said near and far excursions of said probe tip at said selected portions of said cycles;
• and
• control means for receiving said deflection signal and for controlling the sampling of said selected portions of cycles of said deflection signal.

A method for examining surface contours of a specimen using a scanning force microscope, said microscope having a deflection arm having a free end, said deflection arm having a fundamental resonance frequency, probe means secured to said free end of said deflection arm and including a probe tip adapted to follow surface contours of the specimen, and deflection measuring means for measuring motion of the deflection arm and generating a deflection signal indicative of an amount of deflection said deflection arm, the steps of the method comprising:

• causing an oscillation of said free end of said deflection arm to cause the probe tip to oscillate toward and away from said specimen surface contours at a desired frequency in cycles of near and far excursions of said probe tip relative to said specimen surface;
• sampling selected portions of cycles of said output signal corresponding to said cycles of near and far excursions of said probe tip and for generating output signal data representing deflection of said near and far excursions of said probe tip at said selected portions of said cycles;
• and
• controlling the sampling of said selected portions of cycles so that said sampling occurs during predetermined phases of each cycle of said deflection signal.