Differential Scanning Near-Field Microscope
Original Publication Date: 1988-Jul-01
Included in the Prior Art Database: 2005-Feb-15
Differential imaging principles are used in a scanning near-field microscope to significantly reduce the noise found in such imaging systems. In stylus microscopy, such as used in a scanning tunneling microscope, a tip is placed in proximity to the surface of a conductive workpiece. Upon application of a low voltage, tunneling current begins to flow. The current varies due primarily to the modulation of the gap between the tip and the workpiece surface. In addition, the current signal includes noise predominantly at low frequencies up to approximately 100 Hz. Differential imaging shifts the workpiece surface information to a higher frequency by the application of a high frequency, small amplitude lateral vibration on the tip. The amplitude of the vibration is on the order of the lateral resolution of the microscope.