Probe detection system

Abstract

A probe detection system (74) for use with a scanning probe microscope comprises both a height detection system (88) and deflection detection system (28). As a sample surface is scanned, light reflected from a microscopeprobe (16) is separated into two components. Afirstcomponent (84) is analysed by thedeflection detection system (28) and is used in a feedback systemthatmaintainsthe average probe deflection substantially constant during the scan. The second component (86) is analysed by the height detection system (88) from which an indication of the heightof the probe above a fixed reference point, and thereby an image of the sample surface, is obtained. Such a dual detection system is particularly suited for use in fast scanning applications in which thefeedback systemis unableto respond at the raterequired to adjust probe height betweenpixel positions.

Description

technical field

[0001] The present invention relates to the field of probe microscopy and in particular to a detection system for monitoring the position of a microscope probe in relation to a sample surface. Background technique

[0002] The principle behind scanning probe microscopy (SPM) is used to mechanically scan a nanoprobe tip over a sample surface to produce an image of the sample. Features within the image are derived from changes in the interaction between the tip and the sample.

[0003] A specific example of SPM is atomic force microscopy (AFM), where the force interaction between the sample and the sharp tip of the probe is monitored. The probe of a typical AFM consists of a very small cantilever whose base is fixed to a support, with the tip at the opposite (free) end of the cantilever. When the probe tip is brought into close proximity to the sample, an interaction force is created between the sample and the tip. If the needle tip is in motion, eg oscillat...

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