Patent ID: 6871527

Claim:
In a measurement head having a housing, a cantilever that can be positioned over a sample, and an optical system to direct a light beam from a light source as an incident beam on the surface of the cantilever, and as a reflected beam from the cantilever to an optical detector, the improvement comprising at least one of the following: (a) a lens for focusing the incident beam onto said cantilever wherein the central axis of said incident beam is offset from the central axis of the reflected beam and each is offset from the central axis of said focusing lens; (b) an integral optics block containing said optical system is provided in said housing, and a flexure is provided mounting the optics block to the housing while allowing the optics block to be translated along the axis of the light beam from the light source; (c) said housing and optics block are formed of composite material or of a ceramic, having the stiffness, low thermal expansion, or both, of a ceramic; or (d) the resonant frequency of vibration of a mechanical path between the cantilever and a sample or between the cantilever and the focusing lens system is greater than about 850 Hz.