Measurement of the Straightness of a Leadscrew-Driven Precision Stage

This paper describes a multi-probe method for measuring the straightness error of a leadscrew-driven stage. Two displacement probes are employed to scan a flat artifact mounted on the stage. The surface profile error of the flat artifact is separated from the straightness error of the stage in a differential output of the probes. The straightness error can thus be obtained accurately from an integration operation of the differential output without the influence of the surface profile error. An improved technique of data processing is adopted for measurement of straightness error components with periodicity shorter than the probe spacing. The influence of the angular error of the stage is compensated for by using the result measured by an autocollimator. Experiments of straightness measurement of a leadscrew-driven stage with a lead of 1 mm were carried out by using two flat artifacts with different degrees of precision. The successful detection of the short-periodicity component of the straightness error with a periodicity equal to the lead indicated the feasibility of the multi-probe method.

Gravity waves propagation in the thermosphere observed from electron density profile and total electron content measurements

Ionospheric observations with five minute intervals between ionograms were made during a campaign from 19th to 23rd June 1996 at the Rome station (41.8N, 12.5E). The data obtained from ionospheric vertical sounding have been analysed together with the Total Electron Content (TEC) data obtained by the GPS receiver measurements. Both the apparatus were installed in the same station. Short periodicity phenomena occurring in the considered period were observed and interpreted as resulting from the propagation of AGWs in the thermosphere. TEC and electron density were then analysed during AGWs activity.

Magnetic Properties of Fe/Ru and Fe/Ir Superlattices with Short Periodicity

ABSTRACTWe present new results on the magnetic properties of constrained, iron base, good quality, single-crystalline superlattices, Fe/Ru and Fe/Ir. It is shown that in the first case there are two magnetically dead layers at the interface while in the second case there is probably none. The magnetic moment of Fe is, in both superlattices, about 1.7μb. The magnetic anisotropy are opposite, in plane for Fe/Ru, perpendicular for Fe/Ir.