Wedge calibration method

A third group of calibration procedures, the (3) direct (single step) [23-25] techniques avoids (many of) these problems. In particular, the so-called improved wedge-calibration method, in which a tip/cantilever is scanned across a calibration sample with two well-defined slopes (see Fig. 2.31), allows one to calculate the calibration factors with an error of ca. 5% [18]. 

In the wedge calibration method, a cantilever is scanned across a calibration sample with two well-defined slopes. The friction signal is recorded as a function of the applied load. At a given load L, friction and normal forces (normal force = load + adhesion A) depend on the direction of motion (Fig. 2.32). 

For measurements in liquid, an additional correction factor that corrects the effect of refraction must be considered. By multiplication with the factor naiiMiquid (n refractive index) one can conveniently rescale the values of lateral photodiode sensitivity obtained in air (6LAlr) employing, e.g., the improved wedge calibration method using a universal calibration specimen, to obtain the correct value for... 

The accuracy of the measurement of radon concentrations with bare track detectors was found to be unsatisfactory due mainly to the changes of the deposition rate of radon progeny onto the detector as a result of air turbulence. In this work, therefore, a method was developed which can correct the contributions of the deposition to the track densities by classifying the etched tracks according to their appearance, i.e. round or wedge shaped. Using this method, about 30% improvement in the error of measurements was achieved. The calibration coefficient ob tained by experiment was 0.00424 tracks/cm /h/(Bq/m ), which agreed well with the calculated value. Comparison was also made of the present method with other passive methods, charcoal and Terradex, as to their performance under the same atmosphere. 

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