Force transducer based on a geometric-optical displacement sensor

Abstract

The vast majority of current force measurement methods determine the deformation of an elastic body to measure the effective force. The leading sensor technology in this market segment is the resistance strain gauge. Because of the measurement principle the stain gauge has some drawbacks. For instance, the measurement suffers from the so-called creeping and a local weakening of the elastic element is necessary to create sufficient local strains. This is also a reason for this technique being limited with respect to the measurement of dynamic loads. In order to overcome these limitations, in this paper a new contactless working geometric-optical displacement transducer is proposed. An optical lever principle is used to reach the required high position resolution to measure the force-induced deformation of an elastic body.Optical displacement transducer, geometric-optical lever, optical force transducer, position sensitive diode, strain gauge

Drift compensation technique of an area-varying capacitive displacement sensor for nanometer resolution

“…Assumed that the device does not rotate after the initial alignment, a simple model of the sensor can be derived as shown in Equation 1. In Equation (1), H is the permittivity, d is the gap, x is the direction of moving of the plate, A(x) is total overlapped area, C e (x), C d , and C n are capacitive variation by the edge effect, the drift, and the other noise in the order named.…”

“…Furthermore, it is a base of the positioning technology. [1][2][3][4] For visualization and manipulation of the objects of nanometer scale, it may provide with one of the most important tools because optical image cannot be obtained in this scale. The merits of capacitive sensors may be a simple structure, a compact size, low cost, and relatively high resolution.…”