Investigation of the Sensor Stabilization System for Non-Contact Scanning Profilometer Based on the Optical Tunneling Method

Abstract

Non-contact profilometer often use scanning method to obtain data about the shape of the surface of the body. In this paper, present investigation and modeling of stabilization gap for non-contact optical profilometer based on the optical tunneling effect (OTE) in the dynamic mode based on the characteristics of its constituent blocks. In operation of such a scanning optical profilometer transducer moves along the test surface, without touching it. To ensure a correct reading of the measurement results is necessary to maintain the gap between the optical module and the test approach permanent body with high accuracy. For this proposed use of tracking feedback system that provides the stabilization of nanometer gap. This allows you to receive signals, depending on the topography of the surface, and on this basis to build a height map. The system of non-contact profilometer stabilization gap comprises a converter approach based OTE, photodetector, the convertor " current - voltage ", the height of the surface of the sensor and a piezomotor. In the process of stabilizing the converter system converts approximations gap d changes in the optical radiation Pfd, and formed a feedback voltage U_{os_d.} According to the difference of voltage U_{os_d} and master voltage U_d0, increments are obtained voltage DU_d, which provides piezomotor control applied to traffic proximity transducer that provides stabilization of the gap d at a given initial level d₀. System of this problems solve the task of selection circuitry, which managed to implement the necessary requirements for the quality of regulation and the task of building a regulator, by compensating unwanted temporal properties of the contour measurement, which is based on dynamic links with large gains and small time constants.