Heterodyne speckle interferometry for measurement of two-dimensional displacement

Abstract

This paper presented a heterodyne speckle interferometer (HSI) for the measurement of two-dimensional in-plane displacement. A diffraction grating is used to split the light source into four beams, which are then reflected into a non-mirror measurement surface at symmetrical incident angles, before being scattered to form an interference pattern. In accordance with the Doppler Effect, in-plane displacement of the surface causes phase variations in speckle interference patterns, from which displacement information can be obtained. Several experiments were performed to evaluate the feasibility of the proposed HSI. Experiment results demonstrate that the proposed system is capable of accurately measuring in-plane displacement with a resolution of approximately 1.5 nm.

Дифракционная Математическая Модель Лазерного Спекл-Интерферометра Поперечных Смещений Рассеивающего Объекта

“…В ряде практических задач в науке, технике, биомедицинских исследованиях возникает практическая необходимость измерять параметры движения рассеивающих объектов -микросмещения, скорость, ускорение. Ряд таких задач решается с помощью спекл-интерферометров, в которых контролируемая рассеивающая поверхность освещается двумя лазерными пучками, падающими под разными углами на поверхность [16][17][18][19].…”

Diffraction mathematical model of a laser speckle interferometer of transverse displacements of a scattering object

“…In a number of practical problems of science, technology, and biomedical research, there is a practical need to measure the motion parameters of scattering objects, i. e., microdisplacements, velocity, and acceleration. A number of such problems are solved using speckle interferometers, in which the controlled scattering surface is illuminated by two laser beams incident at different angles [16][17][18][19].…”

A New 2D Displacement Measurement Method Based on an Eddy Current Sensor and Absolute Encoding

“…Using the Doppler effect, the in-plane displacement of the surface will lead to phase change of the speckle interference pattern, from which the displacement information can be obtained. The resolution of the system reaches 1.5 nm [8]. Wu et al proposed a new optical encoder which can independently and simultaneously measure in-plane and out-of-plane displacement.…”