Faculty of Systems Engineering,
Dept. of Opto-Mechatronics,
930, Sakaedani, Wakayama
Subject of research
Development of the measurement method for sub-nanometer displacement and strain distributionsOur method achieved quick non-contact measurement of displacement and strain distributions of the structure in the highest resolution.
PurposeTo achieve higher quality products, manufacturers in every fields require the method to measure strain distributions in high resolution without contacting. We develop the techniques to realize the method that provides quick and high-accurate results efficiently and we work on its practical application and wide application.
Principle of phase shift digital holography
Displacement can be obtained from phase difference between phases before and after deformations. Phase of 2π indicates displacement in wavelength of light (submicron).
Sub-nanometer resolution can be obtained by performing phase analysis in 1/1000 resolution.
Method of averaging phase difference
The average of phase difference is calculated on the complex plane. Intensity is regarded as weight.
The area with higher intensity provides higher reliability.
The method uses the data with higher intensity for every pixel. (Method of averaging phase difference)
The data becomes more reliable by increasing the number of divisions. (Errors decrease.)
The effect of speckle is removed and data can be obtained in sub-nanometer resolution.