Profile Measurement By Fourier-domain Optical Coherence Tomography

Fourier-domain optical coherence tomography(FD-OCT)profilometry is widely used in biomedical and industrial detection due to its advantages of non-contact,non-destructive measurement and high precision.But there are disadvantages in the FD-OCT profilometry.On the one hand,wavenumber scanning interferometry(WSI)can't detect the sample with large curvature and smooth surface which make its limited application.On the other hand,the result of Spectral domain optical coherence tomography(SD-OCT)contains the noise of self-coherence component and DC component.To solve these problems,improved profile measurement base on WSI and S with balanced detection(BD-SDOCT)were proposed.This paper firstly introduces the significance and background of FD-OCT profilometry and other profilometry which use daily.Then finding out the disadvantages of WSI and SDOCT and proposing the solution.Afterwards,the paper introduces schematic diagram of WSI and SD-OCT,as well as the configuration and selection principles.After introduced the system hardware configuration,the feasibility of profile measuring systems was discussed by its measuring principles.At last,profile measuring system based on WSI and SD-OCT were verified by experiment.It can be known that both the vertical resolution and horizontal resolution of profile measuring system based on WSI are 11.3?m/pixels;in addition,the root-mean-square error of measuring plano-convex lens is ±19.8nm.For BD-SDOCT,resolution along the y direction is 3.3?m/pixels and resolution along the depth direction is 5.4?m/pixels.The front surface and rear surface profile amplitude of smooth surface respectively increase 76.5% and 60%,in addition,the noise of self-coherence component and DC component respectively decline 88% and 62.5%.The profile of speckle surface increases 81.8% and noise declines 69.2%.The front surface profile of resin increases 94.1% and internal signal decreases from 70.8% to 40% with the increase of depth,in addition,the noise declines 73.3%.The Experiment shows that improved profile measurement base on WSI can detect the sample profile with large curvature and smooth surface and possess advantages of high accuracy,simple structure and high stability.The profile measurement base on BD-SDOCT can enhance profile and depress noise.