Research And Application Of Line-scanning Optical Coherence Microscopy(OCM)

Optical coherence microscopy(OCM)is a new technology,which combines confocal microscopy with high resolution and low coherence with effective suppression of scattering light out of coherent gate.This technology is suitable for imaging biological tissue and detecting surface topography measurement of industrial objects.Based on the understanding of the OCM system,a line-scanning OCM system based on the grating is put forward.It takes advantage of the light angle selective of the diffraction grating on the wavelength to realize scanning all locations in the transverse direction at the same time,thus greatly improve the speed of the system.In this paper,the principle and characteristics of the line-scanning OCM system are introduced in detail.Also,it discusses the paraments such as the axial resolution,the lateral resolution,detecting depth,imaging speed and sensitivity and so on.Then,according to the requirement of 3D surface topography measurement,a line-scanning optical coherence microscopy system is designed and the hardware system is debugged.In order to realize the real-time automatic control of line-scanning OCM system,the OCM software was developed based on the LabVIEW platform.Different from the traditional frequency domain OCM system,it is composed of two parts: signal storage module and processing module without the timing control module.For the OCM system established in this paper,experiments with the samples like cover glass,mirror were carried out to verify the performance of the system.The results shows good consistencies with the theoretical calculation.Based on the system,by adding another moving stage for the scanning of the Y-axis,it realizes the surface topography measurement to image the micro cracks on the surface of the rail and determines the location and the size of the cracks.The accuracy of the measured depth and size of the crack is analyzed.The results show that the system can realize the surface topography measurement and the measurement error is less than1%.Moreover,because the system does not need any additional scanning device,the stability and reliability of the system are greatly improved.