Optical Coherence Tomography System Development And Applications In Non-destructive Testing

Optical coherence tomography is a non-invasive high-speed high-resolution imaging technique based on interference. Since birth, increase imaging speed and resolution has been an important research goal in the field of OCT. OCT can not only be applied in the biomedical engineering, but can also be used for non-destructive testing of industrial areas, which put forward higher requirements on resolution and imaging speed.First, for the needs of online nondestructive testing method in glass industry, we present a large range line-field parallel spectral domain optical coherence tomography system. Based on fast area scan CMOS camera, the whole cross-sectional image can be acquired by single shot. Depth-resolved image at different lateral position can be acquired simultaneously, without the lateral scanning mechanism. The axial resolution is 17.9 μm, the lateral resolution in parallel direction and scanning direction is 55.7 μm and 24.8 μm, respectively. The system measurement range is 32 mm in lateral direction and 6 mm in axial direction. At 1 mm axial position, system sensitivity can reach 62 dB at rates of 128 000 A-scan/s. By the presented system, application in glass defect inspection was investigated.Second, for the imaging resolution requirements, we have developed an ultra-high resolution spectral domain OCT system. Lateral resolution and axial resolution of the OCT system are decoupled, even when the probe beam is under low numerical aperture, high axial resolution can still be achieved. Based on the development of super-continuum light source, optimized system design and data processing algorithms, submicron axial resolution has been achieved. After the actual verification, the axial resolution is 0.9 μm, imaging depth is 0.6 mm, signal to noise ratio is better than 100dB. By contrast verification, ultra-high resolution OCT system has great advantages in resolution. Compared with standard OCT system, not only the biological tissue structure but also the non-destructive testing material can be imaged more clearly.This article includes the above-mentioned two parts:a parallel line field spectral domain optical coherence tomography system development, an ultra-high resolution spectral domain OCT system spectral domain OCT systems development. Basic principles of OCT technology and the limitations OCT system performance are analyzed, and the experimental results are given at last.