Three-dimensional Contour Measurement System Based On Optical Coherence Tomography

Optical Coherence Tomography(OCT)technology is a new type of imaging technology developed in the 1990 s.It is an emerging discipline in the fields of optics,mathematics,electronics and computer science.The OCT technology is derived from the Michelson interference principle,which makes full use of the low coherence characteristics of the broadband source to chromate the internal information of the measured object,realizes non-invasive tomography of the measured object,and has high resolution and imaging,Fast speed,high sensitivity and so on.OCT technology is widely used in medical detection.It is used in ophthalmology for eye corneal imaging,eye iris,crystal and other eye tissue examination.Polarization-sensitive OCT technology is especially suitable for early enamel caries and periodontal disease.The detection,OCT technology combined with modern medical instruments is also used to detect the lesions of some parts of the human body.In addition,due to the high resolution and high sensitivity of OCT technology,its application fields are expanding to high-precision physical detection and other fields.OCT technology is mainly divided into time domain OCT and spectral domain OCT.The time domain OCT system moves the position of the mirror by the mechanical device so that the reference light reflected by the mirror and the reflected light of the object under test form interference within a certain optical path difference,and the name of the time domain OCT is also derived therefrom.The reason why the domain OCT system requires mechanical devices greatly reduces the imaging rate and imagin g quality of the system,which limits the development of time domain OCT technology to some extent.The spectral domain OCT system uses a diffraction grating to diffract the composite light of the reference light of the mirror and the reflected light of the object to be measured according to different wavelengths to form a spectrum,and collects spectral information through a photodetector to perform a series of conversion calculations.The internal measurement of the object under test greatly increases the acquisition rate and quality of the OCT system.This paper first introduces the development history of OCT technology and the research,development and application status at home and abroad.It focuses on the theoretical principle of OCT technology,signal demodulation method and DC interference signal suppression.The time domain OCT system and the spectral domain OCT system are introduced in detail,and the advantages and disadvantages of the two systems are pointed out.In the paper,each optical path is decomposed and explained,and the theoretical basis of the position of the diffraction grating is given,and then the design is given.The system steps and the construction and debugging process are explained in detail,and the system structure is analyzed from the perspectives of the main perspective and the top angle.Finally,the core hardware selection and principle of the system are introduced one by one,and then a set of high-precision spectrum is built according to the theoretical knowledge.The maximum depth of measurement of the system is 15 mm,and the measurement accuracy is 5-15?m.Finally,the built-in system is used to measure the non-defective and defective non-biological tissue samples,at the same time,compared with the more intuitive data processing system,the experiment verifies the correctness of the theoretical knowledge and the practicability of the system.