Imaging Of Tooth Samples Based On Random Fiber Laser

Early detection of dental caries has always been a major difficulty in dentistry.The commonly used clinic detection methods such as visual examination and dental radiography are easy to be underestimated or even overlooked at its early stage,and the radiation has ionizing radiation,which is not suitable for repeated detection.Lots of researches have been carried out to find new caries detection methods.Researchers found that the caries caused mineral loss would greatly improve the reflectance of this area in the near-infrared band,therefore it appears as a bright area in the image.Near infrared digital imaging technology has great clinical application prospects because of its unique light source characteristics and no ionizing radiation.Tooth imaging with a certain thickness has a high dependence on the brightness and spectral density of the light source.However,because of the high spatial coherence of the traditional near-infrared laser light source,the speckle caused by interference in the image greatly affects the quality of the imaging,so it is necessary to find a light source with low spatial coherence and high spectral density to achieve near-infrared teeth imaging.Random fiber laser has attracted extensive attention,it provides random Rayleigh feedback and random Raman gain.It has the characteristics of flexible wavelength,simple structure,low spatial coherence and high spectral density.It is an ideal nearinfrared imaging light source.Based on the above research background,this thesis first utilizes the transmission imaging configuration,three different light sources including random fiber laser,broadband light source and narrowband laser was used to illuminate four sound tooth slices and one caries slice.It is found that as a near-infrared speckle free light source,random fiber laser can clearly distinguish the enamel,dentin,caries and crack,it is obviously superior to the ordinary narrow linewidth laser source in terms of clarity without any interference caused speckle pattern,and because of its relatively narrow bandwidth and high spectral density,random fiber laser is also superior to the wide-band light source in terms of brightness and contrast.It is a good near infrared imaging light source because of its low spatial coherence and high spectral density.In order to meet the clinical requirement,backscattering configuration is also used to analyze the caries section.The random fiber laser images in backscattering configuration show better characteristics than in transillumination configuration.For example,the dentin appears as different brightness according to the different mineral content in this area.The mineral concentration in the dentin area can therefore be calculated in this way.Moreover,the results of random fiber laser imaging are compared with those of optical microscope and radiography imaging.The contrasts of caries have been calculated for three different imaging methods and random fiber laser has obviously much higher contrast than the other two imaging methods.It is an ideal near-infrared caries detection light source.Random fiber laser with simple and stable strcture has great potential in clinic caries detection.