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Opticalcoherencetomography (OCT)wasorigi nallydevelopedforimagingintransparenttissue[1] .Since1 995 ,OCThasbeenadvancedtoimagefromophthal mologytonontransparenttissuewithahighimagingres olution[2 ,3 ] .OCTdemonstratesitsgreatestpotentialinsituationswhereconventionalbiopsyiseitherdangerousorineffective[4] .Becauseofthecomplexityofthelightpropagationinnontransparenttissue,theapplicationofOCTinhighlyscatteringbiologicaltissuesuchasskintis suearenotoptimistic.Yadlowsky[5] explainedthatmul tip… 相似文献
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A kind of image distortion in Optical Coherence Tomography (OCT) resulted from average refractive index changes between structures of bio-tissue is discussed for the first time. Analysis is given on following situations:1) Exact refraction index changes between mierostruetures;2)The gradient of average refractive index change between different tissue layers is parallel to the probe beam;3) The gradient of average refractive index change is vertical to the probe beam. The results show that the image distortion of situation 1) is usually negligible ;in situation 2) there is a spread or shrink effect without relative location error; however, in situation 3)there is a significant image error inducing relative location displacement between different structures. Preliminary design to eliminate the distortion is presented, the method of which mainly based on the image classification and pixel array re-arrangement. 相似文献
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Ｌａｓｅｒｄｉｏｄｅ (ＬＤ) ｐｕｍｐｅｄｈｉｇｈａｖｅｒａｇｅｐｏｗｅｒ ,ｈｉｇｈｒｅｐｅｔｉｔｉｏｎｉｎｔｒａｃａｖｉｔｙｆｒｅｑｕｅｎｃｙ ｄｏｕｂｌｅｄｓｏｌｉｄ ｓｔａｔｅｌａｓｅｒｈａｓｍａｎｙａｄｖａｎｔａｇｅｓ,ｓｕｃｈａｓｈｉｇｈｅｆｆｉｃｉｅｎｃｙ ,ｈｉｇｈｐｅａｋｐｏｗｅｒ,ｈｉｇｈ ｐｈｏｔｏｎｅｎｅｒｇｙ ,ｈｉｇｈｂｅａｍ ｑｕａｌｉｔｙ ,ｃｏｍ ｐａｃｔｎｅｓｓａｎｄｌｏｎｇｅｒｌｉｆｅｔｉｍｅ .Ａｍｏｎｇｔｈｅｍ ,ＬＤ ｐｕｍｐｅｄｆｒｅｑｕｅｎｃｙｄｏｕｂｌｅｄ ｇｒｅｅｎ… 相似文献
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Self mixinginterferenceeffectshavebeenwidelystudied[1— 12 ] ,mostofwhichareconductedonsinglemodelasers.Wang[10 ] andYoshitada[11] reportedstudiesonmulti modesemiconductorlasersin 1993and 1994re spectively .Buttoourknowledge ,fewmodelsonLDpumpedmulti modesolid statelaserhavebeenreported .1 Basictheoryandgeneralmodel Theprincipleofself mixinginterferenceeffectsisexplainedasanexternalopticalfeedbackeffect[9] .Thege neralmodelisshowninFig .1,LcandLextstandforthelengthofthecavityandtheexter… 相似文献
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To sharpen the imaging of structures, it is vital to develop a convenient and efficient quantitative algorithm of the optical coherence tomography (OCT) sampling. In this paper a new Monte Carlo model is set up and how light propagates in bio-tissue is analyzed in virtue of mathematics and physics equations. The relations,in which light intensity of Class I and Class 2 light with different wavelengths changes with their permeation depth ,and in which Class I light intensity (signal light intensity) changes with the probing depth, and in which angularly resolved diffuse reflectance and diffuse transmittance change with the exiting angle, are studied. The results show that Monte Carlo simulation results are consistent with the theory data. 相似文献
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A laser diode (LD) pumped Q-swithedh high efficient intracavity frequency -doubled Nd:YAG laser is reported here,The authors have designed and optical and pointed out that the key to increasing harmonic conversion efficiency is to decrease the loss of fundamental wave.In the experiments ,a fundamental mode output laser was acquired,When the pumping power was 12 W ,2.6W average output power at 1064 nm with AO Q-swithc was obtained 2.1 W average output power at 532 nm was obtained with intravity freuency doubling ,and the hihest second harmonic coversion efficiency was 82%. 相似文献
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