The Theory Research Of Optic Transfer Functions Of The Harmonic Microscopy And Experiments Of Imaging

There are some samples of microscopy that do not possess inversion symmetricstructure, and all materials possess non-vanishing third susceptibilities such asbirefraction. When these samples are illuminated with super-intensive peak power,super-fast and super-short laser pulse, they'll be excited to emit the second or thirdharmonic generation due to the nonlinear interaction between specimen materials andlaser beam. Taking advantage of inherent nonlinear optical of a samples in forming thecontrast, the signal, which contains information of structure, was collected to CCD byobject lens of microcopy ,and then generated imaging. The kind of microscope has theapparent advantage that no staining is required and no toxicity is posed to living tissues.Because in the process of second harmonic generation (SHG), or third harmonicgeneration (THG), the energy of optical field don't be transferred to interactionmolecule (after interacting, the quantum mechanics state of molecular come back tooriginal state, the energy and momentum wouldn't change). In this way, a biologicaltissue sample wouldn't be destroyed, so the harmonic microscope is a kind of un-invadedetected technique. The microscopic technique combines with nonlinear opticaltechnique increases mutual effect. The microscope of high numerical aperturestrengthens the conversion efficiency of nonlinear optics at focus and acquires a higherresolution from the shorter wavelength of harmonic generation. The characteristicmakes the SHG and THG microscope are an ideal probe for living tissue and have greatpotential application, and it would greatly improve images quality of microscope.In theory, the thesis discussed the optic transfer functions of harmonic microscopicimaging, comparing with those optic transfer functions of other microscopy imaging.The imaging characteristics of harmonic were also discussed with the optic transferfunctions. In addition, the theory of microscope and nonlinear optic was summarizedbefore discussing the optic transfer functions. In the experiments of harmonic imaging,the laser source is a Nd:YAG pulse laser with Q switch, pumped by Xe flash light.The laser beam is focused into the sample. In order to protect sample from break, thesample was not placed right at focus. Because the peak power of laser is very high, thelaser beam could excite harmonic generation from greater areas of sample. Theseharmonic passed through object lens of microcopy and filter, arrive at CCD.The thesis includes six parts. In the first chapter, the meaning of harmonicimaging is narrated. In the second chapter, the development of microscope issummarized. In the third chapter, the coupling equations of harmonic generation werediscussed. In the forth chapter, the optic transfer functions of microscope harmonicimaging is educed by the help of contrasting. In the fifth chapter, the methods ofexperiments and the results of experiments are depicted. In addition, the conclusion ismade in the final chapter.