Basics ntawm Near-field Optical Microscopy Basics ntawm Near-field Optical Microscopy
The traditional optical microscope consists of optical lenses that can magnify an object up to thousands of times to observe the details. Due to the diffraction effect of light waves, an infinite increase in magnification is not possible because the obstacle of the diffraction limit of light waves will be encountered, and the resolution of the traditional optical microscope cannot be more than half of the wavelength of light. For example, with a wavelength of λ = 400nm of green light as a light source, can only distinguish between two objects that are 200nm apart. In practice λ>400nm, the resolution is somewhat lower. This is due to the fact that optical observation in general is made at a great distance from the object (>>λ).
Nyob ze-field optical microscopy, raws li lub hauv paus ntsiab lus ntawm kev sojntsuam tsis muaj hluav taws xob thiab kev kuaj pom, muaj peev xwm ua txhaum los ntawm qhov kev txwv tsis pub muaj kev cuam tshuam rau qhov zoo tib yam optical microscopes raug, tso cai rau nanoscale kho qhov muag duab thiab nanoscale spectroscopic kev tshawb fawb yuav tsum tau nqa tawm ntawm ultra- siab optical daws teeb meem.
Ze-field optical microscope muaj kev sojntsuam, lub teeb liab kis tau tus mob, kev tswj xyuas scanning, teeb liab ua thiab teeb liab tawm tswv yim. Nyob ze-tsav tiam thiab nrhiav kom tau txoj cai: xwm txheej teeb irradiation rau saum npoo ntawm cov khoom nrog ntau me me microstructures, cov microstructures nyob rau hauv lub luag hauj lwm ntawm qhov teeb meem lub teeb teb, lub resulting reflected yoj muaj ib tug cia li nthwv dej nyob rau saum npoo ntawm cov khoom thiab propagation. nthwv dej mus rau qhov deb. Sudden nthwv dej los ntawm cov qauv zoo hauv cov khoom (cov khoom me dua lub wavelength). Lub propagating yoj los ntawm cov qauv ntxhib ntawm cov khoom (cov khoom loj dua lub wavelength) uas tsis muaj cov ntaub ntawv hais txog cov qauv zoo ntawm cov khoom. Yog tias qhov chaw tawg me me heev yog siv los ua tus nanodetector (xws li kev sojntsuam), muab tso ze txaus rau saum npoo ntawm cov khoom kom ua rau lub nthwv dej nrawm, ua rau nws tawm lub teeb dua. Lub teeb uas tsim los ntawm qhov kev zoo siab no kuj muaj cov tsis muaj kev cuam tshuam nrawm thiab propagating nthwv dej uas tuaj yeem nthuav tawm mus rau qhov deb deb, thiab cov txheej txheem no ua tiav qhov kev tshawb pom ntawm thaj chaw ze. Kev hloov pauv ntawm qhov nrawm nrawm thiab thaj chaw propagating yog linear, thiab propagating teb raug qhia meej txog cov kev hloov pauv hauv qhov chaw zais. Yog tias qhov chaw tawg yog siv los luam theej duab saum npoo ntawm ib qho khoom, tuaj yeem tau txais daim duab ob sab. Raws li lub hauv paus ntsiab lus ntawm reciprocity, lub luag hauj lwm ntawm irradiating lub teeb qhov chaw thiab lub nano-detector yog switched nrog ib tug, thiab cov qauv yog irradiated nrog ib tug nano-teeb qhov chaw (abrupt field), thiab vim yog tawg ntawm irradiating teb. los ntawm cov qauv zoo ntawm cov khoom, cov nthwv dej sai sai tau hloov mus rau hauv nthwv dej propagating uas tuaj yeem kuaj pom ntawm qhov deb, thiab qhov tshwm sim yog tib yam.
Nyob ze-field optical microscopy muaj qhov taw tes-los-taw tes scanning thiab taw tes-los-taw tes kaw los ntawm kev sojntsuam rau saum npoo ntawm cov qauv ua raws li cov duab digital. Daim duab 1 qhia cov duab schematic ntawm ib qho chaw ze-tsawg optical microscope. Nyob rau hauv daim duab, tus qauv xyz ntxhib kwv yees tuaj yeem kho qhov kev ncua deb ntawm qhov kev sojntsuam mus rau tus qauv nrog qhov tseeb ntawm kaum ntawm nanometers; thaum lub xy scanning thiab z tswj tau siv nrog qhov tseeb ntawm 1nm los tswj kev sojntsuam scanning thiab z kev taw qhia cov lus qhia ua raws. Qhov teeb meem laser, pom nyob rau hauv daim duab, yog nkag mus rau hauv lub sojntsuam los ntawm ib tug optical fiber, thiab lub polarization lub xeev ntawm qhov teeb meem teeb yuav hloov tau raws li qhov yuav tsum tau. Thaum qhov teeb meem laser irradiates tus qauv, lub detector yuav cais cov kis tau tus mob thiab xav txog cov teeb liab modulated los ntawm cov qauv thiab amplified los ntawm lub photomultiplier raj, thiab ces ncaj qha los ntawm analogue-rau-digital converter los ntawm lub computer nrhiav los yog los ntawm lub spectroscopy system rau hauv. spectrometer kom tau txais cov ntaub ntawv spectral. Kev tswj hwm qhov system, khaws cov ntaub ntawv, cov duab tso saib thiab cov ntaub ntawv ua tiav los ntawm lub computer. Los ntawm cov txheej txheem kev yees duab saum toj no, nws tuaj yeem pom tau tias qhov ze-tsawg optical microscope tuaj yeem sib sau ua ke peb hom ntaub ntawv, piv txwv li, qhov chaw morphology ntawm tus qauv, qhov ze-tsav qhov muag teeb liab thiab cov teeb liab spectral.
