2 Resolution in microscopy Why is there a barrier in optical microscopy resolution?And how can it be broken?
3 Angular spectrum and diffraction limit Describe field as superposition of plane waves (Fourier transform):Field at z=0 (object) propagates in free space asThe propagator H is oscillating forand exponentially decaying forHigh spatial fluctuations do not propagate: diffraction limit
4 + The diffraction limit in conventional microscopy Image of a point source in a microscope, collecting part of the angular spectrum of the source:Rayleigh criterion: two point sources distinguishable if spaced by the distance between the maximum and the first minimum of the Airy patternq+Numerical Aperture determines resolutionAiry pattern (microscope point spread function)
5 Breaking the diffraction limit in near-field microscopy A small aperture in the near field of the source can scatter also the evanescent field of the source to a detector in the far field.Image obtained by scanning the apertureAlternatively, the aperture can be used to illuminate only a very small spot.
6 Probing beyond the diffraction limit Single emitterMetallic particleAperture probefibre typeAperture probemicrolever type
7 self-assembled monolayer, Modified slide from Kobus Kuipers and Niek van Hulst et al.Transmission of light through a near-field tip200 nmExcitation lightAlNSOM probeFIB treated probeAperture ~ nmProtein, dendrimer, DNA, etc.single fluorophoresFluorescenceThin polymer film,self-assembled monolayer,cell membrane, etc.
8 Focussed ion beam (FIB) etched NSOM probe lwell defined apertureflat endfaceisotropic polarisationhigh brightness up 1 mW35 nmaperture100 nm100 nmglassWith excitation Ex , kz, :aluminumy500 nmxExEyEzVeerman, Otter, Kuipers, van Hulst, Appl. Phys. Lett. 74, 3115 (1998)
9 Shear force feedback: molecular scale topography Steps on graphite (HOPG)Feedback loop:A0Dfpiezo3 x 3 mmw0~ 0.8 nm step~ 3 mono-atomic stepsTuning fork32 kHzQ ~ 500Lateralmovement,A0 ~ 0.1 nm1.7 x 1.7 mmDNA on micasampleDNAwidth 14 nmheight 1.4 nmFeedback on phaseTip -sample < 5 nmRMS ~ 0.1 nmRensen, Ruiter, West, van Hulst, Appl. Phys. Lett (1999)Ruiter, Veerman, v/d Werf, van Hulst, Appl. Phys. Lett (1997)van Hulst, Garcia-Parajo, Moers, Veerman, Ruiter, J. Struct. Biol. 119, 222, (1997)
10 Perylene orange in PMMA 100 nm1 mm90o0oRuiter, Veerman, Garcia-Parajo, van Hulst, J. Phys. Chem. 101 A, 7318 (1997)
11 Single molecular mapping of the near-field distribution DiIC18 moleculesin 10 nm PMMA layer1.2 x 1.2 mm2;3 nm/pix; 3 ms/pix12045 nmFWHM80counts / pixel404008001200distance (nm)Veerman, Garcia-Parajo, Kuipers, van Hulst, J. Microscopy 194, 477 (1999)
12 Mapping the near field of the probe Data from Kobus Kuipers and Niek van Hulst et al.Mapping the near field of the probe
13 NFO for Single Molecule Detection : Reduced excitation volume, high resolution,low background0.00.51.01.52.02.53.01020304050kcounts/slateral scan [mm]FWHM = 75 nmS/B 20Single DiD moleculein30 nm polystyrenewith70 nm aperture probevan Hulst, Veerman, Garcia-Parajo, Kuipers. J. Chem. Phys. 112, 7799 (2000)
15 Time-resolved near-field scanning tunneling microscopy Data from Kobus Kuipers and Niek van Hulst et al.Time-resolved near-field scanning tunneling microscopy120 fs pulsescoupledinto the PhCWTwo arms of the interferometerequal in length givestemporal overlap on the detector
16 Pulse caught in 1 position Data from Kobus Kuipers and Niek van Hulst et al.A light pulse caught in time and space40 nm highridge waveguide239.5 x 7.62 mmPulse envelope239.5 x 7.62 mmFixed time delayTE00 pulse, l =1300 nmduration : 120 fsPulse caught in 1 position
18 Nanophotonics – class schedule Class 1 - Resonances and refractive indexClass 2 - Nanoparticle scatteringClass 3 - Surface plasmon polaritonsClass 4 - Photonic crystalsClass 5 - Local density of optical statesClass 6 – Rare earth ions and quantum dotsClass 7 – MicrocavitiesClass 8 - Nanophotovoltaics Class 9 - MetamaterialsClass 10 – Near-field optics
19 Class schedule Class 1 - Resonances and refractive index Class 2 - Nanoparticle scatteringClass 3 - Surface plasmon polaritonsTour through Ornstein LabHomework assistanceClass 4 - Photonic crystalsClass 5 - Local density of optical statesExcursion to AMOLF-AmsterdamClass 6 – Rare earth ions and quantum dotsClass 7 – MicrocavitiesVisit to Nanoned conferenceClass 8 - Near field opticsClass 9 - NanophotovoltaicsExcursion to Philips Research- EindhovenClass 10 - MetamaterialsClass 11 – Near-field opticsNanophotonics summaryClosing symposium
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