A design of reflection scanning near-field optical microscope and its application to AlGaAs/GaAs heterostructures

Guttroff, G.; Keto, J. M.; Shih, C. K.; Anselm, A. I.; Streetman, B. G.

doi:10.1063/1.115749

Cited by 11 publications

(7 citation statements)

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“…Other feedback schemes have successfully exploited the interferences experienced by the light exiting the NSOM tip aperture and that reflected from the sample surface to control the tip-sample distance using straight NSOM probes. [14][15][16] Here we extend these previous results to show that both small and large topography changes can be accurately imaged using a cantilevered NSOM probe employing an interferometric optical feedback method. The detection scheme incorporates a long working distance microscope to monitor the interferences between light exiting the NSOM tip aperture and that reflecting off the sample surface.…”

Section: Introductionsupporting

confidence: 74%

“…Figure B shows the optical approach curve measured simultaneously with the normal force curve seen in Figure A. Unlike the force approach curve which only senses the sample when the tip is nanometers from the surface, the optical approach curve begins sensing the sample while the tip is several micrometers away. ,− ,− This feature provides a mechanism for tip feedback that inherently has more flexibility in the choice of tip−sample separation.…”

Section: Resultsmentioning

confidence: 99%

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Noncontact Near-Field Scanning Optical Microscopy Imaging Using an Interferometric Optical Feedback Mechanism

1999

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An interferometric optical feedback mechanism is explored for tip−sample distance control in near-field scanning optical microscopy. An optical signal, based on the interference between the light exiting the tip aperture and that reflecting off the sample surface, is used to implement a feedback scheme to regulate tip−sample distance. The noncontact nature of this feedback mechanism may provide greater flexibility in imaging soft or fragile samples. To characterize the performance of the optical feedback mechanism, images are analyzed of a calibration standard, fluorescently doped lipid monolayers, latex spheres, and fixed cells. Images taken of these samples using optical feedback and the standard tapping-mode feedback are comparable in quality. These samples also demonstrate the ability of optical feedback to follow both large and small height changes and accurately reflect the sample topography. In a nonscanning mode, the interferometric signal can be used to noninvasively probe small dynamic height changes of a sample with nanometric spatial resolution. Using a piezo ceramic bimorph to simulate sample movement, we show that nanometric height changes can be detected with millisecond time resolution. This may provide a unique way to probe protein conformational changes free of tip−sample interactions.

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Section: Introductionsupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Noncontact Near-Field Scanning Optical Microscopy Imaging Using an Interferometric Optical Feedback Mechanism

1999

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“…The optical feedback signal is generated by monitoring the excitation light exiting the NSOM probe in an arrangement similar to that of previous reports (Fischer et al ., 1988; Courjon et al ., 1990; Cline & Isaacson, 1995; Guttroff et al ., 1996). The signal is collected from the side with a long‐working‐distance microscope (Infinity Photo‐Optical Company, Boulder, CO), detected with a photomultiplier tube (R1527, Hamamatsu, Bridgewater, NJ), and then sent to a lock‐in amplifier (Model SR830, Stanford Research Systems, Sunnyvale, CA) referenced to the bimorph modulation signal used to oscillate the NSOM probe.…”

Section: Methodsmentioning

confidence: 99%

Near‐field scanning optical microscopy studies of l‐α‐dipalmitoylphosphatidylcholine monolayers at the air–liquid interface

Shiku

Dunn

1999

Journal of Microscopy

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The phase structure in l‐α‐dipalmitoylphosphatidylcholine–2.0 mol% fluorescent 1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethylindocarbocyanine perchlorate Langmuir monolayers dispersed on a 2 m sucrose solution subphase is studied with near‐field scanning optical microscopy (NSOM). Cantilevered NSOM probes operating in a tapping‐mode feedback or an optical interferometric feedback mode are capable of tracking the air–sucrose solution interface. At the micrometre scale, the NSOM fluorescence images reveal lipid domain features similar to those observed previously in supported Langmuir–Blodgett (LB) monolayers. At the submicrometre scale, the small nanometric lipid islands seen in LB films are not observed at the air–sucrose interface. This supports a mechanism in which domain formation in LB films can be induced by means of the transfer process onto the solid support. Progress towards extending these studies to films at the air–water interface using the optical interferometric feedback method is also discussed.

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“…Combining the merits of conventional far-field optical microscopy and its scanning probe counterpart, SNOM is not only capable of imaging a variety of fine structures, showing great application potentials in material science biology [2] and semiconductor technology [3], but also is able to realize local spectrum [4], fluorescence sensing [5] and single atom/molecule detection and identification [6], when incorporating spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Research on the near-field distribution of nanometric apertures: fiber optic probes and the influence of parameters of metal-coated probes

Liu

Wang

2000

SPIE Proceedings

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In this paper near-field distributions of nanometric apertures, the uncoated and metal-coated fiber-optic probes used in near-field scanning optical microscope are characterized by the method of fmite-difference time-domain. Moreover, to give a clear view of the influence of parameters, say, the taper angle (a), the aperture diameter (d), the refractive index of the fiber-optic (n) and the sample (ns), the tip-sample separation (z), on the throughput of metal-coated fiber-optic probes, we investigated it in detail.The result demonstrates that the polarized incident wave becomes depolarized on emitting out of the aperture as well as two kinds ofprobes. It implies that two electric-field components with the polarization direction perpendicular to that of the incident wave are produced. We discussed and analyzed the relationship between the near-field distribution and depolarization in detail. In addition, the impact of aperture shape on the near-field distribution is also considered. The field distributions of the two kinds of probes reveal that both the near-field distribution and the field distributed inside the probe re quite different from one another because ofthe distinction ofthe wave-guide structures between the two kinds of probes.What is more, we analyze quantitatively the effects ofthe metal-coated probes' parameters variation on the probe throughput.The results are that the throughput increases faster than exponentially with the increase of a, d and n. In addition, the sample existing near to the probe will change the near-field distribution of the probe. Namely, the smaller the tip-sample separation is the more strong the interaction of the tip and the sample is. Finally, the increase of the refractive index of the sample will enhance the tip-sample interaction. Accordingly, we propose that the probe throughput will be improved if the probe is immersed into a kind of high refractive-index liquid.

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A design of reflection scanning near-field optical microscope and its application to AlGaAs/GaAs heterostructures

Cited by 11 publications

References 0 publications

Noncontact Near-Field Scanning Optical Microscopy Imaging Using an Interferometric Optical Feedback Mechanism

Noncontact Near-Field Scanning Optical Microscopy Imaging Using an Interferometric Optical Feedback Mechanism

Near‐field scanning optical microscopy studies of l‐α‐dipalmitoylphosphatidylcholine monolayers at the air–liquid interface

Research on the near-field distribution of nanometric apertures: fiber optic probes and the influence of parameters of metal-coated probes

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