Frans B. Segerink

Compact stand-alone atomic force microscope

A stand-alone atomic force microscope (AFM) featuring large scan, friction measurement, atomic resolution, and liquid operation, has been developed. Cantilever displacements are measured using the optical beam deflection method. The laser diode and focusing lens are positioned inside the piezo tube and the cantilever at the end of the piezo tube. Because the laser beam stays oxadn the cantilever during scanning, the scan range is solely determined by the characteristics of the piezo tube. In our case 30 x 30 x 9.5 mum3 (xyz). The optical beam deflection detection method allows simultaneous measurement of height displacements and torsion (induced by lateral forces) of the cantilever. AFM images of dried lymphocytes reveal features in the torsion images, which are oxadnly faintly visible in the normal height images. A new way of detecting the nonlinear behavior of the piezo tube is described. With this information the piezo scan is linearized. The nonlinearity in a 30-mum scan is reduced from 40% to about 1%, as is illustrated with images of a compact disk. The stand-alone AFM can be combined with a (confocal) inverted microscope, yielding a versatile setup for biological applications.

Large area photonic crystal slabs for visible light with waveguiding defect structures: Fabrication with focused ion beam assisted laser interference lithography

Extended photonic crystal slabs with light-guiding defects have been created by a combination of laser interference lithography (LIL) and local focused ion beam (FIB) assisted deposition. Large area, highly uniform photonic crystal slabs for visible light are thus made possible. The Figure shows a freestanding Si3N4-air photonic crystal with a light- guiding defect line running along the center of the slab (total length = 1 mm).

Atomic force microscope with integrated optical microscope for biological applications

Since atomic force microscopy (AFM) is capable of imaging nonconducting surfaces, the technique holds great promises for high‐resolution imaging of biological specimens. A disadvantage of most AFMs is the fact that the relatively large sample surface has to be scanned multiple times to pinpoint a specific biological object of interest. Here an AFM is presented which has an incorporated inverted optical microscope. The optical image from the optical microscope is not obscured by the cantilever. Using a XY stage to move the sample, an object is selected with the optical microscope and an AFM image of the selected object can be obtained. AFM images of chromosomes and K562 cells show the potential of the microscope. The microscope further enables a direct comparison between optically observed features and topological information obtained from AFM images.

Operation of a scanning near-field optical microscope in reflection in combination with a scanning force microscope

Images obtained with a scanning near field optical microscope (SNOM) operating in reflection are presented. We have obtained the first results with a SiN tip as optical probe. The instrument is simultaneously operated as a scanning force microscope (SFM). Moreover, the instrument incorporates an inverted light microscope (LM) for preselection of a scan area. The SiN probe is operated in the contact regime causing a highly improved lateral resolution in the optical image compared to an alternative set-up using a fiber probe, which is also presented. The combined microscope is operated either in open loop or as a force regulated SNOM. Near field optical images can be directly compared with the topography displayed in the simultaneously recorded SFM image.

Atomic force microscope featuring an integrated optical microscope

The atomic force microscope (AFM) is used to image the surface of both conductors and nonconductors. Biological specimens constitute a large group of nonconductors. A disadvantage of most AFMs is the fact that relatively large areas of the sample surface have to be scanned to pinpoint a biological specimen (e.g. cell, chromosome) of interest. The AFM presented here features an incorporated optical microscope. Using an XY- stage to move the sample, an object is selected with the aid of the optical microscope and a high-resolution image of the object can be obtained using the AFM. Results oxadn chromosomes and cells demonstrate the potential of this instrument. The microscope further enables a direct comparison between optically observed features and topological information obtained from AFM images.