摘要:

Methods were developed to characterize tapered capillaries as x‐ray concentrators capable of forming spots of intense x‐ray radiation with micrometer diameters. These tapered capillaries, with somewhat controlled tapers, were produced using a gravity‐based capillary puller. A device was constructed to microscopically inspect these capillaries along two orthogonal axes in order to accurately measure the tapering and bending. Both monochromatic and white hard x rays were concentrated with a variety of tapered capillaries, and the subsequent gains in intensity (flux/area) ranging from 14 to 35 are reported. Using these unique x‐ray concentrators, a simple high‐powered x‐ray fluorescence microscope was constructed and tested. We also found that hard x‐ray beams could be successfully steered by bending the capillary tip with radii as small as 5 m. In addition, preliminary ray‐tracing results obtained from a two‐dimensional ray‐tracing program are described.  

ISSN:0034-6748    

DOI:10.1063/1.1144375

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A simple validinsiturelative intensity calibration technique for soft x‐ray film is described. This is based on film exposure measurements of the uniform line‐shaped distributed soft x‐ray monochromatic irradiation transmitted through a step‐wedge absorption filter. Fitting the calibration data with Henke’s semiempirical equation for thick‐emulsion film, the characteristic curves for Shanghai 5F soft x‐ray film without supercoat (SIOM‐5FW) have been obtained in the wavelength region from 50 to 80 A˚.

ISSN:0034-6748    

DOI:10.1063/1.1144376

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

The design of a sectional piezoactuator is described, and the principle of operation of a tunnel junction digital stabilization system is given. The total settling time of the system while the least significant section is in operation is 1 &mgr;s at 0.01‐nm resolution (in theZdirection). The application of the sectional piezoactuator permitted an increase in operating frequency and also eliminated errors caused by the piezoceramics hysteresis. Introduction of a fast‐acting ALU as a digital accumulator of regulation errors made it possible to achieve high stability of the loop operation at high operating frequencies. The system suggested can adapt the speed of the loop operation depending on the relief steepness values. The blunting of the tip and sample destruction is avoided because there is a mechanism of smooth approach of the tip to the nominal scanning height.

ISSN:0034-6748    

DOI:10.1063/1.1144377

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

We present a new scanning force microscope (SFM) design with a compact fiber‐optic interferometric detection system that provides very high resolution for surface force measurements. The mechanical conception of the instrument includes the implementation of piezoelectric actuators for the interferometer alignment. The result of this approach is a high performance SFM with both easy handling and high versatility.

ISSN:0034-6748    

DOI:10.1063/1.1144477

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

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 on the cantilever during scanning, the scan range is solely determined by the characteristics of the piezo tube. In our case 30×30×9.5 &mgr;m3(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 only 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‐&mgr;m 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.

ISSN:0034-6748    

DOI:10.1063/1.1144378

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A new detection scheme of resonance and antiresonance frequencies of piezoelectric resonators by utilizing an inductive pulse detection method is developed. This method is applied to a disk piezoelectric resonator and advantages over the conventional ones are noticed.  

ISSN:0034-6748    

DOI:10.1063/1.1144379

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

A computer model for correcting the spatial distortion in images acquired with a high‐speed image converter camera is described. The distortion is caused by electrodynamic interaction of the photoelectric currents within the image converter camera, and appears as an inward bowing of the individual high‐speed images. The model is implemented in a postprocessing algorithm, using the pixel values in an image to infer the interacting photoelectric currents and thus allow computation of the distorting force acting on each pixel. The force is converted into a corrective translation using three system parameters which are determined by analyzing images for which the predistortion geometry is known. Measurements on a variety of test images show the model removes up to 85% of the image converter distortion.

ISSN:0034-6748    

DOI:10.1063/1.1144380

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

In the present study, a comprehensive description and a complete process for designing a high‐resolution low‐voltage scanning electron microscope with a field emission gun have been discussed, including the design of two types of magnetic immersion lenses optimized for low‐voltage operation, the evaluation of their resolution, the design of the magnetic lens/secondary electron collector system, the calculation of three‐dimensional trajectories for both secondary electrons and backscattered electrons, and the estimate of their collection efficiency. The computed results and the primary experiments indicate the possibility of achieving nanometer resolution, which basically approaches the electron optical predictable probe size for the low‐voltage scanning electron microscope.

ISSN:0034-6748    

DOI:10.1063/1.1144381

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

The physical architecture and the performance of a quantitative three‐dimensional atom probe recently constructed are described. The development of such an instrument relies on the design of a multi‐impact position sensitive detector. The multidetection system that we have developed is based on the use of a 10×10 anode array placed behind a two microchannel plate assembly in a chevron arrangement. The spread of charge between the microchannel plate and the multianode is used to derive the position of ion striking the detector. Spatial coordinates can be calculated for multiple and simultaneous time‐of‐flight events. The procedure used for the derivation of ion positions from charge measurements is given. Specific experiments were carried out in order to determine the intrinsic spatial resolution of the multidetector. Three‐dimensional reconstruction of two‐phase materials are provided and illustrate the performance of this new apparatus. The reconstructed images demonstrate that atoms are positioned with a precision of a few tenths of a nanometer. The mass resolutionM/&Dgr;M(FWHM) of the apparatus is close to 200.

ISSN:0034-6748    

DOI:10.1063/1.1144382

出版商:AIP    

年代:1993

数据来源: AIP

摘要:

We have built a low temperature scanning force microscope which is able to measure contact and noncontact forces using the dc modes of force microscopy. We demonstrate the capabilities of our instrument on a magneto‐optical disk at room temperature and at 77 K. Using a ferromagnetic thin film tip, the topography and the micromagnetic stray field of the sample is measured using the dc modes of force microscopy. The topographic and magnetic data are precisely correlated. The circular bit structure and the natural domain structure between the homogeneously magnetized bits is clearly visible. A lateral resolution below 100 nm and a force resolution of 10−12N is reproducibly achieved.

ISSN:0034-6748    

DOI:10.1063/1.1144383

出版商:AIP    

年代:1993

数据来源: AIP