Accurate read-out over 6 m

PRm(|b Force microscope for non-conducting surfaces A force microscope that enables noncontact observation of surfaces has been developed by Associate Professor N. Umeda of the Tokyo University of Agriculture and Technology. The microscope uses a pair of different wavelength laser beams to observe insulating materials that do not conduct electricity and whose observation is difficult with a conventional scanning tunnelling microscope (STM). With the microscope, the target specimen is approached by a very sharp tip and the attraction force between the tip and the specimen is used. Vibrating the tip causes the vibration mode to change according to the magnitude of the attraction force. Moving the specimen with respect to the tip changes the attraction force depending on the specimen's surface unevenness, so the vibration mode changes. This change is sensed for deducing the specimen's surface unevenness. A laser beam (wavelength 780 nm) is directed against the base of a cantilever supporting the tip to generate a photothermal oscillation. The lever has a reflection mirror that is irradiated with a separate laser beam (wavelength 633 nm) and its reflected light is sensed: the tip's vibration changes are sensed from the changes in the reflected light's vibration width. The specimen is moved in the tip's direction so that Jthe reflected light has a constant, fixed vibration width, by which the shape is deduced. Similar microscopes are available, but they vibrate the tip electrically, so the tip is charged and the attraction generated by this charge may be measured. This microscope's resolution is presently 10 nm, inferior to the 0.1 nm resolution of conventional STMs; but since these STMs use the tunnel effect, it is necessary to coat the specimen with a thin metal film when making observations of insulating specimens, making it difficult to define surface constructions. The new microscope enables observations of conductive and insulating materials. Associate Professor N. Umeda has conducted observations of optical discs and discovered 1.6/~m wide, 0.1 /~m deep grooves. The future objective is to further improve the

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optical system to enhance the microscope's resolution to 1 nm. Tokyo University of Agriculture and Technology, Faculty of Technology 24-16, Nakamachi 2chome, Koganei City, Tokyo, Japan

Accurate read-out over 6 m Thompson Machine Tool Engineers, Heidenhain's Digital Readout agents have recently completed an unusual contract for David Brown Gears. David Brown Gears required a new Digital Readout for one of their machine tools used in the production of large gear boxes for, amongst other things, Royal Naval warships. However, this particular machine has

axis lengths that measure 6 m x 4mx2m. Although few manufacturers can provide a transducer to cope with the scale lengths required for such a machine, the Heidenhain LB 326 transducer, is capable of measuring up to 30 m and is guaranteed to an accuracy of _+5 #m per metre. David Brown Gears, concerned that the transducer might not retain its accuracy over such large measurements, asked Thompsons to prove the accuracy of the linear scales. Having retrofitted a VRZ 760 Digital Readout and the LB 326 transducers to the machine tool, the accuracy was measured using a laser. The LB 326 was found to be accurate within _+3/~m over 6 m. Heidenhain (GB) Ltd, 200 London Road, Burgess Hill, West Sussex RH15 9RD, UK

Atomic force microscope for 3-D resolution Available as an option to be linked with the NanoScope II scanning probe microscope system, the NanoScope AFM from Digital Instruments is an atomic force microscope. The microscope provides subnanometre three-dimensional resolution and may be used directly on uncoated insulating as well as conducting surfaces, either in air or in liquid. These features allow the production of images and measurements that are unobtainable with any other device. The NanoScope AFM option may be added to the NanoScope II system without factory assistance. It includes a base with specialized electronics, an optical feedback assembly, a 0.5/~m x 0.5/~m scan head, and special control software. The AFM may be configured with optional scanners to produce scans of areas up to 75/~m x 75 #m. To simplify use, all functions of the atomic force microscope option use the same user interface as the NanoScope II STM, and its data is processed using the existing STM image generation and analysis tools. The design of the microscope coupled with the high performance STM feedback system make possible operation with very small forces exerted on a sample. The microscope can be used on polymers, ceramics, oxide layers, dielectrics, glasses, crystal structures,

and biological materials including whole cells. Digital Instruments Inc, 6780 Cortona Drive, Santa Barbara, California 93117, USA

The NanoScope AFM from Digital Instruments gives sub-nanometre 3-D resolution

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