Radiant energy – Inspection of solids or liquids by charged particles
Patent
1996-10-15
1998-08-18
Anderson, Bruce
Radiant energy
Inspection of solids or liquids by charged particles
250307, H01J 3700
Patent
active
057961026
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a measuring device for measuring the intensity and/or polarization of electromagnetic radiation, more in particular of light. Such measuring devices are known in many variants. In this connection, for instance, CCDs often used in video cameras may be thought of, for one thing, and microscopes, for another. There is, however, a need for a measuring device capable of measuring electromagnetic fields having a very low intensity. Moreover, the resolution of the measuring device should be less than the wavelength of the electromagnetic radiation. This enables details, such as geometric, electric and magnetic properties of a preparation, to be observed on a submicron or even a nanometer scale.
SUMMARY OF THE INVENTION
A measuring device according to this invention is characterized by providing the measuring device with a tunnel tip arranged facing a body at some distance, which tunnel tip at least partly consists of a semiconductor material and a control unit for obtaining information about the intensity and/or polarization of the radiation by means of a tunnel current, generated under the influence of the radiation in the tunnel tip, between the tunnel tip and the body and/or a surface photovoltage of the tunnel tip, generated under the influence of the radiation. Surprisingly, it has been found that radiation having only a power of 1 mW per mm.sup.2 at the place of incidence on the tunnel tip already results in a properly observable tunnel current and/or surface photovoltage. In this connection, for instance, a tunnel current on an order of magnitude of 500 pA and/or a surface photovoltage of 500 mV may be thought of.
According to a special embodiment the body, in use, comprises a preparation emitting radiation the intensity and/or polarization of which is determined by the measuring device. The radiation of the preparation detected by the measuring device may then provide relevant physical information about the preparation. More in particular, the above intensity and/or polarization of the radiation is determined for obtaining physical information from the preparation. The manner in which physical information from a preparation can be obtained from the tunnel current and/or surface photovoltage is known per se, is not relevant to the invention, and will therefore not be explained in detail.
According to a special embodiment the measuring device is further provided with a radiation source from which electromagnetic radiation is emitted in the direction of the tunnel tip for measuring the intensity and/or polarization of the radiation emitted. There can thus be obtained information about the radiation source itself.
According to an alternative embodiment of the measuring device the body, in use, comprises a preparation to be investigated, the measuring device further being provided with a radiation source with which electromagnetic radiation is emitted in the direction of the preparation. This radiation emitted will in general undergo an interaction with the preparation which, inter alia, depends on physical properties of the preparation, such as, for instance, the geometry of the preparation and magnetic and/or electric properties of the preparation. The changes experienced by the radiation, such as, for instance, a change of intensity and/or polarization, can be measured very accurately by the measuring device and are subsequently correlated with the above properties of the preparation.
According to a variant of the invention, the preparation is located between the tunnel tip and the radiation source so that the intensity and/or polarization of radiation transmitted by the preparation is measured for determining physical properties of the preparation.
According to another variant the radiation source and the tunnel tip are located on the same side of the preparation so that the intensity and/or polarization of radiation at least partly reflected by the preparation is measured for determining physical properties of the preparation. In particular, near-f
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Abraham Daniel Lee
Jansen Ronald
Prins Menno W. J.
van der Wielen Maurice C. M. M.
Van Kempen Herman
Anderson Bruce
Stichting Katholieke Universiteit Nijmegen
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