Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1995-12-18
1998-06-09
Rosenberger, Richard A.
Optics: measuring and testing
By polarized light examination
With light attenuation
356446, G02B 2100
Patent
active
057643644
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
Different devices are used for magnifying and examining objects and the surfaces of objects in the subminiature size range. For example, light microscopes, electron microscopes and scanning electron microscopes, etc. are employed for this purpose.
These instruments are sufficiently familiar and need not be individually listed here.
However, conventional light microscopes without additional electronic equipment are out of the question when it comes to analysing the recorded image and developing statements concerning it.
The electronic equipment required for this purpose, usually a CCD camera, is relatively complex and the analysis logic, i.e. the necessary computer and the program, are seldom set up in such a way that reproducible results can be obtained.
Devices with an analytical function, where the image itself is mostly generated electronically, are always highly complex, very sophisticated and, above all, very expensive.
PROBLEM
The problems arising during magnification and analysis are numerous and depend on the method used.
In the case of light microscopy, the most commonly used method, the recorded image can, as described above, only be analysed with the aid of an add-on CCD camera and subsequent image processing.
Another problem is the very small solid angle at which detection takes place with this system and others. The same applies to all other systems equipped with lenses or lens-like objectives.
In other magnification methods, the objects have to be specially prepared, e.g. by vacuum evaporation of a metal film. This not only involves a major effort, but also excludes various objects from preparation. Moreover, the area which can be used for detection is again considerably restricted.
Other scanning imaging methods are also only possible if the specimens are prepared or consist of a suitable material.
Up to now, it has only been possible to examine organic, elastic or insulating objects by means of light microscopy.
PROBLEM SOLUTION
The aim now is to develop a method with which all kinds of objects can be magnified in a contactless manner and without preparation and which provides a wealth of information for analysis.
It should also be possible, with certain restrictions, to magnify objects located close below a water surface and to perform a corresponding analysis.
LASER MICROSCOPY
The method of laser microscopy according to the invention, using one or also two hemispherical bowls to provide surfaces for analysis, offers an ideal solution to the problem.
A laser beam is set to the necessary beam width by means of an expanding lens system and then brought into focus with the minimum possible diameter using a lens of short focal length.
As the diameter is limited by the wavelength of the laser light, on the one hand, and also determined by the parameters of beam diameter upstream of the lens and focal length of the lens, on the other hand, beam diameters of approx. 1000 nm, equivalent to 1 .mu.m, at the focus can be achieved with lasers emitting light in the visible range.
However, this alone is not sufficient for achieving magnification with adequate resolution, particularly when evaluating and analysing organic objects, e.g. when analysing erythrocytes. In such cases, the analysis of additional information is indispensable.
In order to do this, it is necessary to detect all the light phenomena occurring upon irradiation of the object with the highly focused laser beam at the largest possible solid angle and to penetrate deep into the surface structure of the particle to be examined.
Thus, the focused beam is moved over the specimen slide by means of mechanical devices or optoelectrical systems, the object being identified and preliminarily analysed in this way. The step size should not exceed the beam diameter in this context.
A hemisphere is positioned around the focal point above the specimen slide and, in the case of transparent specimen slides, also below the specimen slide, the central point(s) of this/these hemisphere(s) being located in the focal point of the laser b
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patent: 4583858 (1986-04-01), Lebling et al.
patent: 4583861 (1986-04-01), Yamaji et al.
patent: 4954722 (1990-09-01), Fine et al.
patent: 4973164 (1990-11-01), Weber et al.
patent: 4991971 (1991-02-01), Geary et al.
IMAB Stiftung
Rosenberger Richard A.
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