Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Patent
1996-12-12
1998-11-24
Allen, Stephon B.
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
2502013, 356359, 356376, G01N 2186, G01B 1124
Patent
active
058411496
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
The invention relates to a method according to claim 1 and a device according to claim 10.
For an operating surgeon, surgical microscopes serve the purpose of optical magnification of the site in which an operation is to be carried out. There are basically three different types of surgical microscopes, which are all intended within the meaning of the invention. These are,:
1. purely optical microscopes, that is to say microscopes which contain only optical and mechanical components, their output being directed to the eye;
2. purely video microscopes, that is to say microscopes which have optical, mechanical and optoelectronic components, the optical output of the microscope being directed exclusively to an optoelectronic image pick-up device (for example, a CCD), and the recorded image being further processed exclusively electronically and possibly represented via a display; and,
3. mixed video microscopes, which jointly contain structural features of the microscopes according to the first-named and second-named points, that is to say an output is directed both directly to a visual observer and to an image pick-up device.
In order to achieve on every occasion an optimum representation of the operation site, it must be possible always to position the visual field plane on a feature on the object to be treated. Since, because of the object structures represented, it is frequently impossible to achieve the focusing, it is necessary to provide a method and a device which render it possible to superimpose the visual field plane and the feature on the object and to determine the position of a feature on the object. Precise knowledge of the position of the feature of the object is important chiefly wherever specific, previously determined depths of incision or lengths of incision are to be observed, or wherever the operating surgeon has to keep an operating instrument to specific wavelengths in order to be able to carry out a precise operation. Chiefly in the case of operations on the brain and in microsurgery, this is frequently imperative in order to avoid injury to healthy tissue. In such operations, the result of the operation (whether a complete success or death) frequently depends on fractions of millimeters. Consequently, efforts have been made to determine the sites as accurately as possible and to permit dimensional measurements. Reference may be made to German Patent Application DE-A-4134481 for an example of such a known design.
In the abovementioned German Application, a surgical microscope is described in which the aim is to perform a precise determination of the location on an object being viewed of a specific point generated by means of a laser beam. Proposed for this purpose is a sighting method in which exact focusing of the microscope or matching of the visual field plane and the feature of the object is achieved by the "bringing into coincidence" of visual field marks. Not until after this sighting method is the exact position of the marked feature on the object determined from the optical system data. In accordance with the this technique, these system data are intended to be determined by suitable position detectors or angle detectors on drive units for the respective adjustment of adjustable optical components.
The determination of the position of a feature on an object is thus performed indirectly after the "bringing into coincidence" by eye, or via an image-processing device by measuring paths, angles etc. via sensors which are connected to adjusting devices for optical components and via subsequent calculation of the corresponding data.
This is unsatisfactory and insufficient in many cases. Even the "bringing into coincidence" is affected by errors. A further reason for inaccuracies resides in the fact that both the optomechanical components and the mechanical/electrical components (sensors) have tolerances which can vary nonlinearly. The result of this is the risk that position data determined in such a way are incorrect. In the extreme case, such incorrect data could lead to
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patent: 5042949 (1991-08-01), Greenberg et al.
patent: 5359417 (1994-10-01), Muller et al.
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Braunecker Bernhard
Mayer Thomas
Rogers John Rice
Spink Roger
Zimmer Klaus-Peter
Allen Stephon B.
Leica Mikroskopie Systeme AG
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