Optics: measuring and testing – Lens or reflective image former testing
Reexamination Certificate
2001-09-05
2004-12-21
Toatley, Jr., Gregory J. (Department: 2877)
Optics: measuring and testing
Lens or reflective image former testing
C356S243100, C600S102000
Reexamination Certificate
active
06833912
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an apparatus for testing the state of the optical system of an endoscope, comprising a first supporting device for the endoscope, a test pattern and a second supporting device for the test pattern.
Such an apparatus is known from U.S. Pat. No. 5,820,547.
An endoscope is particularly used in minimal-invasive surgery as a viewing instrument in order to be able to control from the outside an operation performed through a small incision in the body.
Endoscopes are, however, not only used in medical applications, but also in technical applications, e.g. for observing cavities in machines, combustion chambers of engines and the like, which cannot be observed with the naked eye.
The main element of an endoscope is its optical system. The optical system of an endoscope consists of rod lenses or glass fibers and objective lenses and eyepiece lenses. An endoscope can, additionally, comprise a light conducting system for illuminating the area to be observed. There is a plurality of endoscope types, which differ from each other by their endoscope-specific basic data. Such endoscope-specific basic data are e.g. the angle of view or the viewing direction and the field of view angle of an endoscope. Furthermore, endoscopes can also differ by the magnification ratio of the optical imaging and, moreover, by their geometrical dimensions.
With reference to the viewing direction of the endoscope, there are endoscopes with a straight forward viewing direction, i.e. the viewing direction of the endoscope forms an angle of 0° with the longitudinal axis of the shaft of the endoscope. There are also endoscopes with an oblique view optic, i.e. the viewing direction of the endoscope runs then in an oblique fashion with respect to the longitudinal axis of the shaft in a predetermined angle.
The optical system of an endoscope can be impaired by external influences in the course of time, so that the quality of the image transmission by the optical system is deteriorated and/or deviations of the nominal values of the basic data occur. Medical endoscopes in particular are sterilized after each use, the endoscopes being exposed to hot vapor under high pressure in an autoclave to this end. But also mechanical influences like impacts onto the shaft, e.g. when the endoscope falls down, may impair the optical system of the endoscope.
It is, thus, necessary to revise and/or to repair the endoscope after some time. There is the problem herewith that, if the reparation is improperly performed by not authorized workshops, the initial original state and/or quality standard of the optic is not achieved. For the manufacturer of the endoscope, there is, thus, the need, due to the requirements of customer service, to be able to check the state of the endoscopes with reference to their basic data in a quick and simple manner at least with reference to quality within acceptable tolerances. This includes, besides the qualitative check of the viewing direction and of the field of view angle, e.g. a qualitative estimation of the sharpness and/or of the contrast of the image transmission in the image center and/or in the border region of the image and, if necessary, a check of the state of the light conducting system, should the endoscope be equipped with such a system.
In U.S. Pat. No. 5,820,547 mentioned above, a portable apparatus that is simple in design for testing the state of the optical system of an endoscope is described, which comprises a supporting device for the endoscope to be examined and a test pattern and a supporting device for the test pattern. The supporting device for the endoscope consists of a cylindrical adapter comprising an axial central through bore, into which the distal end portion of the endoscope is inserted. For endoscopes with an oblique view optic, two lateral through bores that run obliquely to the longitudinal axis of the tube are provided, into which these endoscopes can be suitably inserted. The test pattern is fixed at a supporting device, which is firmly connected with the supporting device for the endoscope. The test pattern consists of an arrangement of line patterns of different line thickness, of a line grid and of an arrangement of concentric circles.
While this known apparatus is very simple in design, it has, however, the disadvantage not to be universally adapted to a plurality of different optical systems of endoscopes. For example, the distance between the test pattern and the distal end of the endoscope is firmly predetermined. As the distance between the test pattern and the distal end of the endoscope is firmly predetermined, in an observation of the test pattern through the endoscope, in dependency of the field of view angle, circle sectors of different sizes are seen, respectively, what makes the evaluation of the test more difficult for a user who is not trained technically. Moreover, only endoscope optics with three different viewing directions that are firmly predetermined on the adapter can be tested. The accuracy of the test, apart from that, is low. A check of the function of the light conducting system of the endoscope exceeding this test is not possible.
On the other hand, from U.S. Pat. No. 5,841,525, an apparatus for testing the state of the optical system of an endoscope is known, which is, however, very expensive and which requires periphery equipment like image processing equipment and a computer station for the evaluation of the test. This apparatus is, thus, not transportable and is not suited for performing a quick test in a different location at a customer's.
Further, U.S. Pat. No. 4,613,232 discloses a portable measuring device for testing optical systems of an endoscope consisting of a base plate, a rail with a longitudinally extending V groove for receiving a portion of the endoscope being mounted to extend parallel to the plate on a carriage movable at right angles to the groove. The device includes a vertical shaft mounted on the plate and terminating at one end in a conical point, and the shaft carries at least one extension arm which is mounted to pivot in a plane parallel to the base plate. Each arm adjustably supports a measuring disk which can have its height above the plate changed or its distance from the shaft changed. This known apparatus comprises a measuring disk having known scales and the like, whereby it is possible to exactly measure the angular field, the sight line, the diameter of the exit pupil, the subject field illumination, the depth of field, the focusing range, the visual lens magnification, the distortion and the resolution of the optical system of the endoscope being tested.
The invention has, thus, the object to improve an apparatus of the type mentioned at the outset in such a way that it allows a quick assessment of the quality and a check of the basic data and/or the image quality without time-intensive training of the user.
SUMMARY OF THE INVENTION
According to the invention, the object underlying the present invention is achieved with an apparatus for testing the state of an optical system of an endoscope having a viewing direction and a field of view angle, said apparatus comprising a first supporting device for said endoscope, a test pattern and a second supporting device for said test pattern, wherein said test pattern comprises a pattern, which allows a common check of an actual viewing direction and of an actual field of view angle of said optical system of said endoscope within tolerance values of a nominal value of said viewing direction and a nominal value of said field of view angle.
With this embodiment of the test pattern, the viewing direction and the field of view angle can be checked together in a quick and simple way, i.e. it is possible to judge in a quick and simple manner whether the endoscope tested is defective or in an acceptable state within the tolerances predetermined by the pattern. With the apparatus according to the invention, tests of endoscopes can be carried out by service employees without previous time-intensive training in a locati
Lei Fang
Preuss Volker
Rudischhauser Jürgen
Weitzel Jörg
Karl Storz GmbH & Co. KG
Punnoose Roy M.
St. Onge Steward Johnston & Reens LLC
Toatley , Jr. Gregory J.
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